WORKING MACHINE

Abstract

 A working machine in which a boom (5) is fixed vertically pivotably to a vehicle body (4), to which boom an arm (7) is fixed vertically pivotably with a bucket (10) fixed vertically pivotably to the arm, the boom, arm and bucket being driven by a boom cylinder (6), an arm cylinder (8) and a bucket cylinder (11) repectively. A vibration generator (13) is fixed to the arm, and a rolling-compaction member (19), a chisel (58) or a pile driver to the vibration generator interchangeably. A float valve (84) is provided which allows an expansion chamber to communicate with a contraction chamber of at least one of the boom cylinder, arm cylinder and bucket cylinder, and establishes or cuts off communication between them and a tank. The float valve is opened when a rolling-compaction operation is carried out, and closed when a breaking operation and a pipe driving operation are carried out.

Description

TECHNICAL FIELD

[0001] The present invention relates to a working machine that is employed in carrying out a ramming operation, a crushing operation and so forth, with the use of a vibration generation unit which is attached to the arm of a power shovel or the like.

BACKGROUND ART

[0002] In a construction work where a piping in a water supply or a sewerage system is to be buried in the ground, it is known that first an asphalt or concrete layer on an asphalt or concrete road is crushed and broken, then a groove is excavated there in the ground, the piping is then laid in the groove, which will then be re-filled with an earth and sand, which, after subjected to a ramming operation, will then have an asphalt or a concrete layer laid thereon.

[0003] It has been known that a working machine that is used for such a construction work as described above may include a power shovel in which a boom is mounted on a vehicle body equipped with a traveling body so as to be capable of being swung upwards and downwards, an arm is coupled to such a boom so as to be swung upwards and downwards and a bucket is coupled to such an arm to be capable of being swung up and down.

[0004] It has been found that while such a power shovel is found to be suitable for an operation in which a groove is excavated and re-filled with an earth and sand, it is inefficient to carry out a crushing operation in which a concrete layer or the like is crushed and broken.

[0005] Accordingly, an improved and hydraulically operated crushing machine (i. e., a breaker) has been proposed that has a construction in which a vibration generating unit is attached to the arm of a power shovel and is provided with a chisel member, and it has been proposed to carry out a crushing operation by means of such a hydraulically operated crushing machine. However, it has been found that such a hydraulically operated crushing machine with an ability to strike a chisel member with a piston of the vibration generating unit to induce such a vibration thereof had to be dedicated solely to a crushing operation and could not be utilized in a ramming operation by the use of, for example, a ramming plate.

[0006] Also, while a bucket in such a power shovel as mentioned above may be used to carry out a ramming operation, it has been found that the bucket has then to be swung up and down upon swinging each of a boom and an arm associated therewith upwards and downwards. Not only is such a combined operation rendered extremely complicated with the result that the bucket so acted on will be slowed in its swinging movements both upwards and downwards and can allow only a poor ramming operating efficiency to ensue, but this may result in a poor operability in controlling the posture of a ramming plate as described above with such an arm and such a boom of the power shovel.

[0007] Then, it is conceivable, as disclosed, for example, in Japanese Examined Utility Model Publication No. Hei 6-21923, to attach to the arm of the power shovel a hydraulically operated ramming machine that is so designed that a piston equipped at its forward end with a ramming plate may be capable of being hydraulically reciprocated, to ram an earth and sand with such a ramming plate.

[0008] However, in carrying out a ramming operation by means of a hydraulically operated ramming machine as described above, it is required to push the ramming plate of such a hydraulically operated ramming machine against the ground by swinging both the boom and the arm downwards by means of a boom cylinder assembly and an arm cylinder assembly, respectively. Thus, since then in such a state a ramming has to be effected only with a force whereby a piston as described above is hydraulically pushed downwards, it has been found that a sufficiently large ramming force cannot be obtained. In addition, since such a hydraulically operated ramming machine is inherently constructed to directly attach the ramming plate at the forward end portion of the piston which is vertically reciprocated under a changing hydraulic pressure, it is exclusively dedicated to a ramming operation and cannot be utilized, for example, for a crushing operation using a chisel member, and so forth.

[0009] Accordingly, with the above described problems in the prior art taken into account, it is an object of the present invention to provide a working machine which is capable of obtaining a sufficiently large ramming force for any ramming operation, has an enhanced ramming operation efficiency and is designed to be capable of being readily switched to a crushing operation or a pile driving operation.

SUMMARY OF THE INVENTION

[0010] In order to achieve the above described problem, there is provided a working machine which comprises: a vehicle body; a boom mounted on the said vehicle body so that it may be capable of being swung upwards and downwards; an arm coupled to the said boom so that it may be capable of being swung upwards and downwards; a bucket coupled to the said arm so that it may be capable of being swung up and down in a rotary oscillation; a system for hydraulically driving the said boom, the said arm and the said bucket by means of a boom cylinder assembly, an arm cylinder assembly and a bucket cylinder assembly, respectively, each of the said assemblies having an extending chamber and a retracting chamber which are adapted to be each in a fluid communication with a tank in the said hydraulic system; a vibration generating unit coupled to the said arm and being provided with a ramming member, a chisel member and a pile driving member so that the said members may be exchangeably attached to the said vibration generation unit; and a floating valve means in the said hydraulic system for establishing and blocking the said fluid communication, the said floating valve means being adapted to be opened when a ramming operation is to be performed and adapted to be closed when either of a crushing operation and a pile driving operation is to be performed.

[0011] According to the above described construction, it can be seen that in performing a ramming operation, the weights of a body portion of the said vibration generation unit and a piston rod of the said bucket cylinder assembly; the weights of the body portion of the said vibration generation unit, the piston rod of the said bucket cylinder assembly and the said arm; or the weights of the body portion of the said vibration generating unit, the piston rod of the said bucket cylinder assembly, the said arm and the said boom, may be utilized as constituting a ramming force. This will enable an increased overall ramming force to be produced in a ramming operation.

[0012] Also, according to the above described construction, it will be seen that a ramming operation can be performed with such a ramming member attached to the body portion of the said vibration generating unit, a crushing operation can be performed with such a chisel member attached to said vibration generating unit, and a pile driving operation can be performed with such a pile driving member attached to the said vibration generating unit. This will allow a single working machine to be sufficient to carry out all of a ramming operation, a crushing operation and a pile driving operation, and will permit any such operation to be interchangeably altered with ease among them.

[0013] Also, in a construction as mentioned above, the said bucket cylinder assembly may be coupled to the said arm and may have the said piston rod of its own coupled via a link mechanism to the said bucket; the said link mechanism may comprise a plurality of links which can act to couple the body of the said vibration generating unit to the said arm; the body portion of the said vibration generating unit may be mounted inside of the said arm; the said bucket may be coupled to the said arm via the said body portion of the vibration generating unit; and the body portion of the said vibration generating unit may be coupled to a forward end portion of the said arm, in place of the said bucket.

[0014] Also, in a construction as described above, it is desirable that the said vibration generating unit be formed in a body portion thereof with a piston bore and a guide bore which are formed consecutively with each other; a piston be inserted into, and slidably fitted in, the said piston bore so that it may, under a changing hydraulic pressure, be reciprocated therein; and the said guide bore have a rod body of the said ramming member and a base end portion of either of the said chisel member and the said pile driving member removably inserted therein, the said working machine desirably further comprising a mechanism whereby the said rod body of the ramming member can be displaced in such a manner that it may in its displacement follow a displacement of the said piston.

[0015] And, it is preferred that the preceding mechanism be constituted of a spring member for energizing the said rod body to move towards the said piston; be constituted of a cylinder unit extending across the said rod body and the said body portion; or be constituted of a flexible cylindrical body that may be coupled between the said rod body and an end portion of the said piston.

[0016] Also, in a construction as described above, the said spring member may be interposed between a spring reception portion provided in the said rod body and spring catches which may be slidably inserted and fitted between the said rod body and are engageable with and disengageable from said body so that the said spring catches can engage with and disengage from the said body portion while the said spring member is being compressed. Alternatively, the said spring member may be interposed between a spring reception portion provided in the said rod body and a guide ring capable of being attached to and detached from the said body portion to allow an attachable and detachable ring to be fitted to the said rod body outside of the said guide ring so that when the said spring member is compressed the said guide ring can be fitted to the said body and thereafter the said attachable and detachable ring can be detached from the said rod body.

[0017] Also, in a construction as described above, the said working machine may further comprises an upper pressure reception chamber and a lower pressure reception chamber which are defined at an upper end side and a lower end side of the said piston, said upper pressure reception chamber being possibly connected to a tank via a switching valve and a restriction, the said switching valve being possibly so configured that when the said rod body of the ramming member is inserted into the said guide bore, the said upper pressure reception chamber can communicate with the said tank via the said restriction and otherwise it may be blocked from the said tank.

[0018] Further, the said upper pressure reception chamber may be provided with an auxiliary pressure reception chamber which is also connected to the said tank via the said switching valve and the said restriction, the said switching valve being then possibly so configured that when the said rod body of the said ramming member is inserted into the said guide bore, the said auxiliary pressure reception chamber can communicate with the said tank via the said restriction and otherwise it can directly communicate with the said tank.

BRIEF EXPLANATION OF THE DRAWINGS

[0019] The present invention will better be understood from the following detailed description and the drawings attached hereto showing certain illustrative embodiments of the present invention. In this connection, it should be noted that such embodiments as illustrated in the accompanying drawings are intended in no way to limit the present invention but to facilitate an explanation and understanding thereof.

[0020] In the accompanying drawings:

Fig. 1 is an entire front view that shows a first embodiment which constitutes a working machine according to the present invention;

Fig. 2 is a longitudinal cross sectional view that shows a first example of a vibration generating unit in the state in which it is equipped with a ramming member in the above mentioned embodiment of the present invention;

Fig. 3 is a cross sectional view taken along the line III-III of Fig. 2;

Fig. 4 is a cross sectional view taken along the line IV-IV of Fig. 2:

Fig. 5 is a decomposed perspective view that shows a first example of a spring attachment portion in the vibration generating unit shown in Fig. 2;

Fig. 6 is a cross sectional view taken along the line VI-VI of Fig. 2;

Fig. 7 is a cross sectional view that shows the vibration generating unit shown in Fig. 2 but in the state in which it is equipped with a chisel member;

Fig. 8 is a cross sectional view that shows a second example of the spring attachment portion;

Fig. 9 is a top plan view that shows an attachable and detachable ring at the spring attachment portion shown in Fig. 8;

Fig. 10 is a transverse cross sectional view that shows the vicinity of an elongated recess portion of the rod body of the
vibration generating unit;

Fig. 11 is a cross sectional view that shows a structure in principle of the vibration generating unit;

Fig. 12 is an illustrative view that shows a structure in principle of the vibration generating unit;

Fig. 13 is a circuit diagram that shows a hydraulic circuit in the first embodiment mentioned above of the present invention;

Fig. 14 is an explanatory view that shows a ramming operation according to the above mentioned first embodiment of the present invention;

Fig. 15 is a graphic diagram that shows graphs which are representative of a displacement of the body portion, a displacement of the ramming plate and a change in the ramming force, which are produced while a ramming operation is being carried out;

Fig. 16 is a longitudinal cross sectional view that shows a second example of the vibration generating unit;

Fig. 17 is an illustrative view that shows a structure in principle of a third example of the vibration generating unit;

Fig. 18 is a cross sectional view that shows a third example of the spring attachment portion;

Fig. 19 is a cross sectional view that shows a fourth example of the spring attachment portion;

Fig. 20 is a cross sectional view that shows a fifth example of the spring attachment portion;

Fig. 21 is a cross sectional view that shows a cylinder attachment portion which corresponds to the above mentioned spring attachment portion;

Fig. 22 is a cross sectional view that shows another example of the structure in which the rod body in its displacement is designed to follow a displacement of the piston;

Fig. 23 is an entire front view that shows a second embodiment of a working machine according to the present invention; and

Fig. 24 is an entire front view that shows a third embodiment of a working machine according to the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION

[0021] Hereinafter, suitable embodiments of the present invention with respect to a working machine will be set forth with reference to the accompanying drawings hereof.

(Entire Structure of a Power Shovel)

[0022] Fig. 1 shows a working machine that constitutes a first embodiment of the present invention. As shown in Fig. 1, an upper vehicle body 3 is mounted, so as to be turnable, on a lower vehicle body 2 equipped with a traveling body 1, and they constitutes an integrated vehicle body 4. A boom 5 is mounted, so as to be capable of being swung upwards and downwards, on the upper vehicle body 3, and is adapted to be driven by a boom cylinder assembly 6. An arm 7 is coupled to the boom 5 and the arm 7 so as to be capable of being swung upwards and downwards, and is adapted to be driven by an arm cylinder assembly 8. Thus, the boom 5 and so forth constitutes a machine arm section 9 in the working machine. Further, the arm 7 has a forward end portion thereof to which a bucket 10 is coupled so as to be capable of being swung up and down in a rotary oscillation or reciprocation, and is adapted to be driven by a bucket cylinder assembly 11 as described later.

[0023] A vibration generating unit 13 has a body portion 14 which is coupled to the arm 7 via a first and a second link 15 and 16. The arm 7 has a base end portion thereof to which is coupled one end of the bucket cylinder assembly 11 at whose other end its piston rod 12 is coupled to the body portion 14 of the above mentioned vibration generating unit 13. The body portion 14 is coupled to the bucket 10 via the third link 17 and thus constitutes a portion of a link mechanism 18 for coupling the bucket cylinder 11 and the bucket 10 together. And, a ramming member 19 is detachably attached to the body portion 14 of the above described vibration generating mechanism 13, thus constituting a ramming machine section in the working machine.

[0024] Further, as will be described later, a floating valve 84 is provided that is designed to establish and block a fluid communication through an extending chamber 11a and a retracting chamber 11b of the bucket cylinder assembly 11 with a tank for bringing the bucket cylinder assembly 11 into a floating state when a ramming work is curried out.

(Operation of the Bucket)

[0025] If the piston rod 12 of the bucket cylinder assembly 11 is extended, the bucket 10 will assume a posture in which it is swung or rotated upwards at the side opposite to the side of the link mechanism 18 to scoop up an amount of earth and sand, as shown in Fig. 1. With this posture taken, the bucket 10 will also be located opposite to the side of the ramming member 19. Then, the ramming member 19 will be located far from the link mechanism 18 and will not interfere therewith, thus becoming capable of performing a ramming operation with the bucket 10 that remains coupled to the arm 7.

[0026] If the piston rod 12 of the bucket cylinder assembly 11 is retracted, the bucket 10 has a posture in which it is swung or rotated towards the link mechanism 18 to initiate an excavating operation. Since this would cause the ramming member 19 and the bucket 10 to interfere with each other, the ramming member 19 will be preliminarily removed.

[0027] Also, since a thrust force for the piston 12 in the bucket cylinder assembly 11 is transferred to the bucket 10 via the body portion 14 and the third link 17, this thrust force can be effectively used as an excavating force. In other words, since the body portion 14 is a part which constitutes the link mechanism 18, the piston 12 and the bucket 10 will be so rigidly coupled together that there may be no loss in the transmission of the thrust force.

[0028] This will cause an excavating force to be enlarged.

(Structure of the Vibration Generating Unit)

[0029] The body 14 comprises an upper body 20, a lower body 21 that is fitted over a lower end portion of the upper body 20, and a cap body 22 that is fitted over an upper end portion of the upper body 20, as shown in Fig.2. The upper body 20 is formed with a piston bore 23 extending vertically, the lower body 21 is formed with a guide bore 24 extending vertically, and the cap body 22 is formed with a bore 25, with the bore 25, the piston 23 and 24 being coaxially connected together in series.

[0030] The piston bore 23 mentioned above has a piston 30 slidably inserted therein, defining an upper pressure receiving chamber 31, a lower pressure receiving chamber 32 and a drain port 33. And, the piston 30 has an upper end portion thereof which is slidably inserted in the bore 25 of the cap body 22. It should be noted at this point that in order to raise the downward displacement speed of the piston 30, a nitrogen gas may be sealed into a chamber 34 of the bore 25 to push the piston 30 downwards with its pressure, or alternatively, the piston 30 may be pushed 30 downwards with a spring not shown.

[0031] The guide bore 24 mentioned above has an upper end portion of a rod body 35 inserted vertically slidably therein. The rod body 35 is prevented from rotating about its center axis owing to the construction in which a longitudinally elongated recess 36 formed in a side surface of the upper end portion of the rod body 35 has a pin 37 fitted thereover so that it may be fitted in, and may pass orthogonally to, the lower body 21. Also, the rod body 35 has a lower end portion thereof which is projected downwards from a lower end portion of the lower body 21, and the projected lower end portion has a ramming plate 38 attached thereto so as to constitute the above mentioned ramming member 19. And, the vibration generation unit 13 and the ramming member 19 are now designed to constitute a ramming machine section of hydraulically operated type.

[0032] The rod body 35 mentioned above is designed to be pushed upwards by an elastic member, e. g., a spring 40, so that its upper end surface 35a may normally be in contact with a lower end surface 30a of the piston 30. Thus, when the piston 30 is vertically displaced, the rod body 35 will be displaced vertically following a displacement of the piston 30, thereby vertically displacing the ramming plate 38 so as to cause the ground surface to be rammed.

[0033] It should be noted here that if the above mentioned spring 40 is not provided, the rod body 35 will be displaced downwards by its own weight. When the piston 30 is displaced downwards, the upper end surface 35a of the rod body 35 will depart from the lower end surface 30 of the piston 30. Then, in the state in which the ramming plate 38 remains in contact with the ground surface, the piston 30 will be vertically displaced. Accordingly, it is then not possible to ram the ground surface by vertically displacing the ramming plate 38.

[0034] Next, an explanation will be given with respect to the attachment structure of the above mentioned spring 40.

[0035] As shown in Fig. 2, the lower end surface of the lower body 21 has a cylindrical body 43 with an upper flange 41 and a lower flange 42 attached thereto so that the upper flange 41 may be fastened thereto by bolts 44. And, as shown Figs. 3, 4 and 5, the lower flange 42 of the cylindrical body 43 is located on a pair of the linear outer surfaces 45 and 45 which are at mutually 180° rotated symmetrical positions and on the positions which are rotated by 90° from the said linear outer surfaces 45 and assumes an outer configuration having a pair of arcuate outer surfaces 46 and 46 which are located at mutually 180° rotated symmetrical positions. And, on each of the arcuate outer surfaces there is formed, respectively, an engagement recess 47.

[0036] As shown in Fig. 2, at an approximately central site of the rod body 35, there is provided a ring shaped spring reception portion 48, which may be formed integrally with the rod body 35 or may be a separate member that can be secured to the rod body 35 by means of bolts, pins or the like.

[0037] As shown in Fig. 2, the rod body 35 has at a lower end portion thereof a cylindrical spring catch 49 slidably fitted thereon, which consists of a small diameter cylinder 50 and a large diameter cylinder 52 that is formed integrally therewith at an upper end portion thereof. The spring catch 49 is formed on a lower inside surface of the small diameter cylinder 50 with a ring shaped projection 51 in an integration therewith, and on an upper inside surface of the large diameter cylinder 52 and in an integration therewith with a pair of engagement projections 53 and 53 which are located at mutually 180° rotated symmetrical positions and which are engaged with the engagement recesses 47 and 47, respectively, of the lower flange 42 of the cylindrical body 43. In this way, the spring catch 49 is coupled with the cylindrical body 43 so that it may not be rotated. Furthermore, the above mentioned spring 40 is interposed between the ring shaped projection 51 and the spring reception portion 48 so that the rod body 35 may be pushed up by the elastic force of the spring 40.

[0038] An explanation will next be given with respect to an operation in which the rod body 35 is inserted into the lower body 21.

[0039] First, after the state in which the ramming plate 38 is removed from the rod body 35 has been established, the spring catch 49 will be inserted into the lower end portion of the rod body 35 so that the spring 40 may be disposed between the ring shaped projection 51 and the spring reception portion 48.

[0040] Next, after the state in which the upper end portion of the rod body 35 is inserted into the guide bore 24 of the lower body 21 has been established, the pin 37 will be passed through the elongated recess 36 and will be thereby fitted in the lower body 21 so as to prevent the rod body 35 from rotating. Then, the engagement projections 53 in a pair of the spring catch 49 will be aligned so that they may be opposite to the linear outer surfaces 45 in a pair, respectively, of the lower flange 42. The spring catch 49 will then be displaced upwards while the spring 40 is compressed so that the engagement projections 53 in the pair may be located upwards of the lower flange 42.

[0041] In the above mentioned state, the spring catch 49 will be rotated by 90° about its center axis to align the engagement projections 53 in the pair with the engagement recesses 47 in the pair, respectively. If the spring catch 49 is detached in this state, it will be displaced downwards by the elastic force of the spring 40 to cause the engagement projections 53 in the pair to engage with the engagement recesses 47 in the pair, respectively, so that the cylindrical body 43 and the spring catch 49 may be coupled together.

[0042] Where the rod body 35 is pulled out, it should be noted that the foregoing operation may be reversed.

[0043] Also, the rod body 35 and the ramming plate 38 are coupled together as shown in Figs. 2 and 6. In other words, the ramming plate 38 is provided with a pair of projecting portions 54 between which is entered the forward end portion 35a of the rod body 35. A pin 55 is passed through the forward end portion 35a of the rod body 35 to couple the latter and the ramming plate 38 together. Moreover, a pair of retainers 56 are pushed against the both end surfaces, respectively, of the forward end portion 35a of the rod body 35 by the elastic force of a spring 57.

[0044] This being the case, it will be seen that the ramming plate 38 may not be freely oscillated with respect to the rod body 35 and it is only when more than a given degree of the force is applied that the ramming plate 38 will first be oscillated with respect to the rod body 35. Accordingly, during a ramming operation the ramming plate 38 will be capable of maintaining its posture even if it is left from the surface being rammed.

[0045] Next, an explanation will be given with respect to a civil engineering work operation with a working machine of the present invention.

[0046] First, after the state in which the rod body 35 is removed from the body portion 14 of the vibration generating unit 13 has been established as mentioned above, a groove excavating and filling operation will be carried out with the bucket 10.

[0047] Next, as shown in Fig. 2, the rod body 35 will be attached to the body portion 14 of the vibration generating unit 13, and the piston 30 will be vertically reciprocated by controlling the delivery of a pressure fluid into the upper pressure receiving chamber 31 and the lower pressure receiving chamber 32. This will cause the ramming plate 38 as well as the rod body 35 to be vertically reciprocated to initiate a ramming operation.

[0048] Also, as shown in Fig. 7, if after the rod body 35 is pulled out of the body portion 14 of the vibration generating unit 13 the base end portion of a chisel member 58 is inserted into the guide bore 24 of the lower body 21 and the pin 37 is used to prevent its rotation, the chisel member 58 will be displaced downwards by its own weight to detach its upper end surface from the lower end surface 30a of the piston 30. If the piston 30 is then vertically reciprocated, a crushing operation can be carried out with the chisel member 58 periodically stricken at its base end portion. Thus, the working machine according to the present invention can be utilized as a usual breaker of chisel type as well.

[0049] It should be noted here that not only is the upper end portion of the chisel member 58 identical in shape to the upper end portion of the rod body 35, but also it has a side surface that is formed with a cut-out recess 59 along which the pin 37 is passed.

[0050] It will be seen that a working machine according to the present invention as described in the foregoing serves as a single unique working machine which has the ability to carry out all of a bucketing operation, a ramming operation and a crushing operation. Where operations are altered from one to another, e. g., from a ramming operation to a crushing operation, then it can suffice only to alter operating members, e. g., from a ramming member 19 to a chisel member 58; hence a change from one operation to another is extremely simple.

[0051] Especially, as shown in connection with the first embodiment described in the foregoing, it will be seen that since with the cylindrical spring catch 49 vertically displaced or rotated the spring 40 can simply be attached to and detached from the upper body 21, the rod body 35 of the ramming member 19 can be attached to and detached from the body portion 14 readily and in a short period of time, thus rendering a changing operation extremely with ease.

[0052] By the way, it may be seen that if the spring 40 mentioned above is not provided the rod body 35 will be displaced downwards by its own weight, and when piston 30 is displaced upwards the upper end surface 35a of the rod body 35 will be apart from the lower end surface 30a of the piston 30. Since the piston 30 is then to be vertically displaced in the state in which the ramming plate 38 is held in contact with the ground surface, it follows that the ramming plate 38 can only be vibrated by periodically striking the rod body 35 with the piston 30 in order to carry out a required ramming operation.

[0053] An impact sound, heat, deformation, friction and so forth involved by the piston 30 striking the rod body 35 will thus be created, resulting in a loss in the striking energy. Therefore, the kinetic energy of the piston 30 will not be fully transferred to the ramming plate 38 and a reduced efficiency in the ramming operation will ensue. And yet, the impact sound generated will lead to an increased noise. Yet further, if the ramming plate 38 is displaced over an irregular surface, it will then tend to be inclined, making it difficult to ram such a surface and hard to return the ramming plate to orient in a horizontal plane. The eventual result will be a decisive difficulty to continuously carry out the given ramming operation.

[0054] It should be noted that all of these source problems which lead to an eventual defective ramming operation will be eliminated by the provision of a working machine according to the present invention. More specifically, the spring 40 acts to push up the rod body 35 of the ramming member 19 and is thus effective to keep it always in contact with the lower end surface 30a of the piston 30. Therefore, since during any given ramming operation the ramming plate 38 should be vertically reciprocated following a vertical reciprocation of the piston 30 and the ramming operation should be performed while repetitively striking the surface being rammed with the ramming plate 38, the kinetic energy of the piston 30 and the ramming member 19 should act directly on the ground surface and the ramming efficiency should become superior. And yet, since the ramming plate 38 can be displaced while being floated over the ground surface, not only can any irregular ground surface be rammed with ease, but also the easiness of a horizontal displacement of the ramming plate 38 which tuches on and lifts over the ground surface repetitively makes any continuous ramming operation readily achievable. In addition, the rod body 35 is no longer stricken by the piston 30 with no impact sound generated and hence with a markedly reduced noise emitted.

[0055] Also, as described earlier, with the chisel member 58 mounted, the working machine according to the present invention can act as a usual breaker and is then capable of performing a crushing operation with an enhanced efficiency.

[0056] By the way, if an attachment structure as mentioned above is taken for the spring 40, it should be noted that not only is a force required that is sufficient to lift up the rod body 35 when it is attached and detached, but also a force is necessary that is capable of compressing the spring 40. While a greater force of operation is thus then needed, the use of an attachment structure (the second example), as will be described below, for the spring 40 will make a less force of operation required sufficient.

[0057] As shown in Fig. 8, before the rod body 35 is inserted into the guide bore 21 of the lower body 21, the spring 40 is in the state in which it has preliminarily be assembled in the rod body 35. In other words, the lower end portion of the rod body 35 is fitted with a snap ring 107 above which there are fitted an attachment and detachment ring 108 as shown in Fig. 9 and a guide ring 109. Then, the spring 40 is placed between the guide ring 109 and the spring catch 48 so that it may be compressed to have a preset length. It should be noted at this point that the lower end portion of the lower body 21 is fitted with the guide ring 109. With a pair of come-off proof pins 101 and 110 inserted at portions of their boundary, the guide ring 109 is so constructed that it may be prevented from coming off the lower end portion of the lower body 21.

[0058] Therefore, it will be noted that if after the rod body 35 having the spring 40 assembled therewith as mentioned above is inserted into the guide bore 24 of the lower body 21 the come-off proof pins 110 and 110 are inserted at those portions of the boundary between the lower end portion of the lower body 21 and the guide ring 109 and finally the attachment and detachment ring 108 is removed, a fitting of the rod body 35 into the lower body 21 will be completed. Then, since it suffices to lift up the rod body 35, a minimum force of operation as required will be sufficient.

[0059] Further, as described earlier, where a structure is taken in which the rod body 35 is prevented from freely rotating about its center axis by means of the pins 37 which are passed orthogonally to the lower body 21 and fitted with the longitudinally elongated recess 35 formed in the side surface of the upper end portion of the rod body 35, a problem arises in that where an irregular ground is to be rammed an axial rotary force may be generated for the rod body 35 owing to a rotary torque produced on the ramming plate 38 so that either of the both angular portions of the elongated recess 36 can be pressed against the peripheral surface of a said pin 37 with an excessive force, and its repulsive force may act on the pin 37 from the lower body 21 so that the pins 37 can no longer be rotated to allow the rod body 35 to slide on the pin 37 and their wears to proceed, or, if the pin 37 is still rotated, the pin 37 can slide on the lower body 21 while receiving a large repulsive force therefrom to allow their wears to proceed and thus the rod body 35 and the pin 37 to be promptly damaged. Also, if a force of friction between the rod body 35 and a said pin 37 is increased, a problem arises in that their rotary resistance may, when the rod body 35 is reciprocated, become excessive so that the weight of the spring 40 alone cannot allow the rod body 35 to follow a displacement of the piston 30 and as a result can permit the rod body 35 to be randomly displaced, thus making it difficult to proceed with a ramming operation. If a structure as will be described below is taken, however, these problems will be resolved altogether.

[0060] Fig. 10 is a cross sectional view that shows this structure. In Fig. 10, the lower body 21 is formed with a transversely extending bore 21a penetrating in a direction that is orthogonal to the rod body 35. The transverse bore 21a has a shaft 112 slidably fitted therein that is threaded with a flanged plug 111 at one end thereof. The other end of the shaft 112 has a come-off proof ring pin fitted therein and penetrated transversely therethrough. And the shaft 112 has at a central, small diameter region a roller 114 rotatably supported thereby. The roller 114 has a peripheral surface thereof that is capable of contacting with the surface of the elongated recess 36 of the rod body 35. Also, the shaft 112 is formed through an axial center thereof with a bore for lubrication 112a. The bore for lubrication 112a is adapted to be filled with a lubricating fluid and has one end threaded with a plug 115 for preventing the fluid from flowing out. Then, the shaft 112 is so constructed that the lubricating fluid may be supplied and flow via a small bore 112b into a space between the above mentioned central, small diameter region and the roller 114. And, the roller 114 at each of its both ends is fitted with a fluid seal 116 and a retention ring 117 for holding it in place, one combination located at the side of the ring pin 113 and the other combination located inside of the plug 111 as shown. An O-ring 118 is fitted in the shaft 112 between one end thereof and the plug 118 as shown. Further, the inner surface of the transverse bore 21a is formed at each of the side of the rod body 35 and its opposite side with a relief cut-out 21b. These serve to prevent the outer surface of the roller 114 from contacting the inner surface of the transverse bore 21a.

[0061] According to the construction shown in Fig. 10, the rod body 35 is reciprocated as the piston 30 is reciprocated, and the roller 114 is rotated in reciprocation as the rod body 35 is reciprocated.

[0062] Then, if a rotary torque is produced, e. g., on the ramming plate 38 to generate an axial rotary force for the rod body 35 so that either of the both angular portions of the elongated recess 36 may be pressed against the peripheral surface of a said pin 37 with an excessive force, the roller 114 will be allowed to be freely rotated following a reciprocation of the rod body 35 because the inner surface of the transverse bore 21a is formed at each of the side of the rod body 35 and it opposite side with a relief cut-out 21b which acts to prevent the outer surface of the roller 114 from contacting with the inner surface of the transverse bore 21. Therefore, not only will there be no wear of the inner surface of the transverse bore 21, but also the wear of each of the roller 114 and the rod body 35 will be markedly reduced. What should then ensue are an elongated useful life of each of these components and a facilitated maintenance effort therefor.

[0063] Also, with the roller 114 being freely rotated following a reciprocation of the rod body 35, it can be seen that the force of friction between the rod body 35 and a said pin 37 will be reduced and the rotary resistance of the rod body 35 when it is reciprocated will be lowered. Therefore, the weight of the spring 40 alone will become sufficient to enable the rod body 35 to be displaced precisely following a displacement of the piston 30. As a result, there should be no random movement of the rod body 35, thus significantly facilitating any given ramming operation.

[0064] Next, an explanation will be given with respect to a structure in principle of the first embodiment of the vibration generating unit 13.

[0065] As shown in Fig. 11, the piston 30 for slidable insertion into the piston bore 23 is provided with a large diameter portion 30a, and a small diameter rod portion 30c and a large diameter rod portion 30b which are formed above and below the large diameter portion 30a to make the pressure receiving are of the upper pressure receiving chamber 31 larger and the pressure receiving area of the lower pressure receiving chamber 32 smaller. In addition, a spool 61 is slidably inserted into a spool bore 60 formed in the upper body 20, thus constituting a switching valve 62. The spool bore 60 is formed with a pump port 63, a main port 64 and a tank port 65, and the spool 61 has a first pressure chamber 66 and a second pressure chamber 67, at its both end sides, respectively, as shown.

[0066] The spool 61 is designed to establish and block a fluid communication among the pump port 63, the main port 64 and the tank port 65. More specifically, the spool 1 is thrusted to assume a first position with a pressure fluid in the large diameter, first pressure chamber 66 to establish a fluid communication between the main port 64 and the tank port 65 while blocking a fluid communication between the pump port 63 and the main port 64, and is thrusted to assume a second position with a pressure fluid in the small diameter, second pressure chamber 67 to establish a fluid communication between the pump port 63 and the main port 64 while blocking a fluid communication between the main port 64 and the tank port 65.

[0067] The tank port 65 is normally in a fluid communication with the drain port 33 formed in the piston bore 23, the first pressure chamber 66 is in a fluid communication with an auxiliary port 68 formed in the piston bore 23, and the auxiliary port 68 is and is not in a fluid communication with the drain port 33 and a first port 70 by means of a switching piston 69 that is formed integrally with the piston 30. A servo valve 71 is constructed in this manner. Also, the main port 64 is designed to communicate with a second port 72 and to supply the first port 70 and the pump port 63 with a pressure fluid from a hydraulic pump 73.

[0068] Furthermore, the spool bore 60 is formed with a subsidiary port 74, the piston bore 23 is formed with a first and a second communication port 75 and 76, and the spool 61 is formed therein with an axial bore 77 so that the pressure fluid caused to flow into the pump port 63 may flow via the axial bore 77 into the subsidiary port 74 and from the latter via the first communication port 75 and the auxiliary port 68 into the first pressure chamber 66.

[0069] Such a vibration generating unit as described above can be represented by a diagram as shown in Fig. 12 in which the switching valve 62 is indicated as a four-port and two-position valve. And, when the switching valve 62 is in its second position B, the subsidiary port 74 will be in a fluid communication with the tank port 65.

[0070] An explanation will now be given with respect to an operation of the above mentioned vibration generating unit.

[0071] When the piston 30 is in an intermediate position thereof as shown in Fig. 11, the first communication port 75 and the auxiliary port 68 will communicate with each other. This will allow the pressure fluid in the pump port 63 to be delivered via the axial bore 77, the subsidiary port 74, the first communication port 75 and the auxiliary port 68 into the first pressure chamber 66 to cause the spool 61 to take the first position A. Since the pressure fluid in the upper pressure receiving chamber 31 is thereby allowed to flow via the second port 72, the main port 64 and the tank port 65 into the drain port 33, the piston 30 will be displaced upwards (in the direction of the arrow a) with the pressure fluid in the lower pressure receiving chamber 32.

[0072] When the piston 30 is displaced to reach its upper stroke end position, the first communication port 75 will be blocked and the auxiliary port 68 will be brought into a fluid communication with the drain port 33. This will allow the pressure fluid in the first pressure chamber 66 to flow out into a tank 78 and thus the spool 61 to be displaced to reach its second position B with the pressure fluid in the second pressure chamber 67. As a result, the pressure fluid in the pump port 63 will flow via the main port 64 and the second port 72 into the upper pressure receiving chamber 31. The piston 30 will thus be displaced downwards.

[0073] When the piston 30 is displaced to reach its lower stroke end position, the first port 70 and the second communication port 76 will communicate with each other to cause a pressure fluid from the auxiliary port 68 into the first pressure chamber 66. As a result, the spool 61 will assume its first position A to allow the piston 30 to be displaced upwards, whereafter the foregoing operation will be repeated.

[0074] Now, the description will proceed to an explanation of a hydraulic circuit that is designed to supply a pressure fluid into each of the cylinder assemblies and the vibration generating unit in the above mentioned first embodiment of the invention.

[0075] As shown in Fig. 13, the hydraulic pump 73 has its fluid discharge outlet 73a that is provided with a boom valve 80, an arm valve 81, a bucket valve 82 and a switching valve 83 for the vibration generating unit. Each of the boom valve 80, the arm valve 81 and the bucket valve 82 is adapted to be switched variably to a neutral position b, an elongating position c and a retracting position d under a pilot pressure from a pilot valve not shown. The switching valve 83 has a solenoid 83a that is adapted to be energized electrically so as to be switched from a blocking position f to a communicating position g.

[0076] Further, there is provided a floating valve 84 that is designed to communicate the extending chamber 11a and the retracting chamber 11b of the previously mentioned bucket cylinder assembly 11 with the fluid tank. This bucket floating valve 84 is normally held in a blocking position h but, with a solenoid 84a thereof electrically energized, is switched to a floating position i. The electrical energization for this solenoid 84a is, as for the solenoid 83a of the switching valve 83, is controlled by a controller 85.

[0077] The controller 85 is designed to electrically energize the solenoid 83a of the switching valve 83 in response to an start-up signal of actuation for the vibration generating unit that is furnished from a first operating member 86, and to electrically energize the solenoid 84a of the floating valve 84 in response to an start-up signal for a ramming operation that is furnished from a second operating member 87.

[0078] With the system so constructed as described above, it can be seen that if the signal of actuation for the vibration generating unit is entered into the controller 85 from the first operating member 86 and the signal for a ramming operation is entered into the controller 85 from the second operating member 87, the switching valve 83 will be switched to the communicating position g to supply the pressure fluid into the vibration generating unit 13, thus initiating a vertical reciprocation of the piston 30 as mentioned earlier, and at the same time the floating valve 84 will be switched to the floating position i to bring the bucket cylinder assembly 11 into a floating state in which it is extended and retracted with an external force, thereby permitting the body portion 14 of the vibration generating unit 13 to be vertically reciprocated with an external force as well.

[0079] An explanation will now be given with respect to a ramming operation in the state above.

[0080] First, since the bucket cylinder assembly 11 may be extended and retracted with an external force, it will have an extending operation with the weight of the vibration generating unit 13 to allow the ramming plate 38 to come into contact with the ground surface D as shown Fig. 14(a).

[0081] And, with the upper pressure receiving chamber 31 and the lower pressure receiving chamber 32 being supplied each with a pressure fluid, a difference in their pressure receiving areas will cause the piston 30 to tend to be displaced downwards. However, since the ramming plate 38 coupled to the rod body 35 is in contact with the ground surface, the piston 30 cannot be displaced downwards and instead the body portion 14 will be displaced upwards. Then, the bucket cylinder assembly 11 will have a retracting operation.

[0082] Next, when the piston 30 is displaced to reach the upper stroke end position, the upper pressure chamber 31 will become in communication with the fluid tank 48 as shown in Fig. 14(b) and the lower pressure receiving chamber 32 alone can then be supplied with the pressure fluid. The piston 30 will thus be displaced upwards.

[0083] Then, the body portion 14 (including the piston rod 12 of the bucket cylinder assembly 11) will, without having a sudden stop, be displaced upwards to a certain extent due to a force of inertia acted thereon. This will cause the piston 30 to be displaced upwards and the rod body 35 and the ramming plate 38 to be moved up as well via the spring 40, hence permitting the ramming plate 38 to be detached from the ground surface D. At the same time, the piston 30, the rod body 35 and the ramming plate 38 which are small in inertia, will be further moved upwards. Thus, the ramming plate 38 will be considerably departed from the ground surface D, as shown in Fig. 14(c).

[0084] Next, while the piston 30, the rod body 35 and the ramming plate 38 are being lifted up, the body portion 14 will cease moving upwards. It will then commence moving down and, after the piston 30, the rod body 35 and the ramming plate 38 has ceased moving up, the upper pressure receiving chamber 31 will be supplied with a pressure fluid to allow the piston 30 with a small inertia to be displaced downward, thereby permitting the ramming plate 38 to come in contact with the ground surface D, as shown in Fig. 11(d).

[0085] In this instance, since the body portion 14 is moved upwards after having being moved downwards to a certain extent due to an inertia, the piston 30 will in the mean time will be forced downwards with the pressure fluid in the upper pressure receiving chamber 31, thus pressing the ramming plate 38 intensively against the ground surface D so as to ram it, as shown in Fig. 14(e).

[0086] The foregoing operation is graphically shown in Fig. 15.

[0087] In a ramming operation which is carried out with the bucket cylinder assembly 11 in a floating state as described above, it can be seen that the body portion 14 and the piston rod 12 of the bucket cylinder assembly 11 on the one hand and the piston 30, the rod body 35 and the ramming plate 38 on the other hand are relatively displaced up and down. This means that the force of inertia created by the weight of the body portion 14 and the piston rod 12 of the bucket cylinder assembly 11 can be utilized as a ramming force, and thus a significantly enhanced overall ramming force can then be obtained. It should be noted in this connection that the boom cylinder assembly 6 and/or the arm cylinder assembly 8 can be made in a floating state as well so that the weight of the arm 7 and the boom 5 or the weight of the arm 7 or the boom 5 may also be utilized to a ramming force.

[0088] Next, an explanation will be given with respect to a second example of vibration generating unit.

[0089] As shown in Fig. 16, there is provided a low pressure circuit 121 that connects the upper pressure receiving chamber 31 of a said vibration generating unit 13 via a restriction 120 to the fluid tank 78. Also provided is a switching valve 122 that is designed to establish and block a fluid communication with the low pressure circuit 121. The switching valve 122 is adapted to assume a position of communication j with a spring 123 associated therewith and to assume a blocking position k when a solenoid 124 associated therewith is electrically energized.

[0090] When a ramming operation as discussed above is carried out using this example, the switching valve 122 is first held at the communicating position j with the solenoid 124 not electrically energized to allow the upper pressure receiving chamber 31 of the vibration generating unit 13 to communicate with the fluid tank 78. Since this causes a portion of the pressure fluid flowing into the upper pressure receiving chamber 31 to flow out into the fluid tank 78 via the restriction 120, the pressure within the upper pressure receiving chamber 31 will not rise abruptly but will do gradually. In other words, when the piston 30 is displaced downwards to bring the ramming plate 38 into contact with the ground surface D as shown in Fig. 14(a), then the pressure in the upper pressure chamber 31 will not rise abruptly. Therefore, since the body portion 14 and the piston rod 12 will be lifted fast so that there may be no large shock applied to the arm 7, the boom 5 or the upper vehicle body 3 via the bucket cylinder assembly 11 or to the pressure fluid therein, the operator's riding comfort will be improved.

[0091] Also, if the chisel member 58 is substituted for the ramming member 19 and its base end portion is fitted as shown in Fig. 7 to carry out a crushing operation, the solenoid 124 will be electrically energized to switch the switching valve 122 to the blocking position k. Then, there will be an interruption between the upper pressure receiving chamber 31 of the vibration generating unit 13 and the fluid tank 78, and the pressure within the pressure receiving chamber 31 will thus be elevated. Accordingly, an increased force for striking the base end portion of the chisel member 58 will result, thus permitting the crushing operation to be carried out at an enhanced efficiency.

[0092] Next, an explanation will be given with respect to a third example of the vibration generating unit that permits both a ramming operation and a crushing operation to be each carried out at an increased efficiency.

[0093] This requires an auxiliary pressure receiving chamber 125 to be provided in the upper body 20 as shown in Fig. 17. And, the auxiliary pressure receiving chamber 125 is adapted to be connected switchably to the main port 64 and the fluid tank 78 of the switching valve 62 via the switching valve 126. More specifically, the switching valve 126 has a first position l and a second position m which are switchable. When the switching valve 126 is in the first position l, the auxiliary pressure receiving chamber 125 will be allowed to communicate with the main port 64 and to the fluid tank 78 via the restriction 127. Also, when the switching valve 126 is in the second position m, the fluid communication between the auxiliary pressure receiving chamber 125 and the main port 64 will be blocked while permitting the fluid communication between the auxiliary pressure receiving chamber 125 and the fluid tank 78 to be established.

[0094] With this example so constructed as described above, it can be seen that if the switching valve 126 is in the first position l, a pressure fluid will be supplied into both the upper pressure receiving chamber 31 and the auxiliary pressure receiving chamber 125 while the upper pressure receiving chamber 31 and the auxiliary pressure receiving chamber 125 will be allowed to communicate with the fluid tank 78 via the restriction 127. Accordingly, since the piston 30 is thrusted downwards with the pressure fluid that is fed into both of the upper pressure receiving chamber 31 and the auxiliary pressure receiving chamber 125, a difference between the pressure receiving area that generates a pressure acting to push the piston 30 downwards and the pressure receiving area that generates a pressure acting to push the piston 30 upwards will be increased. And yet, with the upper pressure receiving chamber 31 and the auxiliary pressure receiving chamber 125 communicating with the fluid tank 78 via the restriction 127, neither the pressure within the upper pressure receiving chamber 31 nor the pressure within the auxiliary pressure receiving chamber 125 will rise abruptly, thus improving the operator's riding comfort as in the above mentioned second example.

[0095] Also, where instead of the ramming member 19 the chisel member 58 is fitted to carry out a crushing operation, it can be seen that if the switching valve 126 is switched to the second position m, the auxiliary pressure receiving chamber 125 will communicate with the fluid tank 78 and thus the upper pressure receiving chamber 31 alone will be furnished with a pressure fluid. Accordingly, as the pressure receiving area that generates a pressure acting to push the piston 30 downwards is decreased, the velocity with which the piston 30 is displaced will be accelerated. And yet, since the quantity of supply of the pressure fluid into the upper pressure receiving chamber 31 is increased by the amount of pressure fluid not supplied into the auxiliary pressure receiving chamber 125 to elevate the pressure within the upper pressure receiving chamber 31, the force with which the base end portion of the chisel member 58 is stricken by the piston 30 will be increased, thereby permitting a crushing operation to be carried out at an enhanced efficiency.

[0096] Next, an explanation will be given with respect to other examples of the attachment structure of the spring 40.

[0097] Its third example requires the spring catch 49 to be provided in an integration with a flange 90 that is secured and fastened directly to the lower end surface of the lower body 21 by means of bolts 91 as shown in Fig. 18.

[0098] Also, its fourth example requires the inner surface of the upper end portion of the spring catch 49 to be formed with a female threaded portion 92 which is in mesh with a male threaded portion 93 formed in the peripheral surface of the lower end portion of the lower body 21, as shown in Fig. 19, thereby attaching the spring catch 49 to the lower body 21.

[0099] Alternatively, there is, as shown in Fig. 20, provided a fifth example thereof in which a ring 95 having a plurality of brackets 94 is secured and fastened to the lower end surface of the lower body 21, a spring mounting ring 96 is made integral with the rod body 35 or secured and fastened thereto by means of bolts, and the spring 40 has its both ends coupled to the ring 96 and the brackets 94, respectively, to energize the rod body 35 upwards.

[0100] While in each of the examples described above the elastic member is constituted by a spring, this member may alternatively be comprised of a combination of dished springs, a rubber material, a resinous material having an elasticity or the like, and may be mounted in the same manner as is the spring shown.

[0101] Also, the above mentioned elastic member may still alternatively make use of a cylinder, such as a gas cylinder or an air cylinder or a hydraulic cylinder having an energy storage function, a unit that when energized is adapted to be extended and retracted, and then there may, as shown in Fig. 21 representing a sixth embodiment, be provided a cylinder 97 having a cylinder tube 98 coupled to the lower body 21 and a piston 99 coupled to the rod body 35.

[0102] An explanation will next be given with respect to other examples of the mechanism in which the rod body 35 is displaced following a displacement of the piston 30 that is required for the ramming machine section.

[0103] As shown in Fig. 22, there is provided a projection 100 that is made integral with the lower end portion of the piston 30, and so that the upper end surface of the rod body 35 may contact with the projection 100 a flexible coupling 101 is provided for coupling them together.

[0104] The flexible coupling 101 is designed to fit the two end portions of a cylindrical body 102 composed of a flexible material on the projection 100 and on the upper end portion of the rod body 35 respectively and to be secured to them by means of bolts respectively. The flexible coupling 101 may, for an example, be a universal joint.

[0105] And, an opening window portion 104 is formed at a site that is opposing to the coupling portion of the earlier mentioned lower body 21, and is used for coupling and decoupling the above mentioned cylindrical body 102 with ease. Normally, a covering 105 is used to close the opening window portion 104. In this regard it should be noted that the piston 30 and the rod body 35 may be made integral with each other.

[0106] While in each of the examples described above the body portion 14 of the vibration generating unit 13 is attached as a portion of the link mechanism 18 to the arm 7, it may be mounted inside of the arm 7 as in Fig. 23 that represents a second embodiment of the working machine according to the present invention, or may alternatively be attached directly to the forward end portion of the arm 7 as in Fig. 24 that represents a third embodiment of the working machine according to the present invention.

[0107] In such cases it should be noted that as shown in Figs. 23 and 24, the floating valve 84 will be provided for the boom cylinder assembly 6 so that its extending chamber 6a and its retracting chamber 6b may communicate with each other therethrough so as to establish or block their fluid communication with a fluid tank. Thus, when a ramming operation is to be carried out, the boom cylinder assembly 6 will be thereby brought into a floating state.

[0108] With the system so constructed as discussed above, an increased ramming force can be obtained since the overall weight of the boom 5, the arm 7 and the body portion 14 is rendered to contribute thereto.

[0109] It should also be noted that as shown in Fig. 24, in a case where a ramming operation is carried out with the arm 7 postured to have an inclination with respect to a vertical axis, the floating valve 84 may be provided for the arm 7 as well so that the extending chamber 8a and the retracting chamber 8b of the arm cylinder assembly 8 may communicate with each other therethrough so as to establish or block their fluid communication with a fluid tank.

[0110] Also, as is the rod body 35 a pile driving member may be inserted into the lower body 21 and attached thereto.

[0111] As set forth in the foregoing description, it can be seen that according to the present invention, where a ramming operation is carried out, the weights of a body portion of the vibration generation unit and a piston rod of the bucket cylinder assembly; the weights of the body portion of the vibration generation unit, the piston rod of the bucket cylinder assembly and the arm; or the weights of the body portion of the vibration generating unit, the piston rod of the bucket cylinder assembly, the arm and the boom, may be utilized as constituting a ramming force. This will enable an increased overall ramming force to be produced in a ramming operation.

[0112] Also, according to the present invention, it can be seen that a ramming operation can be performed with the rod body 35 of the ramming member 19 inserted into and attached to the guide bore 24 of the body portion 14 of the vibration generating unit 13, a crushing operation can be performed with the base end portion of the chisel member 59 so inserted and attached as mentioned above, and a pile driving operation can be performed with the base end portion of a pile driving member so inserted and attached as mentioned above. This will allow a single working machine to be sufficient to carry out all of a ramming operation, a crushing operation and a pile driving operation, and will permit any such operation to be interchangeably altered with ease among them.

[0113] Also, if such a rod body 35 of the ramming member 19 is designed to be displaced integrally with the piston 30, it will be seen that where a ramming operation is performed in which the ramming member 19 is oriented downwards, such a ramming member 19 can, together with the piston 30, be displaced upwards and downwards to allow the ramming member 19 to carry out the operation in a spaced relationship with the ground surface. Hence, any ramming operation can be carried out at an enhanced efficiency, whether on an irregular ground surface or in a continuity with ease.

[0114] While the present invention has hereinbefore been set forth with respect to certain illustrative embodiments thereof, it will readily be appreciated by a person skilled in the art to be obvious that many alterations thereof, omissions therefrom and additions thereto can be made without departing from the essence and the scope of the present invention. Accordingly, it should be understood that the present invention is not limited to the specific embodiments thereof set out above, but includes all possible embodiments thereof that can be made within the scope with respect to the features specifically set forth in the appended claims and encompasses all the equivalents thereof.

Claims

1. A working machine, which comprises:

a vehicle body;

a boom mounted on said vehicle body so that it may be capable of being swung upwards and downwards;

an arm coupled to said boom so that it may be capable of being swung upwards and downwards;

a bucket coupled to said arm so that it may be capable of being swung up and down in a rotary oscillation;

a system for hydraulically driving said boom, said arm and said bucket by means of a boom cylinder assembly, an arm cylinder assembly and a bucket cylinder assembly, respectively, each of said assemblies having an extending chamber and a retracting chamber which are adapted to be each in a fluid communication with a tank in said hydraulic system;

a vibration generating unit coupled to said arm and being provided with a ramming member, a chisel member and a pile driving member so that said members may be exchangeably attached to said vibration generation unit; and

a floating valve means in said hydraulic system for establishing and blocking said fluid communication, said floating valve means being adapted to be opened when a ramming operation is to be performed and adapted to be closed when either of a crushing operation and a pile driving operation is to be performed.

2. A working machine, as set forth in claim 1, in which said bucket cylinder assembly is coupled to said arm and has a piston rod which is coupled via a link mechanism to said bucket; and said link mechanism comprises a plurality of links which act to couple a body portion of said vibration generating unit to said arm.

3. A working machine, as set forth in claim 1, in which a body portion of said vibration generating unit is mounted inside of said arm; and said bucket is coupled to said arm via said body portion of the vibration generating unit.

4. A working machine, as set forth in claim 1, in which a body portion of said vibration generating unit is coupled to a forward end portion of said arm, in place of said bucket.

5. A working machine, as set forth in claim 1, in which said vibration generating unit is formed in a body portion thereof with a piston bore and a guide bore which are formed consecutively with each other; a piston is inserted into, and slidably fitted in, said piston bore so that it may, under a changing hydraulic pressure, be reciprocated therein; and said guide bore has a rod body of said ramming member and a base end portion of either of said chisel member and said pile driving member removably inserted therein, said working machine further comprising a mechanism whereby said rod body of the ramming member can be displaced in such a manner that it may in its displacement follow a displacement of said piston.

6. A working machine, as set forth in claim 5, said mechanism is constituted of a spring member for energizing said rod body to move towards said piston.

7. A working machine, as set forth in claim 5, in which said mechanism is constituted of a cylinder unit extending across said rod body and said body portion.

8. A working machine, as set forth in claim 5, in which said mechanism is constituted of a flexible cylindrical body that is coupled between said rod body and an end portion of said piston.

9. A working machine, as set forth in claim 6, in which said spring member is interposed between a spring reception portion provided in said rod body and spring catches which is slidably inserted and fitted between said rod body and are engageable with and disengageable from said body portion so that said spring catches may engage with and disengage from said body portion while said spring member is being compressed.

10. A working machine, as set forth in claim 6, in which said spring member is interposed between a spring reception portion provided in said rod body and a guide ring capable of being attached to and detached from said body portion to allow an attachable and detachable ring to be fitted to said rod body outside of said guide ring so that when said spring member is compressed said guide ring may be fitted to said body portion and thereafter said attachable and detachable ring may be detached from said rod body.

11. A working machine, as set forth in claim 5, further comprising an upper pressure reception chamber and a lower pressure reception chamber which are defined at an upper end side and a lower end side of said piston, respectively, said upper pressure reception chamber being connected to a tank via a switching valve and a restriction, said switching valve being so configured that when said rod body of the ramming member is inserted into said guide bore, said upper pressure reception chamber may communicate with said tank via said restriction and otherwise it may be blocked from said tank.

12. A working machine, as set forth in claim 11, in which said upper pressure reception chamber is provided with an auxiliary pressure reception chamber which is also connected to said tank via said switching valve and said restriction, said switching valve being then so configured that when said rod body of said ramming member is inserted into said guide bore, said auxiliary pressure reception chamber may communicate with said tank via said restriction and otherwise it may directly communicate with said tank.

Drawing