Earth-working machine

Description

[0001] The present invention relates to an earth-working machine such as an excavator for digging ditches in road construction.

[0002] As shown in Figure 1 of the accompanying drawings, a known excavator 1 for trenching in and along one lane of a road is placed on that lane, blocking off the traffic on the lane while allowing the traffic on the other lane. In operation, a bucket arm 2 of the excavator 1 is moved up and down to cause a bucket 3 on the bucket arm 2 to dig a trench 4 in and along the road lane. The material scooped by the bucket 3 is then dumped onto a loading platform 6 of a truck 5 positioned behind the excavator 1. As the trench 4 is dug, the excavator 1 is required to move back in the direction of the arrow Z so as to avoid falling into the trench 4 which has just been dug. To transfer the material dug from the trench 4 to the loading platform 6, it is necessary to turn the bucket 3 and hence the bucket arm 2 along a semicircular path Y about a centre X of the excavator 1. Since the path Y of the bucket 3 extends into the other road lane, the traffic on the other lane must be either stopped totally or interrupted when the bucket arm 2 is to swing over in order to prevent an accident. However, such entire or temporary traffic interruption is bound to cause a traffic jam while the road is under construction. Furthermore, the large radius of swinging movement of the bucket arm 2 involves the danger of the bucket 3 hitting and injuring careless people who may walk into the range of turning movement of the bucket arm 2.

[0003] It has been proposed, for example U.S. 1,528,222 or U.S. 4,183,711, to have the bucket assembly pivotally mounted on the excavator, so that the excavator and bucket can be pivoted through a limited range with respect to each other. Even with this arrangement the bucket assembly projects beyond the excavator, as the excavator is rotated so that there is still essentially the same disadvantage as the prior art described and illustrated in Figure 1.

[0004] The present invention seeks to provide an earth-working machine having an earth-working mechanism capable of turning along a path of reduced radius, and which therefore may operate without interfering with other activities around the machine, such as for example, traffic.

[0005] Further, the present invention seeks to provide an earth-working machine operable within a small space so as to avoid accidents such as traffic accidents or injuries to people around the machine.

[0006] According to the present invention there is provided an earth-working machine comprising: a mobile chassis; a first gear fixedly mounted on the mobile chassis; a turntable pivotally mounted on the first gear to rotate through 360°; a carriage rotatably mounted on the turntable and eccentric to the first gear; a second gear mounted on the carriage and eccentric to the first gear; an earth-working mechanism mounted on the carriage; a first driving means mounted on the turntable in driving engagement with the first gear to rotate the turntable; characterised in that the carriage is rotatable through 360° and there is means engaging with the second gear for rotating the carriage about an axis of the second gear, independently of the first driving means.

[0007] Preferred embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, wherein:

Figure 1 is a plan view of a conventional excavator operating to dig a ditch;

Figure 2 is a perspective view of an excavator according to an embodiment of the present invention;

Figure 3 is a side elevation of the excavator shown in Figure 2;

Figure 4 is a front elevation of the excavator of Figure 2;

Figure 5 is a plan view of an excavator according to an embodiment of the present invention;

Figure 6 is an enlarged cross-sectional view taken along line X-X of Figure 5;

Figure 7 is an exploded perspective view of a turning mechanism on the excavator illustrated in Figure 5;

Figure 8 is a plan view of the turning mechanism of Figure 7, as assembled;

Figures 9 and 10 are plan views of the excavator of Figure 5 arranged to dig a trench;

Figure 11 is an enlarged cross-sectional view of an excavator according to a still further embodiment of the present invention;

Figure 12 is an enlarged fragmentary cross-sectional view of a clutch mechanism on the excavator shown in Figure 11;

Figure 13 is an exploded perspective view of a turning mechanism on the excavator shown in Figure 11; and

Figure 14 is a plan view of the turning mechanism, as assembled, of Figure 13.

[0008] As shown in Figures 2 to 8, the excavator is of the self-propelled type having a flat mobile chassis 10 supporting two pairs of wheels 11 which each carry an endless track 12. The mobile chassis 10 includes a central support base 13 (Figures 3, 4 and 6) mounted thereon and having an upper annular flange on which an octagonal turntable 14 is rotatably mounted. As better shown in Figure 5, the turntable 14 supports thereon an engine 15, a fuel tank 16, and a hydraulic oil tank 17 arranged along a rear edge of the turntable 14. A hydraulic motor 18 is also mounted on the turntable 14 adjacent to the fuel tank 16 and has a drive shaft 36 (Figure 6) directed downwardly of the turntable 14. As illustrated in Figures 2 and 3, an annular horizontal holder base 19 is fixedly mounted on the turntable 14 at a front edge thereof. The annular holder base 19 has an axis held in horizontally eccentric relation to the axis of the support base 13 and hence the turntable 14. A circular carriage 20 is rotatably mounted coaxially on the holder base 19.

[0009] As shown in Figure 3, the carriage 20 includes a vertical support 21 to which a pair of vertically spaced legs 22 is secured. A bracket 26 is pivotably mounted on the legs 22 and supports thereon a bent boom 27 which is vertically angularly movable about a pivot on the bracket 26. The boom 27 supports on its distal end a bucket arm 28 having a bucket 29 pivotally mounted on a distal end of the bucket arm 28. Hydraulic cylinders 30, 31, 32 are coupled respectively between the bracket 26 and a central portion of the boom 27, between a central portion of the boom 27 and an end of the bucket arm 28, and between the bucket arm 28 and the bucket 29. The boom 27, the bucket arm 28, the bucket 29, and the hydraulic cylinders 30, 31, 32 jointly constitute an excavating mechanism 47. The bracket 26 also supports a seat base 23 on which there are mounted an operator seat 24 and a hydraulic control box 25 having a plurality of control levers 25a.

[0010] As illustrated in Figure 6, an annular internal gear 33 is fixedly mounted on an annular flange of the support base 13. A slider ring 35 is disposed securely below the turntable 14and rotatablyfitted about the internal gear 33 with ball bearings 34 interposed therebetween. Accordingly, the turntable 14 is rotatable on the first gear 33. A pinion 37 is fixed to the drive shaft 36 of the hydraulic motor 18 and held in driving mesh with the internal gear 33. The turntable 14 has an L-shaped bracket 38 which extends downwards into the internal gear 33. The holder base 19 supports an annular holder 43. The carriage 20 has an annular internal gear 45 fixed to the underside thereof, which rotatably fits in the annular holder 43 with ball bearings 44. The carriage 20 is rotatably upon the annular holder43. Theturntable 14 supports another hydraulic motor 50 and a T-shaped support 51 dependent therefrom and supporting on its lower end a bearing mount 52 on which a pair of bearings 53, 54 is mounted within the support base 13. The hydraulic motor 50 has a drive shaft 55 extending downwards through the internal gear 33 into the support base 13 and has a lower end journalled in the bearing 53. An intermediate vertical shaft 56 is journalled in a bearing 40 on the turntable 14 and in the bearing 54 on the bearing mount 52. As illustrate in Figure 7, sprockets 57, 58 are secured to the shafts 55, 56, respectively, and an endless chain 59 is trained around the sprockets 57, 58. A pinion 46 held in mesh with the internal gear 45 is fixed to the upper end of the intermediate shaft 56, as shown in Figures 6 and 7.

[0011] Operation of the excavator thus constructed is as follows: the control levers 25a are actuated by the operator sitting on the seat 24 to operate the hydraulic cylinders 30, 31, 32 to move the bucket 29 up and down for digging a ditch. The bucket 29 with the scooped material therein is brought from the position shown in Figure 3 to the position of Figure 4 in which the bottom of the bucket 29 is located slightly higher than the various devices on the turntable 14. The bucket 29 is then turned rearwardly of the chassis 10 toward a truck (not shown) parked behind the excavator.

[0012] In operation, the bucket 29 (Figure 2) with the material dug can be brought over the chassis 10 from the front to the rear position by actuating the hydraulic motors 18,50 in synchronism to turn the turntable 14 and the carriage 20 in opposite directions. More specifically, the hydraulic motor 18 is actuated to turn the turntable 14 about the axis of the internal gear 33. The carriage 20 is angularly moved with the turntable 14 about the axis thereof. The hydraulic motor 50 is also operated to rotate the pinion 46 through the drive shaft 55, the sprocket 57, the chain 59, the sprocket 58, and the intermediate shaft 56. The internal gear 45 is then caused by the pinion 46 to rotate about its own axis. The carriage 20 is rotated about the axis of the internal gear 45 while revolving around the axis of the turntable 14. The hydraulic motors 18, 50 are designed to rotate their shafts 36, 55 in opposite directions so that the excavating mechanism 47 (Figures 9 and 10) will turn in a direction opposite to the direction in which the turntable 14 rotates, toward the rear position over the engine 15, the fuel tank 16 and the hydraulic oil tank 17. By designing the system such that the carriage 20 will rotate through an angle twice largerthan the angle of rotation of the turntable 14, the carriage 20 rotates through 360° when the turntable rotates through 180° to bring the excavating mechanism 47 from a front central position forward of the chassis 10 to a rear central position rearward of the chassis 10. While the excavating mechanism 47 is rotating above the carriage 20, the carriage 20 is positioned on one side of the chassis 10 with the excavating mechanism 47 as folded being located on the other side. There is no danger for the excavating mechanism 47 to project laterally when the turntable makes angular movement through 90°. Therefore, the excavating mechanism 47 can be turned around within the width of the chassis 10.

[0013] The hydraulic motors 18, 50 can be actuated independently of each other to allow the excavating mechanism 47 to dig side trenches as shown in Figures 9 and 10. More specifically, the hydraulic motor 18 is actuated to turn the turntable 14 slightly until the carriage 20 is angularly shifted counterclockwise to one side of the chassis 14 through an angle of 8₁ as shown in Figure 9. Then the hydraulic motor 50 is operated to rotate the carriage 20 clockwise with respect to the turntable 14 through the same angle 8₁.

[0014] The excavating mechanism 47 is now directed parallel to the longitudinal direction of the excavator with the bucket located in a lateral position spaced a distance W1 from the longitudinal axis of the excavator so as to make the bucket ready for trenching a side ditch. Thereafter, the hydraulic cylinder of the excavating mechanism can be actuated to enable the bucket to dig a side ditch or laterally enlarge an existing ditch. As shown in Figure 10, the turntable 14 and the carriage 20 may be turned clockwise and counterclockwise through angle of 8₂, respectively, to allow the bucket to trench another side ditch spaced a distance W2 from the longitudinal axis of the excavator. Although not shown, the turntable 14 and the carriage 20 may be adjusted in their angles of turn to enable the excavating mechanism 47 to project laterally beyond the width of the chassis 10 for digging an outside trench beyond one of the endless tracks.

[0015] Figures 11 to 14 illustrate an excavator according to a further embodiment of the present invention. According to the embodiment of Figures 11 and 12, an intermediate shaft 41 journalled in the bearings 39, 40 has a vertical axial extension 80 extending through the internal gear 45 and has axial splines 80a (Figure 12). A pinion 81 is axially slidably splined to the axial extension 80 and normally held in driving mesh with the internal gear 45. The pinion 81 is axially movable out of meshing engagement with the internal gear 45 when shifted in the direction of the arrow (Figure 12). A lever 82 is pivotably mounted at one end on a support post 83 mounted on the turntable 14 and has on the other end a roller 85 riding in a groove 84 defined in the pinion 81. An actuator lever 86 is connected to the lever 82 and depress- able toward the turntable 14 for angularly moving the lever 82 about the pivot on the support post 83 to shift the pinion 81 out of meshing engagement with the internal gear 45. The turntable 14 supports another hydraulic motor 87 below the carriage 20. The hydraulic motor 87 has a drive shaft 88 extending upwards into the internal gear 45 and has a pinion 89 held in driving mesh with the internal gear 45.

[0016] The excavator of this embodiment operates for synchronous rotation of the turntable 14 and the carriage 20, the hydraulic motor 18 is actuated, the motor 87 is inactivated, and the pinion 81 kept in mesh with the internal gear 45. The turntable 14 is then rotated about the axis of the internal gear 33, and at the same time the pinions 42, 81 are rotated about their own axes. The internal gear 45 in mesh with the pinion 81 and hence the carriage 20 is rotated about the axis of the annular holder 43. The carriage 20 is thus rotated in one direction about its own axis while angularly moving with the turntable 14 in an opposite direction about the axis of the latter. The bucket folded to the excavating mechanism is moved over the turntable 14 from a front position to a rear position without laterally projecting out of the space range substantially equal to the width of the excavator chassis.

[0017] When it is desired to rotate the turntable 14 and the carriage 20 independently of each other, the actuator lever 86 is depressed to turn the lever 82 counterclockwise to shift the pinion 81 upwards out of meshing engagement with the internal gear 45. The internal gear 45 can then rotate independently of the internal gear 33. The hydraulic motor 87 is then actuated to rotate the pinion 89 and thereby the internal gear 45 in mesh therewith. The carriage 20 is therefore rotated solely by the hydraulic motor 87. The excavating mechanism can freely be rotated with the carriage 20 through 360° to any desired position. Accordingly, the excavating mechanism can be positioned as desired with respect to the turntable 14; for example, the excavating mechanism may be shifted sideways to trench a side ditch, or may be stored over the turntable 14 with the latter remaining unrotated. For rotating the turntable 14 and the carriage 20 synchronously again, the actuator lever 86 is moved back to bring the pinion 81 downwards to mesh with the internal gear 45. The hydraulic motor 18 is then actuated while the hydraulic motor 87 is rendered inoperative.

[0018] With the arrangements of the present invention, the bucket of the excavating mechanism can be brought back and forth between front and rear positions with respect to the chassis over the devices mounted on the turntable. The bucket need not project laterally and hence interfere with activities around the excavator such as traffic on a lane of the road adjacent to the lane on which the excavator is used. Consequently, the digging operation of the excavator can be carried out in a minimum space range allowing as much traffic as possible adjacent to the excavator while in operation. According to embodiments of the invention, the carriage can be rotated independently of the turntable so that the excavating mechanism . can be laterally shifted for trenching desired side ditches or stored back above the turntable easily.

[0019] Although certain preferred embodiments have been shown and described, it should be understood that many changes and modifications may be made therein without departing from the scope of the appended claims.

Claims

1. An earth-working machine comprising: a mobile chassis (10); a first gear (33) fixedly mounted on the mobile chassis (10); a turntable (14) rotatably mounted on the first gear (33) to rotate through 360°; a carriage (20) pivotally mounted on the turntable (14) and eccentric to the first gear; a second gear (45) mounted on the carriage and eccentric to the first gear (33); an earth-working mechanism (47) mounted on the carriage (20); a first driving means (18) mounted on the turntable (14) in driving engagement with the first gear (33) to rotate the turntable (14); characterised in that the carriage is rotatable through 360° and there is means (46, 50, 57, 58, 59; 87) engaging with the second gear (45) for rotating the carriage (20) about an axis of the second gear (45), independently of the first driving means.

2. An earth-working machine as claimed in claim 1, wherein the means for rotating the carriage is a hydraulic motor (50; 87).

3. An earth-working machine as claimed in claim 2, wherein the hydraulic motor (50) is mounted on the turntable (14) and has a first shaft (55), a first sprocket (57) mounted on the first shaft (55), a bearing (40) supported on the turntable (14), a second shaft (56) journalled in the bearing 40), a second sprocket (58) mounted on the second shaft (56), a chain (59) trained around the first and second sprockets (57, 58) in mesh therewith, and a pinion (46.) mounted on the second shaft (56) and held in driving mesh with the second gear (45), whereby the carriage (20) can be rotated by the second hydraulic motor (50).

4. An earth-working machine according to claim 2, wherein the hydraulic motor (87) is mounted on said turntable (14) and has a driving pinion (89) held in driving mesh with the second gear (45), whereby said carriage (20) can be rotated by said second hydraulic motor (87).

5. An earth-working machine according to claim 2, wherein said rotating means has at least one bearing (39, 40) supported on said turntable (14), a shaft (41) journalled in the bearing (39, 40) and including an axial extension (80) which has splines (80a), a second pinion (42) fixed to the shaft (41) and meshing with the first gear (33), another pinion (81) splined to the axial extension (80), and clutch means (82-86) actuatable to shift the other pinion (81) on the axial extension (80) into or out of meshing engagement with the second gear (45), whereby the carriage (20) can be rotated with the turntable (14) or by the second hydraulic motor (87) independently of the turntable.

6. An earth-working machine according to claim 5, wherein the clutch means comprises a support post (83) mounted on the turntable (14), a lever (82) pivotally mounted on the support post (83), a roller (85) rotatably mounted on the lever (82) and riding in a groove (84) defined in the pinion (81) on the axial extension (80), and an actuator rod (86) connected to the lever (82) for angularly moving the lever (82) to shift that pinion (81) out of meshing engagement with the second gear (45).

7. An earth-working machine as claimed in any preceding claim, wherein the mobile chassis (10) has a base (13) for supporting the first gear (33), and the turntable (14) has a slip ring (35; 65) held in rolling engagement with the first gear (33).

8. An earth-working machine as claimed in any preceding claim wherein the turntable (14) has a holder base (19) and an annular holder (43; 73) secured to the holder base (19), and the second gear (45) is held in sliding engagement with the annular holder (43; 73).

9. An earth-working machine as claimed in any preceding claim wherein the first driving means is a hydraulic motor (18).

Ansprüche

1. Maschine für Erdarbeiten mit einem Fahrgestell (10), einem auf dem Fahrgestell (10) fest angebrachten ersten Zahnrad (33), einer Drehscheibe (14), die auf dem ersten Zahnrad (33) um 360° drehbar angebracht ist, einem Schlitten (20), der auf der Drehscheibe (14) exzentrisch zu dem ersten Zahnrad drehbar angebracht ist, einem zweiten Zahnrad (45), das exzentrisch zum ersten Zahnrad (33) auf dem Schlitten angebracht ist, einem auf dem Schlitten (20) angebrachten Mechanismus (47) für Erdarbeiten und einem ersten Antriebsmittel (18), das in Antriebseingriff mit dem eresten Zahnrad (33) auf der Drehscheibe (14) angebracht ist, um die Drehscheibe (14) zu drehen, dadurch gekennzeichnet, daß der Schlitten um 360° drehbar ist und mit dem zweiten Zahnrad (45) in Eingriff befindliche Mittel (46, 50, 57, 58, 59; 87) zur von dem ersten Antriebsmittel unabhängigen Drehung des Schlittens (20) um eine Achse des zweiten Zahnrads (45) vorgesehen sind.

2. Maschine für Erdarbeiten nach Anspruch 1, bei der die Mittel zur Drehung des Schlittens ein hydraulischer Motor (50; 87) ist.

3. Maschine für Erdarbeiten nach Anspruch 2, bei der der hydraulische Motor auf der Drehscheibe (14) angebracht ist und eine erste Welle (55), ein auf der ersten Welle (55) angebrachtes erstes Kettenrad (57), ein auf der Drehscheibe (14) gelagertes Lager (40), eine in dem Lager (40) drehbar gelagerte zweite Welle (56), ein auf der zweiten Welle (56) angebrachtes zweites Kettenrad (58), eine um das erste und das zweite Kettenrad (57, 58) gezogene une mit diesen in Eingriff befindliche Kette (59) und ein auf der zweiten Welle (56) angebrachtes, in Antriebseingriff mit dem zweiten Zahnrad (45) gehaltenes Ritzel (46) hat, wodurch der Schlitten (20) durch den zweiten hydraulischen Motor (50) gedreht werden kann.

4. Maschine für Erdarbeiten nach Anspruch 2, bei der der hydraulische Motor (87) auf der genannten Drehscheibe (14) angebracht ist und ein in Antriebseingriff mit dem zweiten Zahnrad (45) gehaltenes Antriebsritzel (89) hat, wodurch der Schlitten (20) durch den zweiten hydraulischen Motor (87) gedreht werden kann.

5. Maschine für Erdarbeiten nach Anspruch 2, bei der das Mittel zur Drehung wenigstens ein auf der Drehscheibe (14) gelagertes Lager (39, 40), eine in dem Lager (39, 40) drehbar gelagerte und eine axiale Verlägerung (80) mit Passfedern (80a) aufweisende Welle (41), ein auf der Welle (41) befestigtes, mit dem ersten Zahnrad (33) kämmendes zweites Ritzel (42), ein auf die axiale Verlängerung (80) aufgekeiltes weiteres Ritzel (81) une betätigbare Kupplungsmittel (82-86) hat zur Verschiebung des weiteren Ritzels (81) auf der axialen Verlängerung (80) in den oder aus dem Kämmeingriff mit dem zweiten Zahnrad (45), wodurch der Schlitten (20) mit der Drehscheibe (14) oder durch den zweiten hydraulischen Motor (87) unabhängig von der Drehscheibe gedreht werden kann.

6. Maschine für Erdarbeiten nach Anspruch 5, bei der das Kupplungsmittel einen auf der Drehscheibe (14) angebrachten Stützpfosten (83), einen auf dem Stützpfosten (83) schwenkbar angebrachten Hebel (82), eine auf dem Hebel (82) drehbar angebrachte und in einer in dem Ritzel (81) auf der axialen Verlängerung (80) ausgebildeten Rille (84) laufenden Rolle (85) und eine mit dem Hebel (82) für die Winkelbewegung des Hebels (82) verbundene Betätigungsstange (86) umfaßt, um das Ritzel aus dem Eingriff mit dem zweiten Zahnrad (45) zu verschieben.

7. Maschine für Erdarbeiten nach einem der vorhergehenden Ansprüche, bei der das Fahrgestell (10) eine Basis (13) zur Halterung des ersten Zahnrads (33) hat und die Drehscheibe (14) einen in Rolleingriff mit dem ersten Zahnrad (33) gehaltenen Schleifring (35; 65) hat.

8. Maschine für Erdarbeiten nach einem der vorhergehenden Ansprüche, bei der die Drehscheibe (14) eine Halterbasis (19) und einen an der Halterbasis (19) befestigten ringförmigen Halter (43; 73) hat und das zweite Zahnrad (45) in Gleiteingriff mit dem ringförmigen Halter (43; 73) gehalten wird.

9. Maschine für Erdarbeiten nach einem der vorhergehenden Ansprüche, bei der das erste Antriebsmittel ein hydraulischer Motor (18) ist.

Revendications

1. Engin de terrassement qui comprend un châssis mobile (10); un premier organe denté (33) fixé sur le châssis mobile (10); une plaque tournante (14) montée à rotation sur le premier organe denté (33) de façon à pouvoir tourner à 360°; un chariot (20) monté à pivotement sur la plaque tournante (14) et excentriquement par rapport au premier organe denté (33); un second organe denté (45) monté sur le chariot et excentrique par rapport au premier organe dfnté (33); un mécanisme d'excavation (47) monté sur le chariot (20); un premier moyen d'entraînement monté sur la plaque tournante (14) en liaison cinématique avec le premier organe denté (33) afin de faire tourner la plaque tournante (14), caractérisé en ce que le chariot peut tourner à 360° et en ce que des moyens (46, 50, 57, 58, 59; 87) en liaison avec le second organe denté sont prévus pour faire tourner le chariot autour d'un axe du second organe denté, indépendamment du premier moyen d'actionnement.

2. Engin de terrassement, selon la revendication 1, caractérisé en ce que le moyen pour faire tourner le chariot est un moteur hydraulique (50; 87).

3. Enfin de terrassement, selon la revendication 2, caractérisé en ce que le moteur hydraulique (50) est monté sur la plaque tournant (14) et comporte un premier arbre (55), une première roue dentée de chaîne (57) montée sur le premier arbre (55), un palier (40) monté sur la plaque tournante (14), un second arbre (56) tournant dans le palier (40), une seconde roue dentée de chaîne (58) montée sur le second arbre (56), une chaîne (59) passant autour de la première et de la seconde roues dentées (57, 58) en engrénant sur elles, et un pignon (46) monté sur le second arbre (56) et tenu en prise cinématique avec le second organe dentré (45), ce qui fait que le chariot (20° peut être entreîné en rotation par le second moteur hydraulique (50).

4. Engin de terrassement, selon la revendication 2, caractérisé en ce que le moteur hydraulique (87) est monté sur ladite plaque tournante (14) et possède un pignon menant (89) tenu engréné avec le second organe denté (45), ce qui fait que ledit chariot peut être entraîné en rotation par le second moteur hydraulique (87).

5. Engin de terrassement, selon la revendication 2, caractérisé en ce que ledit moyen de rotation comporte, au moins, un palier (39, 40) supporté sur ladite plaque tournante (14), un arbre (41) tournant dans le palier (39, 40) et présentant un prolongement axial (80) ayant des cannelures (80a), un second pignon (42) fixé sur l'arbre (41) et engrénant avec le premier organe denté (33), un autre pignon (81) enfilé par ses cannelures sur le prolongement axial cannelé (80) et des moyens d'embrayage ou d'accouplement (82-86) pouvant être actionnés pour déplacer cet autre pignon (81) sur le prolongement axial (80) afin de l'engré- ner et le désengréner avec le second organe denté (45), ce qui fait qu'on peut faire tourner le chariot (20) avec la plaque tournante (14) ou au moyen du second moteur hydraulique (87), indépendamment de ladite plaque tournante.

6. Engin de terrassement, selon la revendication 5, caractérisé en ce que les moyens d'embrayage ou d'accouplement comprennent un pilier de support (83) monté sur la plaque tournante (14), un levier (82) monté à pivotement sur le pilier de support (83), un galet (85) monté à rotation sur le levier (82) et circulant dans une rainure (84) formée dans le pignon (81) enfilé sur le prolongement axial (80), et une tige d'actionnement (86) reliée au levier (82) pour déplacer angulairement de levier (82) afin de déplacer ledit pignon (81) hors de sa position d'engènement avec le second organe denté (45).

7. Engin de terrassement, selon l'une, quelconque des revendications précédentes, caractérisé en ce que le châssis mobile (10) a une base (13) pour supporter le premier organe denté (33), tandis que la plaque tournante (14) a une bague coulissante (35; 65) tenue au contact du premier organe denté (33).

8. Engin de terrassement, selon l'une quelconque des revendications précédentes, caractérisé en ce que la plaque tournante (14) a une base de montage (19) et une monture annulaire (43; 73) fixée sur ladite base (19), le second organe denté étant tenu appliqué à glissement contre ladite monture annulaire (43; 73).

9. Engin de terrassement, selon l'une quelconque des revendications précédentes, caractérisé en ce que le premier moyen d'actionnement est un moteur hydraulique (18).

Drawing