|
(11) | EP 0 143 003 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
|
|
|
|
|||||||||||||||||||||||||||
| (54) | Road milling or cutting machine |
| (57) A road milling or cutting attachment adapted to be mounted on the boom of a hydraulic
machine comprises a frame. a road surface cutting member rotatably mounted in the
frame and a low speed, high torque hydraulic motor directly coupled to the cutting
member. Preferably the cutting member is formed of at least two arcuate parts detachably
secured to mounting flanges on a drive shaft by detachable securing members, the frame
having openings permitting access to the securing members to enable the cutting members
to be readily mounted on and detached from the shaft. Preferably a portion of the
frame is detachable to enable axial removal of the drive shaft and permit access to
the shaft bearings. |
[0002] In the course of road maintainance and for the purpose of gaining access to piped services embedded beneath road surfaces it is frequently necess-ary to remove a portion of the surface and effect resurfacing or to cut through the surface to enable complete sections to be removed for the purpose of digging trenches or the like.
[0003] The removal of areas of road surfaces is generally effected using a road planing machine but such machines, even in their more compact forms, are bulky and expensive. Moreover they require to be brought to and from site on trailer vehicles and generally are not suitable for the removal of small surface areas such as are required for trenching or for patching of the road surface.
[0004] It has previously been proposed to mount a road surface cutting or milling machine on the arm of an excavating or loading machine of the kind having a hydraulically operated boom to which various implements may be fitted. However previously proposed equipment of this kind has suffered from the disadvantage that it is cumbersome and difficult to maintain and it is an object of the present invention to obviate or mitigate this disadvantage.
[0005] According to the invention there is provided a road milling or cutting attachment adapted to be mounted on the boom of a hydraulic machine, the attachment comprising a frame, a road surface cutting member rotatably mounted in the frame and a low speed, high torque hydraulic motor directly coupled to the cutting member.
[0006] The hydraulic motor is preferably designed to operate at a-speed of 75 to 200 r.p.m. The cutting member may comprise a cylindrical drum the periphery of which is fitted with cutting picks whereby to remove a strip of the road surface approximately equal in width to the width of the drum. Alternatively the cutting member may comprise one or more discs having picks mounted on their peripheries whereby to produce one or more elongated cuts or slits in the road surface.
[0007] Preferably the cutting members are formed of at least two arcuate parts detachably secured to mounting flanges on a drive shaft by detachable securing members, said frame having openings therein permitting access to said securing members through the frame to enable the cutting members to be readily mounted on and detached from the shaft.
[0008] Preferably also said frame incorporates a yoke portion the arms of which support bearings in which said drive shaft is rotatably mounted, one arm of said yoke being detachable to enable axial removal of the shaft and permit access to the shaft bearings.
[0009] An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:-
Fig. 1 is a side view of a road milling or cutting machine according to the invention;
Fig. 2 is a part-sectional side elevation in the direction of arrow "A" in Fig. 1; and
Fig. 3 is an exploded perspective view of the machine.
[0010] The machine comprises an attachment adapted to be carried on the boom of a hydraulic machine such as an excavator or a tractor fitted with a back-hoe. For this purpose the machine incorporates a mounting member 5 provided with upstanding brackets 6 by means of which the mounting member is connected to the excavator boom. The frame of the machine incorporates a yoke member having a cross piece 7 and a pair of depending arms 8A and 8B. A main drive shaft 9 has its ends journalled in bearings 10 carried by the free ends of the arms 8A and 8B and is provided with a pair of axially spaced flanges 11 towards its opposite ends incorporating through holes 12 by means of which cutting devices may be bolted to the drive shaft as will be described hereafter.
[0011] A leading axle carrier 15 and a trailing axle carrier 16 are pivotally mounted on each end of the main drive shaft and are provided with respective pairs of ground engaging wheels 17 and 18, the free ends of the trailing axle carriers being connected by a cross piece 19 and the free ends of the leading axle carriers being interconnected by an axle 20 on which the wheels 17 are mounted. The leading axle carriers 15 incorporate upwardly and rearwardly directed extensions 21 the arms of which at opposite sides of the machine are connected by a cross-piece 22. A threaded adjuster 23 is engaged with complementary threaded nuts 19A, 22A on the cross-pieces 19and 22 such that rotation of the adjuster 23 moves the two cross-pieces towards or away from one another and thus changes the angle of inclination between the leading and trailing axle carriers 15 and 16. As the angle between the carriers increases the cutting unit mounted on the main drive shaft 9 moves downwardly, thereby altering the depth to which it will remove the road surface.
[0012] A two part arcuate guard having a forward portion 27A and a rearward portion 27B respectively mounted on the leading and trailing axle carriers 15. and 16 and slidably engaged with one another, is mounted on the machine to enclose the rotating cutter unit. The sliding connection between the two parts of the guard enables them to move relative to one another when the cutting height of the attachment is altered. The overlapping portions of the guard are designed to have minimum internal projections which might interfere with passage of material carried round by the drum during the cutting operation.
[0013] The main drive shaft 9 may be fitted either with a cutter unit in the form of a cutter drum as shown at 30 or one or more cutter discs (not shown). These cutter units may be presented to the drive shaft in a radial direction for which purpose they are formed of two semi-circular or semi-cylindrical portions 30A, 30B having end flanges 31 provided with bolt holes 32 complementary to the holes 12 on the fixed flanges 11 carried by the shaft 9. The cutter drum and cutter discs may thus be mounted on and detached from the shaft without requiring the frame to be dismantled or the shaft bearings removed to permit axial withdrawal. A plurality nf cutting picks 33 are mounted on the cutter drum 30 (and on the alternatively usable disc or discs which are not shown) and serve during rotation to dig into the road surface and remove it to a depth determined by the height adjustment of the unit.
[0014] In order to rotate the drum or cutter discs the main drive shaft 9 is directly coupled to a hydraulic motor 35. The motor is a low speed, high torque motor having an operating speed in the region and a torque rating of 800-2150 lb.ft. of 75 to 200 r.p.m./and is supplied with hydraulic fluid from the excavator through pipelines travelling along the excavator boom. The mounting member 5 is provided with apertures 36 through which the pipes 37 pass in their passage between the boom and the motor 35 whereby to prevent the pipes from flexing and becoming trapped or interfering with operation of the boom or the attachment. By virtue of the direct connection of the hydraulic motor 35 to the main shaft of the machine it is not necessary to employ a gear box or other speed reducing mechanism and the construction of the attachment is thereby simplified and maintainance reduced. Preferably the motor operates at around 140 rpm producing a torque rating of approximately 1500 1b.ft.
[0015] In order to prevent material removed from the road from being thrown out at the sides of the attachment, a pair of sideguards 40 are pivotally mounted on the trailing axle carrier 16. Each guard 40 is provided with an outwardly directed foot or skid portion 41 at its lower edge which slides over the grcund during use. The upper leading portion 40A of the guard projects between the yoke arm 8A or 8B and the associated axle carrier which restrains the guard against outward bending movement in the event it is subjected to side loads. In order to deflect loose material clear of the trailing wheels 18 of the attachment, a deflector 42 is carried by each of the guards 40. The deflector extends across the associated trailing wheel 18 and is rearwardly inclined whereby to carry loose material clear of the path of travel of the wheels, thereby avoiding interference with the depth of cutting due to accumulation of loose material. In order to prevent adherence of asphalt to the wheels during use of the attachment the rolling surfaces of the wheels are coated with polyurethane or other suitable plastics material.
[0016] The upper portion of each guard 40 is cut away at 40B in the region beneath the associated arm 8A or 8B of the yoke 7 to leave an opening 45 through which access can be gained to the studs 13 securing the cutter drum 30 or disc in position on the main drive shaft 9. These studs may therefore be removed or replaced in turn by rotating the drive shaft to bring the next stud 13 opposite the opening 45 and by sequentially detaching the studs at each side of the drum, each half 30A, 30B of the drum or blade may be detached from the main drive shaft 9 and removed radially clear of the attachment. In this way drums of different cutting width can be fitted to the attachment or the drums replaced by a pair of cutter discs secured one to each of the flanges 11 on the main drive shaft, these operations being effected without requiring the frame 7, 8A,8B to be dismantled or the drive shaft 9 removed.
[0017] In order to facilitate access to the bearings 10 in which the main drive shaft 9 is supported, the arm 8A of the yoke which is disposed at the opposite side of the attachment to the drive motor 35 is detachably connected to the cross-piece 7 by bolts 8C and may be unbolted and detached. The bearing 10 in which the associated end of the drive shaft 9 runs comes away with the arm 8A and following detachment of the cutter drum 30 or disc the drive shaft 9 may be withdrawn axially from its bearings 10 in the yoke 8B at the opposite side of the machine. In this way access to both bearings can be easily gained for purposes of maintainance or repair. The motor 35 is also detachably bolted to the associated arm 8B of the yoke by bolts 35A to enable ready removal for repair or maintainance.
[0018] In order to enable the attachment to be connected to the booms of different types of excavator, alternative mounting brackets 5 require to be provided. The bracket 5 is detachably bolted to the cross-piece 7 of the main frame by bolts 5A, whereby mounting brackets may be readily interchanged to suit different types of excavator to which the attachment may require to be fitted.
[0019] In use of the machine it is attached to the boom of an excavator or the like and a cutter drum or cutter discs suited to the job in hand are fitted to the main drive shaft 9. The excavator boom is then extended to place the attachment at some distance from the machine and the adjuster 23 is rotated to adjust the attachment to the desired cutting depth. The hydraulic motor 35 is then energised and the boom drawn towards the excavating machine. This causes the attachment to be drawn over the road surface running on its wheels 17 and 18 while the cutter drum 30 or disc digs into the surface and removes material by a milling or cutting action. Once the boom has been drawn towards the machine as far as possible the operation is repeated. Where a patch of road is to be removed the boom is traversed across the excavator and extended to act on a further strip of road surface adjacent to the strip previously milled. This procedure can be repeated as often as is required to remove a rectangular or other shaped patch of road surface. In the event the attachment is being used to form a trench, after the first strip of surface has been removed, the excavator is driven in the direction of the line of the trench, the boom extended to the end of the previously removed section and then drawn towards the excavator to remove a further section along the line of the trench.
[0020] When used for milling or planing the surface of a road the cutter drum is normally employed and cutting depths of the order of 2-to 4 inches may be attained. Where one or more cutter discs are employed these will generally cut to a greater depth of around 6 inches to enable the surface to be pulled away subsequently by an excavator bucket. The speed of operation and the nature of the cutting unit employed will depend on the hydraulic supply of the machine to which the attachment is fitted and on the nature of the operation to be carried out on the road surface.
[0021] By virtue of the arrangement described, areas of road surface may be removed for repair or trenching purposes by means of an attachment fitted to the boom of a conventional excavator rather than requiring the employment of a separate road planing or cutting machine. The construction of the attachment is such that it may be readily adapted to fit excavator booms of various different types and may be quickly and easily modified by fitting of different cutting units. Moreover the cutting units and the shaft on which they are mounted are readily accessible for repair or maintainance purposes.
[0022] Various modifications may be made without departing from the invention. For example alternative means of adjusting the cutting height may be employed and if desired the unit could be arranged to rotate about a vertical axis to enable accurate alignment to be attained under awkward operating conditions.
1. A road milling or cutting attachment adapted to be mounted on the boom of a hydraulic
machine, the attachment comprising a frame, a road surface cutting member rotatably
mounted in the frame and a low speed, high torque hydraulic motor directly coupled
to the cutting member.
2. An attachment according to claim 1 wherein said hydraulic motor is designed to
operate at a speed of 75 to 200 r.p.m.
'3. An attachment according to claim 1 or 2 wherein said cutting member comprises
a cylindrical drum the periphery of which is fitted with cutting picks whereby to
remove a strip of the road surface dpproximately equal in width to the width of the drum.
4. An attachment according to claim 1 or 2 wherein said cutting member comprises one
or more discs having picks mounted on their peripheries whereby to produce one or
more elongated cuts or slits in the road surface.
5. An attachment according to any preceding claim wherein said cutting member is formed
of at least two arcuate parts detachably secured to mounting flanges on a drive shaft
by detachable securing members, said frame having openings therein permitting access
to said securing members through the frame to enable the cutting members to be readily
mounted on and detached from the shaft.
6. A road milling or cutting attachment adapted to be mounted on the boom of a hydraulic
machine, the attachment comprising a frame, a drive shaft rotatably mounted in said
frame, and a road surface cutting member rotatably mounted on said shaft, said cutting
member comprising arcuate parts detachably secured to mounting flanges on said drive
shaft by detachable securing members, said frame having openings therein permitting
access to said securing members through the frame to enable the cutting members to
be readily mounted on and detached from the shaft.
7. An attachment according to any preceding claim wherein said frame incorporates
a yoke portion the arms of which support bearings in which said drive shaft is rotatably
mounted, one arm of said yoke being detachable to enable axial removal of the shaft
and permit access to the shaft bearings.
8. A road milling or cutting attachment adapted to be mounted on the boom of a hydraulic
machine, the attachment comprising a frame incorporating a yoke the arms of which
support bearings in which a drive shaft is rotatablj mounted, and a road surface cutting
member mounted on said shaft for rotation therewith, one arm of said yoke being detachable
to enable axial removal of said shaft and permit access to said bearings.
9. An attachment according to any preceding claim wherein said motor is detachably
mounted on said frame.
10. An attachment according to any preceding claim wherein said frame is mounted on
front and rear axle carriers mounted for relative pivotal movement about the axis
of rotation of said cutting member and rotatably supporting ground-engaging wheels,
means being provided for altering the angle between said carriers to vary the distance
of said axis of rotation from the ground and hence alter the working depth of said
cutting member.
11. An attachment according to claim 10 including arcuate guard members surrounding
said cutting member and mounted on respective ones of said axle carriers, said guard
members being slidably mounted one within the other.
12. An attachment according to any preceding claim wherein said frame includes alternatively
usable detachable mounting brackets to enable mounting of the attachment on different
hydraulic machines.
13. An attachment according to any preceding claim including guard means to prevent
lateral discharge of material removed from the road surface.
14. An attachment according to claim 13 wherein said duard means is adapted to slide
over the ground surface and is constrained against lateral movement.
15. A road milling or cutting attachment substantially as hert-inbefore described
with reference to the accompanying drawings.
16. A hydraulic machine fitted with an attachment according to any preceding claim.