Earth-moving machine

Abstract: An earth-moving machine is provided with a first actuating cylinder (13) for pivotably moving a lifting arm (5) around a pivot shaft (9), and with a second actuating cylinder (23), for maintaining a loading unit (18) in a pre-determined angular position during oscillation of the lifting arm (5). The first (13) and the second actuating cylinder (23) are disposed adjacent and parallel to one another, and are mechanically connected to one another in order to increase the resistance of the second actuating cylinder (23) to the load generated thereon by the lifting arm (5).

Description: The present invention relates to an earth-moving vehicle and more particularly to a machine of the type comprising a frame; a lifting arm which is fitted such as to rotate relative to the frame itself and around a first shaft; and a loading unit, which is fitted such as to rotate relative to the lifting arm around a second shaft, which is substantially parallel to the said first shaft. The machine additionally comprises a first actuating cylinder, which imparts oscillation to the lifting arm around the first shaft. An orienting device further is provided for maintaining the said loading unit in a predetermined angular position during oscillation of the lifting arm; said orienting device comprising a second and a third actuating cylinder, which are connected to one another by means of a hydraulic circuit. Such a machine is shown for instance in FR-A-2600317. The said first and second actuating cylinders have respective longitudinal shafts which are substantially parallel to one another and are disposed adjacent to one another. Both cylinders are positioned below the lifting arm and are both hinged to the frame and to the lifting arm itself, at respectively a third and fourth shaft, which are substantially parallel to the first and second shafts. The third actuating cylinder is accommodated inside an end portion of the lifting arm which projects downwards from, and is disposed transversely relative to, the lifting arm itself, and is pivoted both on the lifting arm and on the loading unit. During oscillation of the lifting arm around the first shaft, the second actuating cylinder is actuated as a result of the movement of the first actuating cylinder. In turn, and by means of the said hydraulic circuit, the second actuator controls the functioning of the third actuating cylinder, and thus, the angular position of the loading unit around the second shaft. Since the end portion of the lifting arm must have dimensions which are predetermined so as not to impede the view of the loading unit by an operator located in the driving cab of the vehicle, the dimensions of the third actuating cylinder are also predetermined and at least limited to dimensions which are adapted to said end portion. In other words, the cross-section and length of the third actuating cylinder have a limit value, which in turn determines the capacity of oil which must be contained inside the said hydraulic circuit. In addition, when, on the one hand, the maximum amplitude of oscillation of the lifting arm around the first shaft has been determined, and, on the other hand, the distance between the said third and fourth shafts have been determined, the length of the first and of the second actuating cylinders are equally determined. It will be apparent from the foregoing that, when the length of the second actuating cylinder and the capacity of the hydraulic circuit have been determined, the cross-section of the second actuating cylinder itself is also determined. Consequently, the conventional vehicles of the above-described type have some disadvantages, the main one of which being that, when the amplitude of the oscillation of the lifting arm, and the distance between the said third and fourth shafts exceed pre-determined values, the calculated cross-section of the second actuating cylinder would become relatively reduced. As a consequence, such an actuating cylinder could be bent under and/or be damaged by the load generated on the second actuating cylinder itself by the lifting arm. Hitherto, the above problem has been solved in different ways. In one embodiment, the cross-section of the second actuating cylinder, although calculated as needing to be reduced, nevertheless is chosen to be equal to the cross-section of the first actuating cylinder. This not only results in a more expensive cylinder, but also requires the third actuating cylinder to be proportionally larger, again increasing the cost and complicating the assembly thereof to the end portion of the lifting arm in a manner not to obstruct the view of the vehicle operator. In another embodiment, the length of the second actuating cylinder is reduced, whereby its cross-section proportionally may be increased. Consequently however, in this solution, the second actuating cylinder no longer fits on the pivot mountings connecting the first actuating cylinder to the lifting arm and the vehicle frame, thereby requiring additional pivots to be provided. It is therefore an object of the present invention to provide an earth-moving machine which is free from the above-described disadvantages. According to the present invention, an earth-moving machine, as claimed in Claim 1, is provided. The present invention will now be described further, by way of example, with reference to the accompanying drawings, which illustrate a non-limiting embodiment of the invention, in which: Figure 1 is a side view, with parts removed for sake of clarity, of a preferred embodiment of the vehicle according to the present invention; and Figure 2 is a front view, with enlarged parts, of the vehicle in Figure 1. With reference to Figures 1 and 2, the reference number 1 indicates as a whole an earth-moving vehicle comprising a frame 2 which can support two axles which are of a known type and are not illustrated. The two axles have respective shafts 3 which are substantially parallel to one another, and are each provided with a respective pair of traction wheels 4, fitted co-axially to the corresponding shafts 3. The machine 1 additionally comprises a lifting arm 5 of a telescopic type, a driving cab 6, which is disposed laterally relative to the arm 5, and an engine which is of a known type and is not illustrated. The engine is provided to propel the vehicle 1, and is disposed on the opposite side of the cab 6 relative to the arm 5. The arm 5 comprises a lower portion 7 which is hinged on the frame 2, such as to oscillate relative thereto under the action of an actuating device 8, around a shaft 9 provided substantially parallel to the shafts 3. The arm further comprises an upper portion 10, which is mounted such as to slide along the portion 7 under control of an actuating cylinder 11. A portion 12, which is supported by the upper portion 10, extends downwardly and transversely relative thereto. The device 8 comprises an actuating cylinder 13 of the hydraulic type, having a longitudinal axis 14, which is substantially transversal to the shaft 9, and is interposed between the frame 2 and an intermediate point of the portion 7 at the bottom side thereof. The cylinder 13 is hinged to the frame 2 at one of its free ends, in order to pivot, relative to the frame 2, around a shaft 15 having a fulcrum substantially parallel to the shaft 9. The free end of the rod 16 of the cylinder 13 is hingeably connected to the portion 7, such as to pivot, relative to the arm 5, around a shaft 17 which has a fulcrum substantially parallel to the shaft 15. The arm 5 is additionally provided with a loading unit 18, substantially L-shaped and comprising a vertical back-plate 19 and horizontally extending forks 21. The vertical plate 19 is hingeably attached to the portion 12 for pivotal movement around a shaft 20, which is provided parallel to the shafts 15 and 17. The forks 21 are connected to the lower end of the back-plate 19 and extend perpendicular thereto. The vehicle 1 additionally comprises an orienting device 22, which is operable to oscillate the unit 18 around the shaft 20, in a manner to maintain the forks 21 substantially parallel to the ground during pivotal movement of the arm 5 around the shaft 9. The device 22 comprises a hydraulic double-acting actuating cylinder 23, which is disposed beneath the lower portion 7 in a position adjacent to the cylinder 13, with its longitudinal axis 24 substantially parallel to the axis 14 of the cylinder 13. The cylinder 23 is hingeably attached to the frame 2 at one of its free ends, in order to pivot relative to the frame 2 around the shaft 15, whereas the free end of the cylinder rod 25 is connected to the lower portion 7 by means of the pivot shaft 17. From the foregoing, it will be appreciated that the cylinder 23 has a length which is substantially identical to the length of the cylinder 13, and a diameter which, when added to the diameter of the cylinder 13, approximates by default a width of the portion 7 measured parallel to the shafts 15 and 17. The orienting device 22 additionally comprises a further hydraulic double-acting actuating cylinder 26, which is pivotably connected at one of its free ends, through a pivot shaft 27, to the portion 12 for relative movement thereto. The cylinder 26 comprises a rod 28, of which the free end is attached to a pivot shaft 29 operatively connected to the back-plate 19. The pivot shafts 27 and 29 are substantially parallel to the shafts 15 and 17. Each rod 25 and 28 is shaped such as to define, inside the corresponding cylinder 23 and 26, two chambers with a variable volume, not illustrated. The orienting device 22 finally comprises a re-circulation hydraulic circuit 30, which in turn comprises two hydraulic hoses 31, 32, each of which connects one of the said chambers of the cylinder 23 hydraulically to one of the chambers of the cylinder 26. In use, axial displacement of the rod 25 is controlled by the axial displacement of the rod 16, and in turn, and by means of the circuit 30, controls the axial displacement of the rod 28, and thus the angular position of the unit 18 around the shaft 20. Finally, the vehicle 1 comprises a connection device 33, which connects the two cylinders 13 and 23 mechanically to each other, such as to improve the resistance of the cylinder 23 to the load generated thereon by the lifting arm 5. The device 33 comprises a pair of tubular bushes 34 of which one is welded onto the outer surface of the cylinder 13 and the other onto the outer surface of the cylinder 23. The bushes 34 are disposed in a position such as to face each other and to be coaxial relative to a longitudinal axis 35, which is substantially parallel to the axes 14 and 24. A clamping bolt 36, which engages the two bushes 34, is provided in a position substantially coaxial to the axis 35. The connection to the cylinder 13 reinforces the weaker cylinder 23 and avoids intolerable bending under the load of the lifting arm 5.

Claims: Material handling vehicle comprising : a frame (2); a lifting arm (5), connected to the frame (2) for pivotal movement around a first shaft (9) ; a loading unit (18), operatively connected to the lifting arm (5) for pivotal movement around a second shaft (20), substantially parallel to the said first shaft (9); a first actuating cylinder (13), operable to pivot said lifting arm (5) around said first shaft (9) and having a longitudinal axis (14); and an orienting device (22) for maintaining said loading unit (18) in a pre-determined angular position during pivotal movement of said lifting arm (5); said orienting device (22) comprising a second actuating cylinder (23) having a longitudinal axis (24) which is substantially parallel with the longitudinal axis (14) of said first actuating cylinder (13); both said first and second actuating cylinders (13, 23) being hingeably connected to said frame (2) and said arm (5) respectively at a third (15) and a fourth (17) shaft, which are substantially parallel to one another and to the said first (9) and second (20) shafts; and characterized in that the vehicle, in addition to the mechanical connections between the first (13) and second (23) cylinders established through the third (15) and fourth (17) shafts, further comprises connecting means (33) for mechanically connecting in a stabilising manner said first (13) and second (23) actuating cylinders to one another, so as to increase the resistance of said second actuator (23) to the load generated thereon by said lifting arm (5). A vehicle according to claim 1, characterized in that said connecting means (33) comprise : at least two tubular elements (34), which are provided substantially coaxial relative to one another respectively on said first (13) and second actuating cylinders (23); and screw means (36) for fixing said at least two tubular elements (34) relative to one another. A vehicle according to claim 2, characterized in that said screw means (36) comprise a bolt. A vehicle according to claim 2 or 3, characterized in that said tubular elements (34) present a further longitudinal axis (35), which is substantially parallel to said longitudinal axes (14, 24) of said first and second actuating cylinders (13, 23). A vehicle according to any of the preceding claims, characterized in that said first and second actuating cylinders (13, 23) are disposed adjacent to one another underneath said lifting arm (5). A vehicle according to any of the preceding claims, characterized in that said first and second actuating cylinders (13, 23) have respectively a first and a second diameter; the sum of said first and second diameters approximating the width of said lifting arm (5), measured parallel to said first shaft (9). A vehicle according to any of the preceding claims, characterized in that said first and second actuating cylinders (13, 23) are hydraulically operated. A vehicle according to any of the preceding claims, characterized in that said orienting device (22) additionally comprises : a third hydraulic actuating cylinder (26) hingeably connected on the one hand to said lifting arm (5) and on the other hand to said loading unit (18), and a hydraulic circuit (30) connecting said second actuating cylinder (23) to said third actuating cylinder (26). A vehicle according to any of the preceding claims, characterized in that said lifting arm (5) is telescopic. A vehicle according to any of the preceding claims, characterized in that said second actuating device (23) is dimensioned such that, as a separate unit, it would be unable to withstand the loads of the lifting arm (5) imposed thereon during normal operation of said vehicle (1). A vehicle according to any of the preceding claims, characterized in that the vehicle (1) additionally comprises a driving cab (6), and propulsion means for movement of the vehicle; said propulsion means and said driving cab (6) being disposed on the frame (2) on opposite sides of said lifting arm (5).

Inventors: CONTOLI PIERCARLO, RAGAZZINI CORRADO, CONTOLI, PIERCARLO, RAGAZZINI, CORRADO
Applicants: CNH ITALIA SPA, CNH ITALIA S.P.A.
Application year: 2001
Main classification: E02F3
IPC codes: B66F9, E02F3