GB2111118A - Releasable pivot assembly for tipping vehicles - Google Patents

Abstract

A releasable pivot assembly for tipping bodies of vehicles comprises in combination: a trunnion (1) having a cylindrical bearing section (2); a twin lugged bearer member (3) adapted and arranged to engage with the trunnion; and a hydraulically-actuated locking pin which is insertable through aligned apertures (4) in the lugs (5) of the bearer member, to prevent the bearer member from being withdrawn from engagement with the cylindrical bearing surface (2) of the trunnion (1). The bearer member (3) has between its twin lugs a curved abutment surface (6) with which it bears on the trunnion to permit it rolling contact axially along the cylindrical surface (2) of the trunnion (1). <IMAGE>

Description

SPECIFICATION Tipping vehicles This invention relates to haulage and tipping vehicles.

It is known to provide for a vehicle a tipping body capable of tipping not only rearwards but also to both sides. The load carrying box is raised for tipping by means of a cental ram mounted on a gimbal at its lower end and engaging the underside of the box through a universal joint, typically a ball and socket joint. The gimbal mounting is carried on a sub-frame attached to the vehicle chassis. The box is connected to this sub-frame by four pivots which are each "releasable joints in the following sense. The pivots are arranged two on each side, one pair at the front of the box and one pair at the rear. For rearward tipping, the front pair of pivots are released while the rear pair are maintained engaged so that they function as hinges when the ram is operated to raise the box its front end being lifted.If the box is to be tipped to the left, the left side pair of pivots are maintained engaged while the right hand pair are released. When the ram is operated, the right hand side of the box is lifted, the box tilting about the engaged left hand pair of pivots functioning as hinges. Conversely when the box is to be tilted to the right, the right hand pair of pivots are maintained engaged and the left hand pair is released to enable the left hand side of the box to be lifted by the ram with the box being tilted about the right hand pair of pivots which function as hinges.

All four pivots have to be both releasable and capable of being maintained engaged so that they can perform their hinge function. In the case of each front pivot this hinge function takes place about a single longitudinal axis. In the case of the rear pivots, the hinge function is performed about a longitudinal axis during sideways tipping, and about a transverse axis during tipping to the rear.

When the pivots are maintained engaged and performing their hinge function they may be subjected to large upward loadings when the ram is operated and in particular during the early part of its lifting stroke.

The present invention has for its object to provide a pivot capable of performing all these functions satisfactorily and which is simple, robust and cheap to make and fit.

The invention provides a releasable pivot assembly for this purpose which comprises three parts namely a cylindrical trunnion, and adapted and arranged to engage therewith, a twin lugged bearer member, the lugs of which are adapted to embrace the trunnion, and a locking pin which is insertable through aligned apertures in the lugs to prevent the bearer from being withdrawn from engagement with the trunnion, the bearer having between the lugs, a curved abutment surface which permits rolling contact with a cylindrical surface of the trunnion.

In one embodiment this surface is provided by a roller mounted between the lugs. In another version this curved abutment surface of the lug is shaped by initial casting or machining.

This curved abutment surface of the lug making rolling contact with the trunnion allows tilting in one direction, while tilting in the direction at right angles to the first, is catered for by rotation of the bearer about the trunnion.

Either the trunnions are disposed on the load carrying box of the tipper vehicle while the bearer members are fixed to the sub-frame attached to the vehicle chassis; or vice versa, the trunnions are on the sub-frame and the bearers are disposed on the underside of the box.

If all the four trunnions in the four pivot assemblies have parallel axes there may be movement allowed to the box relative to the sub-frame in a direction parallel to the axes of the trunnions. Preferably therefore, in the case of a pair of pivots at the front of the box, which functioning as hinges, only have to accommodate sideways tipping, their trunnions will have their axis disposed longitudinally of the vehicle, while the trunnions of the rear pair of joints will have their axes disposed in substantial alignment with one another, transversely of the vehicle.

More positive engagement of the bearers with the trunnions is obtained if the bearing surface of the trunnions is cylindrical and the tread of the curved bearing surface of the bearers is of a re-entrant U-shape in cross section so as to conform with the cylindrical trunnion for rolling contact therealong and for sliding contact therearound.

The trunnions may each be supported at one or both of their ends. The lugs will be sufficiently long that when the locking pins are inserted in the aligned apertures of the lugs, there is sufficient clearance to permit the bearer to perform its rolling movement as required on the trunnion. However the pins once inserted will prevent the bearer from being disengaged from the trunnion and will resist loading from the lifting ram which tends towards effecting such disengagement.

One example of a releasable pivot assembly is shown in the accompanying drawings.

Figure 1 is a perspective view of a bearing number with twin apertured lugs.

Figures 2 and 3 are respectively, an end and a side view showing the bearing number of Fig. 1 engaged with and resting on a trunnion.

Figures 4 and 5 are partly sectional views of locking pin assenblies which can be carried on a bearing member as depicted in Fig. 6.

Figure 7 shows diagrammatically a hydrau lic circuit for selectively locking and unlocking a pair of front pins and a pair of rear pins at the four corners of a tipping container body.

Referring now to the drawings and first to Figs. 1 to 3, there is here illustrated a releasable pivot assembly which will constitute one of four such assemblies provided on a tipping body of a vehicle. The pivot assembly shown in Figs. 1 to 3 comprise essentially a trunnion 1 having a cylindrical bearing section 2, a twin lugged bearer member 3 adapted and arranged to engage with the trunnion 1, and a locking rin not shown in these drawings but which is selectively insertable into or disengageable from the aligned apertures 4 in the lugs 5 of the bearer member 3 to prevent the bearer member 3 from being withdrawn from engagement with the cylindrical bearing section 2 of the trunnion 1.The bearer member has between its twin lugs 5 a curved surface 6 with which it bears on the trunnion to permit it rolling contact axially along the cylindrical surface of the trunnion. Tilting of the bearer member is also permitted in the direction circumferentially of the cylindrical surface of the trunnion.

As will be clear, four such trunnions may be provided either disposed on the load carrying box of the tipper vehicle with the bearer member being correspondingly disposed on a sub frame attached to the vehicle chassis or vice versa, the four trunnions may be provided on the sub frame and the bearers may be disposed on the underside of the tipping box.

All four pivots require to be both releasable, or on the other hand deliberately maintained engaged so that theyd can perform a hinge function. Preferably in the case of front mounted pivots, this hinge function takes place about an axis which is generally at right angles to the fore and aft longitudinal axis of the vehicle. In the case of the rear mounted pivots, the hinge functon is preferably performed about the longitudinal axis when tipping and about a transverse axis when tipping to the rear. Thus it is preferably the case that the front trunnions have their axes at right angles to the disposition of the axes of the rear trunnions, this arrangement affording rigidity to the mounting of the body when all the bearer members are locked in engagement with their respective trunnions.

A spring biased hydraulically actuated locking assembly for engaging and disengaging a locking pin from aligned apertures 4 in a bearer member 3 is illustrated in Figs. 4 to 6.

In Figs. 4 and 5, the locking pin 11 is biased by means of a spring 1 2 towards the position where it extends through aligned apertures 4 in a bearer member 3.

The pin has a head 1 3 which may be backed by a seal ring 1 4 interposed between the head and a cup 1 5 housing the spring 12, these elements all being slidable within a cylinder 16. The head 13, the sealing ring 14 and the cup member 1 5 together constitute a piston movable in the cylinder 1 6 which piston may move to the right or the left of the drawings on the introduction into the cylinder of hydraulic fluid under pressure; inlet ports being shown at 17 in Fig. 4 and 18 in Fig. 5.

Such a cylinder 1 6 will be carried on a flange 1 9 and, as shown in Fig. 6, such flange 1 9 may be bolted to a leg 5 of a bearing member 3.

Referring now to Fig. 7 there is here shown diagrammatically a circuit for hydraulically operating a pair of front pins 21 and 22 which are normally biased to be in an unlocked condition, and a pair of rear pins 23 and 24 which are normally biased to be in a locked condition. In such a circuit the hydraulic pressure may be employed to move the pins against biasing springs. For tipping rearwards, the rear pins 23 and 24 will remain in their locked position when the system may be maintained under negative or low pressure.

When it is desired to tip the body to the left or to the right, a valve of an hydraulic pressure system will be operated to bring pressure to bear in diagonally opposite cylinders to activate a front pin into a locking position and to deactivate a rear pin to an unlocked position, such rear pin being on the opposite side of the body of the activated front pin. Thus, for example, for tipping in one direction pressure will be supplied to the pins 21 and 24 while for tipping to the opposite side, pressure will be applied to the pins 22 and 23. For rearward tipping the pins 21 and 22 will be in the unlocked position and the pins 23 and 24 will be locked. When the vehicle tipping body is to be in motion then all pins will be locked.

Safety interlocks may be provided in the hydraulic circuit arrangement in order to prevent operation of the lifting ram except when selective combinations of locking pins are engaged. For example, the ram may be prevented from operating when diagonally opposite pins are not in their locking position so as to render the releasable joints at diagonally opposite corners of the load carrying box, hingably inoperative.

Reverting to Figs. 1 to 3, it will be appreciated that the trunnion 1 may be supported at one or both of its ends. The lugs 5 will be sufficiently long so that when the locking pins are inserted in the aperture there is sufficient clearance to permit the bearing to perform its rolling movement as required. However, the pin, once inserted, will prevent the bearer member 3 from disengaging with its trunnions and furthermore these pins will resist upward loading which will be exerted by the lifting ram.

The curved surface 6 of the bearing member 3 may be constituted by a roller mounted for rotation between the twin lugs 5.

Claims (5)

1. A releasable pivot assembly for tipping bodies of vehicles comprising in combination: a trunnion having a cylindrical bearing section; a twin lugged bearer member adapted and arranged to engage with the trunnion; and a locking pin which is insertable through aligned apertures in the lugs of the bearer member, to prevent the bearer member from being withdrawn from engagement with the cylindrical bearing surface of the trunnion, and wherein the bearer member has between its twin lugs a curved abutment surface with which it bears on the trunnion to permit it rolling contact axially along the cylindrical surface of the trunnion.

2. A pivot assembly according to claim 1 and wherein the trunnion is supported at both ends.

3. A pivot assembly according to claim 1 and including spring means for biasing the pin into or out of engagement with the aligned recesses in the lugs.

4. A pivot assembly according to claim 1 and wherein the curved abutment surface is constituted by a roller mounted for rotation between the lugs.

5. A pivot assembly according to claim 1 and substantially as described with reference either to Figs. 1 to 3, or to Figs. 4 to 6, or to Fig. 7 of the accompanying drawings.