GB2289036A

GB2289036A - Work vehicle

Info

Publication number: GB2289036A
Application number: GB9408796A
Authority: GB
Inventors: David John Bowes Brown
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 1994-05-04
Filing date: 1994-05-04
Publication date: 1995-11-08
Also published as: IT1279185B1; ITTO950353A0; ITTO950353A1; GB9408796D0

Abstract

A work vehicle has a boom (3), including a tool (4, 5) at one end of the boom, and with the boom pivotally connected at the other end to the vehicle. A support, including a pair of spaced posts (8), supports and restricts lateral movement of the boom in its lowered position. The boom (3) is provided with replacement wear pads (11), which reduces friction between the boom and the support and protects the boom from damage. Preferably the pads (11) are mounted via shims. Preferably the posts and pads have chamfered surfaces to act as guides during lowering. <IMAGE>

Description

WORK VEHICLE The present invention relates to a work vehicle having a boom which is provided, in use, with a tool, such as a hook, bucket, or load carriage at one end, and which is pivotally connected at the other end to the vehicle body for raising and lowering movement. Such a vehicle is hereinafter referred to as of the kind described.

During vehicle travel or operations such as digging, the boom is subjected to lateral forces, which place undue stress on the boom pivot and chassis of the vehicle. This is particularly the case when the vehicle is travelling over uneven ground with the boom lowered and with a load, such as a bucketful of earth, carried by the free end of the boom.

According to the present invention, a work vehicle of the kind described is provided with a support fixed to the vehicle chassis at a location remote from the pivotal connection for supporting and restricting lateral movement of the boom, at least when the boom is in a lowered position.

Lateral movement of the boom is thus restricted so that the stresses on the boom, pivot and chassis are reduced.

The support is preferably provided by two upstanding posts, one on each side of the boom.

To reduce friction between the boom and support, and to protect the boom from damage when it abuts the support, a pair of wear pads are preferably provided, one on each side of the boom, and mounted on either the boom or the support. It is marginally preferable to provide the wear pads on the boom, as this avoids unsightly grease smears on the boom when it is raised.

To prevent interference between the wear pads and the support when the boom is lowered, a clearance is preferably provided between each wear pad and the support. A minimal clearance of less than 5mm is envisaged.

In order to further allow for any slight misalignment between the boom and support, a chamfered surface is preferably provided to guide the boom into engagement with the support. Thus, when the posts are provided on the chassis, and the wear pads are provided on the boom, at least the lower end of each wear pad or the upper end of each post may be chamfered.

The wear pads are preferably releasably mounted so that they can be readily replaced. As a wear pad is worn down, shims of various thicknesses can be mounted behind the wear pad so that the required clearance is always maintained.

The invention is particularly applicable on a vehicle having an engine module and an operator cab disposed on opposite sides of the central longitudinal axis of the vehicle with a gap therebetween, and wherein the boom is pivotally mounted adjacent to the rear of the vehicle about an axis transverse to the longitudinal axis of the vehicle so that in its lowered position the boom is substantially horizontal and lies in the gap between the engine module and the operator cab and is out of the line of sight of the operator in the cab. Such a vehicle is disclosed in GB-A2268155. In this case, the support is preferably located forwardly of the engine module and operator cab.

An example of a work vehicle constructed in accordance with the present invention will now be described with reference to the accompanying drawings in which: Fig. 1 is a side view of the vehicle; Fig. 2 is a plan view of the vehicle; Fig. 3 is a transverse section through the vehicle showing the support; Fig. 4 shows the mounting of a wear pad to the boom; and Fig. 5 is a view of the opposite side of the vehicle to that shown in figure 1, with the boom slightly raised.

The work vehicle shown in figures 1, 2 and 5 comprises a chassis which has a cab 1 and engine module 2 respectively disposed on opposite sides of a boom 3 when, in a lowered position, the boom lies along a central longitudinal axis of the vehicle. At one end of the boom 3, a tool such as a bucket 4 or fork carriage 5 is pivotally mounted. The opposite end of the boom 3 is pivotally mounted at a transverse pivot 6 to the chassis.

The boom 3 is raised and lowered about the pivot 6 by a hydraulic jack (not shown), and the angle of the tool 4,5 relatively to the boom is varied by a pair of hydraulic jacks 7.

A pair of support posts 8 are welded to the chassis, one on each side of the boom 3, in a position slightly forwards of the cab 1 and engine module 2.

Facing each support post 8 is a wear pad 11 which is mounted to a side plate 12 of the boom 3 so as to have a clearance of approximately 3mm with respect to the post 8.

The wear pads are made of an oil impregnated nylon such as Nylacast Oilon (Registered Trade Mark). As shown in figure 4, each wear pad 11 is provided with a pair of countersunk holes 13 through which the wear pad 11 is bolted to the side plate 12 by bolts 14. Between the wear plate 11 and side plate 12 is at least one shim 15 which is selected to provide the required clearance between the wear pad 11 and the post 8. The lower end of the wear pad 11 is provided with a chamfer 16 and the upper end of the support post 8 is similarly provided with a chamfer 17.

In use, when the work vehicle is travelling, when the bucket 4 is digging, or when the fork 5 is picking up a load from the ground, the boom 3 is in its lowered positioned in which it is received in the gap between the cab 1 and engine module 2. During such operations it will be subjected to lateral forces, for example owing to vibrations when travelling, or loads on the tool 4,5. If left unsupported, this may cause damage to the boom 3, pivot 6 or the vehicle chassis. The provision of the support posts 8 and wear pads 11 restricts any lateral movement of the boom 3 and therefore reduces the stresses on the boom 3, pivot 6 and the vehicle chassis.

As can be seen from figure 5, the boom is supported while in a lowered positioned, in this case at an elevational angle of up to 6.30. When the boom 3 is lowered below this position, the wear pads 11 are positioned between the support post 8 and restrict the boom movement. When the boom 3 is lowered into such a position, any misalignment of the boom, is readily accommodated by a combination of the clearance between the support post 8 and wear pads 11 and the chamfers 16,17 provided on the wear pads and support posts.

Over time, the wear pads 11 will wear down so that the clearance between a wear pad and a support post 8 is increased to such a level that the support does not work effectively. In this case, the wear pad 11 is removed by removing the bolts 14, and an additional shim 15 is placed between the wear pad 11 and the boom 3. This process can be repeated several times, after which the wear pad 11 can be replaced.

Claims

1. A work vehicle having a boom with a tool at one end and which is pivotally connected at the other end to the vehicle body for raising and lowering movement, and a support fixed to the vehicle chassis at a location remote from the pivotal connection for supporting and restricting lateral movement of the boom, at least when the boom is in a lowered position.

2. A work vehicle according to claim 1, wherein the support comprises two upstanding posts, one on each side of the boom.

3. A work vehicle according to claim 1 or claim 2, wherein a pair of wear pads are provided, one on each side of the boom, and mounted on either the boom or the support.

4. A work vehicle according to claim 3, wherein a clearance is provided between each wear pad and the support.

5. A work vehicle according to claim 3 or claim 4, wherein the wear pads are releasably mounted with shims mounted behind them.

6. A work vehicle according to any one of the preceding claims, wherein a chamfered surface is provided to guide the boom into engagement with the support.

7. A work vehicle according to any one of the preceding claims, wherein the vehicle comprises an engine module and an operator cab disposed on opposite sides of the central longitudinal axis of the vehicle with a gap therebetween, and wherein the boom is pivotally mounted towards the rear of the vehicle about an axis transverse to the longitudinal axis of the vehicle so that in its lowered position the boom is substantially horizontal and lies in the gap between the engine module and the operator cab and is out of the line of sight of the operator in the cab.