GB2231859A - A jack for a vehicle - Google Patents

Abstract

A jack for a vehicle is provided. The jack (1) including at least two limbs (2, 3) pivotally connected together, means (13) to effect relative pivotal movement of the limbs, a load support (10) which is pivotally attached to a free end (12) of one of the limbs (2) and may be raised and lowered by pivotal movement of the limbs and a control mechanism (11) extending between the load support (10) and the other (5) of the at least two limbs to provide pivotal control of the load support about said attachment (12) during raising and lowering of the load support. The mechanism (11) comprises a resilient metal rod passing through a bush (16). <IMAGE>

Description

A JACK FOR A VEHICLE This invention relates to jacks for vehicles of the type having 2 or more limbs pivotally connected together such that relative pivotal movement of the limbs will raise and lower a vehicle supported on the jack.

In order to raise a vehicle having a large ground clearance using a jack, it is normally necessary to extend the jack over a considerable part of its travel before a load support on the jack engages the jacking point of the vehicle. It is difficult, when the jack is folded, accurately to judge where to place the jack on the ground to ensure engagement of the load support with the jacking point when the jack is extended. It is therefore often desirable in these circumstances to attach the load support to the jacking point of the vehicle before winding down the jack to meet the ground, as a more precise location of the jack is achieved, also the procedure is less fiddly.

In order for the jack to engage the ground directly underneath the jacking point however, orientation between the load support and a ground contact point of the jack must be maintained.

According to the present invention there is provided a jack for a vehicle, the jack including at least two limbs pivotally connected together, means to effect relative pivotal movement of the limbs, a load support which is pivotally attached to a free end of one of the limbs and may be raised and lowered by pivotal movement of the limbs and a control mechanism extending between the load support and the other of the at least two limbs to provide pivotal control of the load support about said attachment during raising and lowering of the load support.

Control of the load support during pivotal movement thereof about its supporting limb of the jack is thus provided.

Preferably the control mechanism includes an elongate member extending between the load support and a position fixed along the length of the other of the at least two limbs.

A simple means of controlling pivotal movement of load support is thus provided.

The elongate member may engage the load support to be in constant alignment therewith and pivotally engages the other of the at least two limbs at said fixed position.

Preferably the elongate member is affixed to the load support and slidably engages a bush pivotally attached to the other of the at least two limbs.

The axis of the elongate member may pass normally through the pivot axis of the load support.

The control mechanism may be sufficiently resilient to permit limited pivotal deflection of the load support from the controlled pivotal movement thereof. In a preferred form the elongated member is a rod of resilient material.

Tilting cf the vehicle body during raising thereof by the jack may thus be accommodated.

Where the jack is of the pantograph type having four limbs arranged in quadrilateral form, ground contacting means and the load support may be positioned respectively adjacent diammetrically opposed pivots of said quadrilateral, the load support being pivotally attached to a length of the one limb extending outside the quadrilateral, and the ground contacting means may be an extension of the limb pivotally connected to the end of the first limb remote from the load support.

The present invention finds particular merit in this embodiment where, by careful arrangement of the geometry of the jack, the ground contact means may be arranged to lie directly beneath the load support at all times during raising and lowering of the jack.

The load support may be attachable to part of the vehicle being raised in order to ensure correct location of the jack with respect to the vehicle.

The present invention will now be more particularly described by way of example with reference to a preferred embodiment thereof as illustrated in the accompanying drawing of which: Figure 1 is a schematic side elevation of the jack according to the invention, and Figure 2 is an enlarged detail view in perspective of the upper portion of the jack of Figure 1.

Referring to the drawing, a jack 1 comprises four limbs 2, 3, 4, 5 pivotally connected together at pivots 6, 7, 8, 9, a load support 10, a control mechanism 11 to control pivotal movement of the load support 10 about its pivot 12 and means to effect relative pivotal movement of the limbs. This means to effect relative pivotal movement is in the form of a hand cranked threaded spindle 13 arranged to draw together pivots 7 and 9 on being turned in one sense and to extend apart said pivots upon being turned in the opposite sense.

The load support 10 is mounted on its pivot 12 on a free end of a length 14 of a limb extending from limb 2 outside a quadrilateral formed by the limbs 2, 3, 4, 5.

Ground contacting means is an extension 15 to limb 3.

The control mechanism 11 includes a bush 16 pivotally mounted to the limb 5 and defining an aperture 17 therethrough, also an elongate member in the form of a metal rod 18 attached to the load support 10 and arranged such that its axis passes normally through the axis of the pivot 12, the rod 18 slidably engaging the bush 16 through the aperture 17.

The jack 1 supports a vehicle 19 and the load support 10 has a "T" shape slidable to engage a channel (not shown) at the jacking point of the vehicle 19 so as to enable the jack to be attached to the vehicle.

It will be appreciated that during relative pivotal movement of limbs 2 and 5 the metal rod 18 will slide through the bush 16 and the load support 10 will rotate in a controlled manner about its pivot 12; this pivotal rotation being controlled by the constant alignment of the load support 10 with the bush 16.

If the distances between pivot 6 and pivot 12, pivot 6 and the bush, and pivot 8 and the free end of the extension 15 are respectively all equal, and if the sides of the quadrilateral are all equal, the alignment of the load support with the end of the extension 15, which is in contact with the ground, will be constant throughout raising and lowering of the jack.

Variations in the geometry (ie the relative lengths of the limbs) of the arrangement as shown in the drawing may equally produce substantially the above mentioned alignment of load support and ground contact point. It will be appreciated that other desired alignments may be achieved by suitable "tuning" of the geometry of the jack. For example, it may be desired to omit the extension 15 to limb 3 so that contact with the ground is made effectively in the region of the pivot 8. In this case the geometry may be arranged such that alignment of the load support with the pivot 8 remains substantially constant. A pivotable ground support member may attached to pivot 8 for such an arrangement.

It will be appreciated from the foregoing that a simple and effective means of controlling pivotal movement of the load support of the jack is provided by the invention so that the jack may be attached to the jacking point of the vehicle before being extended to meet the ground at a desired position beneath the jacking point.

Claims (11)

1. A jack for a vehicle, the jack including at least two limbs pivotally connected together, means to effect relative pivotal movement of the limbs, a load support which is pivotally attached to a free end of one of the limbs and may be raised and lowered by pivotal movement of the limbs and a control mechanism extending between the load support and the other of the at least two limbs to provide pivotal control of the load support about said attachment during raising and lowering of the load support.

2. jack as in claim 1, wherein the control mechanism includes an elongate member extending between the load support and a position fixed along the length of the other of the at least two limbs.

3. A jack as in claim 2, wherein the elongate member engages the load support to be in constant alignment therewith and pivotally engages the other of the at least two limbs at said fixed position.

4. A jack as in claim 3, wherein the elongate member is affixed to the load support and slidably engages a bush pivotally attached to the other of the at least two limbs.

5. A jack as in claim 3 or 4, wherein the axis of the elongate member passes normally through the pivot axis of the load support.

6. A jack as in any preceding claim, wherein the control mechanism is sufficiently resilient to permit limited pivotal deflection of the load support from the controlled pivotal movement thereof.

7. A jack as in claim 6, wherein the elongate member is a rod of resilient material.

8. A jack as in any preceding claim, wherein the jack is of the pantograph type having four limbs arranged in quadrilateral form, ground contacting means and the load support being positioned respectively adjacent diammetrically opposed pivots of said quadrilateral, the load support being pivotally attached to a length of the one limb extending outside the quadrilateral.

9. A jack as in claim 8, wherein the ground contacting means is an extension of the limb pivotally connected to the end of the first limb remote from the load support.

10. A jack as in any preceding claim, wherein the load support is attachable to part of the vehicle being raised.

11. A jack for a vehicle substantially as described herein with reference to the accompanying drawings.