GB2244975A

GB2244975A - Jack for a motor vehicle

Info

Publication number: GB2244975A
Application number: GB9013259A
Authority: GB
Inventors: Mark James Arthur Baker
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1990-06-14
Filing date: 1990-06-14
Publication date: 1991-12-18
Also published as: GB9013259D0

Abstract

A jack for a motor vehicle comprises an expandable and collapsible jacking mechanism (10, 12, 14, 16, 18), a base plate (22) pivotably connected to the lower end of the jacking mechanism for supporting the jacking mechanism on the ground and a support plate (24) connected to the upper end of the jacking mechanism for engaging the body of the vehicle, the jacking mechanism being capable of pivoting relative to the ground about an axis parallel to the longitudinal axis of the vehicle in order to follow lateral movements of the vehicle body during jacking. The base plate (22) is mounted on the lower end of the jacking mechanism in a manner which permits a limited degree of pivotal movement of the jacking mechanism relative to the base about a transverse axis to enable the jacking mechanism to follow forward and backward movement of the vehicle body. The mounting may comprise a rubber annulus (30c) between metal sleeves (30a, 30b). A coil spring (34) may be employed to spring load the base plate (22) to a rest position. <IMAGE>

Description

JACK FOR A MOTOR VEHICLE The present invention relates to a jack for a motor vehicle.

When a motor vehicle is raised by means of a jack, for example for the purpose of wheel replacement, there is a tendency for the vehicle to move and a consequent risk of the vehicle rolling off the jack. As one side of the body is raised, the vehicle pivots about the wheels on the other side of the vehicle and causes the jack to tilt within the plane normal to the longitudinal axis of the vehicle.

In order to avoid this problem, it is known to design a jack so that it may pivot relative to the ground and relative to the vehicle without collapsing and without sliding away from under the vehicle.

An example of such a jack is shown in Figure 1 and is a type of scissor jack. Four arms 10, 12, 14 and 16 are connected to one another in the form of a parallelogram.

A screw threaded shaft 18 which can be turned manually by means of a handle 20 is journalled for rotation within a bearing at one corner of the parallelogram and engages a nut at the opposite corner of the parallelogram so that as the shaft 18 is turned, the parallelogram is collapsed and expanded to lower and raise the jack.

A base plate 22 is pivotably mounted on the lower end of an extension of the arm 10 and a support plate 24 is pivotably connected to the upper end of an extension of the arm 12. The support plate 24 can be designed for connection to the vehicle body in a variety of ways, the illustrated support plate 24 having a recess 28 for receiving a ridge or seam projecting from the body to prevent the support plate from moving transversely when the weight of the vehicle is supported by the jack.

Because of the shaping of the lower end of the arm .u, it interferes with the base plate if it is pivoted anticlockwise, as viewed in Figure 1. However, as the jack is raised, the arm 10 can pivot clockwise, as viewed, so that the support plate 24 remains parallel to the base 22 and vertically above the base plate 22 thereby avoiding the danger of the jack collapsing or sliding away from under the vehicle.

While the jack of Figure 1 effectively copes with the inevitable transverse movement of the vehicle body as it is raised, it makes no allowance for possible movement of the vehicle along its longitudinal axis, that is to say parallel to its direction of travel.

The present invention seeks to provide a jack in which some movement of the vehicle along its direction of travel can be taken up without causing the base plate of the jack to tilt off the ground.

According to the present invention, there is provided a jack for a motor vehicle comprising an expandable and collapsible jacking mechanism, a base plate pivotably connected to the lower end of the jacking mechanism for supporting the jacking mechanism on the ground and a support plate connected to the upper end of the jacking mechanism for engaging the body of the vehicle, the jacking mechanism being capable of pivoting relative to the ground about an axis parallel to the longitudinal axis of the vehicle in order to follow lateral movements of the vehicle body during jacking, and wherein the base plate is mounted on the lower end of the jacking mechanism in a manner which permits a limited degree of pivotal movement of the jacking mechanism relative to the the base about a transverse axis to enable the jacking mechanism to follow forward and backward movement of the vehicle body.

Preferably, the connection between the base plate and the jacking mechanism comprises a pivot pin extending parallel to the vehicle longitudinal axis and mounted within a resilient bush.

For example, the pin may be directly connected to the lower end of the jacking mechanism and the outer sleeve of the bush may be secured to the base plate. During forward and backward movement of the vehicle, the bush is deformed to take up the movement without tending to tilt the base plate off the ground.

A coil spring may be arranged about the bush for biasing the base plate into its rest position.

The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side view of a jack as described above, and Figure 2 is a section along the II in Figure 1 through a jack of the invention.

The side view of the jack of the invention does not differ from the the side view shown in Figure 1. A conventional jack of this type has a pivot pin connected to the extension of the arm 10 and extending between two plates projecting from the base plate 22. The jacking mechanism cannot therefore tilt in and out of the plane of the drawing.

In Figure 2, the pivot between the extension arm 10 and the base plate 22 is modified to incorporate a bush 30 comprising concentric outer and inner metal sleeves 30a, 30b separated from one another by a compliant rubber annulus 30c. The lower end of the extension of the arm 10 is connected to a pivot pin 40 whicii received within the inner sleeve 30.

As in Figure 1, the arm 10 can pivot at its lower end relative to the base plate 22 by the pin 40 slipping inside the inner sleeve 30b of the bush 30. The arm 10 can furthermore pivot slightly about an axis perpendicular to the pin 40 owing to the fact that such movement can be taken up by deformation of the rubber annulus 30c.

It is preferred that the base plate should be spring biased into its rest position relative to the arm 10 and this is achieved in Figure 2 by a coil spring 34 surrounding the bush 30. One leg of the coil spring acts on the arm 10 and the other on the base plate 22.

It will be appreciated that alternative techniques may used to permit rotation about two axes. For example, a universal joint may be used in which the pin 40 is replaced by a cross pivotable along one axis relative to the base plate 22 and about a transverse axis relative to the lower end of the arm 10.

It should also be mentioned that while the invention has been described by reference to a scissor jack it is not restricted to such a jack and may be employed with other jacking mechanism.

Claims

1. A jack for a motor vehicle comprising an expandable and collapsible jacking mechanism, a base plate pivotably connected to the lower end of the jacking mechanism for supporting the jacking mechanism on the ground and a support plate connected to the upper end of the jacking mechanism for engaging the body of the vehicle, the jacking mechanism being capable of pivoting relative to the ground about an axis parallel to the longitudinal axis of the vehicle in order to follow lateral movements of the vehicle body during jacking, and wherein the base plate is mounted on the lower end of the jacking mechanism in a manner which permits a limited degree of pivotal movement of the jacking mechanism relative to the the base about a transverse axis to enable the jacking mechanism to follow forward and backward movement of the vehicle body.

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2. A jack as claimed in claim 1, wherein the connection between the base plate and the jacking mechanism comprises a pivot pin extending parallel to the. vehicle longitudinal axis and mounted within a resilient bush.

3. A jack as claimed in claim 2, wherein the pin is directly connected to the lower end of the jacking mechanism and the outer sleeve of the bush is secured to the base plate.

4. A jack as claimed in claim 2 or 3, wherein a coil spring is arranged about the bush for biasing the base plate into its rest position.

5. A jack as claimed in any preceding claim, wherein the jacking mechanism comprises four arms pivotably connected to one another in the form of a parallelogram and having a screw threaded shaft engaged in a nut arranged at one of the corners of the parallelogram for collapsing and expanding the parallelogram to raise and lower the jack, the base plate being connected to an extension of the one of the arms of the parallelogram.

6. A jack for a motor vehicle constructed, arranged and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.