GB2152474A

GB2152474A - Vehicle jack

Info

Publication number: GB2152474A
Application number: GB08427103A
Authority: GB
Inventors: Graham Henry Colton
Original assignee: Metallifacture Ltd
Current assignee: Metallifacture Ltd
Priority date: 1984-01-11
Filing date: 1984-10-26
Publication date: 1985-08-07
Also published as: ES282869Y; DE3446523C2; GB8400608D0; GB8427103D0; DE3446523A1; ES282869U; GB2152474B

Abstract

A parallelogram type jack has a base (10) pivotally supporting two lower links (11, 12) of a parallelogram linkage. Two upper links (13, 14) are pivotted to the lower links and support a load shoe (30). A screw (37) can be rotated to lift or lower the shoe by acting on pivots (11b, 12b) of the linkage. The upper links are pivotted together (20) and have portions (21, 22) projecting beyond the pivot connection. One such portion (21) is pivotted (31) at a fixed location to the shoe (30) and the other portion (22) has pivot members (32, 34) received in elongate slots (33) in the shoe. The arrangement provides increased lift for a parallelogram type jack and the shoe is maintained in a stable horizontal position during lift. <IMAGE>

Description

SPECIFICATION Vehicle jack This invention relates to a vehicle jack.

A popular style of vehicle jack comprises a linkage having four links pivoted in a parallelogram arranged ment. Two lower links are pivoted to a base about spaced axes and two upper links are pivoted to each other by a pivot which supports a load shoe. Each upper link is pivoted to a lower link by pivots which define nuts. A screw extends between and engages with the nuts, so that turning of screw causes the links to move relatively pivotally for raising and lowering the load shoe. The lower links have meshed teeth to relieve the load on the screw threads and the lower pivots.

In an alternative construction, the load shoe may be pivoted at two spaced locations to the two respective upper links, so that the load shoe is supported against pivotal movement under load.

Another modification, is to replace one of the nuts of a bearing member against which one end of the screw bears.

It is important to keep the jack as small as possible in the collapsed state to facilitate stowage. In order to increase the height of lift for this type of jack, it is necessary to increase the lengths of the links, so that the overall length of the collapsed jack may be excessive.

The present invention provides a jack of this general type which can be designed to provide increased lift, without an increase of the length of the jack in its collapsed state.

The present invention provides a vehicle jack comprising a base, four pivoted links arranged generally in a parallelogram with two lower links pivotally mounted on the base and two upper links pivoted to the lower links, a load shoe supported by the upper links, and a screw engaged between opposite sides ofthe linkage and engaged with at last one nut on the linkage, so that the screw can be turned to raise and lowerthe load shoe relative to the base, the upper links crossing each other and being pivoted together at a pivot point spaced from the load shoe.

It has previously been proposed to provide a scissor-like linkage in a jack, e.g. as described in US-2546361 published in 1951.Thishasthedis- advantage that sliding connections are necessary between both the base and the load shoe. A lazy-tong arrangement was proposed in US-2543904 published in 1946. Avariation was also published in 1946 in US-2467657. This avoided sliding connections altogther, by omitting the pivot between each pair of crossing links. Additional support links had to be provided, however, and the whole construction is clumsy and very expensive to produce.

The present invention provides a construction, which can be cheaply made and which has a simple and stable pivotal connection with the base. This construction has the virtues of the proved parallelogram type of jack with the provision for increased lift.

The load shoe is preferably pivoted to both upper end parts of the upper links, one of the pivotal connections being fixed and the other being linearly slidable relative to the load shoe, to maintain stability of the load shoe. The load shoe may have a linear slot receiving the slidable pivotal connection.

The load shoe, preferably, has an engagement member for engaging a support point of the vehicle, which engagement member is offset from the median plane extending between the load shoe pivotal connections, towards the fixed pivotal connections. This reduces the risk of the linkage fouling the vehicle during a lifting operation.

Reference is now made to the accompanying drawings, wherein; Figure 1 is a perspective view of a vehicle jack according to the invention; Figure 2 is a side view of the jack, showing the jack in collapsed position; and Figure 3 is a side view of a load shoe region of the jack, shown in load-supporting position.

The jack shown comprises a pair of lower links 11, 12 and a pair of upper links 13, 14, arranged in a parallelogram configuration. The lower links 11, 12 are pivoted by pivot connections ill, 12a respectiveliy to a base 10 which isachannel-shaped member.

The pivot connections are spaced, and, adjacent ends of the lower links 11,12, have meshing arcuate rows of teeth 15, 16 concentric with the respective pivot connections. The end part of each lower link remote from the arcuate teeth is pivoted to an end part of a corresponding upper link by a pivot connection 11b, 12b respectively.

The upper links 13, 14 cross each other in a scissor-like configuration and are pivoted together by a pivot connection 20 spaced from the ends of the upper links. Upper parts 21,22 of the upper links which extend above the pivot connection 20, are shorter than the lower parts forming part of the parallelogram.

Each ofthe links 11,12,13,14, is of channel form.

The upper links are received within the channels of the lower links. The connecting wall between two parallel side walls of the channel of each upper link, 13, 14, is removed in the upper parts 21,22 to permit the parts to cross each other.

A load shoe 30 of inverted channel form is supported by the upper parts 21, 22. One upper part 21 is pivoted at a fixed connection 31 to the side walls of the shoe and the other upper part 22 carries pivot members 32,34 which are received in linear slots 33 (only one illustrated) in the side walls. The slots extend generally parallel to the base. An engagement member 35 is carried by the shoe for engaging, in this example, with an axle of a vehicle.

The engagement member is offset from the median plane between the pivot connection 31 and the pivot member 32. The member lies close to the vertical plane containing the axis of the pivot connection 31. This reduces the risk of fouling of a vehicle body by the links, in use.

A screw member 37 extends between the parallelogram pivot connections 11b, 12h. One of these pivot connections 12b includes a nut (not shown) which screw-engages with the screw threaded part 37a of the screw member. The screw member extends through and is secured relative to the other pivot connection 1 1b and carries at its free end an attachment member 40 for receiving a handle. A bearing 41 is provided between the pivot connection 11b and the attachment member 40.

In operation, the attachment member 40 is rotated so as to rotate the screw to draw the pivotconnec- tion 126 towards the pivot connection 11b and thereby to raise the shoe 30 relative to the base. Due to the extensions 21,22 ofthe upper links 13,14 beyond their pivot connection 20 in the manner of a scissor arrangement, the lift achieved is higher than that possible where a conventional parallelogram type jack. The shoe remains in a horizontal stable position whatever the degree of lift due to the pivot members 32,34 sliding in the slots 33, whilst continuing to support the load shoe. The collapsed position for stowage is shown in Figure 2, with the pivot members at the left hand end of the slots and operative positions are illustrated in Figures 1 and 3, maximum lift being illustrated in Figure 3 with the pivot members at the right hand ends of the slots.

Claims

1. A vehicle jack comprising a base, four pivoted links arranged generally in a parallelogram with two lower links pivotally mounted on the base and two upper links pivoted to the lower links, a load shoe supported by the upper links, and a screw engaged between opposite sides of the linkage and engaged with at least one nut on the linkage, so that the screw can be turned to raise and lower the load shoe relative to the base, the upper links crossing each other and being pivoted together at a pivot point spaced from the load shoe.

2. A vehicle jack according to Claim 1, wherein the load shoe is pivotally connected to end parts of the upper links, one of the pivotal connections being at a fixed location relative to the load shoe and the other pivotal connection being linearly slidable relative to the load shoe.

3. A vehicle jack according to Claim 2, wherein the load shoe has a linear slot receiving the slidable pivotal connection.

4. A vehicle jack according to Claim 3, wherein the load shoe comprises an inverted channel-shaped member whose side walls have corresponding linear slots for receiving the pivotal connection.

5. A vehicle jack according to any preceding claim, wherein the upper links are of channel form and and the upper end of at least one of the upper links has a portion of the bridging wall between its side walls removed, so that the other upper link can be received between the side walls.

6. A vehicle jack according to any preceding claim, including an engagement member for engaging a support point on a vehicle, the engagement member being offset from a median plane between the pivotal connections between the upper and lower links in a direction towards the fixed pivotal connection.

7. A vehicle jack constructed substantially as herein described with reference to the accompanying drawings.