GB2229764A

GB2229764A - Vehicle jack

Info

Publication number: GB2229764A
Application number: GB8907059A
Authority: GB
Inventors: Graham Henry Colton
Original assignee: Metallifacture Ltd
Current assignee: Metallifacture Ltd
Priority date: 1989-03-29
Filing date: 1989-03-29
Publication date: 1990-10-03
Also published as: GB8907059D0

Abstract

A vehicle jack has pivoted links (12a, 13a,) each of channel form, with the channel sides (26) of one member (12a,) engaged between the channel sides (29) of the other member (13a,) and adjacent thereto. Pivot pins (15a) extend through each pair of adjacent sides and an elongate radial projection (30) is formed on at least one of each two adjacent sides and adjacent to the pivot pin for centering the inner link (12a) in relation to the outer link (13a). This reduces the risk of binding of the links. <IMAGE>

Description

VEHICLE JACK This invention relates to a vehicle jack of the type having an upper support member carrying a vehicleengageable member and pivotally supported on a lower support member and means to effect relative pivotal movement between the support members to effect a lifting operation.

One jack of this type has a tarallelogrammic arrangement of support members including two lower support members pivotally mounted on a base, and two upper support members, pivotally supported on respective lower support members. The upper support members are pivotted together either directly or indirectly through the vehicle-engageable member. The support members are all metal pressings of channel-form and the channel sides of one member of a pair extend between the channel sides of the other member of the pair and are interconnected by pivot means. A screw extends between the pivot means, one of which includes a nut, for operating the jack.

A problem arises with this arrangement, in that, during construction of the jack, the inner member may not be accurately centered relative to the outer member. This may result in jamming of the jack, due to the sides of the inner member binding on the sides of the outer member. Even where the binding does not seriously affect the jack operation, there is a loss of paint from the binding surfaces of the jack, which may lead to the jack being rejected.

One way of reducing this problem has been to flare the sides of the outer member. This substantially increases, however, the cost of manufacturing the metal pressing.

The present invention provides a simple and inexpensive way of overcoming the problem.

In accordance with this invention, there is provided a vehicle jack having an upper support member carrying a vehicle-engageable member and pivotally supported on a lower support member, means to effect relative pivotal movement between the support members to effect a lifting operation, each support member comprising a metal pressing of channel form, the channel sides of one member extending between the channel sides of the other member whereby each channel side of the inner member is adjacent a corresponding channel side of the other member, pivot means pivotally interconnecting the adjacent sides, and a projection formed on at least one of said adjacent sides adjacent the pivot means and between the adjacent sides for centering the inner support member within the outer support member.

Reference is now made to the accompanying drawings, wherein Figure 1 is a perspective view of a parallelogram jack constructed according to the invention; and Figure 2 is an enlarged fragmentary view of a part of the jack of Figure 1.

The jack shown in Figure 1 is of the parallelogram type including a base 11 to which are pivotally secured two lower support members 13a, 13b by pivot pins 14a, 14b. A corresponding upper support memebr 12a, 12b is pivotted to each lower support member 13a, 13b, near ends of the members by pivot pins 15a, 15b. The upper end parts of the upper support members are pivotally connected to a load-receiving element 16, which carries a vehicle-engageable shoe 17.

The lower support members have meshing teeth (not shown). The pivot pins 15a for one pair of members 12a, 13a are defined by trunnions projecting from a cylindrical nut 19. The nut has a transverse thread which receives a screw 20. The pivot pins 15b project from a spring member (not shown) having a trans'verse aperture, through which the screw passes. The screw is fixed to the spring member through a bearing race 21. The screw has a formation 22 at one end for engaging a handle for turning the screw to effect a lifting operation. A jack of this type is known, for example, from GB-1369186.

Each support member is a metal pressing of channel form, the sides of which have extensions beyond the base of the channel. These extensions are formed with apertures for receiving a respective pivot pin. One of the upper support members, 12a is shown in Figure 2 to be of channel form with a base 25, sides 26 and side extensions 27 provided with apertures 28 for the trunnions 15a. The sides 26 are parallel and fit between the sides 29 of one of the lower support members 13a, adjacent a respective one of the sides. In operation of the jacks, there is risk of the sides binding together, especially towards the closed position of the jack. To avoid this and to centre the upper support members 12a, 12b in the lower support members 13a, 13b, each side extension 27 of each upper support member is provided with a projection 30. The projection is formed, by deformation, adjacent the respective aperture 28 on the outer surface of the extension. The projection extends radially of the aperture and has a triangular section, to provide substantially line contact with the inner surface.

of the adjacent side 29 of the lower support member 13a, 13b.

This arrangement ensures minimum contact between the adjacent surfaces of the channel sides to prevent binding of the sides and provide free relative pivotal movement.

Claims

1. A vehicle jack having an upper support member carrying a vehicle-engageable member and pivotally supported on a lower support member, means to effect relative pivotal movement between the support members to effect a lifting operation, each support member comprising a metal pressing of channel form, the channel sides of one member extending between the channel sides of the other member whereby each channel side of the inner member is adjacent a corresponding channel side of the other member, pivot means pivotally interconnecting the adjacent sides, and a projection formed on at least one of said adjacent sides adjacent the pivot means and between the adjacent sides for centering the inner support member within the outer support member.

2. A vehicle jack according to Claim 1, wherein each channel side of the inner member is formed with the projection.

3. A vehicle jack according to Claim 1 or 2, wherein each projection is an elongate ridge extending generally radially of the pivot means.

4. A vehicle jack according to Claim 3, wherein said ridge is generally of triangular section.

D, A vehicle jack according to any preceding claim comprising two pairs of said upper and lower members arranged in a parallelogram.

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

6. A vehicle jack according to Claim 5, including a nut pivotally mounted by said pivot means between the channel sides of one of the inner members, the means to effect a lifting operation including a screw arrangement with the nut.

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

Amendments to the claims have been filed as follows 1. A vehicle jack having an upper support member carrying a vehicle-engageable member and pivotally supported on a lower support member, means to effect relative pivotal movement between the support members to effect a lifting operation, each support member comprising a metal pressing of channel form, the channel sides of one member extending between the channel sides of the other member whereby each channel side of the inner member is adjacent a corresponding channel side of the other member, pivot means pivotally interconnecting the adjacent sides, and a projection formed on at least one channel side between said one channel side and the adjacent corresponding channel side of the other member, for centering the inner support member within the outer support member, the projection being an elongate ridge extending generally radially of the pivot means and providing substantially line contact with said corresponding channel side of the other member.

2. A vehicle jack according to Claim 1, wherein said ridge is generally of triangular section.

3. 4 vehlcle jack according to Claim 1 or 2, rwherein each channel side of the inner member is formed with the projection.

4. A vehicle jack according to any preceding claim comprising two pairs of said upper and lower members arranged in a parallelogram.

D. A venicle jack according to Claim 4, including a nut pivotally mounted by said pivot means between the channel sides of one of the inner members, the means to effect a lifting operation including a screw arrangement with the nut.