GB2030108A

GB2030108A - Load lifting jacks

Info

Publication number: GB2030108A
Application number: GB7925678A
Authority: GB
Original assignee: Aisin Seiki Co Ltd
Current assignee: Aisin Corp
Priority date: 1978-07-25
Filing date: 1979-07-24
Publication date: 1980-04-02
Also published as: JPS6042159B2; JPS5516882A; GB2030108B

Abstract

A load lifting jack suitable for an automobile comprises a pantograph linkage, two of the links 28, 32 which are pivoted at one end of an actuating screw assembly 40, on a pin 36, being pivotted each with respect to one of the other links 12, 16, which are pivoted on a pin 18 at the other end of the screw-assembly, at a position between the ends of the respective other link, whereby the jack is compact and easily stowable. The said position is preferably midway between the ends of the respective other link. The other links 12, 16 are preferably pivotted at their ends remote from the pin 18 one to a base 10 and one to a load engaging head 20 of the jack. In a modification, Fig. 6, one of the links 228 extends beyond the parallelogram and engages in a straight guide slot 52 in the base. In a further modification (Fig. 8), a curved guide slot (54) is used. The links may be flat or of channel section. <IMAGE>

Description

SPECIFICATION Load lifting jacks The invention relates to load lifting jacks which comprise a pantograph linkage and are suitable for lifting the body of an automotive vehicle.

The invention provides a load lifting jack comprising four rigid links pivotted together in a parallelogram, and a screw for determining the distance between opposite corners of the parallelogram and therefore the height of the jack, the links pivotted together at one end of the screw each being pivotted with respect to one of the other links at a position intermediate between the ends of that other link. Preferably the said position is midway between the ends of the other link. The intermediate positioning of the pivots makes the jack compact and easily stowable.

DRAWINGS Figure 1 is a side elevation of the jack according to the invention in a partially elevated initial position; Figure 2 is a side elevation of the jack of Fig. 1 in a fully collapsed position; Figure 3 is a side elevation of another jack according to the invention; Figure 4 is a vertical section along the line IV--IV of Fig. 3; Figure 5 is a horizontal section along the line V-V of Fig. 3; Figure 6 is a side elevation of yet another jack according to the invention; Figure 7 is a vertical section along the line VIl-VIl of Fig. 6; and Figure 8 is a side elevation of yet another jack according to the invention.

Referring first to Fig. 1, the jack comprises a jack base 10 to which is pivotally connected a lower link 1 2 by a pin 14. The link 1 2 is pivotally connected at its upper end to another link 1 6 by a pin 18. To the upper end of the link 1 6 is pivotally connected a load engaging head 20 by a pin 22. The head 20 has a slit 24 into which fits a bottom portion of a vehicle body 26. A link 28 is pivotally connected at its lower end to the middle of the lower link 12 by a pin 30.

Another link 32 is pivotally connected at its upper end to the middle of the link 1 6 by a pin 34. The links 28 and 32 are pivotally connected at their other ends by a pin 36.

The links 1 2 and 1 6 are the same length, as are the links 28 and 32, but the links 28, 32 are of half the length of the links 12, 16. The jack is collapsed into the position shown in Fig. 2 in a portable form when stowed in a vehicle cavity with less length than would be the case if the links 28, 32 were the same length as the links 12, 16.

The pin 1 8 is normal to the plane of the drawing and is provided with an internally screw-threaded bore in which a screwthreaded shaft 40 engages. A rotary drive head 42 is fixed at one end of the screw shaft 40 and outside the link arrangement, where it can be rotated by means of a driving handle (not shown). The pin 36 also is normal to the plane of the drawing, and has an un-tapped bore through which the screw shaft 40 rotatably passes. A ring spacer member 44 is slidably disposed on the screw shaft 40 between the head 42 and the pin 36 so as to facilitate smooth rotation of the screw shaft 40 when operated against a load.

The links in Fig. 1 are formed of heavy gauge flat sheet metal which is sufficiently strong to lift the load. In contrast, in Figs. 3 to 5, each of the links is of channel or a rectangular open-topped cross-section for strengthening purposes. This cross-section reduces the thickness of sheet metal necessary for the links. Many parts in Figs. 3 to 5 correspond to parts in Figs. 1 and 2, and the same reference numerals are used, except that 100 has been added to each.

In Figs. 4 and 5, links 112 and 116 are of identical cross-section with each other, as are links 1 28 and 1 32. This requires the use of less types of manufacturing machine than would be the case if the links were of different cross-sections.

In Figs. 6 and 7, many parts correspond to parts in Figs. 1 and 2, and the same reference numerals are used, except that 200 has been added to each. In Figs. 6 and 7, a base 210 and link 228 carries a pin 50 which has a sliding fit in a guide slot 52. Links 228 and 216 are of the same length, and the slot 52 extends horizontally so that a load engaging head 220 can rise upright along a vertical line on which pins 214 and 222 lie when the jack is operated under load. In other words, the path of the load engaging head 220 is governed by the slot 52 when the head rises against the load. This is often necessary for safety purposes.

Fig. 8 is the same as Figs. 6 and 7 except that a link 328 is of different length from the link 228, and a slot 54 is different from the slot 52 in that it is curved. A pin 56 carried by the link 328 is free to slide in the slot 54.

The curved slot 54 is intended to have a load engaging head 320 travel in an arcuate passage in an imaginary vertical plane when the jack is operated under a load. This arcuate travel of the head is necessary for most applications for holding a jack base 310 stationary on the ground for safety purposes. The reason is that, when the jack is used a portion of a vehicle with which it engages travels in an arcuate passage in the imaginary plane. In order to maintain the base 310 stationary on the ground, the load engaging head 320 must travel strictly in accordance with the passage in which the portion of the load travels.

Claims

1. A load lifting jack comprising four rigid links pivotted together in a parallelogram, and a screw for determining the distance between opposite corners of the parallelogram and therefore the height of the jack, the links pivotted together at one end of the screw each being pivotted with respect to one of the other links at a position intermediate between the ends of that other link.

2. A load lifting jack according to claim 1 in which the said position is midway between the ends of the other link.

3. A load lifting jack according to claim 1 or claim 2 in which the said other links are pivotted one to a base and the other to a load engaging head of the jack.

4. A load lifting jack according to claim 3 in which one of the links extends beyond the parallelogram and engages in a guide in the jack base.

5. A load lifting jack according to claim 4 in which the link carries a pin slidable in a guide slot in the base.

6. A load lifting jack according to claim 4 or claim 5 in which the guide is straight.

7. A load lifting jack according to claim 4 or claim 5 in which the guide is curved downwards away from the base pivot.

8. A load lifting jack according to any preceding claim in which the links are of flat metal.

9. A load lifting jack according to any of claims 1 to 7 in which the links are of interengageable channel section.

10. A load lifting jack as herein described with reference to Figs. 1 and 2 of the drawings.

11. A load lifting jack as herein described with reference to Figs. 3 to 5 of the drawings.

1 2. A load lifting jack as herein described with reference to Figs. 6 and 7 of the drawings.

1 3. A load lifting jack as herein described with reference to Fig. 8 of the drawings.