GB2290070A - A vehicle jack - Google Patents

Abstract

A Y-type vehicle jack has a leg (12) in channel form. A cylindrical plastics nut (46) is positioned at a pivot point (20) of the leg between two spaced, parallel, metallic walls (40, 41) defining the leg channel (44). The walls each have a trunnion (56, 58) that has been pressed from the wall and projects into the channel, each trunnion engaging an axial bearing surface (60, 62) defined by a wall of a recess of the nut in which the respective trunnion is received. The nut is supported by a seat on the leg or push-fitted onto the trunnions. Other jack components may be mounted in a similar manner. <IMAGE>

Description

VEHICLE JACK This invention relates to a vehicle jack of the type in which a plastics component is pivotally mounted between metal sidewalls of an elongate support element of the jack by a trunnion and journal arrangement.

Vehicle jacks commonly include such support elements made of channel-shaped metal, between whose sidewalls a component, such as a nut is pivoted. The nut is provided to receive a screw, which carl bc rotated to effect lift of a jack by pivotally moving the support element relative to another support element of the jack. It is also kllowll to make such a nut of plastics material, as disclosed in EP-B-0320613. In that document, the nut is provided with trunnions1 cach of which is rotatably received in a hole in a respective sidewall. EP-A-0340551 discloses a similar drratigeiient.

The holcs are defined by cdges of the metallic walls, and this presents a problem, especially when the screw is under load, since the metallic edges dig into and damage the plastics trunnions. This offsets an advantage of having a plastics nut, which is easily and cheaply moulded.

Both EP-B-0320613 and EP-A-0340551 overcome this problem by providing metallic bushings around the plastics trunnions in order to reinforce the trunnions and limit wear since the bushings contact the metallic edges when the screw is undcr load.

The provision of metallic bushings requires use of additional manufactured parts and also extra assembly steps tu fit the bushings over the trunnions.

The present invention overcomes this problem and provides for both simple and cheap manufacture and simple assembly of a rotatable plastics nut, or thor plastics coniponeiit, in a jack support element.

The present invention provides a vehicle jack having an clongate support element including a pair of spaced metallic sidewalls, and a plastics component pivotally mounted between the sidewalls by a pair of trunnion and journal arrangements, charactcriscd in that cach trunnion is formed from a respective sidewall and the journals are provided in thc plastics component.

The present invention, tllerefore avoids the need to manufacture and assemble additional parts, thcrcby giving cost and wcight advantages while enabling a plastics nut Ol other plastics component to be used.

In addition, it is known in the art that the use of nut trunnions produces porosity problems and (he invention reduces this problem.

Reference is now made to the accompanying drawings, wherein: Figure 1 is a side elevation of a jack according to the invention; Figure 2 shows a cross section of a pivot point in tine leg of the jack in Fig.l; Figure 3 is an end view of the plastics nut illustrated in Fig.2, but not asscmbled in a jack; Figure 4 is a longitudinal section view along line IV - IV in Fig.3; Figure 5 is a side view in direction V of the nut illustrated in Fig.3, with certain hidden parts shown in phaiitom; Figure 6 is a longitudinal section view along line VI - Vl in Fig.3; Figure 7 comprises a series of views illustrating otie way or mounling a nut on trunnions; and Figure 8 shows an alternative way of mounting a nut on trunnions.

Referring to figure 1, there is shown a Y-type vehicle jack constructed according to the invention, and which comprises an elongate leg 11 having a base 12 at one end and a first pivot point 20 at the other end. An arm 1G is pivutcilly attached at one of its ends to a second pivot point 17 on the leg 12. A vehicle support member 30 is pivotally carried on the other end of the arm 16.

The leg 11 and arm 16 are of channel form, each including two spaced.

parallel melal walls, one of which is shown in Fig.l. The spaced walls of the ieg 12 receive the arm 16 therebetween.

A plastics nut 46 (shown in phantom) is provided in the channel of the leg 12 at the first pivot point 20, and a pivot member 47, (shown in phantom) is provided in the dan'iel of the arm 16 at a pivot point 23 near the vehicle support member 30. The nut and pivot member 46,47 are mounted in the respective channel by means of trunnions 22,24, forming part of a trunilion and journal arrangement.

The nut 46 has a thrcaded bore 67 (Fig.2) extending radially therethrough and engaging a screw 19. The screw l.9 has, at the end nearest the vehicle support member 30, a head 21 including a ball-race bearing, with the head abutting the pivot member 47 and the screw 19 extending radially through the pivot member 47.

A handle 23 is provided for rotating the screw to raise and lower the vehicle support member.

Referring to Fig.2, pivot point 20 is shown in cross section. The plastics nut 46, is positioned in the channel 44 in the leg 1.2 and has an arcuate bearing surface 48,50 provided at each axial end 52,54 of the nut 46.

Cylindrical trunnions 36,58 are pressed from the metal of the walls 40,41 of the leg and project substantially at right angles from each wall 40,41 into the channel 44. As shown in Fig.2, the nut 46 is positioned so that each bearing surface 48,50 has an axially-extending part 60,62 which engages an axial surface 64,66 of a respective one of the trunnions 56,58 when the trunnions journal on the bearing surfaces 48,50.

Turning to Figure 3, there is shown an end-un view uf 1 plastics nut.

The end of the nut shown in Fig.3 is the end that would be neart:t the handle 25 in a jack as shown in Fig.1. The plastics nut 46 has a projection 100,102 on each side. As shown in Fig.5, each projection has an arcuate portion 104 that defines a respective one of the arcuate bcaring surfaces 48,50.

In the embodittlent shown in Fig.S, each arcuate bearing surface 48,50 extends through substantially 1800 and is defined by a recess with an entry portion 48a for receipt of a trunnion it rlle recess.

The nut 46 is mounted in position by engaging the nut on the trunnions 56,58, so that they are received in the recesses in contact with the bearing surfaces 48,50. The mounting of the screw in the nut will position the nut with the bearing surfaces facing away from the handle, so that they are prevented, under the normal loading of the jack, from disengaging from the trunnions.

It is prcfcrrcd that some locating means is provided to hold the nut in engagement with the trunnions. This can be effected in several possible ways.

The extent of each arcuate bearing surface 48,50 may be greater than 1800 to provide an entry to the recess of slightly smaller diameter than eacll trunniun 56,58. The resilience of the nut maternal will then pertilit snap- engagement of the nut onto the trunnions.

Alternatively, as shown in Figure 7 the channel sides 40,41 of the leg l2 may have tabs defining a seat 80 spaced towards the handle from the base 81 of the channel. The nut can be inserted into the channel from the bottom (as shown in Figure 7), or from the handle end, so as to be located on the seat.

In another alternative, as shown in Figure 8, diametrically opposite axially projecting barbs 84,86 are provided on the nut. Each barb has an arcuate end face 85 forming, along with the arcuate bearing surface 48,50, parts of a circle. The barbs can be resiliently forced past the trunnions to snap engage lhe rlul on this lrurlrlions.

In operation, the handle 25 (Fig.l) is turned to rotate the screw 19 and cause the vehicle support member 30 (Fig. 1) to be raised when the handle 25 is turned in one direction, and lowered when the handle 25 is turned in the opposile direction.

As the screw 19 rotates, the nut 46 at the first pivot point 20 on the leg pivots, while the trunnions 56,58 journal on the axial rcccss surfaces 60,62, which act as bearing surfaces.

In use of the jack, wear of the plastics nut is low, in view of the relatively large area of contact between the trunnions and the bearing surfaces of the jiut. Engagement between a plastics bearing surface and a relatively narrow ineLal edge is voided.

Manufacture and assembly is very simple. The nut is a simple plastics moulding and no additional reinforcement is required. The trunnions are simply produced during pressing of the leg of the jack. The nut is very simple mounted in position, without any need for complicated jigs to hold the parts.

Claims (9)

1. A vehicle jack having an elongate support element including a pair of spaccd mctaIlic sidewalls, and a plastics componcnt pivotally mounted between the sidewalls by a pair of trunnion and journal arrangements, characterised in that each trunnion is formed from a rcspcctivc sidewall and the journals are provided in the plastics component.

2. A vehicle jack as in Claim I, wherein each journal is defined by a recess having an arcuate bearing surface and an entry for receipt of a trunnion in the recess.

3. A jack as in Claim 2, wherein each bearing surface defines an arc of greater than 180 fur snap-fitting each bearing surface onlu its respective trunnion.

4. A jack as in Claim 2, wherein the component has opposite axial projections, which cari forceably pass between the trunnions to snap engage with the trunnions for relaining the trunnions in the recess.

5. A jack as in Claim 2, wherein the support element has a seat for supporting Dle component with the trunnions engaged in tile recesses.

6. A jack as in any prcccding claim, wherein cach sidewall and its respective trunnion form an integral prcssing.

7. jack as in Claim 6, wherein the elongate elenient is channel shaped with the sidewalls being integral with a base.

8. A vehicle jack as in any preceding claim, wherein the plastics component is a plastics nut, a rotatable actuating member being radially screw-engaged in the nut to effect raising of the jack when the actuating member is rotated.

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