VEHICLE JACKS

Abstract: The jack comprises two arms (12,14) pivotted at an intermediate point (16), and a bottle jack (18) operable to force the arms apart, thereby raising the jack. The bottle jack is releasable allowing it to be used on its own. The arm (12) is cranked at (16) to allow a standard bottle jack to be accommodated between the ends of the arms (12,14).

Description: The present invention relates to vehicle jacks. Some vehicles, for instance forklift trucks, carry a protective skirt around their base to act as a safety guard by preventing articles passing under the truck. The ground clearance of the skirt may be as little as two inches (five centimetres). In order that maintenance on forklift trucks may be carried out without removing the safety skirt, it is desirable to provide a vehicle jack which can reach under the truck through this limited space. Prior proposals addressing this problem have been found unsatisfactory and mechanically unreliable. A forklift truck jack is described in Materials Handling News, no. 279, February 1981 (Dunstable Bedfordshire, GB). The jack comprises two elongate members pivotally connected to each other at an intermediate point along their lengths, and a fluid operated actuator attached to the ends of the two members to one side of the pivot point, the actuator being operable to cause the members to pivot with respect to one another to cause the distal ends of the members to move apart. The actuator extends vertically above the elongate members at all times while the jack is in use. A jack according to the present invention is characterised in that one of the members is cranked at the pivot point to extend above the other member between the pivot point and the point of attachment to the actuator, and the actuator is located substantially wholly between the points of attachment to the members. Preferably the actuator is releasably attached. The actuator may be so adapted as to be used as a vehicle jack after being released from the members. The actuator may be a bottle jack. Preferably the distal end of the said one member bears on the ground when the jack is raised. Preferably one of the members comprises two arms extending between the pivot point and the distal end and connected at the distal end, the portion of the other member between the pivot point and the distal end nesting between the arms when the jack is fully lowered. One embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings in which: Fig. 1 is an elevation of a jack embodying the present invention; and Fig. 2 is a plan view of the jack of Fig. 1. The vehicle jack 10 comprises two elongate members or arms 12 and 14 pivotally connected to each other at 16. The pivot point is at an intermediate point along the lengths of both arms 12,14. A fluid operated actuator 18 is releasably attached to the ends of the two members 12, 14 to one side of the pivot point 16. The actuator 18 is operable to cause the members 12,14 to pivot with respect to one another to cause the distal ends 14A, 20B to move apart. The arm 12 is formed from two component arms 12A, 12B connected at the distal end by a foot plate 22. The foot plate and the ends of the arms 12A, 12B are rounded to allow the foot plate to rock on the ground when the jack is in use, as will be described. The arms 12A, 12B form between them a space 26 in which the arm 14 may nest between the pivot point 16 and its distal end 14A. A plate 28 is carried at the distal end 14A of the arm 14. The upper surface of the plate 28 is corrugated to allow it to engage securely an article to be lifted. The arm 14 is elongate, and generally straight, and carries ground wheels 24 at the opposite end to the plate 28. The arm 12 is cranked at the pivot point 16. When the arm 14 is nested in the arm 12, the cranked portion of the arm 12 projects upwardly above the arm 14. The actuator 18 is connected between the uppermost end of the arm 12 and the end of the arm 14, near the wheels 24. The actuator 18 is a standard bottle jack of the type which can be used as a vehicle jack in its own right. The bottle jack actuator 18 simply comprises a hydraulic cylinder and piston, a small hand operated pump for charging the cylinder, and a release valve allowing pressure within the cylinder to be vented. The actuator 18 is pivotally connected to the ends of the arms 12, 14. To use the jack described above, the distal ends of the arms 12, 14 are slid under the article to be lifted, until the plate 28 is located under a suitable part of the article, and the foot plate 22 is on firm ground. It will be understood that the nesting of the arms reduces the height of the jack when collapsed, and so allows the jack to be used in situations where little clearance is available, such as when lifting forklift trucks. Once the jack is in position, the actuator 18 is pumped to extend and force apart the ends of the arms. As this happens, the arms pivot at the pivot point 16 and the distal ends of the arms move apart. The foot plate 22 rocks on the ground but does not move significantly across the ground. The plate 28 moves up to engage and lift the article. As the scissor-like action continues, the wheels 24 roll across the ground towards the foot plate 22. The actuator is pumped until the article has been lifted to the desired height. When it is desired to lower the article, the release valve on the actuator 18 is opened to allow pressure slowly to vent from the cylinder, thereby allowing the plate 28 to descend until the arms are once again nested and the jack can be rolled out from underneath the article. The jack described above is of extremely simple construction and is therefore expected to be reliable. It is envisaged that the most likely cause of failure will be a failure in the bottle jack 18, but the releasable attachments of the bottle jack 18 allow it to be removed and replaced quickly and easily, if necessary. The device described also has the advantage that the bottle jack may be removed and used alone in appropriate circumstances, so that the arms may be thought of as an adapter to allow a bottle jack to be used in situations with limited clearance, where bottle jacks could not normally be used. Variations and modifications to the apparatus described above can be made without departing from the scope of the present claims. Other types of actuator can be used, but are preferably removable for reasons explained above.

Claims: 1. A vehicle jack (10) comprising two elongate members (12, 14) pivotally connected to each other at an intermediate point (16) along their lengths, and a fluid operated actuator (18) attached to the ends of the two members to one side of the pivot point, the actuator being operable to cause the members to pivot with respect to one another to cause the distal ends (20A, 20B) of the members to move apart, characterised in that one of the members (12) is cranked at the pivot point to extend above the other member (14) between the pivot point and the point of attachment to the actuator, and the actuator is located substantially wholly between the points of attachment to the members. 2. A jack according to claim 1, characterised in that the actuator (18) is releasably attached. 3. A jack according to claims 1 or 2, characterised in that, the actuator is so adapted as to be used as a vehicle jack after being released from the members. 4. A jack according to any of the preceding claims, characterised in that the actuator (18) is a bottle jack. 5. A jack according to any preceding claim, characterised in that the distal end of the said one member (12) bears on the ground when the jack is raised. 6. A jack according to any of the preceding claims, characterised in that one of the members (12) comprise two arms (12A, 12B) extending between the pivot point and the distal end and connected at the distal end, the portion of the other member between the pivot point (16) and the distal end nesting between the arms when the jack is fully lowered.

Inventors: DETLOFF, PAUL JEREMY, PARKES, LAWRENCE JOHN
Applicants: DETLOFF, PAUL JEREMY, PARKES, LAWRENCE JOHN
Application year: 1988
Main classification: B66F5
IPC codes: B66F5