GB2354753A

GB2354753A - Vehicle jack with safety unit

Info

Publication number: GB2354753A
Application number: GB9923014A
Authority: GB
Inventors: Sidney William Upson
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-09-30
Filing date: 1999-09-30
Publication date: 2001-04-04
Anticipated expiration: 2019-09-30
Also published as: GB2354753B; GB9923014D0

Abstract

The invention provides a jack for raising vehicles, which provides a positive securing means for securely holding the jack in an extended position when in use. The jack comprises a chassis, a boom 5 journalled to the chassis and being moveable under the action of a lifting means 9 from a neutral position to a first raised position wherein it will support a vehicle, and to a second raised position, higher than the first raised position, and constituting a release position, a stay 13 freely journalled to the boom 5 and depending downwards when the boom is in the raised and release positions, and a stop member 15 on the chassis located below the boom, whereby in the first raised position the chassis, the boom and the stay form a triangle having an acute angle formed by the chassis and stay, with the free end 14 of the stay abutting the stop member 15 and a release 17, 18 capable of pushing the stay away from the boom when the boom is in the release position, whereby to clear the stop, and permit the boom to be lowered past the first raised position to the neutral position. Lifting means 9 may comprise a hydraulic ram. Preferably, the stop member 15 is L-shaped with one limb projecting upwards. Preferably, release means comprises first and second release levers 17, 18 attached to a bell crank. Preferably also, a position indicator 12 is provided.

Description

2354753 JACK WITH SAFETY UNIT This invention relates to a jack, especially

intended for raising vehicles, for attention to the underside of the vehicles or for changing wheels. More particularly, it relates to a jack in which a safety member is incorporated whereby to prevent unintended movement of the jack in a downwards direction with possible injury to people working on or below the vehicle.

Workshops where repair or maintenance work is carried out on the underside of vehicles need a means capable of raising the vehicle to a suitable height, and maintaining it at that height while the work is carried out. If the raising means, conventionally a hydraulic jack, should fail there is the danger of collapse and possible serious injury to those engaged in working on the underside of the vehicle.

One conventional jack incorporates a chassis, for instance, mounted on wheels or rollers, and a boom which is capable of being moved from a neutral position in which it is substantially parallel to the base to a raised position in which the vehicle, or one side of the vehicle, is raised from the ground to enable work to be carried out. The boom is provided with a support means at the top for engaging a suitable part on the underside of the vehicle. A stay is hinged freely to the boom, and the lower end of this stay slides along the chassis of the jack as the boom is raised. As the boom is lowered, either intentionally or unintentionally, this stay slides backwards along the chassis until the boom reaches the neutral position. This stay, while providing some support, generally does not have a position in which it may be locked. The present invention provides a safety means whereby, when the boom is in a raised position, the stay is immobilised so that the boom cannot be moved downwards. This is achieved by means of a stop against which the stay abuts. Consequently, the boom, the stay and the base, constitute a triangle when viewed in side elevation. Since the stop prevents the base of this triangle from increasing in length, the support cannot be lowered 2 unintentionally, thereby providing a positive support for a vehicle, which enables work to be carried out on the vehicle.

The present invention provides a jack for raising vehicles, which comprises a chassis, a boom journalled to the chassis and being moveable from a neutral position to a first raised position wherein it will support a vehicle, and to a second raised position constituting a release position, a stay freely journalled to the boom and depending downwards when the boom is in the first and second raised positions, and a stop member on the chassis located below the boom whereby in the first raised position the chassis, the boom and the stay form a triangle having an acute angle formed by the chassis and stay, with the free end of the stay abutting the stop member, and a release capable of pushing the stay away from the boom when the boom is in the release position to clear the stop, and permit the boom to be lowered past the first raised position to the neutral position.

One embodiment of the invention is illustrated in the accompanying Drawings, wherein:

Fig 1 is a side elevation, partially cut away, of a jack according to the invention part way through the operation of being raised to its first raised position, and Fig 2 is a side elevation, partially cut away, of the jack in the first raised position.

Referring now to the Drawing, the jack may be constructed in substantially the same way as conventional jacks, but additional parts are incorporated to ensure that it may be locked in a raised position, and may be securely released when it is to be lowered. Some conventional but unessential parts have been omitted from the Drawings for the sake of clarity.

3 The chassis [11 of the jack is generally of conventional construction, being a U-shaped channel when viewed in longitudinal profile, comprising a base [21 and two side members [4]. The boom chassis may be mounted on wheels or rollers Ka, 4b]. A boom [51 and radius link [61 are journalled to the side members [31 at one end, and at the other end are journalled to a crutch mounting bracket [71 which itself supports a crutch [81 which is adapted to support a vehicle. The boom [51 may be raised by means of a hydraulic ram [91 provided with a valve [101 and operated by handle [111. The actuating member of the ram [91 is itself journalled to the bottom of boom [51, whereby operation of the ram will raise the boom [51 to move clockwise as viewed in the Figure into the raised and release positions. A position indicator [121 provides a convenient means of determining when the boom [51 is in its first raised and its release positions.

A stay [131 is journalled at one end to the boom [51, somewhat above the midpoint of the boom, but closer to that midpoint than to the crutch mounting bracket [7]. The free end [141 of the stay bears upon a stop member [151 when the boom is in its upper position. The stop member is generally L shaped with one limb fastened to, or integral with, a base unit [161, and the other limb being directed upwards. In the first raised position, therefore, the boom, the stay and the hypothetical line formed by the free end of the stay and the bottom of the boom form a triangle which because the free end of the stay bears against the stop member, is a secure means not permitting unintentional lowering of the boom. In this location, the angle formed by the boom and the stay is conveniently from 75 to 851, e.g. about 80'.

The means of releasing the jack when operation on the vehicle has finished comprises a first release lever [171 having at one end a handle [181 and extending longitudinally through the chassis. At its end distant from the handle [181, it is journalled to a bell crank [191. Also journalled to the bell crank is a second release lever [201, which, on rotation of the bell crank can be brought to bear upon the bottom of the stay. The stay also has a neutral 4 finder [211 which operates in a manner to be described below. A stop member for the stay [221 is provided on the boom [5] and a release lever stop member [23] is fixed to a side member of the chassis. The release lever has a portion deviating from the normal line of the lever, the stop falling substantially on the main axis of the lever, so that longitudinal movement of the lever is restricted by the distance it can move in either direction before it abuts its stop member [221.

To raise the boom [51 from the neutral (rest) position to the first raised position, the valve [ 101 on the hydraulic ram [9] is first closed and the handle [11] is operated. This increases the pressure in the ram and forces the lower end of the boom away from the ram, thereby raising the upper end of the boom. The radius link [61 also moves as a result of the raising of the crutch bracket [71 by the boom [5]. The combined effect of the boom and radius link [61 is to hold the crutch in a level position. Correspondingly, the free end [141 of the stay [131 moves towards the right, as seen in Fig 1 of the Drawings and passes over the stop member [151 as the crutch is raised past the first position and descends on to the stop base [161, a slight release of the pressure on the ram allowing it to abut against the angle formed by the stop member [ 151 and the stop base [161. The position indicator [121 will then be at its nearest approach to the end of the chassis. The first release lever [18] is moved to its inward position (to the left as viewed in the Drawing) to allow the free end of the stay to descend.

To lower the boom [51 from its first raised position, the hydraulic ram [9) is operated again to raise the boom [51 and associated crutch [81 into a second raised position. Abutment of the stay against stop member [22] can provide an indication that the crutch has been raised to a sufficient height to permit release. A height of 2 to 3 cm above the first raised position will be sufficient with a jack of normal dimensions to enable the next stage of the release to operate. This involves pulling the first release lever [181 towards the right as shown in the Drawing, the stop member [231 preventing it from being pulled too far, causing the bell crank [191 to rotate in a clockwise direction thereby causing the second lever arm [201 to raise the stay above the stop member [151. Opening the valve [101 will then allow the weight of a vehicle on the jack to urge the crutch and boom [51 downwards, allowing the free end [141 of the stay to pass over the stop member [151 and to move along the stop base unit [161 and the stay to move towards a substantially horizontal attitude with the neutral finder [211 in contact with the base of the chassis. At the same time, the indicator arm [ 121 will be urged longitudinally of the chassis so that its end projects to its greatest extent.

6

Claims

1 A jack for raising vehicles, which comprises a chassis, a boom journalled to the chassis and being moveable from a neutral position to a first raised position wherein it will support a vehicle, and to a second raised position constituting a release position, a stay freely journalled to the boom and depending downwards when the boom is in the first and second raised positions, and a stop member on the chassis located below the boom whereby in the first raised position the chassis, the boom and the stay form a triangle having an acute angle formed by the chassis and stay, with the free end of the stay abutting the stop member, and a release capable of pushing the stay away from the boom when the boom is in the release position to clear the stop, and permit the boom to be lowered past the first raised position to the neutral position.

2. A jack as claimed in Claim 1 wherein the lifting means comprises a hydraulic ram.

3. A jack as claimed in Claim 1 or 2 wherein the stop is an L-shaped member with one limb projecting upwards.

4. A jack as claimed in any of Claims 1 to 3 wherein the release means comprises first and second release levers extending longitudinally through the jack to project therefrom and attached to a bell crank, the first lever and the second lever also being attached to the bell crank and being movable upwards to bear on the bottom of the stay.

5. A jack as claimed in any of Claims 1 to 5 wherein a position indicator comprises a rod journalled to the lower end of the boom and projecting from the operating end of the chassis.