GB2088955A

GB2088955A - Hydraulic Lifting Jack

Info

Publication number: GB2088955A
Application number: GB8134680A
Authority: GB
Original assignee: TOR CAR Srl
Current assignee: TOR CAR Srl
Priority date: 1980-11-19
Filing date: 1981-11-18
Publication date: 1982-06-16
Also published as: IT8053688V0; FR2494248A3; FR2494248B3

Abstract

A hydraulic lifting jack for motor vehicles, includes a thrust chamber (32) which communicates with a pump chamber (64) and houses a slidable telescopic lifting piston (34). The lifting piston (34) includes a hollow outer shaft (36) and an inner rod (38) which is slidable relative to the outer shaft (36) between a retracted position and an extended position in which it projects outwardly from the shaft. The inner rod (38) in biassed axially towards its extended position by a spring (52), and a stop member is provided, which is operable manually to lock the inner rod (38) in its retracted position by engaging above a collor (122) on the outer end of the rod (38). <IMAGE>

Description

SPECIFICATION Hydraulic Lifting Jack The present invention relates to hydraulic lifting jacks, particularly for motor vehicles, of the type including a body having a pump chamber, a pumping piston which is operable in the pump chamber and is connected to an external drive member, a fluid reservoir communicating with the pump chamber through a first non-return valve, a thrust chamber which communicates with the pump chamber through a second non-return valve and is connected to the reservoir through an externally-operable discharge valve, and a lifting piston which is slidable in the thrust chamber.

The object of the present invention is to provide an hydraulic jack of the type specified above, which has reduced dimensions and size and which may be handled and operated in an extremely convenient and practical manner.

In order to achieve this object, the invention provides a hydraulic jack of the aforesaid type, the main characteristic of which lies in the fact that the lifting piston is telescopic and includes a hollow outer shaft and an inner rod which is slidable relative to the outer shaft between a retracted position and an extended position in which it projects outwardly from the outer shaft, the inner rod being biassed axially towards its extended position by a spring, and a stop member being provided which is operable manually to lock the inner rod in its retracted position.

This characteristic allows a considerable reduction in the vertical dimension of the jack when it is not in use, and considerably facilitates its use. In fact, after the jack has been positioned below the vehicle to be raised, in use, the disengagement of the stop member allows the inner rod to adopt its extended position under the action of the spring, so that the lifting piston is brought automatically into contact with the vehicle without the need for further manual operations.

According to the invention, the stop member includes a fork having prongs which are articulated to the body about an axis disposed transverse the lifting piston, and a loop in correspondence with its yoke, which is engageable with a cooperating element carried by the free end of the inner rod of the lifting piston.

According to a further characteristic of the invention, the drive member of the pumping piston is constituted by a foldable pedal which is articulated to the body about an axis parallel to the articulation axis of the stop member, and the stop member further includes a resilient attachment, in the form of a spring fork, for retaining the pedal in its folded position.

Preferably, the arms of the spring fork are bent so as to form a pair of eyes located side by side and constituting a handle to facilitate the carrying of the jack.

One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a hydraulic jack according to the invention: Figure 2 is a vertical sectional view of the jack of Figure 1, showing its lifting piston in a partially extended position; Figure 3 is a view similar to Figure 2 showing the lifting piston in its completely extended position, and Figure 4 is a partial section taken on the line IV-IV of Figure 2.

With reference to the drawings, a hydraulic jack includes a moulded plastics body 10 having a base 12 which is fixed to a metal support plate 1 6 by screws 14. A tubular cylindrical portion 1 8 extends vertically upwardly from the base 12, and is connected to a hollow portion 20 alongside the tubular portion 18. The body 10 is made from a high-strength, shock-resistant, thermoplastic resin, such as polypropylene.

As shown in detail in Figure 2, a tubular cylindrical metal element 22 is fitted coaxially in the tubular cylindrical portion 1 8 and, with the latter, defines an annular space 24 which is bounded at its lower end by the base 12 and is sealed at its upper end by an annular cover 26 of moulded plastics material. The inner face of the cover 26 has an annular peripheral groove 28 with elastically flexible walls which engage the upper edge of the tubular portion 24, and the cover 26 is provided centrally with an annular appendage 30 which seals the upper end of the tubular element 22. The annular space 24 constitutes a reservoir for the hydraulic fluid of the jack, while the interior of the tubular element 22 defines a thrust chamber 32.The hollow portion 20 of the body 10 is closed at its upper end by a cover 21 formed from two moulded plastics parts located side by side.

A telescopic lifting piston 34, comprising a hollow outer shaft 36 and a tubular inner rod 38, is mounted in the thrust chamber 32. The upper end of the hollow shaft 36 passes through and is sealed by the annular lid 32, and is provided at its lower end with a tubular plug 40 which is sealingly slidable along the internal wail of the tubular cylindrical element 22.

The tubular inner rod 38 is provided at its lower end with a tubular plug 42 which is similar to the plug 40 and is sealingly slidable along the internal wall of the hollow shaft 36, and is closed at its upper end by means of a cylindrical plug 44 carrying, at its lower end, an axial tang 46 which projects towards the base 12. The plug 44 is provided at its upper end, that is, outside the rod 38, with a flanged cylindrical appendage 48 on which a bearing member 50 is mounted with clearance. The bearing member 50 is constituted by a metal cup 51 carrying an annular block 53 of plastics material, and its angular position can be varied relative to the cylindrical appendage 48.A helical compression spring 52 is interposed between the lower end of the cylindrical plug 44 and the tubular plug 40 of the outer shaft 36 and, passing through the tubular plug 42, biasses the rod 38 outwardly of the hollow shaft 36, that is, towards an extended position of the telescopic lifting piston 34, as shown in Figure 2 and in broken outline in Figure 1. In this position, the tubular plug 42 of the rod 38 bears against an internal stop shoulder 54 provided close to the upper end of the shaft 36.

The lower part of the hollow portion 20 of the body 10 is formed with a hollow cylindrical projection 56, within which is inserted the lower end of a cylindrical sleeve 58 having an annular peripheral flange 60 which bears on the upper edge of the projection 56. An annular cavity 62 is formed in the lower end of the sleeve 58 and, with the interior of this sleeve 58, forms a pump chamber 64 in which a pumping piston 65 is operable. The pumping piston 65 is sealingly slidable in the sleeve 58 and carries a transverse articulation pin 66 at its upper end, which is inserted in a hole 68 in a lever 70 extending through a slot 72 in the hollow portion 20 of the body 10. The internal end of the lever 70 is pivoted about a pin 74 which is parallel to the pin 66 and is carried by the walls of the hollow portion 20.A tubular rod 78 is articulated to the outer end of the lever 70 about a hinge pin 76 which is parallel to the pins 66, 74. The rod 78 acts as a pedal for driving the pumping piston 65 and carries a shaped rubber block 80 at its free end. The pedal rod 78 may be folded from the position of use, shown in broken outline in Figure 1, to a rest position shown in full outline in Figure 1, in which it extends above the body 10. A slidable sleeve 82 allows the articulation between the lever'70 and the rod 78 to be locked, when the pedal rod 78 is in its extended position of use.

In this position, the pedal rod 78 may oscillate about the pivot pin 74 to drive the pumping piston 65 between the two positions shown by full outline and broken outline, respectively, in Figure 2. A return spring 84 between the annular flange 60 of the sleeve 58 and a collar 86 on the upper end of the pumping piston 65 biasses the pedal rod 78 into the raised position shown in broken outline in Figure 2.

A valve body 88 of plastics material is inserted into the bottom of the cavity of the annular projection 56 below the sleeve 58. The valve body 88 has two passages 90, 92 each controlled by a respective non-return valve. In the example illustrated, the non-return valves comprise ball valves 94, 96. The passage 90 allows the pump chamber 64 to be put into communication with the reservoir 24 through an intake duct 98 formed in the base 12 of the body 10, while the passage 92 allows the pump chamber 64 to be connected to the thrust chamber 32 through a delivery duct 100 also formed in the base 12.

As shown in detail in Figure 4, a discharge duct 102 is also formed in the base 1 2 and connects the thrust chamber 32 directly to the reservoir 24.

Communication between the thrust chamber 32 and the reservoir 24 is controiled by an on-off valve 104 which comprises a cylindrical rotary shutter 106 mounted in a hollow projection 108 of the base 12, and is operated by an external pedal 110. The pedal 110 is moulded in the form of a sector of a circle from plastics material, and may be easily rotated between respective positions corresponding to a closed position and an open position of the discharge valve 104. Two snap-positioning members 112, one of which is shown, allow the pedal 110 to be held in either position. Furthermore, a manually-releasable safety locking device, not shown, may be provided for locking the pedal 110 firmly in the closed position of the discharge valve 1 04.

A stop and retaining member, generally indicated 113 in Figure 1, is preferably formed from a round metal bar shaped to form a lower forked part 114 and an upper forked part 11 6.

The prongs 115 of the lower fork 114 are articulated at their lower ends, about a transverse axis parallel to the pins 66, 74, 76 of the pedal rod 78, to a pair of raised attachment points 118 on the outer surface of the tubular portion 1 8 of the body 10. The yoke of the fork 114 has a central part which is rounded into a loop 120 projecting perpendicular to the yoke, and this central part is connected to the upper fork 11 6.

As described below, the loop 120 is arranged to cooperate with an annular collar 122 which is fixed to the rod 38 of the lifting piston 34 immediately below the bearing member 50.

The arms 124 of the upper fork 116 may be opened out resiliently and are bent at their centres to form two portions 1 26 which are oriented parallel to and away from the prongs 11 5 of the lower fork 114. The portions 126 form two lateral eyes 128 at their free ends.

In the inoperative condition of the jack shown in full outline in Figure 1, the rod 38 of the lifting piston 34 is retracted within the hollow shaft 36 so as to compress the spring 52, and the stop member 11 3 is in its raised position whereby the loop 120 engages the collar 122 to lock the rod 38 in its retracted position. The pedal rod 78 is folded and is locked in this position by the arm portions 126 of the upper fork 11 6, which grip the sleeve 82 fitted over the rod 78. In this condition, the jack has a limited size and may be easily carried and handled by means of the eyes 1 28 which are arranged to receive two fingers of a user's hand.

During use, the pedal rod 78 is disengaged from the upper fork 11 6 and brought into its extended position, as shown in broken outline in Figure 1, the sleeve 82 being positioned over the articulation zone between the lever 70 and the rod 78. The jack is then placed beneath the vehicle to be raised and may be positioned easily and conveniently by means of the pedal rod 78.

Subsequently, the stop member 113 is rotated downwardly to disengage the loop 120 from the collar 122, so that the rod 38, being thrust by the spring 52, automatically approaches the bottom of the vehicle and brings the bearing member 50 into contact with the corresponding lifting zone on the vehicle. By virtue of the mounting described above, the bearing member 50 is able to orient itself parallel to the.surface of this lifting zone. At this stage, the pumping piston 65 is operated by the pedal rod 78 to draw liquid from the reservoir 24 and deliver it to the thrust chamber 32 through the two non-return valves 94, 96. In this way, the lifting piston 34 enables the vehicle to be raised to the desired position.

Figure 3 shows the position of maximum extension of the piston 34, in which the lower end of the shaft 36 is adjacent the cover 26.

In order to return the lifting piston 34 to its retracted position and lower the vehicle, it suffices to operate the pedal 110 so as to open the discharge valve 104, thus placing the thrust chamber 32 in direct communication with the reservoir 24.

From the preceding description, it is clear that a jack according to the invention, as well as being extremely compact and light, and therefore easy to store and carry, is economic to manufacture and extremely practical and convenient to use.

Claims

1. A hydraulic lifting jack, including a body having a pump chamber, a pumping piston which is operable in the pump chamber and is connected to an external drive member, a fluid reservoir communicating with the pump chamber through a first non-return valve, a thrust chamber which communicates with the pump chamber through a second non-return valve and is connected to the reservoir through an externallyoperable discharge valve, a lifting piston which is slidable in the thrust chamber, the lifting piston being telescopic and including a hollow outer shaft and an inner rod which is slidable relative to the outer shaft between a retracted position and an extended position in which it projects outwardly of the outer shaft, the inner rod being biassed axially towards its extended position by a spring, and a stop member which is operable manually to lock the inner rod in its retracted position.

2. A jack according to Claim 1, in which the stop member includes a fork having prongs which are articulated to the body about an axis transverse the lifting piston, and a loop in correspondence with its yoke, which is engageable with a complementary cooperating element carried at the free end of the inner rod of the lifting piston. ~~~~~~~~~~~~~~~~~~~

3. A jack according to Claim 2, in which the drive member of the pumping piston comprises a pedal which is articulated to the body about an axis parallel to the articulation axis of the stop member, the pedal being foldable, when not in use, so as to adopt a position across the top of the body, and in which the stop member further includes a spring fork attachment for retaining the pedal in its folded position.

4. A jack according to Claim 3, in which the arms of the spring fork are bent to form a pair of eyes which are located side by side and constitute a handle.

5. A jack according to any of the preceding claims, in which the body is made from a single piece of moulded plastics material and comprises a base from which a tubular cylindrical portion extends, a tubular cylindrical element which is inserted coaxially in the tubular cylindrical portion and the interior of which defines the thrust chamber, the fluid reservoir being constituted by an annular space between the tubular element and the tubular portion, and a hollow portion alongside the tubular portion, which defines the pump chamber.

6. Ajack according to Claim 5, in which the base is formed with an intake duct and a delivery duct which connect the reservoir to the pump chamber and the pump chamber to the thrust chamber respectively.

7. Ajack according to Claim 6, in which the first and second non-return valves have a common valve body which is connected to the two ducts.

8. Ajack according to Claim 5, in which the tubular cylindrical portion of the body is closed on its side opposite the base by an annular plastics cover which is fitted sealingly onto the edge of the tubular portion and the corresponding edge of the tubular element inserted in the tubular portion.

9. A jack according to any of the preceding claims, in which the thrust chamber is connected to the reservoir by a discharge duct which is formed in the base and houses the discharge valve, the discharge valve including a rotary shutter having a control pedal.

10. A hydraulic lifting jack substantiaily as described herein with reference to, and as shown in, the accompanying drawings.