GB2224719A

GB2224719A - Lifting jack

Info

Publication number: GB2224719A
Application number: GB8924016A
Authority: GB
Inventors: Dieter Weisser; Franz Hafner; Thomas Pfeiffer
Original assignee: EA Storz GmbH and Co KG
Current assignee: EA Storz GmbH and Co KG
Priority date: 1988-10-28
Filing date: 1989-10-25
Publication date: 1990-05-16
Anticipated expiration: 2009-10-25
Also published as: ES1014751Y; GB2224719B; DE3839465A1; GB9211816D0; DE3839465C2; GB2255071A; ES1014620U; ES1014620Y; GB2255071B; ES1014751U; GB8924016D0

Description

2224719 1 LIFTING JACK The invention relates to a so-called side lifting

jack, namely a lifting jack having a hollow upright column which possesses a foot at the bottom and in which are arranged a rotatably mounted, axially undisplaceable threaded spindle extending in the longitudinal direction of the column and a carriage which is displaceable along the latter and which extends through a longitudinal slit in the upright column and is provided with a carrier arm attachable to a vehicle and a nut movable on the threaded spindle. The term "upright" as used herein refers to the orientation of the column during use of the lifting jack.

If the carrier arm of such a lifting jack is under load during lifting of a vehicle, then the upper region of the carriage is pressed against the edge regions of the upright column wall adjacent to the longitudinal slit from the inside, while the lower carriage region is pressed against the rear of the upright column opposite the longitudinal slit. Since the upright column is a tubular metal section having a slit along its length, loading of the carrier arm beyond the usual extent can lead to the longitudinal slit of the upright column being widened by the upper carriage region in an irreversible manner. that is to say the upright column is permanently deformed in an unacceptable way. In this context, it should be pointed out that previously proposed side lifting jacks have upright columns which are manufactured from sheet metal by calendering or rolling, and the carriages comprise two mutually opposing half shells of sheet metal secured to one another which enclose the threaded spindle with spacing and keep the nut movable on the threaded spindle in the lower carriage region. In one form of lifting jack of this type, the carriage has, in the upper region in front of the threaded spindle and behind the longitudinal slit of the upright column, a 2 window in which a plastics slide element is inserted, by means of which the upper carriage region is supported against the inner wall of the upright column when the carrier arm is under load. The nut movable on the threaded spindle is similarly constructed as a plastics element and inserted in a window in the lower carriage region; in this case, the nut protrudes rearwardly beyond the rear of the carriage so that the carriage is supported at the bottom by way of the nut against the inner wall of the upright column when the carrier arm is under load. In this manner, good sliding properties of the carriage in the upright tube are achieved even when the carrier arm is under load. In a known embodiment of this lifting jack, the upper plastics slide element has in cross section transverse to the axis of the upright column at the front an approximately W-shaped profile and the edge regions of the upright column wall adjacent to the longitudinal slit are shaped such that they are adapted to this W-shaped profile and form a respective guide nut for the two rib-shaped protuberances formed by the plastics slide element; if the carrier arm is then excessively loaded, this plastics slide element is not however able to prevent a deformation of the upright -column, in connection with a widening of the longitudinal slit, by the upper carriage region.

The risks of unacceptable deformation of the upright column, which are caused by overloading the carrier arm and increased by the fact that loading of the carrier arm presses the upper carriage region against the edge regions of the upright column wall adjacent to the longitudinal slit of the upright col = and presses the lower carriage region against the rear of the upright column, have hitherto not been taken account of in the prior art and have not been remedied by known constructions.

3 The invention was based on the object of specifying measures which prevent the upright column from being unacceptably deformed, namely in the manner of widening of its longitudinal slit, even when the carrier arm is overloaded, as far as this occurs in practice.

The basic concept of the inventive measures serving as a solution to this object is to construct the upright column and where appropriate the carriage such that the upright column is sufficiently rigid at the points which are decisive for widening of its longitudinal slit for the forces exerted by the carriage on the upright column wall during an overloading occurring in practice of the carrier arm to be resistable and/or to construct the edge regions of the upright column wall adjacent to the longitudinal slit and the metal regions of the carriage for such an overloading such that they engage in one another when the carrier arm. is overloaded, namely in that the carriage prevents widening of the longitudinal slit of the upright column.

In accordance with a first embodiment of the solution in accordance with the invention, a lifting jack of the type mentioned at the outset is constructed such that the cross section of the upright column in the region of the rear of the upright column opposite the longitudinal slit is constructed such that the rigidity of the upright column wall against deformation tending to widen the longitudinal slit is greater there than in those side wall regions of the upright column wall which are located between the rear of the upright column and those edge regions of the upright column wall which are arranged on either side of the longitudinal slit. This can be achieved, for example, by corresponding shaping of the rear of the upright column, but it is simpler, in particular for manufacturing of the upright column, if the wall thickness of the upright column in the region of 4 the rear of the upright column is made greater than in the side regions of the upright column wall. In similar manner, it has an advantageous effect if the cross section of the upright column in the edge regions adjacent to the longitudinal slit is constructed such that the rigidity of the upright column wall there against a deformation widening the longitudinal slit is greater than in the side regions of the upright column wall. This too can be achieved by a corresponding shaping of the upright column, but an embodiment is to be preferred in which the wall thickness of the upright column in the edge regions adjacent to the longitudinal slit is greater than in the side regions of the upright column wall. These measures according to the invention can also be described in that the shape of the upright column is provided with as thin a wall as possible wherever the problem described is not encountered, while a larger wall thickness than that of the known upright columns is chosen for the rear of the upright column and where appropriate also for the edge regions of the upright column wall adjacent to the longitudinal slit.

In the case of the known side lifting jack already described, having two plastics slide elements inserted in windows in the carriage, these slide elements, in particular the upper one, are relatively short (in the longitudinal direction of the upright column) because larger windows would weaken the carriage or the transition from the carriage to the carrier arm to too great an extent; typically, the length of the upper plastics slide element in this known lifting jack is approximately 1/5 of the height or length (in the longitudinal direction of the upright column) of the carriage. It has now been shown that substantially longer plastics slide elements which are not arranged in windows in the carriage can be used to achieve the stated object without the carriage or its transition to the 1 carrier arm being weakened. For a lifting jack of the type mentioned at the outset, having a metal upright column and a metal carriage, it is consequently proposed in accordance with the invention to secure to the carriage on either side of the longitudinal slit elongate plastics slide elements which extend in the longitudinal direction of the column and slide in guide grooves provided on either side of the longitudinal slit in the inner wall of the upright column. These elongate plastics slide elements prevent widening of the longitudinal slit in the manner of a type of wedge-andgroove connection, while a further plastics slide element can be formed in the lower region of the carriage in turn by a plastics nut. As an additional measure it is recommended to increase the wall thickness of the rear of the upright column.

In accordance with another proposed solution for a lifting jack of the type mentioned at the outset, having a metal upright column and a metal carriage, the cross sections of the carriage and the upright column on either side of the longitudinal slit are constructed such that grooves and metal projections provided on the upright column and the carriage and extending in the longitudinal direction of the column engage in one another when the carrier arm is under high load in the manner of grooveand-wedge guides preventing widening of the longitudinal slit and aligned parallel to the displacement plane of the carrier arm. With such a lifting jack, therefore, the carriage may be provided with plastics slide elements which under normal loading of the carrier arm prevent sliding of metal regions of the carriage against the metal upright column wall. while the metal projections and grooves only come into effect when the carrier arm is acted upon by an excessive load which leads to considerable deformation of the plastics slide elements and allows the projections to engage in the grooves, as a 6 result of which the edge regions of the upright column wall extending on either side of the longitudinal slit then hook onto the carriage, which makes it impossible for the longitudinal slit of the upright column to be widened.

Although an upright column according to the invention having differing wall thicknesses could also be manufactured by rolling or calendering, a preferred embodiment of the lifting jack according to the invention has an, in particular, metal upright column which is formed from an extruded section. The same is true for the embodiment with the production of grooves and projections serving for hooking, in which it is then also recommended-to form the, in particular, metal carriage from an extruded section to which the carrier arm is secured.

Further features, advantages and details of the invention emerge from the following description and from the attached illustration in the form of a drawing of three different and particularly advantageous embodiments of the lifting jack according to the invention. In the drawing:

Fig. 1 shows a side view of the first embodiment, with the upright.column shown open in the region of the carriage and with the carriage shown partially in longitudinal section; Fig. 2 shows a section through the embodiment of Fig. 1 along the line 2-2 in Fig. 1, and Figs. 3 and 4 show illustrations corresponding to Fig. 2 of the second and third embodiment.

The lifting jack according to Figs. 1 and 2 has an 7 upright column 10 which has welded to its lower end a foot 12 and which carries at the top, below a cap 14, an angular gearing mechanism (not shown) which can be driven by a hand crank 16 and which sets a threaded spindle 18 in rotation, this threaded spindle being mounted, by means which are not shown, rotatably but axially undisplaceably in the upright column 10. The upright column 10 has, opposite a rear 10b of the upright column, a longitudinal slit 22 through which there extends a carrier arm 24, which is secured directly to a carriage 26 in the embodiment illustrated; this carriage is guided longitudinally displaceably in the hollow upright column 10.

As can clearly be seen from Fig..2, the metal upright column 10 comprises an extruded section having thickened edge regions 10a on either side of the longitudinal slit 22, a rear 10b also of relatively large wall thickness and relatively thin side regions 10c between the edge regions 10a and the rear 10b. The thickened edge regions 10a are provided on the upright column inner wall with projections 10d which are directly adjacent to the longitudinal slit 22 and form rib-like hooking noses extending in the longitudinal direction of the upright column, and to which a respective hooking groove 10e is connected.

The carriage 26 is also formed from a hollow extruded section in whose hollow space 26a. extending in the longitudinal direction of the upright column, the threaded spindle 18 runs. Opposite the hooking projections 10d of the upright column 10, the carriage has a respective hooking groove 26b, while a respective hooking projection 26c of the carriage is opposite the hooking grooves 10e of the upright column 10 and has, in accordance with the invention, a shape similar to a saw tooth.

8 As can be seen from Figs. 1 and 2, plastics slide elements 26e are inserted in grooves 26d of the carriage 26 running almost entirely around, and with the help of these plastics slide elements 26e the carriage is displaceably guided in the upright column 10. To this end, a plastics nut 30 is furthermore inserted in a window 26f of the carriage and is held undisplaceably and non-rotatably by the window, is movable on the threaded spindle 18 and is supported against the rear 10b of the upright column. By rotating the threaded spindle 18, the carriage 26 together with the carrier arm 24 is thus displaced in the longitudinal direction of the upper column 10. In order that the supporting forces between the plastics nut 30 and the rear 10b of the upright column 10 can be better introduced into the carriage 26, the plastics nut 30 is reinforced on its side facing the carrier arm 24 by a metal Plate 30a.

with normal loading of the carrier arm 24, the carriage 26 slides only by means of the plastics slide elements 26e and the plastics nut 30 against the inner wall of the upright column 10, since as a result of the fact that the plastics slide elements 26e almost entirely surround the carriage 26 the projections 10d and 26c are prevented from bearing against the walls of the grooves 26b or 10e respectively. However, if the carrier arm 24 is acted upon by an excessive load, as may easily occur in practice, the plastics slide elements 26e are pressed against the regions of the upright column inner wall adjacent to the edge regions 10a of the upright column with such a force that, as a result of a deformation of the plastics slide elements. the projections 10d and 26c engage in the grooves 26b and 10e opposite them, which has the consequence that the edge regions 10a of the upright column hook onto the carriage 26 and the longitudinal slit 22 cannot be widened. Also preventing this is the fact that the upright column rear 10b, 9 against which the plastics nut 30 is pressed, has a much larger wall thickness than the side regions 10c of the upright column section.

The variants of the lifting jack according to the invention indicated in Figs. 3 and 4 will only be described inasmuch as they differ from the first embodiment of Figs. 1 and 2. The same reference numerals have been used in Figs. 3 and 4 as in Figs. 1 and 2, but a dash has been added in Fig. 3 and two dashes have been added in Fig. 4.

In the embodiment of Fig. 3, the plastics slide elements 26e' surround the carriage 26' to an even greater extent than in the first embodiment, so that the upright column 10' or the upright column section hooks onto the carriage 26' only by means of rib-shaped projections 26c' on the carriage and grooves 1Oe' on the upright column section.

In the embodiment of Fig. 4, two rod-shaped plastics slide elements 26e" extending in the longitudinal direction of the upright column take over the function of hooking the edge regions 10a" of the upright column 1C on the carriage 2611 when the carrier arm 2C is overloaded, that is to say of preventing the longitudinal slit 22" from widening (apart from the thickened construction of the rear 1OW' of the upright column 10"). To this end, the rod-shaped plastics slide elements 26e" extend (in a manner not shown) for example over the upper half of the carriage 2611, they are secured to the carriage and engage in grooves 1Oe" in the inner wall of the upright column 1C. Together with the plastics nut (not shown) of the carriage 2C, the plastics slide elements 26ell thus take over the function of guiding in sliding manner the carriage 2611 in the upright column 1011, and in addition the plastics slide elements 10ell serve to prevent widening of the longitudinal slit 22" if the carrier arm 2C is overloaded.

In contrast to the embodiments of Figs. 1 to 3, in which under normal conditions only the plastics parts thus touch the upright column but the metal carriage, which only engages with the upright column section in the case of overloading, does not, in the embodiment of Fig. 4 only the plastics parts carried by the carriage and not the metal carriage come into contact with the upright column section even in the case of overloading.

k 11

Claims

1. A lifting jack having a hollow upright column which possesses a foot at the bottom and in which are arranged a rotatably mounted, axially undisplaceable threaded spindle extending in the longitudinal direction of the column and a carriage which is displaceable along the latter and which extends through a longitudinal slit in the upright column and is provided with a carrier arm attachable to a vehicle and a nut movable on the threaded spindle, characterized in that the cross section of the upright column in the region of the rear of the upright column opposite the longitudinal slit is constructed such that the rigidity of the upright column wall against deformation.tending to widen the longitudinal slit is greater there than in those side wall regions of the upright column wall which are located between the rear of the upright column and those edge regions of the upright column wall which are arranged on either side of the longitudinal slit.

2. A lifting jack according to Claim 1, characterized in that the wall thickness of the upright column in the region of the rear of the upright column is greater than in the side regions of the upright column wall.

3. A lifting jack according to Claim 1 or 2, characterized in that the cross section of the upright column in the edge regions adjacent to the longitudinal slit is constructed such that the rigidity of the upright column wall there against a deformation widening the longitudinal slit is greater than in the side regions of the upright column wall.

4. A lifting jack according to Claim 3p characterized in that the wall thickness of the upright column in the edge regions adjacent to the longitudinal slit is greater 12 than in the side regions of the upright column wall.

5. A lifting jack having a metal hollow upright column which possesses a foot at the bottom and in which are arranged a rotatably mounted, axially undisplaceable threaded spindle extending in the longitudinal direction of the column and a metal carriage which is displaceable along the latter and which extends through a longitudinal slit in the upright column and is provided with a carrier arm attachable to a vehicle and a nut movable on the threaded spindle, preferably according to any one of Claims 1 to 4, characterized in that, on the outside of the carriage on either side of the longitudinal slit are secured elongate plastics slide elements which extend at least over approximately half the height of the carriage in the longitudinal direction of the column and are slidable guide grooves provided on either side of the longitudinal slit in the inner wall of the upright column.

6. A lifting jack having a metal hollow upright column which possesses a foot at the bottom and in which there are arranged a rotatably mounted, axially undisplaceable threaded spindle extending in the longitudinal direction of the column and a metal carriage which is displaceable along the latter and which extends through a longitudinal slit in the upright column and is provided with a carrier arm attachable to a vehicle and a nut movable on the threaded spindle, preferably according to any one of Claims 1 to 4. characterized in that the cross sections of the carriage and the upright column on either side of the longitudinal slit are constructed such that grooves and metal projections provided on the upright column and the carriage and extending in the longitudinal direction of the column engage in one another when the carrier arm is under high load in the manner of groove- and-wedge guides preventing widening of 13 the longitudinal slit and aligned parallel to the displacement plane of the carrier arm.

7. A lifting jack according to one or more of the preceding claims, characterized in that the carriage is provided with at least one plastics slide element preventing contact between the carriage and the inner wall of the upright column under normal loading of the carrier arm.

8. A lifting jack according to Claim 7, characterized in that the carriage has at least two plastics slide elements which are arranged spaced from one another in the upper and lower region of the carriage and whereof, when the carrier arm is under load, the upper provides support in the region on either side of the longitudinal slit and the lower provides support in the region of the rear of the upright column against the upright column wall.

9. A lifting jack according to one or more of the preceding claims, characterized in that the upright column is formed from an extruded section.

10. A lifting jack according to one or more of the preceding claims, characterized in that the carriage is formed from an extruded section to which the carrier arm is secured.,

11. A lifting jack substantially as hereinbefore described with reference to Figures 1 and 2, or Figure 3, or Figure 4, of the accompanying drawings.

Published 1990 at The Patent Office. State House, 66"71 High Holborn. London WClR4TP. Further copies maybe obtainedfrom. The Patent Office. Sales Branch. St Mary Cray, Orpington, Kent BR5 3RD- Printed by Multiplex techniques ltd. st Mary Cray, Kent, Con. 1/87