GB2128566A

GB2128566A - A trolley

Info

Publication number: GB2128566A
Application number: GB08325038A
Authority: GB
Inventors: John Richard Nuttall
Original assignee: Patrick Mills
Current assignee: Patrick Mills
Priority date: 1982-09-18
Filing date: 1983-09-19
Publication date: 1984-05-02
Also published as: GB8325038D0

Abstract

An adjustable trolley comprises a pair of jaws 2a, 2b carrying respective wheels 8a, 8b or sliders for running along a girder, and a telescopic member 6 which is pivotally connected at opposite ends to respective jaws and which is extended or retracted by screw-threaded means to enable the distance between the jaws to be varied to accommodate different girder sizes. A device 50 for locking the member 6 in adjusted position may be provided, and wheel supports 7a, 7b may carry hardened, serrated metal pads for clamping against a girder to hold the trolley at a desired position. <IMAGE>

Description

SPECIFICATION A trolley The present invention relates to a trolley.

Trolleys exist which comprise a pair of jaws which may be adjusted relative to each other and which support wheels on the free end of the jaws.

In use, the wheels run along the flanges of girders and adjustability of the jaws enables the spacing of the wheels to be varied to cater for girders of different width. Jaw adjustment is effected by means of a bar which has oppositely screwthreaded portions which engage with complementary internally screwthreaded apertures in the supports for the wheels. With such an arrangement a load supported on a girder through the trolley subjects the screw member to axial thrust forces. The length of the screw between the screw threaded portion will be a maximum when the trolley is set for largest beam size. Since the screw member is effectively a pin ended strut the axial thrust forces may lead to buckling when operating at maximum load and setting.

According to the present invention, there is provided an adjustable trolley comprising a pair of jaws, which are movable towards and away from one another, a pair of supports mounted at or near the free ends of respective jaws to enable the trolley to run along a girder or structural support members, a telescopic connection connecting the jaws together and means for extending and retracting the telescopic connection to move the jaws and support connected thereto away from and towards one another respectively to provide for adjustment to cater for support members of differing size.

A preferred embodiment of the invention may comprise any of the following advantageous features: a) The telescopic connection comprises two members pivotally connected to respective jaws.

b) The two members are connected to a further member which can telescope with respect to one of the said two members.

c) The two members are tubes which receives opposite ends respectively of the further members which is also tubullar and which receives the means for extending and retracting.

d) The means for extending and retracting comprises a screwthreaded member screwed into a complementary screwthreaded portion of the inner tube and axially fixed but rotatable with respect to the said one of the two members of (c).

e) Each pivotal connection of (a) comprises a box which is fixed to the respective one of the two members and each box houses a pivot which is connected to the respective one of the jaws.

f) The supports comprise wheels, flanged or unflanged rollers or slides.

g) Each support comprises a clamping pad which may be placed in clamping contact with the girder or structural member at a desired position of the trolley on the girder.

h) Each clamping pad is made of hardened serrated metal.

In order that the invention may be more clearly understood, one embodiment thereof will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a side elevational view of a trolley clamp, Figure 2 shows an end elevational view of the trolley clamp of Figure 1, Figure 3 is an elevational view in section of a telescopic adjustment forming part of the trolley of Figure 1 with the adjustment fully retracted, and Figure 4 is an elevational view in section of the telescopic adjustment of Figure 3 shown extended.

Referring to Figure 1, the trolley 1 comprises two jaws 2a and 2b which are pivotally connected together at pivot 3 and to a shackle 40. Each jaw comprises two side plates 4a and 4b. These side plates are connected together both at the pivot end and at the other end, remote from the pivot end. At this other end, each connection comprises an outer block 5a, 5b pivotally connected by means of pivot pins 5a', 5b' extending therethrough between corresponding side plates 4a, 4b. These blocks 5a, 5b are also welded to a telescopic adjustment member indicated generally by reference numeral 6 which will be described in more detail later.

The blocks 5a and 5b are in turn connected to respective supports 7a and 7b which support respective pairs of flanged wheels 8a and 8b through respective axles 9a and 9b (only one wheel of each pair 8a and 8b is visible in Figure 1) Wheel bearings are shown at 8c. Stiffeners 6a and 6b are connected to respective supports 7a and 7b. A lock 50 prevents rotation of the bar 23 from an adjusted position.

Referring more particularly to Figures 3 and 4, the telescopic adjustment member 6 basically comprises an outer telescope tube 21 and an inner telescopic tube 22, and an externally screwthreaded tommy bar 23. Tubes 22 and 21 are connected to corresponding blocks and supports 5a, 7a, 5b, 7b. An end cap 28 is fixed to the free end of the tube 22. The other end of the inner tube 22 extends slidably into the other outer tube 21. The screwthreaded tommy bar 23 is screwed into an internally screwthreaded portion 29 of the inner tube 22 and is retained therein by means of a retaining ring 30 fixed to the end of the bar disposed in the tube 22 but slidable within that tube 22. Locknuts 32a retain the bar 29 within the tube 21. The tommy bar 23 has an apertured larger diameter portion 31 at its other end and operating bar 23a is inserted through the aperture.The bar 23 extends, at its end adjacent the portion 31 through an end retaining cap 32 which is fixed within the adjacent end of the tube 21. A thrust collar with associated locking device is disposed on the bar 23 to transfer axial thrust to the tube 21 and at the same time permit rotational movement of the bar within the tube 21. The effective length of tommy bar 23 under axial thrust is indicated at 'L' on Figure 2.

In operation of the trolley, the tommy bar 23 is rotated to extend the telescopic member 6 and thereby open the jaws 2a and 2b to a spacing sufficient to enable the trolley to be placed over the flange of an I-beam. The bar 23 is then rotated in the opposite direction to close the jaws until the wheels 8a and 8b can be supported on the flange.

The trolley may then be rolled to the desired position on the I-beam and if desired, fixed in that position by rotating the bar 23 further until the pads 1 0a and 1 Ob grip the lateral edges of the flange. During the adjustment procedure, the pivotal connection of the jaws 2a and 2b to the member 6 enables the supports 7a, 7b and wheels 8a and 8b to remain parallel to each other. With this arrangement forces on the screwthread 23 which is the weakest and most vulnerable part of the assembly are reduced over what they would be if the connection between screwthreaded bar and jaws was direct. This is because the screw member 23 has a considerably reduced effective length (see Figure 2). It is also 'built in' at its ends thereby providing end constraining movements i.e.

at threaded region 29 of 22 and by 32 at the opposite end. The screw member, therefore, is a 'built in strut' within an outer sleeve (telescopic) arrangement and as such forms an exceptionally strong load bearing adjusting member that will not buckle even under extreme conditions.

It will be appreciated that the above embodiment has been described by way of example, and many variations are possible without departing from the scope of the invention. For example the wheels 8a, 8b may be replaced by rollers or slides.

The wheels could be plain rather than flanged.

With such an arrangement, clamping pads could be provided to clamp the trolley to the girder to prevent yawing of the trolley on the girder. These pads, which would preferably consist of hardened serrated metal plates would be fixed to the inner surfaces of the supports 7a nd 7b adjacent the flange of the girder.

Claims

1. An adjustable trolley comprising a pair of jaws, which are movable towards and away from one another, a pair of supports mounted at or near the free ends of respective jaws to enable the trolley to run along a girder or structural support members, a telescopic connection connecting the jaws together and means for extending and retracting the telescopic connection to move the jaws and support connected thereto away from and towards one another respectively to provide for adjustment to cater for support members of differing size.

2. An adjustable trolley as claimed in claim 1, in which the telescopic connection comprises two members pivotally connected to respective jaws.

3. An adjustable trolley as claimed in claim 2, in which the two members are connected to a further member which can telescope with respect to one of the said two members.

4. An adjustable trolley as claimed in claim 3, in which the two members are tubes which receives opposite ends respectively of the further member which is also tubular and which receives the means for extending and retracting.

5. An adjustable trolley as claimed in claim 4, in which the means for extending and retracting comprises a screwthreaded member screwed into a complementary screwthreaded portion of the inner tube and axially fixed but rotatable with respect to the said one of the two members.

6. An adjustable trolley as claimed in claims 2, 3, 4 or 5, in which each pivotal connection comprises a box which is fixed to the respective one of the two members and each box houses a pivot which is connected to the respective one of the jaws.

7. An adjustable trolley as claimed in any preceding claim, in which the supports comprise wheels, flanged or unflanged rollers or slides.

8. An adjustable trolley as claimed in any preceding claim, in which each support comprises a clamping pad which may be placed in clamping contact with the girder or structural member at a desired position of the trolley on the girder.

9. An adjustable trolley as claimed in claim 8, in which each clamping pad is made of hardened serrated metal.

10. An adjustable trolley substantially as hereinbefore described with reference to the accompanying drawings.