GB1604143A - Tractor mechanism - Google Patents

Description

(54) TRACTOR MECHANISM (71) I, BARRIE HERBERT, a British subject of Unity Road, Lowmoor Industrial Estate, Kirkby-in-Ashfield, Nottinghamshire NG17 7LE do hereby declare the invention for which I pray that a patent may be granted to me and the method by which it is to be performed be particularly described in and by the following statement: This invention relates to tractor mechanisms and more particularly concerns tractor mechanism which are adapted to run on an overhead rail.

According to the present invention I provide a tractor mechanism adapted to run on an overhead rail having opposed horizontally extending flanges said tractor mechanism comprising a frame including a pair of side members arranged to extend one or each side of the rail, said frame being provided with at least one pair of upper rollers arranged to run on the upper surfaces of said opposed flanges of the rail and a pair of lower rollers arranged to contact the undersurface of said rail flanges, a first of said lower rollers being mounted for rotation about an axis which is forward of a plane or planes including the axis of axes of rotation of said upper rollers and perpendicular to the longitudinal axis of said rail and a second of said lower rollers being mounted for rotation about an axis which is rearward of said plane or planes; and a drive unit pivoted on the frame and comprising a motor operatively connected to a driver roller arranged to contact the undersurface of said rail flanges, the pivot of said drive unit being offset from, and parallel with, the axis of rotation of said drive roller so that said drive unit can pivot relative to said frame when the load is attached to the frame to cause an increase in friction between said drive roller and said rail flanges with an increase in load.

In a preferred construction the end of said drive unit remote from its pivot to the frame is provided with resilient means to bias the dnve roller into engagement with the undersurface of the rail flanges. The resilient means may comprise a pair of threaded rods carrying springs retained by threaded nuts.

In order to stabilise the unit it may be provided with transverse alignment rollers which can engage the rail. In one preferred construction two pairs of alignment rollers are provided one on each side of the rail, the rollers being arranged so as to engage the edges of said flanges.

Reference is now made to the accompanying drawings, in which: Figure 1 is a perspective view from below of one form of tractor mechanism according to the present invention.

Figure 2 is a side elevation of the mechanism shown in Figure 1 with the motor removed; and Figure 3 is an end elevation of the mechanism shown in Figure 1 with the motor omitted.

The mechanism comprises a frame 10 which includes a pair of side members 11 and 12. These side members are arranged to be disposed on each side of the I-beam rail 13 upon which the tractor mechanism is designed to run.

As can be seen clearly from Figure 3 the frame is provided with a pair of rollers 14 which are fixed at 15 to the frame and which run on the opposed flanges 16 of the I-beam rail. The frame side members 11 and 12 also support spindles 17 and 18 which carry rollers 19 and 20 engaged with the undersurface of the flanges 16.

The drive unit comprises a pair of plates 21 and 22, the plate 21 carrying a gear box 23 and associated electric motor 24. The motor 24 is arranged to drive through the gear box 23, a spindle 25 which carries a drive roller 26 which engages with the under-surface of the flanges 16.

The plates 21 and 22 of the drive unit are pivoted at 27 to the frame 10 and at the end remote from the pivot 27 are supported by a pair of compression springs 28 carried on threaded rods 29 and retained by nuts 30.

The frame is provided with attachment means in the form of a Pair of lugs 31 having opposed apertures 32 for receiving an attachment pin (not shown).

The tractor mechanism of the present invention is relatively simple to construct and is also extremely convenient in use. The pivot arrangement for the drive unit ensures that when the load applied at the attachment means is increased then a greater pressure is applied by the drive roller and thus a corresponding increase in friction between the drive roller and the undersurface of the flanges 16 is obtained.

Furthermore for maintenance purposes it is relatively easy to remove the pivot pin 27 and disassemble the drive unit from the frame which can remain in position on the rail.

The tractor mechanism can be employed for transporting any devices along a rail, for example, skips cranes and hoists.

WHAT I CLAIM IS: 1. A tractor mechanism adapted to run on an overhead rail having opposed horizontally extending flanges said tractor mechanism comprising a frame including a pair of side members arranged to extend one on each side of the rail said frame being provided with at least one pair of upper rollers arranged to run on the upper surfaces of said opposed flanges of the rail and a pair of lower rollers arranged to contact the undersurface of said rail flanges, a first of said lower rollers being mounted for rotation about an axis which is forward of a plane or planes including the axis of axes of rotation of said upper rollers and perpendicular to the longitudinal axis of said rail and a second of said lower rollers being mounted for rotation about an axis which is rearward of said plane or lanes, and a drive unit pivoted on the frame and comprising a motor operatively connected to a drive roller arranged to contact the undersurface of said rail flanges, the pivot of said drive unit being offset from, and parallel with, the axis of rotation of said dnve roller so that said drive unit can pivot relative to said frame when the load is attached to the frame to cause an increase in friction between said drive roller and said rail flanges with an increase in load.

2. A tractor mechanism according to Claim 1 in which the end of said drive unit remote from its pivot to the frame is provided with resilient means to bias the drive roller into engagement with the undersurface of the rail flanges.

3. A tractor mechanism according to Claim 2 in which the resilient means comprises a pair of threaded rods carrying springs retained by threaded nuts.

4. A tractor mechanism according to any of Claims 1 to 3 having transverse alignment rollers which can engage the rail.

5. A tractor mechanism according to Claim 4 having two pairs of alignment rollers, one on each side of the rail, the rollers being arranged so as to contct the edges of said flanges.

6. A tractor mechanism substantiallv as herein described with reference to, and as shown in, the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. pivoted at 27 to the frame 10 and at the end remote from the pivot 27 are supported by a pair of compression springs 28 carried on threaded rods 29 and retained by nuts 30. The frame is provided with attachment means in the form of a Pair of lugs 31 having opposed apertures 32 for receiving an attachment pin (not shown). The tractor mechanism of the present invention is relatively simple to construct and is also extremely convenient in use. The pivot arrangement for the drive unit ensures that when the load applied at the attachment means is increased then a greater pressure is applied by the drive roller and thus a corresponding increase in friction between the drive roller and the undersurface of the flanges 16 is obtained. Furthermore for maintenance purposes it is relatively easy to remove the pivot pin 27 and disassemble the drive unit from the frame which can remain in position on the rail. The tractor mechanism can be employed for transporting any devices along a rail, for example, skips cranes and hoists. WHAT I CLAIM IS:

1. A tractor mechanism adapted to run on an overhead rail having opposed horizontally extending flanges said tractor mechanism comprising a frame including a pair of side members arranged to extend one on each side of the rail said frame being provided with at least one pair of upper rollers arranged to run on the upper surfaces of said opposed flanges of the rail and a pair of lower rollers arranged to contact the undersurface of said rail flanges, a first of said lower rollers being mounted for rotation about an axis which is forward of a plane or planes including the axis of axes of rotation of said upper rollers and perpendicular to the longitudinal axis of said rail and a second of said lower rollers being mounted for rotation about an axis which is rearward of said plane or lanes, and a drive unit pivoted on the frame and comprising a motor operatively connected to a drive roller arranged to contact the undersurface of said rail flanges, the pivot of said drive unit being offset from, and parallel with, the axis of rotation of said dnve roller so that said drive unit can pivot relative to said frame when the load is attached to the frame to cause an increase in friction between said drive roller and said rail flanges with an increase in load.

2. A tractor mechanism according to Claim 1 in which the end of said drive unit remote from its pivot to the frame is provided with resilient means to bias the drive roller into engagement with the undersurface of the rail flanges.

3. A tractor mechanism according to Claim 2 in which the resilient means comprises a pair of threaded rods carrying springs retained by threaded nuts.

4. A tractor mechanism according to any of Claims 1 to 3 having transverse alignment rollers which can engage the rail.

5. A tractor mechanism according to Claim 4 having two pairs of alignment rollers, one on each side of the rail, the rollers being arranged so as to contct the edges of said flanges.

6. A tractor mechanism substantiallv as herein described with reference to, and as shown in, the accompanying drawings.