GB1584745A - Castors - Google Patents

Description

(54) IMPROVEMENTS IN CASTORS (71) We, XEROX CORPORATION, of Xerox Square, Rochester, New w ork, United States of America, a corporation organised under the laws of the State of New Rork, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to castors and particularly to twin wheel castors incorporating brakes for locking the castor wheels against rotation.

Castors are known which have integral brakes, e.g. from U.S. Patents 2987141, 3025930 and 3162888 but these suffer more or less from complexity and/or space requirements.

The present invention provides a twin wheel castor including a pair of hollow castor wheels and a manually operable brake including brake means engageable with the internal surfaces of both castor wheels. With such an arrangement the brake mechanism may be at least partially accommodated within the wheels.

A particularly simple form of brake mechanism may be provided by arranging that the brake means engage the inside of the periphery of each wheel. In a preferred form of such mechanism, the brake means is carried by an arm supported from the castor spindle and movable axially of the spindle, brake actuation means being provided releasably to urge the arm in a direction to engage the brake means. The brake actuation means may, for example, comprise a thumb wheel screwed onto the spindle.

Or, it may comprise a slotted cam lever mounted on the spindle.

In order that the invention may be more readily understood, reference will now be made to the accompanying drawings, in which: Figure 1 is a partial section through one embodiment of castor according to the invention, Figure 2 is a partial section along the line II-II of Figure 1, Figure 3 is a section, similar to that of Figure 2, through a second embodiment of castor according to the invention, and Figure 4 is a scrap view of the brake mechanism of the castor shown IN Figure 3.

Referring to Figures 1 and 2, an embodiment of twin-wheel castor according to the invention is shown which incorporates a simple brake mechanism which is operative to lock the castor wheels against rotary movement and at the same time may be used to lock the castor against pivoting movement.

The castor comprises two hollow wheels 2 mounted on a common axle 4 for independent rotary movement. The axle is supported in a bearing block 6. The bearing block 6 itself carries the castor spindle or stud 8 which is mounted to the block by a ball bearing (not visible) within a recess in the block so as to allow rotation of the spindle relative to the block, and thus pivoting movement of the castor. The spindle is screw-threaded for connecting it to a machine or other device to be supported on the castor. The hollow castor wheels 2 are generally cup-shaped in cross-section, having peripheral flanges 10, with their internal surfaces facing inwardly towards each other.

A manually operated brake, generally indicated at 12, includes rubber pads 14 arranged to engage the insides of the wheel flanges 10. The brake pads are mounted on an arm 16, supported from the castor spindle 8. As seen in Figure 2 the arm 16, which may be made of sheet steel or die cast aluminium, is generally U-shaped with the brake pads 14 at one end, the other end (which is apertured at 18) being a sliding fit over the spindle 8. A brake actuator 20 in the form of a thumb-wheel screwed on to the spindle 8 is operable through a thrust washer 22 to drive the apertured end of the arm 16 down the spindle so engaging the brake pads 14 with the insides of the wheel flanges 10. The brake is released by unscrewing the thumb-wheel 20.

It will be seen that with this arrangement a very simple but effective brake mechanism is provided which is partially accommodated within the hollow wheels and does not extend substantially outside the castor. Further, it does not interfere with the ground clearance of the device supported by it and the area between castors is not intruded upon allowing the device to be moved by a fork lift truck.

It is to be understood that in addition to locking the castor wheels against rotary movement, the brake may in a preferred form of the invention, also be used to lock the castor against pivoting movement. Thus the brake arm 16 may be dimensioned so that as the brake pads 14 engage the wheels 2 the apertured end 18 of the arm engages the bearing block 6 and locks the latter against movement relative to the spindle 8.

In a variation, the brake arm 16 may be sufficiently resilient that it will first engage the brake pads 14 to lock the wheels 2 against rotary motion, further downward movement of the thumb-wheel 20 causing the arm 16 to flex until the apertured end 18 of the arm engages the bearing block 6 as described above.

Referring now to Figures 3 and 4 a second embodiment of the invention is shown which has a different form of brake actuating mechanism. Like parts to those described with reference to Figures 1 and 2 are identified by like references. In this embodiment the brake actuator comprises a cam lever 30 having a slotted cam portion 32 embracing the spindle 8. The cam portion 32 is disposed between the thrust washer 22 and a fixed reaction surface 34, which is suitably the underside of a shock mount 36 by which the castor is connected to the device D on which it is mounted.

The cam portion 32 is thicker at one end of the slot 33 than the other and thus the brake arm 16 may be moved downwardly and released by movement of the lever 30 between positions in which the spindle 8 seats against opposite ends of the slot 33.

The lever could be moved by direct application of pressure to actuate and release the brake but preferably, as shown, it is pivoted at 38 to the shock mount 36 adjacent the spindle 8 so that it may be foot operated by applying a horizontal force to the lever end 40.

Although particular embodiments of the invention have been described, it will be understood that various modifications may be made to the specific details described herein without departing from the scope of the invention as defined in the appended claims. For example, the castor may be adapted for mounting to a device to be supported thereby by means other than the threaded spindle or shock mount described.

While the castor may be used to support any device, it may by way of example be used to support a photocopier.

If desired, as an anti-vibration measure, a soft rubber washer may be fitted over the spindle between the underside of the apertured end 18 of the brake arm and the top of the bearing block 6. This will also tend to act as a return biasing means for the arm when it is released. A light spring could be substituted for this washer.

WHAT WE CLAIM IS: 1. A twin wheel castor including a pair of hollow castor wheels and a manually operable brake including brake means engageable with the internal surfaces of both castor wheels.

2. A castor according to claim 1 in which the brake means is arranged to engage the inside of the periphery of each wheel.

3. A castor according to claim 2 in which the brake means is carried by an arm supported from the castor spindle and movable axially of the spindle, brake actuation means being provided releasably to urge the arm in a direction to engage the brake means.

4. A castor according to claim 3 in which the brake actuation means comprises a thumb wheel screwed onto the spindle.

5. A castor according to claim 3 in which the brake actuation means comprises a slotted cam lever mounted on the spindle.

6. A castor according to claim 3, 4 or 5, in which the brake actuation means serves also to lock the castor against pivoting movement.

7. A twin wheel castor constructed, arranged and adapted to operate substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

8. A twin wheel castor, constructed, arranged and adapted to operate substantially as hereinbefore described with reference to Figures 3 and 4 of the accompanying drawings.

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

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. mechanism is provided which is partially accommodated within the hollow wheels and does not extend substantially outside the castor. Further, it does not interfere with the ground clearance of the device supported by it and the area between castors is not intruded upon allowing the device to be moved by a fork lift truck. It is to be understood that in addition to locking the castor wheels against rotary movement, the brake may in a preferred form of the invention, also be used to lock the castor against pivoting movement. Thus the brake arm 16 may be dimensioned so that as the brake pads 14 engage the wheels 2 the apertured end 18 of the arm engages the bearing block 6 and locks the latter against movement relative to the spindle 8. In a variation, the brake arm 16 may be sufficiently resilient that it will first engage the brake pads 14 to lock the wheels 2 against rotary motion, further downward movement of the thumb-wheel 20 causing the arm 16 to flex until the apertured end 18 of the arm engages the bearing block 6 as described above. Referring now to Figures 3 and 4 a second embodiment of the invention is shown which has a different form of brake actuating mechanism. Like parts to those described with reference to Figures 1 and 2 are identified by like references. In this embodiment the brake actuator comprises a cam lever 30 having a slotted cam portion 32 embracing the spindle 8. The cam portion 32 is disposed between the thrust washer 22 and a fixed reaction surface 34, which is suitably the underside of a shock mount 36 by which the castor is connected to the device D on which it is mounted. The cam portion 32 is thicker at one end of the slot 33 than the other and thus the brake arm 16 may be moved downwardly and released by movement of the lever 30 between positions in which the spindle 8 seats against opposite ends of the slot 33. The lever could be moved by direct application of pressure to actuate and release the brake but preferably, as shown, it is pivoted at 38 to the shock mount 36 adjacent the spindle 8 so that it may be foot operated by applying a horizontal force to the lever end 40. Although particular embodiments of the invention have been described, it will be understood that various modifications may be made to the specific details described herein without departing from the scope of the invention as defined in the appended claims. For example, the castor may be adapted for mounting to a device to be supported thereby by means other than the threaded spindle or shock mount described. While the castor may be used to support any device, it may by way of example be used to support a photocopier. If desired, as an anti-vibration measure, a soft rubber washer may be fitted over the spindle between the underside of the apertured end 18 of the brake arm and the top of the bearing block 6. This will also tend to act as a return biasing means for the arm when it is released. A light spring could be substituted for this washer. WHAT WE CLAIM IS:

1. A twin wheel castor including a pair of hollow castor wheels and a manually operable brake including brake means engageable with the internal surfaces of both castor wheels.

2. A castor according to claim 1 in which the brake means is arranged to engage the inside of the periphery of each wheel.

3. A castor according to claim 2 in which the brake means is carried by an arm supported from the castor spindle and movable axially of the spindle, brake actuation means being provided releasably to urge the arm in a direction to engage the brake means.

4. A castor according to claim 3 in which the brake actuation means comprises a thumb wheel screwed onto the spindle.

5. A castor according to claim 3 in which the brake actuation means comprises a slotted cam lever mounted on the spindle.

6. A castor according to claim 3, 4 or 5, in which the brake actuation means serves also to lock the castor against pivoting movement.

7. A twin wheel castor constructed, arranged and adapted to operate substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

8. A twin wheel castor, constructed, arranged and adapted to operate substantially as hereinbefore described with reference to Figures 3 and 4 of the accompanying drawings.