GB2277913A

GB2277913A - Collector shoe assemblies for electric rail vehicles.

Info

Publication number: GB2277913A
Application number: GB9309854A
Authority: GB
Inventors: David Julian Hartland
Original assignee: Brecknell Willis and Co Ltd
Current assignee: Brecknell Willis and Co Ltd
Priority date: 1993-05-13
Filing date: 1993-05-13
Publication date: 1994-11-16
Anticipated expiration: 2013-05-13
Also published as: GB2277913B; GB9309854D0

Abstract

A collector shoe assembly mounted on an electric rail vehicle includes a shoe (14) which is biassed into engagement with a conductor rail (13). The collector shoe (14) is carried by a pivot arm (15) and a flexible strap (17) is connected to the pivot arm (15). The output element (19) of an air motor (20) is connected to the flexible strap (17) so that, in normal use, a degree of lost motion is afforded to permit movement of the collector shoe (14) under the action of its biassing means (21). In an emergency, however, the motor output element (19) is moved upwardly into its emergency position and the collector shoe (14) is moved clear of the conductor rail (13). <IMAGE>

Description

COLLECTOR SHOE ASSEMBLIES FOR ELECTRIC RAIL VEHICLES Field of the Invention This invention relates to collector shoe assemblies which are mounted on electric rail vehicles and which include means whereby the shoe is biassed into engagement with the conductor rail for the supply of power to the vehicle prime mover.

Background to the Invention Although, in use, the collector shoe is biassed into engagement with the conductor rail and maintains contact with the conductor rail to ensure the continuous supply of power, there are occasions, for example, in emergencies or when maintenance work is being carried out, when it is necessary to hold the collector shoe out of engagement with the conductor rail.

A number of different designs of collector shoe assembly have accordingly been proposed which include means for holding off the collector shoe. In one such arrangement, a primary pneumatic piston and cylinder assembly acts on a carrying arm for the collector shoe. The piston and cylinder assembly normally acts to pivot the carrying arm in a direction such that continuous engagement of the shoe with the rail is maintained.

When, however, it is desired to effect displacement of the collector shoe, the pneumatic piston and cylinder assembly is activated in the reverse direction and appropriate pivotal movement of the collector shoe carrying arm is obtained. In order to ensure that the carrying arm will remain in the required position, a latch mechanism is provided which engages with the retracted arm and holds it in that position. A secondary pneumatic piston and cylinder mechanism is then provided for effecting release of the latch mechanism, when so required.

Sne latch mechanism is not used very often; typically less than once per year. During the remainder of the time it is subject to wear and tear; it can rattle and, when it needs to function, can have become worn or distorted. Such an arrangement thus does not offer the required safety confidence factor.

In addition, because two pneumatic piston and cylinder mechanisms are required, with the need for corresponding valve operating gear within the vehicle, such an arrangement is expensive to install and to maintain.

It is accordingly an object of the present invention to provide an improved collector shoe assembly for an electric rail vehicle.

It is a further object of the present invention to provide an improved method of controlling the collector shoe assembly of an electric rail vehicle with a supply rail.

Summary of the Invention According to a first aspect of the present invention there is provided a collector shoe assembly for an electric rail vehicle, said assembly comprising a mounting for attachment to the vehicle, a collector shoe for engagement with a supply rail, a pivot arm interconnecting the collector shoe and the mounting, biassing means acting on the pivot arm to urge the collector shoe into continuous engagement with the supply rail, a flexible strap connected to the pivot arm and to the output element of an air motor such that, when the motor output element is in its normal, in use, position, a degree of lost motion is afforded so as to allow movement of the collector shoe under the action of the biassing means whereas, when the motor output element is moved into its emergency position, the collector shoe will be moved into a position clear of the supply rail.

According to a second aspect of the present invention there is provided a method of controlling the engagement of a collector shoe assembly of an electric rail vehicle with a supply rail, said method comprising: a) providing a mounting for attachment to the vehicle and a pivot arm interconnecting the collector shoe and the mounting, b) providing biassing means acting on the pivot arm to urge the collector shoe into continuous engagement with the supply rail, c) providing an air motor having an output element and a flexible strap which interconnects the pivot arm and the output element in such manner that, when the motor output element is in its normal, in use, position, a degree of lost motion is afforded so as to allow movement of the collector shoe under the action of the biassing means, and, when so required, d) activating the air motor to move the output element away from the pivot arm and hence, through the action of the flexible strap, displace the collector shoe into a position clear of the supply rail.

It is to be understood that the term "flexible strap" as used herein includes a chain, cord, belt or like flexible element.

The air motor preferably has a rotary element which drives a lead screw which has threaded engagement with a block to which the flexible belt is attached, the connection between the rotary element and the block being such that rotational movement of the rotary element produces linear movement of the block whereas the application of a longitudinal load to the block does not result in movement of the rotary element, i.e. a one-way system is provided such that activation of the motor in either direction will effect movement of the block which will then remain in the position into which it has been moved.

This arrangement thus ensures that, if there should be a failure of the air supply to the motor after the collector shoe has been moved out of engagement with the supply rail, the shoe will remain in its retracted position.

The pivotal arm which carries the collector shoe preferably forms part of a parallelogram linkage. This will ensure that the engagement surface of the shoe will be held in a position parallel to the presented surface of the supply rail while permitting the required movements of the shoe within the limited space available at the side of the rail vehicle. The parallelogram linkage is preferably acted on by spring means which serves to bias the collector shoe into engagement with the supply rail.

Brief Description of the Drawings Figure 1 is a view showing the shoegear mounted on the side of a rail vehicle, and Figure 2 is an end view of the shoegear.

Description of the Preferred Embodiment The assembly shown in the drawings is mounted on a bogie side frame 10 which includes a mounting for an axle carrying a wheel 11 which engages a running rail 12. A conductor rail 13 extends parallel to the running rail 13 and carries the power supply to the vehicle drive system. A lightweight collector shoe 14 is arranged to engage the conductor rail 13 and is carried by a carrying arm 15 which forms part of a parallelogram linkage 16. The collector shoe 14 is movable between the positions indicated in Figure 2.

The carrying arm 15 is acted upon by a flexible strap 17 the upper end of which is connected to a block 18 which is movable linearly under the control of a rotary output element 19 of an air motor 20. A gearbox may be interposed between the output element 19 and the block 18 to ensure that rotary movement of the output element 19 (in either direction) is transmitted to the block 18 (to move it either upwardly or downwardly) whereas the application of either an upward or downward force to the block 18 does not produce any resulting movement of either the block 18 or the output element 19.

In use, the air motor 20 is not activated and the block 18 is in the position shown such that, by virtue of the lost motion connection afforded by the flexible strap 17, the collector shoe 14 is free to move upwardly and downwardly under the control of the parallelogram linkage system 16 whilst remaining in contact with the conductor rail 13 under the action of spring means 21.

When the air motor 20 is activated, the block 18 will be moved upwardly and, through the action of the strap 17, the collector shoe 14 will also be moved upwardly, i.e. into its retracted height position. The connection between the output element 19 of the motor 20 and the block 18 is then such that, regardless of any possible failure of the air supply for the motor 20, the collector shoe 14 will be maintained in its retracted position.

The valve control gear within the vehicle will be extremely simple in that it will merely be necessary to provide for activation of the air motor 20 in either direction and no ancillary pneumatic systems will be required.

Then, therefore, the collector shoe 14 needs to be moved away from the conductor rail 13, whether in an emergency or for maintenance purposes, the motor will be activated in the appropriate direction and the collector shoe 14 will be raised.

The collector shoe 14 will then remain in its raised position until the appropriate valvegear within the vehicle is operated to activate the motor 20 in the opposite direction.

Claims

Claims:

1. A collector shoe assembly for an electric rail vehicle, said assembly comprising a mounting for attachment to the vehicle, a collector shoe for engagement with a supply rail, a pivot arm interconnecting the collector shoe and the mounting, biassing means acting on the pivot arm to urge the collector shoe into continuous engagement with the supply rail, a flexible strap connected to the pivot arm and to the output element of an air motor such that, when the motor output element is in its normal, in use, position, a degree of lost motion is afforded so as to allow movement of the collector shoe under the action of the biassing means whereas, when the motor output element is moved into its emergency position, the collector shoe will be moved into a position clear of the supply rail.

2. An assembly as claimed in Claim 1, in which the motor output element is a rotary element which drives a lead screw which has threaded engagement with a block to which the flexible strap is attached.

3. An assembly as claimed in Claim 1, in which the pivot arm which carries the collector shoe forms part of a parallelogram linkage.

4. An assembly as claimed in Claim 3, in which the parallelogram linkage is acted on by spring means which serves to bias the collector shoe into engagement with the supply rail.

5. A method of controlling the engagement of a collector shoe assembly of an electric rail vehicle with a supply rail, said method comprising: a) providing a mounting for attachment to the vehicle and a pivot arm interconnecting the collector shoe and the mounting, b) providing biassing means acting on the pivot arm to urge the collector shoe into continuous engagement with the supply rail, c) providing an air motor having an output element and a flexible strap which interconnects the pivot arm and the output element in such manner that, when the motor output element is in its normal, in use, position, a degree of lost motion is afforded so as to allow movement of the collector shoe under the action of the biassing means and, when so required, d) activating the air motor to move the output element away from the pivot arm and hence, through the action of the flexible strap, displace the collector shoe into a position clear of the supply rail.

6. A method as claimed in Claim 5 and substantially as hereinbefore described.

7. A collector shoe assembly for an electric rail vehicle substantially as hereinbefore described with reference to and as shown in the accompanying drawings.