Patent GB-190222829-A (GB)
Title: Improvements in Electro-pneumatic Controlling Systems for Railway Vehicles.
Inventor: TALL FREDERICK WILLIAM LE
Filed: 1902-10-20
Granted: 1903-09-03
Abstract: 22,829. Le Tall, F. W., [ Westinghouse, G.]. Oct. 20. Motors, controlling.-Relates to electro-pneumatic controlling - systems for electrically - propelled vehicles, in which the admission of compressed air to the cylinders for operating the controlling- switches is governed by electromagnetic means controlled by a hand-switch. The control system is particularly adapted for the multiple - unit system. In the present invention, means are provided for preventing a controlling - drum from moving more than its prop3r distance at each stroke of the piston ; means are also provided for stopping the step-by-step movement at certain predetermined positions, and also for preventing the movement of the controller should the current exceed a limit. The Figure shows the general arrangement with the invention incorporated. The controlling-drum shaft 1 is fitted with two ratchet-wheels 2, 3, with which the pawls 4, 5 connected with the piston 6 engage. To prevent the controlling-drum from being rotated beyond the proper distance at each step, a stop pawl 41 is operated by a projection 44 on the pa wl 5, or other suitable projection, at each stroke. The current for energizing the magnet 10 controlling the valve for admitting the air to the cylinder 7 is supplied from the battery 13 through the handoperated switch fitted with contacts 20 ..... 25. In series with the electromagnet 10 is the " repeat " switch 33, which is carried on a rod 34 fitted with collars 37, 38 so that it is moved to break the circuit at the end of each stroke of the piston. The magnet 13 is thus de-energized, and the valve operated to allow the air to escape from the cylinder. The piston is then returned by its spring, and the switch 33 again closed, thus closing the circuit and permitting another movement of the piston. In order to stop the step-bystep movement at a predetermined position of the controller, a contact-arm 30 is geared to it, and at the desired position connects the contacts 27, 28, short-circuiting the switch 33 and so preventing the magnet 10 from being de-energized. By moving the hand-operated switch into another position, the step-by-step movement is again allowed, until the contact 30 engages the contact 29, when the switch 33 is again short-circuited. By suitably arranging the contacts of the handoperated switch, and also the shape &c. of the contact 30, other "stops" may be arranged for. To stop the step-by-step movement, should the current exceed a limit, an electromagnet 48 in shunt with one of the motor fields 49, or otherwise arranged, connects the contacts 45, 46, and so short-circuits the " repeat " switch 33. If other cars in the train are fitted with similar controlling- apparatus to that shown, the magnets 10 in all the cars will be energized from the battery 13 and controlled by the "repeat" switch 33 on the car with the hand-switch, and the stopping and limiting actions will be similarly governed. The Provisional Specification states that two stopping- switches may be provided for the two positions, and may be controlled electro-pueumatically. It also states that the limit switch may be arranged to operate an air cylinder, and return the controller to the ' off' position when the current exceeds a limit.