Patent GB-189817422-A (GB)
Title: Improvements in Devices for Controlling Motors at a Distance.
Inventor: CHAPMAN JOSEPH CRAWHALL
Filed: 1898-08-12
Granted: 1899-07-29
Abstract: 17,422. Chapman, J. C., [Gill, E. R.]. Aug. 12. Electric locomotives and motor vehicles.-Relates to means for controlling motors at a distance, especially applicable to electric railways and tramways, both where single cars are used or where trains are run. Fig. 1 shows a form of the invention in which the main electric motor 5 which is to be controlled is made to supply power for operating the rheostat or other controller 1. The rheostat is actuated in one direction or the other by loose arms 6, 7, either of which may be made to engage magnetically with a disc on the motor. The engagement of the magnets is dependent on the movements of a handle 21 forming part of a switch, called the manipulator,' having contacts 25, 26 and brushes 14, 15 by which one or other of the magnet circuits is closed, and certain other functions are performed. The magnet which is rendered operative, and therefore the direction of movement of the rheostat, is made dependent on the direction in which the handle 21 is adjusted. This is effected through the medium of the frictionally-held arm 23, and of a loose lever 16 carried by the brush-lever 13, whereby one or other of the brushes 14, 15 is brought into action. The movement of the rheostat arm is intermittently terminated, and thereby made proportional to the adjustment of the manipulator by the interruptions in the magnet circuits due to the breaks between the contacts a, b, c, d. When full speed or stoppage is desired at once, the handle 21 is thrown at once to its extreme position, and the overlapping of the contacts in the brushes 14, 15 ensures the maintenance of the magnet circuits in spite of the breaks in the iuterruptor. A stop is provided to prevent too sudden reversal. This is made to release the manipulator handle by the lever 13 only when suitable resistances are in the motor circuit. Means are also described by which resistance is thrown in automatically whenever the current fails, so that no damage may be done by the revival of the current. The further function performed by the manipulator is by means of the contacts 42, 43 to close circuits in the solenoid apparatus 37, 38 by which the main current is directed through the medium of the commutator 53 and brush 61 so as to drive the motor in the required direction. In a modification, a form of interruptor is employed in which the terminals a, b, c, d are carried on an insulating-base mounted on a dash-pot. In another modification, special provision is made for lessening the tendency to sparking in the manipulator, in which the circuits of the solenoids in the current-directing apparatus are never broken, but in which one or other of the solenoids can be short-circuited. In a further modification, the actuation of the rheostat or other controller of the motor is effected by solenoid apparatus independently of the motor. Fig. 9 shows a form of the invention especially adapted for all kinds of prime movers which run always in the same direction or are reversed by means independent of the manipulator handle 21. In this the electric controller, throttle valve, sluice valve, or other power regulator is adjusted by movements of the rack 109 carried by the core of a solenoid with contrary windings of greatly different resistances. The movement of the core is made proportional to that of the manipulator handle 21 by means of the interrupting-switch, one member of which is carried by the cross-bar 114 attached to the core, and the core is locked by means of a hydraulic cylinder 117. The locking and release are effected by a plug valve 119, normally kept closed by a magnet 122 in opposition to a spring which tends to open it. The magnet 122 by which this valve is controlled is thrown out of action whenever the manipulator is adjusted by the action of the magnet 123, thus allowing the valve to open. The valve remains open until the desired movement is completed, when, owing to the action of the interrupting-switch, the action of the magnet 123 is neutralized and the valve is electromagnetically closed again.