Patent GB-190807589-A (GB)
Title: Improved Means for Controlling Motors and Brakes of Power-driven Vehicles.
Inventor: FRANCIS JAMES EDWARD
Filed: 1908-04-06
Granted: 1909-04-06
Abstract: 7589. Francis, J. E. April 6. Locomotive railway and tramway vehicles; motor vehicles; motor road vehicles.-The speed of a motor - vehicle is automatically controlled to prevent slipping or skidding of the driving- wheels by operating two elements from a powerdriven and a following axle respectively, and, by causing these elements to act oppositely upon suitable mechanism so that any differential effect operates to lessen the power of the engine or motor, or of the braking, as the case may be. In the form shown in Fig. 1, two centrifugal governors 9, 10 are driven from the power axle 1 and the following axle 6 respectively, so that their speeds are equal when no slip of the driving-wheels is occurring. The pulls of the governors act on the ends of a lever 15, which is connected through a link 18 with a valve 16 in the admission pipe of the engine. If slip occurs, one governor pulls more than the other, and the engine supply is throttled. In the case of an electric motor, such mechanical devices may open and close a switch to cut off the supply of energy on slipping, or in a modification, to cut in suitable resistances. Such mechanical devices may also be employed to arrest further progression of the accelerating-mechanism in an automatic control system, and to cut in additional resistance in the motor circuit. Such an arrangement is shown in Fig. 3 in connexion with a well-known multiple-unit electro-pneumatic control system, described in Specification No. 7208, A.D. 1904, [Abridgment Class Electricity, Regulating &c.]. In this system, resistance switches 24 are closed to cut out the corresponding resistance when the pick-up coils 25 are energized by a battery circuit, the return wire 26 being common to all the pick-up coils. To apply the present invention, an electro-magnetic switch 28 which is normally closed is arranged in the common return 26. The coil 29 is arranged in a shunt circuit 30, 31 from the battery. When the master controller 34 is moved into one of its positions, the circuit is completed from the positive terminal of the battery, through contacts 35, 36, 37, wire 30, coil 29, return 31, and switch arm 33 attached to the lever 15, to the negative terminal of the battery. Should the lever 15 be moved as previously described, the switch 28 is opened. In order to cut in additional resistance as well, a normally closed switch 38 may be arranged in the motor circuits between the resistances controlled by the switches 24 and the motor. The switch 38 may be operated electro-pneumatically by a coil 40 arranged in a shunt 41, 42 from the battery, the circuit being from the positive pole of the battery, contacts 35, 36, 37, lead 41, coil 40, lead 42, contact 43, and switch arm 33, to the negative pole of the battery. The two switches 28, 38 may be simultaneously operated by one solenoid 40. A switch operated by the lever 15 may also be arranged to shunt the field of the motor. In the case of an alternating-current motor, such switch may control the supply circuit or cut in and out a choke coil in such circuit, or may vary the point of connexion between the motor circuit and transformer winding in a well-known manner. Instead of the mechanical devices described, two equal direct-current generators may be substituted for the governors ; their armature currents oppose and normally neutralize each other, but when slip takes place, a current passes which is used to energize a solenoid operating a break switch in the supply circuit. Such differential current may operate any of the aforesaid mechanical devices. Fig. 5 shows the generators energizing two solenoids 51, 52, which operate the combined switches 28, 38, Fig. 3. When skidding occurs through braking, the braking-pressure is reduced by using any of the preceding devices to open a valve controlling the fluid braking-pressure, and in the case of vacuum brakes to admit air to the vacuum chamber. When all the wheels are braked, an idle-wheel will be provided to drive one generator. In the case of an electro-magnetic track brake operating also brake blocks on the wheels, the pull of the magnet may be reduced either by mechanically or electrically operated devices as described. Fig. 7 shows one arrangement, in which when a current passes through the solenoid 63, resistances 61 are thrown into the electromagnetic track-brake circuit.