GB691525A - Improvements in logs - Google Patents

Abstract

691,525. Controllers. ABBEY, A. (Svenska Ackumulator Aktiebolaget Jungner). Jan. 27, 1949 No. 2304/49. [A Specification was laid open to inspection under Sect. 91 of the Acts, Oct. 11, 1949.] Class 38 (iii) [Also in Group XIX] The speed of an electric motor 18 is maintained at a desired value by a clockwork or other source of constant speed 33 controlling means for varying the resistance in the motor feeding circuit, said means comprising a contact arm 38 co-operating with and movable relatively to one or more rotatable resistors 24, 25, 26, the clockwork or other source of constant speed being arranged so that the difference of speed between the electric motor 18 and the clockwork 33 determines the value of the one or more resistors that is or are inserted in the motor feeding circuit. The resistors may, as shown, be mounted on a shaft driven by the electric motor and the contact arm 38 may be mounted on a shaft driven by the source 33 of constant speed. Alternatively, the resistor may be on a shaft driven by the source of constant speed and the contact arm 38 may be mounted on a shaft driven by the electric motor. The operation of the apparatus is as follows. Initially, a strained spring 30 causes the contact arm 38 to engage a stop 28<SP>1</SP> on a contact disc 28. When the motor 18 is energised, it initially rotates at a speed greater than is required. By turning the wheels 22 and 23, the motor 18 causes the contact arm 38 to leave the stop 28<SP>1</SP> as well as a further straining of the spring 30 in a manner freeing the clockwork 33. The clockwork source of constant speed 33 then rotates the shaft 32 at a speed which is less than the speed of the wheel 22 at that instant. As a result the spring 30 is further strained and an additional displacement is o .tained between the contact arm 38 and the disc 28. The contact arm 38 now begins to engage the next contact 26<SP>1</SP> on the disc 28 whereby a resistance 26 is inserted in the motor circuit to cause it to reduce speed. Should the speed still be too high, the contact arm 38 will move to engage the next contact 25<SP>1</SP> and so on until the speed of the motor 18 is reduced to the required amount. The apparatus then serves to automatically maintain the motor 18 at this speed.