Patent GB-190624239-A (GB)
Title: An Improved Method of and Means for Electrically Driving Printing and other Machines.
Inventor: MITCHELL WALTER ATWELL
Filed: 1906-10-30
Granted: 1907-07-18
Abstract: 24,239. Mitchell, W. A. Oct. 30. Right to Patent relinquished. Driving machines by electromotors.-In driving printing and other machines by means of a main motor and an auxiliary motor, a free-wheel clutch is interposed between the two motors so that, when the main motor is energized and overruns the smaller motor, the clutch serves mechanically to separate the two machines, the main motor being supplied with current when the arm of a rotary controller reaches a certain position and the current of the auxiliary motor cut off by the controller when it is overrun. The current to the machines is supplied through electro - magnetic switches which are closed, mechanically, by the movement of the controller arm and retained closed, electrically, by a shunt current from the supply, the main current being opened by shortcircuiting, by means of push-buttons which may be operated by the controller, the retaining-coils of these main electro-magnetic switches. The main motor A, Fig. 1, is shown with shunt field winding a and the auxiliary motor B with series field winding b, the supply of current to the machines from the mains X, Y through the main electro-magnetic switches D, E, F being regulated by the controller with handle C. In starting the machinery, the handle of the controller is moved from the zero position shown, the crank-arm C<x>, Fig. 2, upon the handle engaging with and depressing a toepiece at the end of a pivoted lever, the end of which is provided with an arm J which serves to close the switches D, E, F. The motor B is then supplied with current through the resistance R, which is connected to the portion of the controller that lies between the starting-point and the contact Y X. Further movement of the controller cuts out the resistance R and speeds up the motor, which drives the armature of the main motor through the worm gearing B<1> and through the free-wheel ball clutch G, which has spring-pressed balls B in inclined channels in the periphery of the inner wheel, as shown in Figs. 4, 5, and 7, the main armature being connected to the load. The main switches are maintained closed, electro-magnetically, by current from the mains passing through lamps and through each of the retainiogsolenoids of the switches. When the controller handle reaches the position in which the contactpiece c upon it engages the contact r<x>, the maximum speed of the small motor is attained and further movement energizes the main motor through the resistance R<1>, and disconnects the small motor by short-circuiting the retaining-coil of the electro magnetic switeh E by depressing a push-button and thereby causing the switch E to open. To prevent sparking, when changing over from the auxiliary motor to the main motor, a shunt discharge R<2> and a pair of lamps R<3> are connected in the circuit as shown. Further movement of the controller speeds up the motor, and, in passing over the contacts r<x x> , the resistance R<4> is step by step cut into the fields, further increasing the speed. To stop the machine, a pushbutton may be hand-pressed to short-circuit the detaining-solenoid, or the controller handle may be reversed until the handle operates one or other of two push-buttons, which are actuated only upon the reverse movement of the arm.