Patent GB-190716366-A (GB)
Title: Improvements in Starters for Electric Motors.
Inventor: MAYO WILLIAM CORNELIUS
Filed: 1907-07-16
Granted: 1908-03-19
Abstract: 16,366. Mayo, W. C., and Houlehan, J. Feb. 11, [date applied for under Patents Act, 1901]. Switches. - Resistance is cut out of a motorarmature circuit independently of the 'speed of travel of the operating- handle, and dependent upon the fluctuations of current through the armature due to the cutting- out of successive steps of resistance. A atep-bystep movement is given to the switch arm by an escapement mechanism, which is operated always to the same extent by the current surges. The operating and resistance levers 31, 36, Fig. 2, respectively, are concentrically pivoted on a stud 2, Figs. 2 and 3, and their hubs 30, 35 are connected by a spring 39. The hub of the lever 31 is also connected by a spring 32 to the stud, so that it ordinarily has a bias to the 'off' position. One wire 5 is held in contact with the central stud by a nut 4 on one side of the base 1, and a flange 3 on the stud is pressed by the nut against the other side of the base. When the parts are in the 'off' position with both arms pulled over to the left, a cam-surface 53, Fig. 2, on the lever 31 engages beneath and lifts a pin 52 on a block 41, which slides by means of its stem 47 in lugs 43 on the resistance arm 36. In this position, the end of the stem 47 is locked by a hook 48, and the resistance arm is prevented from cutting out resistance. The switch is operated to start the motor by moving the arm 31 over to the right. This energizes the field 24 by current passing from the main 18 through the stud 26, hold-on magnet 28, conductor 70, stud 69, arm 31, conductor 5, solenoid 66, and stud 21 to the main 19. The block 41, when released by the cam 53, falls under the pressure of a spring 45, and places teeth 44 on its underside in engagement with teeth in the ratchet-wheel 40, which is normally loosely pivoted on the stud 2 but, when locked to the arm 36, is biased to the right under the influence of the spring connecting the arms. Simultaneously with the above operations, the armature circuit is completed through all the resistance 9 by conductors 16, 12, 10, 29, and, joining the field circuit at conductor 70, returns with it through the solenoid 66 to the line. An essential feature is the periodic release of the ratchet-wheel, to the same extent each time, by means of an anchor escapement 62, a part 65 of which is pulled into the solenoid 66 after the cutting-out of each step of resistance. After the motor has speeded up and reduced the armature current for the new conditions, a spring 61 pulls the upper part of the escapement back against the ratchet teeth, permitting of a small rotation of the wheel, and catting out another step of resistance. The pull of the spring is made greater at the beginning of the starting operations by means of a cam 56 on the hub of the arm 36. The cam moves an arm 57 about a pivot 58, one eni of the spring being attached to the escapement, and the other passed into one of a series of holes in the arm 57. When the current is cut off, the arm 31 is returned by the spring 32, and a hook extension 55 on the cam 53 pulls back the arm 36 by engaging the pin 52.