Patent GB-496947-A (GB)
Title: Improvements in or relating to the electric control of variable speed gears
IPC: H02P5/00
Filed: 1937-06-04
Abstract: 496,947. Change-speed gearing. SIEMENS-SCHUCKERTWERKE .AIVT.-GF's..June 4, 1937, No. 15575. Convention date, June 4, 1936. [Class 80 (ii)) Change-speed gearing having sliding wheeis and clutches 104, 102, actuated electrically under the control of manual selector-switches 116, is provided with a centrifugal governor 119 on a stepped-wheel shaft 106, which governor delays the supply of current to a gear-establishing solenoid 27 until the shaft 106 is rotating in neutral within a predetermined low-speed range, under the influence either of a low-speed " inch - ing motor " 117, or a brake, Fig. 2 (not shown). The inching motor drives the stepped-wheel shaft through a clutch 118 and an irreversible worm-gear 117<1>, so as to be capable of either increasing or reducing the speed of the shaft. Each of the push-button switches 116 controls one speed through circuits only one of which is shown on the drawing, which latter illustrates the gear at the completion of a gearestablishing movement. Depression of a selected push-button 116 (position shown) first disengages a friction or positive double mainclutch 108, which provides a forward or reverse drive between a main motor 105 and the stepped-wheel shaft 106, such disengagement being effected by the opening of push-button contacts 17, through which is normally energized one of two clutch-engaging solenoids 16, 16<1>, controlled by a forward and reverse selector-switch 15. The disengaging movement of the main-clutch 108 closes a contact 30, starting the inching motor 117, and contacts 10, which complete a circuit through the now closed push-button contacts 9 to a solenoid 11, which unlocks all the selector-rods 109, 109<1>, 10911, 109<111> by turning a rock-shaft 114 which lifts tappets 113 adapted to engage notches in the selector-rods in gear-positions of the latter. The selector-rods are instantly moved to neutral by double-acting springs 110, closing contacts 24, 23, 21<1>, 22 which energize a solenoid 25 for engaging the clutch 118 connecting the inching motor to the shaft 106 which, at this time, is completely disconnected from the driving motor 105 and driven shaft 100. When the speed of the shaft 106 comes within the predetermined low-speed range, the governor 119 closes contacts for energizing a solenoid 120, which closes " hold-on contacts 29, opens contacts 12 which de-energize the locking solenoid 11, and closes contacts 26 energizing a gear-establishing solenoid 27. The solenoid 27 operates the selector-rods 109 &c. through a pair of intergeared segments 115 which impart a turning movement in opposite directions to shafts 115<1>, 115<11>, lying transversely of and above all the selector-rods and carrying tappets 111, 112, each of which can be selectively engaged with the ends of notches in the selector-rods 109 &c. when the latter are in the neutral position. Such selective engagement is effected by solenoids such as 4, 7, selectively energized by the closing of additional contacts 2, 6 on the push-buttons 116. As soon as the selector-rods 109 &c. have moved to gear-establishing positions, in which they are locked by the falling of the tappets 113, they break the circuit through contacts, e.g. 22, 23, to the solenoid 25, causing the inching-motor clutch 118 to disengage. On release of the push-button 116, the contacts 17 are again closed to engage the mainclutch 108 by the solenoid 16, or 16<1>, which also breaks the circuit of the '' hold-on " contact 29 of the relay 120 by opening the contact 10, and opens the contacts 30 switching of the inching motor 117. In Fig. 2 (not shown), the inching motor is replaced by a brake, which is normally held disengaged by a weight on the end of a lever. The governor operates two sets of contacts, one set closing above a predetermined speed to energize a solenoid and engage the brake, and another set which closes at a predetermined lower speed after the brakesolenoid has been de-energized to complete the circuit to the gear-establishing relay.