Patent GB-729117-A (GB)
Title: Improvements in and relating to drive units, e.g. for printing presses of unit type
Inventor: TAYLOR HENRY
IPC: H02P5/68
Filed: 1951-01-26
Abstract: 729,117. Electric motor driving arrangements. WITTON-JAMES, Ltd. April 28, 1952 [Jan. 26, 1951], No. 2092/51. Class 35. [Also in Groups XVI and XXIV] Driving arrangements.-In a driving unit for a printing press of the kind having a number of printing units interconnected by a press shaft and a number of driving units coupled to the press shaft each driving unit comprises an auxiliary motor for " inching " and slow-running, and a main motor for normal running, the motors being coupled together through a worm gearing and an electromagnetic clutch, means being provided automatically to de-energize the clutch at or about the moment the drive is taken over by the main motor and to re-energize the clutch at or about the moment the drive is taken over by the auxiliary motor when the press is slowing down. The shaft 1a, Fig. 2, of the main motor 1 is connected at' one end to the press shaft by a chain gear and at the other end to one member 10c, 10d of a clutch 01. The auxiliary motor 2 drives a clutch member 10a through a chain gear 8 and a worm gear 9. The clutch members 10a, 10d are connected by chain gearing 18, 19 to aligned spindles 20, 21 having rotatable elements 14, 16 carrying electrical contacts 22, 23 on arms 15, 17. The chain gearing 18 is such that the element 14 is driven slightly faster than the element 16, e.g. 5 per cent faster, and each element 14, 16 is arranged so that it can run faster than its driving spindle 20, 21. The contacts 22, 23 are arranged in a controlling circuit as shown in Fig. 4. The relay coil 24, which is adapted to close contacts 25 and 27 when energized, may be energized through contacts 22, 23 as described, or through contacts 30 controlled by a stop-button or through contacts 26 and either 27 or 28. Connected in series with the clutch coil 11 is a resistance 12 designed to reduce the voltage on the clutch coil, e.g. to half full voltage. The resistance 12 is short-circuited when contacts 31 and 32 are closed so that full voltage is applied to coil 11. The clutch can slip when a fractional voltage is applied and it may then be used as a brake for slowing down the press, the worm gear preventing the other clutch member 10a from turning. Contacts 26 are "Zero" contacts and closed only at the start position of the speed controller. Normally closed contacts 28 are open when the master relay is energized under " slow-running " and " speed-up " conditions. The master relay, when closed, energizes an auxiliary motor relay which closes an auxiliary motor contactor causing the auxiliary motor to rotate, and driving the press at slowrunning speed. Normally open contacts 31 associated with the auxiliary motor contactor close intermittently with " inching " and continuously with " slow-running." Normally closed contacts 32 associated with the main motor relay are opened when the main motor is running so that only fractional voltage may be applied to the coil 11. The operation of the circuit is as follows. When the press is to be started the clutch relay coil 24 is energized by way of contacts 26 and 28 and then holds itself in by means of contacts 27. This energizes clutch coil 11 but only fractional voltage is applied because shorting contacts 31 are open. When the auxiliary motor is energized by depression of an " inch " button to cause "inching" of the press, the auxiliary motor contactor closes contacts 31 short-circuiting resistance 12 and applying full voltage to the clutch coil 11. The initial partial energization prevents delay in the operation of the clutch when the " inching " button is pressed and also serves to bring the press to a stand-still when the button is released, the partially energized clutch then acting as a brake. " Inching " may be effected in either direction. When the press is to be speeded up a "speed-up" push button is pressed. This causes the auxiliary motor to drive the press forward so. that contact 22 engages contact 23 and ensures energization of the clutch coil even when " zero" contacts 26 open as the speed controller is driven up from the zero position. When the controller causes energization of the main motor the contacts. 32 open and reduce the excitation of the clutch coil facilitating the take-over of the drive by the main motor. As soon as the speed of the main motor slightly exceeds the speed of the worm wheel driven by the auxiliary motor the contacts 22, 23 separate and de-energize clutch coil 11. The leading side of the arm 17 (the side without the; contact) collides with the trailing-side of arm 15 and so entrains the element 14. The arms 15, 16 remain in this condition until the press slows down. During slow-down a similar sequence of operations is made in the reverse order. The auxiliary motor is started up in readiness to take over the drive and when contacts 23, 22 re-engage the clutch coil is reenergized. When the press is to be finally stopped a stop button is pressed, both motor contactors become de-energized and contacts 31 open so that the' clutch coil is only partially energized and acts as a brake to bring the press to a stand-still. To avoid the necessity for the clutch 10 to slip when the main motor takes over the drive from the auxiliary motor some lost motion is provided between the clutch member 10c, connected to the main motor shaft 1a, and the part 10d connected to the switch part 16. This is effected by providing coupling studs 34 on the member 10c which are received with clearance in openings in the part 10d. Specification 626,385, [Group XVI], is referred to.