Shaft angle adjustment of a synchronized tandem-press production line

In a production line including N successive presses each having a crankshaft disengagably coupled to an associated one of N first motors to be driven thereby at an angular speed synchronized with the rotation of a separate reference shaft, the crankshafts of successive ones of the presses normally exhibiting, when driven by the associated first motors, a progressive shift in angular position relative to that of the reference shaft, an arrangement for adjusting the angular positions of the crankshafts with respect to the reference shaft while each crankshaft is disengaged from the associated first motor, which comprises:

• N normally disabled second motors operative when enabled for individually rotating the N crankshafts at an angular speed slightly greater than the speed of the reference shaft;
• a synchro transmitter;
• normally disengaged clutch means operative when engaged for coupling the reference shaft to the synchro transmitter;
• N synchro control transformers coupled mechanically to the crankshafts of the respective presses and electrically to the output of the synchro transmitter, each control transformer producing a control voltage indicative of the deviation of the angular position of the associated crankshaft from that of the reference shaft, the control voltage falling within a prescribed range when such deviation is within a prescribed angular range .+-. .theta.;
• N normally unoperated switching means operative to enable the respective second motors;
• N means individually coupled to the outputs of the respective control transformers and rendered effective when the associated control voltage is within the prescribed range for individually operating the N switching means;
• and means operative when the crankshafts are disengaged from the associated first motors for engaging the clutch means.