4000 Switch Machine - Alstom

NORMAL AND REVERSE LOCKINGBoth the throw bar and lock rod must be locked at end of stroke in the “normal” and “reverse”switch point positions.The throw bar is locked when the crank has traveled over the center of the throw bar, as shownin Figure 2-1. When the crank is in the over-center position any load on the throw bar (pointpressure) drives the crank roller into the locking pocket of the throw bar. The cogging action ofthe motor and the gear train hold the crank in the over-center position if there is no load on thethrow bar (point pressure).The lock rod is locked when the cam bar dog is centered in the notch of the lock rod. If thecrank isn’t over center of the throw bar or the cam bar dog isn’t centered in the lock rod notchthen the motor limit cams must be adjusted per the Motor Limit Switch Adjustment Procedure.POSITION MARKS(LOCKED POSITION)CRANKTHROWBARMID-STROKE(UN-LOCKED)POSITIONMARKSFigure 2-1. Throw Bar Locking PositionP2444, Rev. Jan/07 2-4ALSTOM Signaling Inc.