TM 10-3930-659-10 Section III.  PRINCIPLES OF OPERATION 1-11.  DRIVE TRAIN SYSTEM. a. Engine.  The engine is a six-cylinder turbocharged diesel which supplies rotational power to the transmission.  The cooling   system   is   pressurized   and   includes   a   thermostat,   controlled   bypass,   and   coolant   recovery   bottle.      Engine lubrication Is pressurized and oil is continuously cleaned by full-flow filters. b.  Drive Dampener.  The drive dampener connects the engine to the transmission and absorbs torque spikes that could develop In the drive train. c.    Transmission.    The  transmission  Input  shaft  turns  at  engine  speed.    A  speed  reduction  takes  place  within  the transmission according to the speed range selected by the operator.  The direction of forklift truck travel is also determined by the transmission. Both speed and direction selection are made by hydraulically operated clutches in the transmission. d.      Drive   Shafts.      The   drive   shafts   transmit   rotation   of   the   transmission   output   to   the   front   and   rear   axles. Connections at both ends are made through universal joints to compensate for any misalinement. e.  Front and Rear Axles.  The front and rear axles are identical In operating principle.  The rear axle is different in that it oscillates 11° above and below horizontal. Both axles drive whenever the transmission is engaged.  Neither axle can be independently disconnected. 1-12.  SERVICE BRAKE SYSTEM. a.  Introduction.  The service brakes are foot controlled, hydraulic-type brakes. The system Is supplied pressurized hydraulic oil by a pressure compensated pump that Is driven by the engine. b.  Brake and Forks Pump.  The brake and forks pump Is a variable displacement, pressure compensated, piston- type pump.  It supplies flow to both the service brake system and to the fork attachment cylinder circuits. c.  Accumulators.  The accumulators in the brake system store a charge of pressurized oil which allows a number of brake applications in the event of pump failure or engine shutdown. d.  Brake Valves.  The two brake valves are identical and are operated by separate foot pedals.  Depressing either foot pedal will cause all four wheel brakes to operate. e.  Wheel Brakes.  A wet disc-type brake arrangement is found at each wheel. When hydraulic pressure is routed to the  brake  pistons  via  the  brake  valves,  the  pistons  move  outward  and  compress  the  brake  disc  against  the  stationary backing plate,  slowing or stopping the vehicle. 1-10