TM 10-3930-664-10 1-21. HYDRAULIC SYSTEM HYDRAULIC TANK.  Contains oil for operation of the steering and hydraulic systems. HYDRAULIC  PUMP.    Gear  pump  mounted  to  and  driven  by  the  engine.    Supplies  high  pressure  hydraulic  oil  for  the steering system and hydraulic system. DIRECTIONAL CONTROL VALVE.  Operated by two mechanical joysticks.  Directs the flow of hydraulic oil to cylinders to control the mast functions: lift/lower, tilt, sideshift, and rotate. HYDRAULIC  FILTER.    Removes  any  fluids  or  contaminants  suspended  in  the  hydraulic  oil  before  the  oil  returns  to  the tank to prevent damage to any of the hydraulic components. DIVERTER VALVE.  Controls the flow of hydraulic oil to and from the freelift cylinder or the mainlift cylinders to ensure that the lift and lower functions operate properly. SEQUENCE VALVE.  Prevents the flow of hydraulic oil through the diverter valve to the mainlift cylinders until the freelift cylinder has completely extended. TILT CYLINDERS.  Two cylinders which operate together to raise or lower the fork tips by tilting the entire mast assembly. Controlled by the rear joystick on the directional control valve.  Pushing the joystick forward causes the cylinders to extend and tilt the mast assembly forward.  When the joystick is pulled back, the cylinders retract and tilt the mast assembly to the rear. 1-13