TM 10-3930-653-14&P HYDRAULIC CIRCULATION SYSTEM (MAIN CIRCUIT) The hydraulic circulation system of the main circuit is connected with the hydraulic circuit for the power steering. The  oil  from  the  main  pump  is  therefore  divided  for  the  main  circuit.    The  hydraulic  piping  is  of  O-ring  fitting  type  with excellent sealing performance, providing secure oil tightness. The hydraulic oil sent from the main pump is divided by the flow divider valve, and the hydraulic oil for the main circuit flows from the flow divider port "OUT" to the control valve.  With the control valve in neutral position the oil returns to the oil tank, passing through the valve. When the lift lever is pulled, the hydraulic oil from the control valve flows through the flow regulator and reaches the lower part of the lift cylinder piston to push up the piston rod. When the lift lever is pushed, the cirucit between the lower part of the lift cylinder piston and the oil tank is opened, and the piston begins to descend due to the weight of piston rod, carriage, fork, etc.  In this case, the oil returning to the control  valve  is  regualted  by  the  flow  regualtor.    When  the  tilt  lever  is  operated,  the  hydraulic  oil  from  the  main  pump reaches one side of the piston to push it.  The oil pushed by the piston returns to the oil tank through the control valve. Fig.  4-475.  Hydraulic Circulation System 4-239