TM 10-3930-671-24 Main Hydraulic System Description and Operation The   main   hydraulic   system   consists   of   the   hydraulic sump tank, main hydraulic pump, hydraulic oil filter, main control     valve,     steering     priority     demand     valve     and associated hydraulic lines and hoses. The    hydraulic    sump    is    a    separate,    removable    tank installed in the right-hand side compartment of the truck frame.  It has a large opening at the top with a removable cover which includes the fill filter return tube/ breather, oil level dipstick, and oil line.  The cover is held on with a V- band  clamp  for  positive  sealing  and  ease  of  servicing. The  sump  breather  is  a  standard  Clark  part.    From  the sump tank, oil is fed by the main gear-type pump through the  steering  priority  demand  valve  to  the  main  control valve.    The  priority  demand  (flow  control)  valve  diverts the  necessary  flow  to  the  steering  system.    From  the main control valve oil is directed to either the lift cylinders or the tilt cylinders.  Oil returns to the sump tank through the  full-flow  return  line  filter.    The  spin-on,  throwaway hydraulic    oil    filter    fits    on    a    threaded    adapter    base mounted near the sump tank cover.  The main hydraulic pump  is  mounted  to  an  SAE  pad  on  the  transmission driven  by  either  a  silent  chain  or  direct  gear  drive  train from the engine. F-447