TM 5-3825-226-24 TESTING AND ADJUSTING The   5S5123   Hydraulic   Testing   Group   is   used   to make the pressure test of the hydraulic system.  Before any   tests   are   made,   visually   inspect   the   complete hydraulic  system  for  leakage  of  oil  and  for  parts  that have  damage.    For  some  of  the  tests,  a  timer  and  a measuring rule (either for inches or for millimeters) are usable tools. WARNING When     testing     and     adjusting     the hydraulic system, move the machine to    a    smooth    horizontal    location. Move away from machines that are at work and any personnel.  There must be only one operator.  Keep all other personnel     either     away     from     the machine  or  where  the  operator  can see the other personnel. VISUAL CHECKS A  visual  inspection  of  the  hydraulic  system  and  its components   is   the   first   step   when   a   diagnosis   of   a problem  is  made.    Stop  the  engine,  lower  the  water distributor to the ground and when the oil is cool so any pressure  in  the  tank  will  be  at  a  minimum,  make  the inspections that follow: 1. Measure the oil level.  Slowly turn the filler cap until  it  is  loose  to  let  the  tank  pressure  lower before the filler cap is removed.  Look for air in the oil in the tank. 2. Remove the filter element and look for particles removed  from  the  oil  by  the  filter  element.    A magnet    will    separate    ferrous    particles    from nonferrous  particles  (piston  rings,  O-ring  seals, etc.). 3. Check  all  oil  lines  and  connections  for  damage or leaks. OPERATION CHECKS Checks of water distributor operation can be used to find  the  source  of  oil  leakage  in  the  hydraulic  system. The oil in the hydraulic system must be at an operating temperature of 1000 to 120OF (380 to 400C). Drift   of   Lift   Cylinders   Check   the   drift   of   the   lift cylinders.    Lift  the  bowl  6  to  10  in.    (152  to  254  mm), then move the control lever to the HOLD position.  After three   minutes,   put   a   mark   on   the   side   of   the   water distributor at the bottom of the draft arm 6 in.  (152 mm) from  the  front  of  the  distributor.    After  five  minutes, make   the   measurement   for   drift.      Drift   on   a   new machine is not more than .31 in.  (7.9 mm). If the drift is too much: 1. Check the carry check valves. 2. Check the piston seals in the lift cylinders. MEASURING DRIFT OF LIFT CYLINDERS (Typical Example) Travel Time of Lift Cylinders Lower  the  water  distributor  to  the  ground.    Run  the engine  at  high  idle  rpm.    Use  a  stop  watch  to  find  the time needed to fully lift the water distributor. The time to lift the water distributor from the ground to maximum height is approximately 2 seconds. If the travel time is not correct: 1. Check pump efficiency. 2. Check the settings of the relief valve for the lift cylinder circuit. 3. Check  the  operation  of  the  valve  spool  in  the control valve for the lift cylinders. 4. Check the piston seals in the lift cylinders. CHECKING PUMP EFFICIENCY For  any  pump  test  at  a  given  rpm,  the  pump  flow (gpm)  at  100  psi  (7.0  kg/cm2)  (690  kPa)  will  be  larger than  the  pump  flow  (gpm)  at  1000  psi  (70.0  kg/cm2) (6900 kPa). The difference between the pump flow of two operating pressures is the flow loss. 5-10