TM 5-3825-226-24 STEERING HYDRAULIC SYSTEM PUMP EFFICIENCY CHECK 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. Method of finding flow loss... Pump flow at 100 psi ................ 57.5 gpm (litre/min)* Pump flow at 1000 psi  .............. -52.0 gpm (litre/min)* Flow loss .................................. 5.5 gpm (litre/min)* Flow loss when given as a percent of pump flow is used as a measure of pump performance. Example of finding percent of flow loss... gpm flow loss Percent x 100 = of flow Pump flow @ 100 psi loss * 5.5 or x100+= 9.5% * 5.5 If the percent of flow loss is more than 10%, pump performance is not good enough. *  Numbers  in  examples  are  for  illustration  and  are  not values for any specific pump or pump condition.  See SPECIFICATIONS  for  pump  flow  of  a  new  pump  at 100 psi and 1000 psi. Test On The Machine Install a 9S2000 Flow Meter.  Measure pump flow at 100  psi  (7.0  kg/cm²)  (690  kPa)  and  at  1000  psi  (70.0 kg/cm2) (6900 kPa) with engine at 2000 rpm. NOTE:        See    Tee    Test    Tooling    Chart    Form    No. REG00910. Formula I: gpm @ 100 psi - gpm @ 1000 psi Percent x 100 = of flow gpm @ 100 psi loss Test On The Bench If the test bench can not be run at 1000 psi at a high rpm,  do  the  first  part  of  the  test  with  the  pump  shaft rotation  at  1000  rpm.    Measure  pump  flow  at  100  psi (7.0  kg/cm2)  (690  kPa)  and  at  1000  psi  (70.0  kg/cm2) (6900 kPa).  Then to measure the pump flow for the last part of the test, see SPECIFICATIONS for:  Pump rpm at 100 psi with the engine at 2000 rpm. Formula II: gpm @ 100 psi - gpm @ 1000 psi Percent x 100 = of flow gpm @ 100 psi @ 2000 rpm loss STEERING CONTROL VALVE The values shown in the SPECIFICATIONS are for hydraulic oil that is 150°F  (65°C).    Run  the  engine  and operate the hydraulic system to increase the temperature  of  the  hydraulic  oil.    Stop  the  engine  and loosen the filler cap to let the air out of the supply tank before a test hose and gauge are installed or removed. Relief Valve for the Steering Circuit The   steering   control   valve   is   located   under   the operator's station. ( ) ( ) ) ( ) ( 2-111