The following photos show the various port locations available on the hydrostatic tandem pump for checking system pressure. Completing these pressure tests will diagnose any mechanical problem in the hydrostatic system. 2 LH Side And Top View Port A Port C Port D Port B F Gauge port B C4257 High pressure relief valves D and B NOTE: Without Internal charge pump model shown RH Side and Bottom View High pressure relief valves A and C Gauge port C Gauge port A E C4258 Charge pressure relief valve Gauge port D Tandem pump flow can also measure pump performance. 1 Connect a flow meter between the high pressure ports, one section at a time.
2 Start the engine and increase operating speed between 1775 ~ 1800 rpm. 3 Restrict the flow to show 2000 psi (137.8 bar) over charge pressure inlet. Example: Charge pressure = 220 psi (15.2 bar) Gauge pressure reading would need to be 2220 psi (153 bar). 4 Minimum flow reading should be 13.5 gal / min. (51 l / min). WARNING Raise the machine securely from the ground before performing system checks to prevent sudden move- ment. 2-10 PRESSURE TESTS 2.5 WARNING t Use caution when dealing with hydraulic fluid under pressure. Escaping fluid under pressure can pene- rate the skin and cause serious injury.
Installing a gauge into the system gauge port ‘A’ , ‘B’ , ‘C’ or ‘D’ will verify the status of the high pressure relief valves. Checking the pressure at port ‘E’ will give accurate charge pressure reading. The charge pressure can also be obtained by placing a gauge on the quick coupler in the engine compartment. (fig C4258) Checking the pressure at port ‘F’ will verify case drain pressure.
Gauge Information A B System Pressure Gauge 10,000 psi gauge (690 bar) 9/16 - 18 O-Ring Fitting 10,000 psi gauge (690 bar) 9/16 - 18 O-Ring Fitting B C D System Pressure Gauge 10,000 psi gauge (690 bar) 9/16 - O-Ring Fitting E Charge Pressure Inlet Port 500 psi Gauge (34.5 bar) 7/8 - 14 O-Ring fitting F Case Drain Port 500 psi Gauge (34.5 bar) 1 - 1/16 - 12 O-Ring Fitting