Pump makes noise and the steering cylinder rod
does not move smoothly.
1. Air in the steering hydraulic circuit.
2. The pump has too much wear.
3. Loose connection of the oil line on the inlet side of
5. The relief valve opens at low oil pressure.
6. The oil level in the tank is low.
a. Bleed hydraulic oil lines.
b. Check pump, repair or replace as necessary.
c. Tighten line connection.
d. Replace oil with oil of proper viscosity.
e. Adjust relief valve as necessary.
f. Fill tank to proper level.
STEERING HYDROAULIC 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)
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)*
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 ) x100 =
(Pump flow @ 100 psi) )
or (*5.5 ) x 100 = 9.5%
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. REG009
(gpm100 psi - gpm @ 1000 psi) x 100 =
(gpm @ 100)
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 k, g/cm2) (6900
kPa). Then to measure the pump flow, s for the last part
of the test, see SPECIFICATIONS for: Pump rpm at 100
psi with the engine at 2000 rpm.
(gpm @ 100 psi - gpm @ 1000 psi) x 100 =
(gpm @ 100 psi @ 2000 rpm )
STEERING CONTROL VALVE
The values shown in the SPECIFICATIONS are for
hydraulic oil that is I 50°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 airout 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