Relief Valve Adjustment; Relief Valve Pressure Check - Yale 524150797 Maintenance Manual

Relief Valve Adjustment

RELIEF VALVE PRESSURE CHECK

WARNING
DO NOT make repairs or adjustments unless you
have been properly trained and authorized to do
so. Improper repairs and adjustments can create
dangerous operating conditions. DO NOT operate
a lift truck that needs repair. Report the problem
to your supervisor immediately. If repairs are nec-
essary, turn the key switch to the OFF position,
attach a DO NOT OPERATE tag to the control han-
dle, and disconnect the battery.
Always wear the proper protective equipment in-
cluding eye protection and petroleum resistant
gloves when servicing hydraulic components.
Thoroughly wash oil from exposed areas of skin
as soon as possible.
Completely lower all lift components and relieve
pressure before disassembling any part of the lift
pump or disconnecting any hydraulic hoses.
The hydraulic oil is hot at normal operating tem-
peratures. Be careful when draining the oil.
Never put your hands on pressurized hydraulic
components. Pressurized hydraulic oil escaping
through pin-hole leaks can be injected into the
skin.
CAUTION
DO NOT OVERFILL. Oil will leak from the breather/
filler cap if too full.
NOTE: Check the hydraulic oil level in the reservoir
when oil is at room temperature. Remove breather
cap and add recommended hydraulic oil to proper
level, as required. See Hydraulic Pump Reservoir.
1. Operate lift truck until hydraulic oil reaches oper-
ating temperature (43 to 49°C (110 to 120°F)).
2. Lower the forks completely to relieve pressure
from hydraulic circuit.
3. Turn key switch to the OFF position and discon-
nect the battery.
4. Block load wheels to prevent lift truck from mov-
ing.
12
Relief Valve Adjustment
5. Remove the drive unit compartment cover. Refer
6. Discharge the capacitor. See Special Precau-
7. Clean any buildup of dirt from around the lift pump
Hydraulic oil hoses and lines may be under pres-
sure. Slowly loosen the hydraulic connections to
ensure pressure has been relieved.
8. Disconnect the hydraulic hose at the pump.
9. Install a tee fitting and a pressure gauge of at
10. Verify the oil is at an operating temperature of 43
11. Raise the forks completely and continue to hold
NOTE: The pump will stop after a short period of
time. Release the lower button then press and hold
again to continue.
12. If the relief pressure is incorrect, refer to Relief
13. After the proper relief pressure is obtained, lower
14. Turn the key switch to the OFF position and dis-
15. Discharge the capacitor. See Special Precau-
to AC Motor Repair 0620YRM1513, Accessing
the Drive Unit Compartment.
tions.
and motor assembly.
WARNING
least 24.8 MPa (3600 psi).
to 49°C (110 to 120°F).
the lift button. Read the pressure gauge while the
pump is in relief. See the Table 1 for correct pres-
sure.
Valve Adjust in this section.
the forks completely to relieve pressure from hy-
draulic circuit.
connect the battery.
tions.
Table 1. Relief Valve Settings
Model
4500 lb
* +0.6 -0.0 MPa (+87 -0 psi)@ 21°C (70°F)
Oil Temperature Full Flow
1900 YRM 1506
Relief Setting*
22.0 MPa (3200 psi)