Relief Valve Adjustment 1900 YRM 1018
Relief Valve Adjustment
RELIEF VALVE PRESSURE CHECK
WARNING
DO NOT make rep
airs or adjustments unless you
have been pro
perly trained and authorized to do so.
Improper rep
airs and adjustments can create dan-
gerous opera
ting conditions. DO NOT operate a lift
truck that ne
eds repair. Report the problem to your
supervisor i
mmediately. If repairs are necessary,
turn the key
switch to the OFF position, attach a DO
NOT OPERATE
tag to the control handle, and dis-
connect the
battery.
Always wear
the proper protective equipment in-
cluding eye
protection and petroleum resistant
gloves when
servicing hydraulic components.
Thoroughl
y wash oil from exposed areas of skin as
soon as pos
sible.
Completel
y lower all lift components and relieve
pressure b
efore disassembling any part of the lift
pump or dis
connecting any hydraulic hoses.
The hydrau
lic oil is hot at normal operating temper-
atures. B
e careful when draining the oil.
Never put
your hands on pressurized hydraulic
componen
ts. Pressurized hydraulic oil escaping
through p
in-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 operat-
ing temperature (43 to 49
C (110 to 120 F)).
2. Lower the forks completely to relieve pressure from
hydraulic circuit.
3. Tur n key to th e OFF position and disconnect the
battery.
4. Block load wheels to prevent lift truck from moving.
5. Remove the drive unit compartment covers.
6. Discharge the capacitor. See Special Precautions.
7. Clean any buildup of dirt from around the lift pump
and motor assembly.
WARNING
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 least
24.8 MPa (3600 psi).
10. Verify the oil is at an operating temperature of 43 to
49
C (110 to 120 F).
11. Raise the forks completely and continue to hold the
lift button. Read the pressure gauge while the pump
is in relief. See Relief Valve Settings for correct
pressures.
Table 1. Relief Valve Settings
Model
Relief Setting*
4000 lb 16.9 MPa (2450 psi)
4500 lb
12 Volt
19.3 MPa (2800 psi)
4500 lb
24 Volt
18.6 MPa (2700 psi)
5000 lb 22.0 MPa (3200 psi)
*+0.6 0.0 MPa (+87 0psi)@21C(70F)
Oil Temperature Full Flow
NOTE: Thepumpwillstopafterashortperiodoftime.
Releasethelowerbuttonthenpressandholdagainto
continue.
12. If the relief pressure is incorrect, refer to Relief
Valve Adjust.
13. After the proper relief pressure is obtained, lower
the forks completely to relieve pressure from hy-
draulic circuit.
10
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