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Dealer Service 23
MAN0450 (10/28/2005)
DEALER SERVICE
The information in this section is written for dealer ser-
vice personnel. The repair described here requires
special skills and tools. If your shop is not properly
equipped or your mechanics are not properly trained in
this type of repair, it may be more time and cost effec-
tive to replace complete assemblies.
Keep hands and body away from pressurized
lines. Use paper or cardboard, not hands or other
body parts to check for leaks. Wear safety goggles.
Hydraulic fluid under pressure can easily penetrate
skin and will cause serious injury or death.
Make sure that all operating and service person-
nel know that if hydraulic fluid penetrates skin, it
must be surgically removed as soon as possible by
a doctor familiar with this form of injury or gan-
grene, serious injury, or death will result. CON-
TACT A PHYSICIAN IMMEDIATELY IF FLUID
ENTERS SKIN OR EYES. DO NOT DELAY.
Before working on backhoe, extend boom and
dipperstick and place bucket on ground. Make sure
that all system pressure has been relieved by oper-
ating controls before maintenance, service, or dis-
connecting any hydraulic lines.
Always wear relatively tight and belted clothing
to avoid getting caught in moving parts. Wear
sturdy, rough-soled work shoes and protective
equipment for eyes, hair, hands, hearing, and head;
and respirator or filter mask where appropriate.
BH70-X
HYDRAULIC VALVE REPAIR
Refer to Figure 13.
Valve repair should be accomplished in a clean work
place. Note the configuration of the parts before disas-
sembling valve and control linkage. This will make
reassembly easier.
System Relief Valve
Adjustment of system relief pressure must be
done by a qualified, experienced dealership. Incor-
rect adjustment can result in system failures and
serious personal injury.
No individual parts are available for relief valve.
Replace entire assembly if required.
Pressure Setting Adjustment
NOTE: Before changing the pressure setting on the
valve, determine tractor hydraulic system pressure.
Many tractors do not create 2000 psi. If your tractor
does not create 2000 psi, changing the relief valve set-
ting will not improve the backhoe performance.
To adjust relief valve setting, place a 3000 psi pressure
gauge in the line attached to the valve inlet (IN) port.
Remove cap from top of main relief (1, Figure 13). Turn
adjusting screw clockwise to increase pressure and
counter clockwise to decrease pressure. Start tractor
and set throttle for full engine speed. Move right stabi-
lizer control lever to raise stabilizer to transport position
and hold the lever so full pressure builds. Adjust screw
to attain 2000 psi. Shut off tractor and replace cap.
Port Relief Valves
Pressure settings on port relief valves are preset at the
factory. Although they are adjustable, they must not be
reset in the field using backhoe hydraulic system. An
incorrect setting could cause hydraulic pump to fail or
backhoe cylinder rods to buckle.
Replace Port Relief Valves
It is not necessary to remove the entire valve assembly
from the console to replace individual port relief valves.
Be sure to install valve cartridges set at the correct
pressure. Valves are similar and can be easily mixed
up.
NOTE: Valve cartridges have small sealing washers
attached to them. When replacing valve, check cavity
in valve housing for any loose washers.
Load Check Valve Replacement
The load check valves (4) are located between the
valve work ports. Remove load check assembly using
CAUTION
Port Relief Valve Pressure Setting
Cartridge 2 2470 psi
Cartridge 3 2610 psi