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.
CAUTION
Always wear relatively tight and belted clothing to avoid getting caught in moving parts. Wear sturdy,
HYDRAULIC VALVE REPAIR
Refer to Figure 17.
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 17). 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.
Port Relief Valve | Pressure Setting |
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Cartridge 2 | 2000 psi |
Cartridge 3 | 2500 psi |
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Load Check Valve Replacement
The load check valves (4) are located between the valve work ports. Remove load check assembly using a large screwdriver. Inspect seat in valve housing for any dirt or damage. Replace load check if required.
22 Dealer Service | MAN0306 (Rev. 6/16/2006) |
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