5-2 Lower Mechanism: Travel Drive Unit Does not switch to the low-speed rotation.
It switches to the low-speed rotation but switches to the high-speed rotation during running.
The pressure of the Ps port dose not decrease after setting the speed control switch to low speed.
Make sure that the pressure of the Ps port is 0.5 MPa or less and review the piping system.
The spring of the 2nd-speed valve is damaged.
Disassemble the unit to remove the foreign matter and then replace the spring.
No spring is set in the 2nd-speed control valve.
Assemble a spring in place.
Foreign matter gotten into between the spool and the base plate prevents the spool from returning.
Disassemble the unit to remove the foreign matter. Check the degree of the damage by following the maintenance procedures. If it is still usable, re-assemble the unit. If it is no longer usable, replace it by using the base plate kit.
A clogged orifice of the 2nd-speed oil path prevents the pressure in the 2ndspeed piston chamber from being released.
Disassemble the unit to remove the foreign matter and re-assemble it.
A fatigued spring of the 2nd-speed valve reduces the switchover pressure.
Disassemble the unit to replace the spring.
A clogged pilot pipe causes leak from 2nd-speed control valve and the pilot pressure rises to the switchover pressure.
Clean the inside of the pipe to remove the foreign matter. In addition, review the piping system.
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