Travel Unit [5] 2-speed control function section troubleshooting Countermeasure and solution After investigating whether pilot pressure oil is reaching the Ps port, investigate the causes of problems and countermeasures for each piece of equipment and perform inspection and repair.
There is foreign matter caught between the spool and base plate, and the spool will not switch.
After performing disassembly and removing foreign matter, investigate the degree of damage according to the Maintenance Procedures and perform reassembly if reusing is possible. If reusing is impossible, perform replacement with the base plate kit.
There is abnormal wear in the sliding sections of the 2-speed control piston section, and pressurized oil is leaking into the case.
Perform disassembly and replace using the flange holder kit.
The 2-speed control piston is not fit in place.
TE R
NA L
Pilot pressure oil is not reaching the Ps port.
IN
Will not switch to high-speed rotation
Possible cause
Attach the 2-speed pistons in the correct position.
E
Problem
Perform disassembly and reassemble after removing foreign matter.
Switching to high-speed rotation occurs, but switching to low-speed rotation occurs if the hydraulic oil temperature increases.
There is abnormal wear in the sliding sections of the 2-speed control piston section, and pressurized oil is leaking into the case.
Perform disassembly and replace using the flange holder kit.
Will not switch to low-speed rotation
Even if the speed control switch is set to low speed, the Ps port pressure does not decrease.
Investigate whether the Ps port pressure is 0.5 MPa or lower and recheck the line system.
The 2-speed control valve spring is damaged.
Perform disassembly and replace the spring after removing foreign matter.
The 2-speed control valve spring is not fit in place.
Attach the spring in the correct position.
There is foreign matter caught between the spool and base plate, and the spool will not return.
After performing disassembly and removing foreign matter, investigate the degree of damage according to the Maintenance Procedures. Perform reassembly if reusing is possible. If reusing is impossible, perform replacement with the base plate kit.
Foreign matter is clogging the orifice in the 2-speed oil path, and pressure cannot escape from inside the 2-speed control piston chamber.
Perform disassembly and reassemble after removing foreign matter.
The 2-speed control valve spring is worn and the switching pressure is reduced.
Perform disassembly and replace the spring.
Foreign matter is clogging the pilot line, and the pilot pressure increases up to switchover pressure due to leaking from the 2-speed control valve.
Clean the inside of the line and remove foreign matter. Also, recheck the line system.
CO US N F E ID O E F N TS TI M AL GL : F O OR BA T L H
Foreign matter is clogging the orifice in the 2-speed oil path, and pressurized oil is not reaching the 2-speed control piston.
Switching to lowspeed rotation occurs, but switching to highspeed rotation occurs during operation.
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RSM-13-02-001E 69
