7.Option Flow Setting

[2]Troubleshooting for parking brake

Trouble Description

While the motor is stopped with an external load on it, the motor rotates.

Motor drive force is not delivered. The motor section is abnormally hot. Possible Cause

A worn disk reduces the torque of the parking brake.

Contact defect or other problem deteriorates the disk surface and reduces the parking brake torque.

A fatigued or damaged spring reduces the parking brake torque.

The external load is too much for the parking brake capacity.

A damaged O-ring causes the pressurized oil to escape and the parking brake cannot be released.

A clogged orifice of the oil path for parking brake release prevents the pressurized oil from entering to the parking brake cylinder chamber and the parking brake cannot be released.

A clogged or long and narrow drain pipe rises the drain pressure and the parking brake cannot be released. Countermeasure and Solution

Disassemble the unit to replace the parking brake disk. Clean the part, and re-assemble the unit.

Disassemble the unit to replace the disk. In addition, repair the surface of the counterpart of the disk and re-assemble the unit.

Disassemble the unit to replace the spring. Clean the part, and re-assemble the unit.

Review the external load and correct the value.

Disassemble the unit to replace the Oring. Clean the part, and re-assemble the unit.

Disassemble the unit to remove the foreign matter in the orifice. Clean the part, and re-assemble the unit. In addition, flush inside the pipe.

Clean the drain pipe. In addition, review the piping system and reduce the pipe line resistance.

[3]Troubleshooting for relief valve

Trouble Description

Motor does not rotate. Or, the rotation is slow.

Motor does not stop. Or, it takes a long time to stop.

Big shock occurs when stopping running. Possible Cause Countermeasure and Solution

Foreign matter gotten in between the poppet seat and the poppet of the relief valve causes seat defect and high pressure oil leaks to the low-pressure side. Disassemble the unit to remove the foreign matter. Clean the part, and reassemble the unit.

A broken spring of the relief valve causes the high pressure oil to leak to the low-pressure side.

A fatigued spring of the relief valve reduces the set pressure and a relief operation occurs at a low pressure.

Foreign matter gotten into the seat section between the free piston and the base plate of the relief valve reduces the set pressure.

A clogged orifice set to the poppet of the relief valve reduces the set pressure.

Foreign matter gotten in between the poppet seat and the poppet of the relief valve causes seat defect and the relief valve cannot close. Replace the relief valve. Disassemble the motor to clean the parts and re-assemble it.

Replace the relief valve.

Uninstall the relief valve to remove the foreign matter.

Uninstall the relief valve to remove the foreign matter.

Disassemble the unit to remove the foreign matter. Clean the part, and reassemble the unit.

The spring of the relief valve is broken and the relief valve cannot close.

A fatigued spring of the relief valve reduces the set pressure and the brake capacity is lowered.

Foreign matter gotten into the seat section between the free piston and the base plate of the relief valve reduces the set pressure and the brake capacity is lowered. Replace the relief valve. Disassemble the motor to clean the parts and re-assemble it.

Replace the relief valve.

Uninstall the relief valve to remove the foreign matter.

A clogged orifice set to the poppet of the relief valve reduces the set pressure and the brake capacity is lowered. Uninstall the relief valve to remove the foreign matter.

Foreign matter gotten into the sliding section of the poppet prevents the poppet from moving.

Foreign matter gotten into the free piston prevents it from moving. Replace the relief valve.

Uninstall the relief valve to remove the foreign matter and re-assemble it.

The set pressure of the relief is too high. Replace the relief valve.