Hydraulic Case Drain

May 22, 2015

Often in hydraulic systems, hydraulic motors and pumps run case drain hoses.  The reason for this is to drain excess internal oil leakage from the motor.  This is certainly critical in a piston motor and pump as the pistons have some internal leakage as they are actually just metal on metal.  If no case drain hose is installed then the result will be, at the least, a blown shaft seal, and at worst, a split or damaged housing.

With gear pumps the leakage drains back into the suction hose internally, so no case drain is required.  With gear motors and geroller/geroter motors, the oil can drain into the outlet port, however, that means that the oil pressure in the outlet port must not exceed the pressure rating of the seal.  If it does, then a case drain needs to be installed.  This will then usually mean you can run motors in series without damaging the motor.

Running a case drain can also assist with cooling, and also lubrication of the motors in some instances.

You must always check the manufacturer’s specification on maximum outlet and case pressures for correct installation.

If you require assistance with your hydraulic system, motors, pumps, hoses, seals, case drain, oil, lubricants or anything else for that matter, please give us a call on (03) 5382 0574 or call in and see us at Horsham Hydraulics, 84 Golf Course Road, Horsham Victoria 3400