Troubleshooting; Excessive Noise And/Or Vibration; System Operating Hot; Motor Shifting Irregularities - Danfoss K Frame Series Service Manual

Service Manual
K and L Frame Variable Motors, Cartridge Mount

Troubleshooting

Excessive noise and/or vibration

Item Description
Check oil level in reservoir Insufficient hydraulic fluid could lead to cavitation that
and oil supply to the motor. would cause system noise.
Check for air in the system. Air trapped within the system lines, or the motor itself,
could result in cavitation that would cause system noise.
Inspect the output shaft A loose or incorrect shaft coupling will produce vibrations
couplings. that could result in system noise.
Inspect the output shaft Misaligned shafts create excessive frictional vibration that
alignment. could result in system noise.
Hydraulic oil viscosity above Viscosity above acceptable limits will result in cavitation
limits. that would lead to system noise.

System operating hot

Item Description
Check oil level in reservoir Insufficient amount of hydraulic fluid will not meet the
and oil supply to the pump. cooling demands of the system.
Inspect the heat exchanger, If the heat exchanger fails, or becomes obstructed, it may
(if so equipped). not meet the cooling demands of the system.
Check the system relief If a system relief valve becomes unseated for an extended
valves. period of time or fails for any other reason, the system
could become overheated.

Motor shifting irregularities

Item Description
Check the electrical Electrical signal is needed to energize the valve coil. The
connection and electrical energized coil is shifting the motor.
signal to the shifting valve
coil.
Check valve coil The energized valve coil is moving the valve spool. That
leads to motor shifting.
Check shifting pressure. Shifting pressure moves servo piston. Obstruction could
result in slow or no shift conditions.
14 | © Danfoss | July 2017
Action
Fill the reservoir to the proper level and ensure that oil
supply to the motor is adequate and the lines are
unobstructed.
Ensure that all of the system lines and components are
purged of air.
Ensure that the correct coupling is used and that it fits
properly onto the shaft.
Ensure that the shafts are properly aligned.
Replace hydraulic oil with appropriate fluid for operating
conditions. Refer to publication 5200L0463 for information
on fluid selection.
Action
Fill the reservoir to the proper level.
Ensure that heat exchanger is receiving adequate air flow
and that the heat exchanger is in good operating
condition. Repair or replace as necessary.
Repair or replace any malfunctioning relief valves as
applicable and verify that the loads on the machine are not
excessive.
Action
Ensure that the electrical connection between controller
valve coil is alright. Check wires and connectors. Check
electric signal. Valve coil can be energized with 12V PWM-
signal or directly with 12V.
Measure valve coil resistance. Value needs to be 5,3ohms
+-5%. Replace valve if resistance is differing.
Shifting pressure at full energized valve coil (1500mA)
needs to be at 20-32bar [290-464psi] or system input
pressure, whichever is lower. Replace shifting valve when
measured pressure is differing.
520L0631 | AX00000042en-US0402