The majority of motor problems fall into these categories:

Improper fluid — The motor is no different than any of the other components of the hydraulic system—it must have clean fluid, in adequate supply, and of the proper quality and viscosity.

Poor maintenance — A poor maintenance program runs a close second in the cause of major problems. Typical slips in a program include:

  • failure to check and repair lines and connections to stop leaks; faulty connections can allow dirt and air into the system, lower pressure, and cause erratic operation.
  • failure to install the motor correctly. Motor shaft misalignment can cause bearing wear which can lead to lost efficiency. A misaligned shaft also can reduce the torque, increase friction drag and heating, and result in shaft failure.
  • failure to find the cause of a motor malfunction. If a motor fails, always look for the cause of the failure. Obviously, if the cause is not corrected, failure will recur.

Improper operation — Exceeding a motor’s operating limits promotes motor failure. Every motor has design limitations on pressure, speed, torque, displacement, load, and temperature. Excessive pressure can generate heat because of motor slippage, and can cause the motor to exceed torque limits. Excessive speed can cause heating and can cause wear of bearings and other internal parts.

Excessive torque can cause fatigue and stress to bearings and the motor shaft, especially on applications that require frequent motor reversing. Excessive load can create bearing and shaft fatigue. And finally, excessive temperature can cause loss of efficiency because the oil becomes thinner, and can produce rapid wear because of lack of lubrication.