The German servomotor specialist Wittenstein cyber motor has developed a hollow-shaft, direct-drive motor with a stator that can be split to fit around a shaft. The permanently excited synchronous motor can be used in applications where axial installation and removal are impossible.

The motor (shown above) was developed to solve a problem for a customer which needed to replace a chain roller drive with an integrated direct drive, but could not mount a conventional stator axially. It also wanted to be able to remove the stator easily for maintenance. In addition, the new drive had to be compact and had to be able to operate at high temperatures.

Wittenstein came up with a design based on a hollow-shaft direct drive with two three-phase halves. Each half incorporates a stainless-steel water cooling system, allowing the motor to operate at rotor temperatures of up to 200ºC.

The “wing” motor is mounted by attaching the two stator halves to fixing lugs which allow the wings to be joined precisely around the shaft and disassembled easily for servicing.

The 99kW motor can produce up to 1.9kN of torque and operate efficiently at speeds of up to 1,750 rpm. It has an outer diameter of 543mm and a hollow-shaft diameter of 365mm.