Rabinow's Rapid Reversing Motor is a very efficient method of reversing the direction of rotation of an electric motor. In some applications of motors, rapid reversal is required as, for example, in moving white-hot metal back and forth between rollers in the production of sheet steel.
Jacob Rabinow is demonstrating the device, which consists of a spring-steel shaft permanently fastened to the output shaft of the electric motor. The other end of the long shaft has a small tooth-clutch armature welded to it. Two stationary tooth-clutch members are located opposite to and near the rotating central clutch member.
When the motor is running normally, the shaft and the clutch armature revolve with the motor armature. When the operator wants to reverse the rotation of the motor, the toothed clutch is suddenly stopped by engaging one of the stationary clutch-members with the rotating member. This stops the end of the spring shaft. The inertia of the electric motor shaft winds the spring shaft for about 20 degrees and the shaft reverses the rotation of the motor. This is done with no loss of energy as generally occurs in stopping and reversing a motor.
In the model shown, the motor was used as a single-phase induction motor; it was not necessary to shut off the current during the reversing process. The motor could run in either direction equally well. In applying this invention to large motors, it is necessary to reverse the electrical connections during the mechanical reversion. If properly done, there will be no current surges when the motor reverses. For large motors, the "spring" action could be supplied by a pneumatic cylinder or other means rather than by a steel spring. In the model shown, the motor reversed from 3200 RPM in one direction to 3200 RPM in the other direction in 3 milliseconds.
The Patent drawing of the rapid-reversing motor clearly shows the construction of the device.
Last Updated on October 29, 2004
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