Blocks, for lifting very heavy weights, are sometimes provided with an electric motor for driving the worm.
The winch hauling the rock uses the northern hemisphere 's largest electric motor - 7000 hp.
The electric motor is powered by rechargeable batteries, and is the primary source of energy during low speeds, such as in heavy traffic.
In the form of standard coil recommended by the Berlin Reichsanstalt the coil is immersed in an insulating oil which is kept stirred by means of a small electric motor during the time of making the measurement.
In the Hospitalier ondograph, 1 a synchronous electric motor driven in step with the periodic current in the circuit being tested drives a cylinder of insulating material having a metallic slip let into its edge.
