Abstract: A method for manufacturing a hollow cylindrical magnetic yoke assembly for a magnet-type electric motor, including a plurality of permanent magnets attached to the inner peripheral surface of the yoke. The method comprises the steps of expanding a hollow cylindrical tube of a magnetic material by an expander having a plurality of expander elements capable of being moved radially outwards to expand the radius of the tube. The number of the expander elements is equal to the number of the permanent magnets of the electric motor, and one permanent magnet is fitted to each concaved surface of the magnetic yoke formed by the convexed cylindrical outer surface of each expander element.

Abstract: A starter with a gear reduction mechanism including an internal ring gear formed of synthetic resin and a reinforcing member. The internal ring gear has a cylindrical portion and a toothed portion formed on an inner peripheral surface of the cylindrical portion. The reinforcing member is secured around an outer surface of the cylindrical portion.

Abstract: A planetary gear starter with a molded synthetic resin ring gear supported by a frame is disclosed. The ring gear has longitudinally-extending ribs formed in its outer surface which confront longitudinally-extending inward projections formed in the inner surface of the frame. A cylindrical elastic member has an annular portion which is press fit over the ring gear and longitudinally-extending projections which fit into the cavities formed between adjacent ribs and inward projections in the frame. The projections of the elastic member serve as shock absorbers and elastically transmit torque from the ring gear to the frame. The elastic member has an annular portion which reinforces the open end of the ring gear.