Abstract: A coaxial starter motor comprising a d.c. motor having a hollow rotary shaft extended forward and a planetary speed reduction gear having a sun gear disposed on the outer periphery of the rotary shaft. The starter motor comprises an over-runing clutch of which inner sleeve rotates in one direction and is provided at the inner circumference with helical splines, the over-runing clutch being disposed on the front side of the rotary shaft and rotated at a reduced speed by the planetary gear speed reduction gear. Also provided is an output sleeve mounted on the front end portion of the rotary shaft and having a pinion at its front end portion and axially movably and relatively rotatably supported by a bearing, in which helical splines formed close to the rear portion of the outer periphery is in mesh with helical splines of the inner sleeve. A solenoid switch is disposed on the rear end portion of the d. c.

Abstract: In a starting electric motor comprising: a movable pinion cylinder slidably mounted on the extension of the output shaft of the motor, the movable pinion cylinder having the front end portion formed into a pinion part, the rear end portion formed into a clutch inner part of an overrunning clutch, and the middle portion formed into a slidably supporting surface held by a first bearing fitted in the front frame, the shaft extension being supported by the front frame through the movable pinion cylinder, the movable pinion cylinder is slidably and rotatably supported on the shaft extension by a second bearing fixedly fitted in an inner cylindrical wall which is extended in the movable pinion cylinder from the clutch inner part to the middle portion with a gap relatively large between the inner cylindrical wall and the shaft extension.

Abstract: An engine starter includes an electric motor having a hollow rotary shaft for causing a turning force to start an engine, a hollow inner clutch rotatably supported in the hollow rotary shaft through a one-way clutch, a pinion shaft provided with a pinion which is engaged with a ring gear of the engine, a spline-fitted in the hollow inner clutch to move in the axial direction thereof, an electromagnetic switch attached to one end of the electric motor for turning on or off the electric motor, and a moving body which moves in conjunction with the electromagnetic switch to move the pinion shaft in the axial direction thereof to engage the pinion with the ring gear.

Abstract: A coaxial type starter used to start an engine of a vehicle is disclosed. The starter comprises first and second bearings which are respectively disposed between the outer circumferential portion of a carrier of an epicyclic reduction gear which is formed integral with a clutch outer member of an overrunning clutch and a fixed portion of the starter and between the inner circumferential portion of the carrier and the outer circumferential portion of an armature rotary shaft of a d.c. motor. Accordingly, the carrier of the epicyclic reduction gear is prevented from becoming eccentric by the first bearing, and the armature rotary shaft of the d.c. motor which is supported by the carrier through the second bearing is also prevented from becoming eccentric. Thus, it is possible to eliminate any risk of the planet gears of the epicyclic reduction gear being damaged or generating noise.

Abstract: A planet gear starter comprising a d.c. motor equipped with an epicycle reduction gear in which an internal gear is directly formed in the inner surface of a yoke of the d.c. motor.