From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Modified starter motor engagement scheme for the Phantom III chassis.
| Identifier | ExFiles\Box 62\1\ scan0348 | |
| Date | 5th December 1935 guessed | |
| Wst 86134 MODIFIED SCHEME OF STARTER MOTOR ENGAGEMENT FOR PHANTOM III CHASSIS. The starter motor is arranged with a hollow shaft with a movable pinion capable of sliding horizontally along internal splines in the driving end of the armature shaft. A solenoid mounted on the commutator end of the motor is made to slide the pinion along the splines into mesh with the engine flywheel by means of a long spring loaded rod mechanically connected to the pinion and operated by the solenoid plunger. With any arrangement of this nature it is important that a slight rotary movement be imparted to the pinion when it is being advanced horizontally into mesh with the flywheel otherwise the teeth will jam. The rotary movement must also be entirely independent angularly to the horizontal movement, at any point, of the pinion so that in the rare event of a "corner jam" a re-entry can be effected. Several schemes are in existence of solenoid operated pinions but in none of them to our knowledge is the rotary movement of the pinion independent of the horizontal movement. This we consider fundamentally important. A further feature of the scheme, which to our knowledge is also original, is the method of disengaging the pinion from the flywheel when the engine starts. Disengagement is effected automatically by the decrease in motor torque and current when the engine fires. A heavy current series winding on the engaging solenoid serves to hold the pinion into gear as long as the motor is turning the engine. This series winding is necessary as when the main motor circuit is in operation the engaging solenoid winding is virtually short circuited (see diagram). When the engine fires the decrease in current flowing in this series winding due to a reduction in the motor torque allows the spring loaded plunger to return to the off position releasing the motor pinion from the flywheel gear. | ||