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).
Description of the operation of a starter motor's friction clutch and pinion engagement mechanism.
| Identifier | ExFiles\Box 40\5\ Scan059 | |
| Date | 16th December 1921 guessed | |
| - 2 - This washer, which is of a special cork composition, and forms part of a friction clutch as will be shown later, is held on its other face against the flange face of an internally threaded nut 9. The flanged nut 9 rides on the threaded sleeve 2. The barrel casing 5 is closed by means of a cover 10, which is held in place by a spring lock ring not shown in the sketch for simplicity. The dished washer 11 is slightly compressed and forms a small friction clutch which facilitates operation under certain conditions. Its slipping torque is low, and its function an auxiliary one, so that it will be disregarded in the following explanation. Operation. The device is operated simply by closing the starting switch. This causes the starter shaft 1 with its threaded sleeve 2 to rotate rapidly within the flanged nut 9, the inertia of which establishes a speed difference between it and the shaft. The nut will thus travel longitudinally along the threaded shaft, pushing ahead of itself the entire barrel and pinion assembly through the spring 7. The pinion 4 enters then into mesh with the flywheel gear ring. The longitudinal motion of the device stops when the plate 6 meets the stop shoulder "B" of the threaded sleeve 2, fitted with two washers 12 and 13. The entire system is then in the position shown in Sketch No.2. With the nut 9 stopped in its longitudinal motion and the pinion engaged with the flywheel gear as shown in Sketch 2, the continued rotation of the starter shaft tightens the nut 9 against the clutch assembly 8-6, and the axial pressure on the clutch face rises considerably. In other words, the clutch becomes self-tightening to meet the load of starting. The starting torque is thus transmitted from the starter shaft 1 and threaded sleeve 2 to the flanged nut 9, friction clutch 8-6, barrel 5, pinion 4 and flywheel gear ring, and normal cranking takes place. It will be noted in the above operation that the spring 7 does not enter into play to any very great extent, and that it does not carry any torque whatever. It may also be mentioned that the automatic tightening of the friction clutch in proportion to the cranking load throws this load on the starter gradually, and very effectively absorbs the shock of starting. Of | ||