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).
Explanation of the operation of an automatic meshing device, including its engagement, disengagement, and behavior under non-ideal conditions.
| Identifier | ExFiles\Box 40\5\ Scan060 | |
| Date | 16th December 1921 guessed | |
| - 3 - course, this entire operation requires but a fraction of a second. After normal cranking has taken place as just described and the engine is running under its own power, disengaging or coming out of mesh of the device is caused by the over-riding speed of the pinion, barrel and nut with respect to the starter shaft, the device being then thrown back in its original position. The purpose of the small spring 14 is merely to prevent the device from coming into contact with the flywheel of its own accord, especially when the car is running down hill. The engagement of the automatic meshing device does not always take place in the simple manner described above. It may happen, when the pinion is pushed forward into mesh with the flywheel gear ring, that a tooth of the pinion strikes the extremity of a flywheel tooth and "butts" against it. This prevents the normal entrance or meshing of the pinion, since it stops its forward motion. Under these conditions, the device as represented in Sketch No.1 will advance the short distance (about 1/4 inch) which separates the pinion from the flywheel gear ring. The pinion meets a flywheel tooth and stops advancing any further. However, the continued rotation of the starter shaft 1 and threaded sleeve 2 maintain the flanged nut 9 in its normal longitudinal motion forward until, as shown in Sketch No.3 and as explained before, the plate 6 meets the shoulder stop of the threaded sleeve 2. In this forward motion, the nut 9 carries along with it the clutch members and the barrel 5, which slides along the pinion teeth. The spring 7 on the other hand finds itself compressed between the plate 6 and the flange of the pinion member. As soon as the device reaches the position shown in Sketch No.3, the clutch tightens automatically as explained in the case of normal operation. The barrel is therefore forced to turn with the starter shaft, being driven through the nut, clutch and splined plate 6. The pinion, being driven by the notched barrel 5, must also follow. But, as clearly shown on the drawing, the pinion is simply spring pressed forward against the flywheel, with a strength which limited to a safe value by the suitable choice of the spring 7, and is not applied against it solidly. Being free to slide longitudinally against this pressure, while rotating, it can therefore ride around | ||