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).
Technical description of an electrical drive system's components, assembly, and testing.
| Identifier | ExFiles\Box 52\3\ Scan371 | |
| Date | 1st August 1919 | |
| OY10-F28/8/19-5 The whole assembly is then impregnated with Bakelite under vacuum and pressure, and afterbaking becomes virtually as solid as a piece as though it was turned out of hardwood. The final operation is to mount it on centres and grind away the projecting ends of the laminated teeth, both outside and inside, so that they may run with a small and uniform air gap. This piece is not coupled to the engine, and thus does not receive the full vibration of the engine impulses. It must receive, however, a certain magnetic "reflection" of these, and does receive road shocks direct. It is said to stand up perfectly in practice. The teeth are prevented from escaping by piano-wire bindings. (3) Face commutators are used for both armatures, these having been found most desirable, since the engine-vibrations which might throw off brushes of ordinary type are principally at right angles to the axis of the crankshaft, and therefore do not affect the face brushes. The motor armature is mounted on discs at each end, the rear one of which runs on a ball bearing on the stationary armature shaft, while the front end is also mounted on a ball-bearing and is coupled to the driving shaft, which passes through the stationary armature shaft. The front disc engages with the ends of the copper conductors of the armature, to transmit the driving torque. (4) The fields are of four-pole type, arranged as a star. They are laminated and mounted upon the hollow stationary shaft which is attached to an extension of the engine casing. They are shunt-wound, with a small series winding (added (for a reason I did not follow). The winding of the small poles is brought outside and coupled with the controller to give the speed regulation as described above. The general scheme of the device, as it is to be arranged on the Cadillac car, is shown on the attached sketch print. (13) TEST. The Chalmers car, to which the original experimental device was fitted, did not have the drive in its final form. The control in this case was by four rearrangements of the field windings, giving four speeds forward and reverse. There was a neutral spot between each of the four "speeds", which caused the engine to race if the foot was kept on the accelerator, and caused the speeds to come in with a shock. It was therefore necessary to change speed almost with the care used on a 4-speed sliding change. 14. Due to a lack of sufficient "capacity" in the device as fitted, | ||