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).
Letter detailing specifications for a starter motor, including shaft dimensions, bearings, terminals, and rotation.
| Identifier | ExFiles\Box 51\5\ Scan145 | |
| Date | 10th May 1921 | |
| R R. {Sir Henry Royce} 199 (250T) (SD676 19-7-17) MP18086s DA {Bernard Day - Chassis Design} /THR2/CB10-5-21. contd. We shall require a drawing giving full particulars of the motor end of the shaft, and it will be noted that we desire to have a shoulder on the shaft against which our distance bush butts. This shoulder can, within reason, be made to suit yourselves, but we require shaft drawing to give the dimension X on "N" Scheme 838. On receipt of this drawing with these particulars we shall be able to complete the shaft. We should like to point out also, that the outer race of the ball bearing for the driving end is clamped, and therefore any lateral movement of the shaft must be provided for on the commutator end. Also, small numerals which appear underneath the dimensions of our drawing are permissible limits of variation in thousandths of an inch. We also notice on your print No.5325 only one terminal leading away from the machine. Presumably this motor is of the "earthed" type? We of course, require the same to be of the insulated "return" type, and we wish to have the terminals with one on top vertical centre-line and one at 90° i.e. on the horizontal centre-line (on left hand side looking at pinion end). We think it would be advisable to give your a few more particulars of the starter motor. The direction of rotation will be anti-clockwise, looking on the commutator end. We will require to start a six-cylinder engine - cylinders 3"x4.5" on a gear ratio of 8.4 to 1. When the parts are all completed, we would propose to send them on to you in order that they may be completely assembled for motor testing purposes before finally dispatching to us. We will arrange for an official order for this experimental motor to be forwarded in the course of a few days. Yours faithfully, FOR ROLLS-ROYCE LIMITED. | ||