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).
The requirements for a hoist motor and braking system, including automatic stopping and constant speed.
| Identifier | Morton\M7\ img016 | |
| Date | 12th August 1912 guessed | |
| -6- Messrs Royce Ld(contd) a motor. This will require a machine amply large enough for the work which is the sine qua non of a getting a constant speed machine. I, therefore, urge upon you the necessity of embodying in the next hoist which is <handwritten insertion>required for</handwritten insertion> automatic stopping at a constant point, an extremely constant speed motor, powerful & quick acting brakes and plenty of momentum in the brake drum or armature. (1) Constant speed motor. (2) Fairly high speed so as to make it easy to get 1,3,4 & 5 (3) Considerable momentum in the brake drum or armature. (4) Powerful brakes. (5) Quick acting brakes that contain little inertia so as to act quickly without jerks. In addition to this I think Mr Bentley's idea of using a resistance across the armature to be quite practical providing that he does not attempt to cut this resistance down to a short circuit, but use simply a constant resistance that will allow of the standard armature current or at most twice the standard armature current to pass upon being cut in. It can be done by the same relay as is used to break the supply of current to the armature, the effect on the machine will be exactly equivalent to the brake, and as this can be cut in more quickly than the brake it should help to make the hoist stop to a constant level. It will be seen that this magnetic brake will be off or ineffective at the time the hoist stops, but by that time the mechanical brake will be effectively & tightly on and should act that the hoist will stop in less distance and with less jerk than if the mechanical brake only were used. We have, therefore, quite a group of ideas, which, if they are all carried out well, will I am sure give us | ||