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).
Calculations and considerations for gear change timing, braking forces, and control lever design.
| Identifier | WestWitteringFiles\U\2January1930-September1930\ Scan071 | |
| Date | 12th April 1930 guessed | |
| (4) (3) A time allowance of 1 sec. is made from one gear to another. The time during which the brake will be in action is then found to be 1 sec. x 1.5/8 = 1/5 th. sec. Braking requirements have then been found for a change from top to third at 1000 r.p.m. of the engine as follows :- The torque required to arrest the 3rd. speed drum from 1000 r.p.m., speed up the clutch disc to 1350 r.p.m. and slow down more or less all parts of the gear in 1/5th sec. is 390 lbs. inches. With a drum 3.750" radius and a co-efficient of friction of .150 the shoe load is 700 lbs. Allowing .020 clearance and .050 for wear and spring of the parts, the work required to operate the brake spring is 49 in. lbs. This is done in 1" movement of the handle, so that the load required is 49 lbs. A change from 1st. to 2nd at 2000 r.p.m. of the engine is twice as exacting as the above change. It may be that there are legitimate assumptions which when made, will enable it to be shown that a lighter control is possible. The situation may be thought to justify the complication of a power relay provided that a suitable and reliable relay can be schemed. In this case there are modifications in the control which may be thought to be improvements, such as :- i. The placing of the change lever at neutral may not withdraw the dogs except when the clutch is in. Coasting presents difficulties of re-engagement. ii. A quadrant type of control may be used which would enable one neutral between R.{Sir Henry Royce} and 1st. to be provided at which the dogs were free. The quadrant type of control demands the steering column position. This has advantages from the coachwork point of view. Coasting presents some difficulties and seems to require a neutral between 3rd. and top marked on the quadrant at which the dogs are not withdrawn in addition to the neutral between R.{Sir Henry Royce} and 1st. In this case parts of the gear rotate at high | ||