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).
Analysis of the MK.30 gearbox, detailing reverse gear ratios and torques on the four clutches.
| Identifier | ExFiles\Box 136\2\ scan0292 | |
| Date | 8th August 1940 | |
| -3- Ev{Ivan Evernden - coachwork}/Tln.2/JH.8.8.40. (4) Reverse gear. This is at the input end of the box and can be associated with any of the 4 forward gear ratios. It is a fixed planet carrier gear giving a reduction of .375. Thus possible overall reverse ratios are :- .375 .234 .146 .091. There is no point in making the two lower ratios available to the driver. Incidentally the reverse gear parts are identical on the MK.30. and the MK.{R. E. B. Meade-King} 10/12 boxes. (5) Torques on the 4 clutches. The ratios of the MK.30 box are Direct 1.00 3rd. .72 2nd. .46 1st. .33 The torques on the magnetic clutches are as follows. Input torque = T 1st. train. Armature clutched to stationary magnet. Torque = 1.17 T. Armature clutched to turn at engine speed Torque = .54 T. 2nd. train. Armature clutched to stationary magnet Torque = .85 T. Armature clutched to turn at prop. shaft speed. Torque = .61 T. If the coefficient of friction between the clutch faces is of the order of .15 then the clutches of the MK.30. box will resist an input torque of 2400 lbs.ins. with quite a low induction density in the iron. The MK.30 has been quoted to us as a 3 litre gearbox weighing 96 lbs. At the moment we do not know how bearing problems limit the design. Cont'd.{John DeLooze - Company Secretary} | ||