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).
Observations on the difficulties and potential remedies for a Maybach dog clutch gearbox, with diagrams.
| Identifier | WestWitteringFiles\V\October1930-February1931\ Scan364 | |
| Date | 20th February 1931 | |
| SECRET ORIGINAL TO HS.{Lord Ernest Hives - Chair} FROM DA{Bernard Day - Chassis Design}/HDY{William Hardy}? COPY TO SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} E.{Mr Elliott - Chief Engineer} BY.{R.W. Bailey - Chief Engineer} RE MAYBACH DOGS. X3531 X2200 OBSERVATIONS With regard to HS{Lord Ernest Hives - Chair}2/MJ.I8.2.31. and HS{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}'s. proposed trial of a Maybach Car we give below some observations on the difficulties and possible remedies( based partly on our trial of I4.EX. with the temporary scheme of hand controlled Maybach dogs on the lines of Chrysler) in case any are of help in pointing to the features which need investigation. (I) The hand controlled scheme with a neutral position of the dogs demands some protection against engagement of the dogs at speeds which are far from synchronous. We think that without this some smashed transmissions will result; engaging top gear after coasting, for example, with the engine idling and the clutch in, perhaps. In spite of the fact that all the dogs we have seen have had square engagement corners, it seems to us that a certain amount of tooth rounding may be possible without preventing the dog from engaging at synchronous speeds. The difficulty appears to be with third speed which requires the clutch to be in and may have to engage with the engine on full throttle. The principal danger seems to arise from the top speed dogs as they engage when the car is faster than the engine. These dogs can, and should, be engaged with the clutch out and so need present no more face for engagement than do the present sliding gears, and so would give the same immunity from damage as is given now. [Diagram 1 annotations] TOP SPEED ROUNDED WHEN RELATIVE SPEEDS EXCESSIVE THE TEETH JUMP ONE ANOTHER BUT WHEN CORRECTLY SYNCHRONISED TEETH ENGAGE (2) It is certain that the clicking noise made by the dogs when sliding over one another would be reduced by a smaller face angle and we believe that quite a small face angle of say 2.deg. is sufficient to keep them apart. The difficulty is the loss of engagement face; top gear at least might be flatter. May-bach have presumably got over the trouble somehow. The jar, which sometimes occurs when engaging 3rd. with the throttle considerably opened due to the dogs synchronising when not in a position to engage, and more noticeable the lower the speed) would be reduced with an increased number of teeth. Salerni had nine. Increasing the number of teeth probably aggravates No 2 [Handwritten: DIFFICULTY?] [Diagram 2 annotations] SYNCHRONISED HERE | ||