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).
Trial report on the performance and silence of a Maybach car's 4-speed gearbox in Berlin.
| Identifier | Morton\M19\ img033 | |
| Date | 2nd March 1931 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to Dr. R.{Sir Henry Royce} Hy.{Tom Haldenby - Plant Engineer} ORIGINAL Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}17/KT.2.3.31. X3531. X2200. TRIAL OF MAYBACH CAR. BERLIN. We tried two of the Maybach cars in company with Dr. Maybach. The only difference between the 7 & 8 litre cars apart from the slightly greater bore giving the increased capacity is that only the 8 litre cars have the latest 4 easy changes, 4 silent speeds gearboxes. We were able to test the cars on the Berlin motor test track which is straight several miles long and has no speed limit. This enabled us to form a fair impression of the silence and smoothness of the car at all speeds. GEARBOX. 4 Speeds Silent. We have dealt with one or two technical points connected with this box in a separate memo., to which we have also attached a sectional drawing. A general impression of its behaviour is as follows. (1) Silence (a) In Neutral. In neutral there are three pairs of helical gears turning over. Under the circumstances it is not surprising that they are audible. The noise is not excessive, but is greater than the amount of sound that we should at present pass in our side shafts by quite an appreciable amount. This appears to be inevitable on this type of box and would excite adverse comments on a car having silent idling characteristics of a Rolls-Royce. We tried two cars with the 4 speed box and their characteristics were very similar. We think that they were much on the same standard as the Wilson gearbox when in neutral on the 5 1/2 litre Daimler. (b) Under Load. The indirect gears are quite good for silence considering that there are always two pairs of helical gears under load. Third speed is not quite as silent as the latest Chrysler spool gear but possibly the advantage would be reversed with age due to the better support of the helical gear. Top gear suffers slightly from the idle gears turning over in the gearbox, again this might be more noticeable with a more silent power unit. | ||