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).
Preliminary report on the performance of the Spectre All Helical Gearbox, detailing issues with reverse gear, noise, gear disengagement, and oil distribution.
| Identifier | ExFiles\Box 123\3\ scan0195 | |
| Date | 23th November 1934 | |
| To E.{Mr Elliott - Chief Engineer} c. to Hdy.{William Hardy} c. to RHC.{R. H. Coverley - Production Engineer} Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}6/KW.23.11.34. SpectreCodename for Phantom III All Helical Gearbox - Preliminary Report. We have run the first of these boxes on the Vulture car. On the first run on the rig, reverse gear worked out under load. To prevent this Hdy.{William Hardy} instructed layshaft gears of left-hand spiral so that the gear should work into mesh. On the road reverse gear was found to work into mesh on both drive and overrun, a load on the gear lever of more than 20 lbs. being required to keep the lever from moving when half engaged. As regards silence, the idling so far is not up to standard and at about 2000 r.p.m. on all the indirect gears a whine from the constant mesh gears is present. Above this speed both 3rd and 2nd gears are sufficiently quiet, but at and below 2000 r.p.m. the silence is not up to 40/50 standard. First and reverse gears are very much quieter than anything previously tried, a good standard for future production. Several ascents of various local hills have been done at full torque on all the gears. 2nd gear however jumps out on the drive after quite a short distance. No other gear shows any tendency to move on either drive or overrun. It was noticed that when the box is cold a huge effort, namely of 40 lbs, at the lever, is required to disengage 1st gear when the car is moving, as against 12 lbs. stationary. When hot the pull is 12 lbs. either moving or stationary. The effort to engage 2nd gear is also excessive when cold. A further point is that when filling the box with oil through the front compartment, 4 pints brings the oil up to the correct dipstick level. A long time is then required before oil gets through to the back of the box. 6 pints gives the correct level in both halves. When running slowl in top gear the level in the rear is 1.3" higher than in front, pointing to more adequate oilways between the halves being required. | ||