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).
Technical analysis of the issues and principles of hydraulic transmissions, with a focus on the Lentz gear system.
| Identifier | ExFiles\Box 136\4\ scan0011 | |
| Date | 15th January 1912 guessed | |
| (2) type, but in the Lentz gear, the losses on the high gears will probably be greatest. 4. I believe most hydraulic transmissions suffer from the difficulty of air finding its way into the passages which are under oil pressure and forming a mixture of oil and air, with the result that the efficiency falls to a figure somewhere between that for an oil pump and that for an air pump on similar lines (an air pump of this type would of course be extremely inefficient and leaky). The Lentz gear does not appear to overcome this difficulty in any way, and from the description published in the "Motor" of November 14th 1911, it would appear that in order to overcome the difficulty of oil leaking out from the casings, the inventor has arranged for all points which connect with the outside, to be at points which are under suction and not under pressure from the pumps; this I believe will only aggravate the difficulty of pumping froth instead of oil. Beyond these difficulties, there are the usual losses from heating which can of course be compared to the ordinary rise in temperature of bevel and worm axles. I think the principle of employing 3 pumps and their combinations to obtain the various speed changes is good, as it enables the inventor to overcome the varying torque which is inherent to all types of hydraulic gear which employ variable | ||