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).
Letter to Mr. Basil Johnson detailing the 'Lashlock' device and its applications.
| Identifier | ExFiles\Box 154\3\ scan0052 | |
| Date | 25th October 1927 | |
| OY1.R.102527 October 25th, 1927. Mr. Basil Johnson, Rolls Royce Ltd., London, England. (To accompany letter of OY12.R.102427) (Copy for attention of London File) " " Mr. Hives) " " Mr. Bailey) RE: STEERING, ETC. BETHLEHEM "LASHLOCK" Dear Mr. Johnson: The "Lashlock" was developed as part of the amplifier, but is of much wider application. To make the amplifier a finished job, it is necessary to apply a light pressure to the driven-pins (p.4) of the amplifier by some form of cam or wedge mechanism such that pressure from one brake shoe at a time will be rigidly held, but pressure from both shoes together in opposite directions (due to change in temperature of the whole unit) will cause the pins to move. This eliminates backlash in the amplifier The device in its simplest form is shown in Fig. 1 p.5 and the left hand side of Fig. 6 p.6. Both rollers pressing equally on the wedge will move it back easily but either roller pressing alone cannot move it at all. As applied to the torque amplifier it is shown in Fig. 5 p.6. Another interesting application is to gun-laying gear as shown in model Fig.9 p.7 The widest application is probably to the lead-screw shown in Fig.7p.6 All of these devices have the same characteristic:- (a) The spring pressure on the gear, or nut is very light. (b) The "abutment" against thrust from one direction is absolutely rigid. (c) Worn places on the thread or gears are filled out by the expanding action of the wedge. When the nut leaves a worn part of the screw and enters an unworn part, the nut is contracted by the balanced pressure of the two rollers on the wedge. (Continued) | ||