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).
Alternative schemes and design details for a bonnet lock for the 40/50 and 20 HP models.
| Identifier | ExFiles\Box 25\1\ Scan099 | |
| Date | 3rd January 1927 | |
| To DA{Bernard Day - Chassis Design}/EV.{Ivan Evernden - coachwork} BY Hs.{Lord Ernest Hives - Chair} from R.{Sir Henry Royce} c. to BJ. Wor.{Arthur Wormald - General Works Manager} A.E. OMA BONNET LOCK - 40/50 AND 20 HP. Handwritten: X1140 R2/M3.1.27. X. 8260 X. 5260 X. 1140 If our new bonnet catches do not prove a success we shall require some scheme of catch which holds the bonnet to the pads - perhaps a spring plunger as shewn in fig.4. We have now 3 schemes proposed for the lock - (1) Four existing pads-double catches on lock. (2) Clear central locking hook. (3) Six pads - central one for lock. We had abandoned (1) for various reasons, but I am now inclined to think it the best scheme: perhaps you at WW. can suggest something better than either. I have several objections to (2) as worked out, and I doubt if we can make it robust, and sufficiently clear, so I am having another try at (1). SEE ORIGINAL FOR SKETCH - fig.1. If the details are simple and robust (i.e. inexpensive and not likely to get out of order) we do not mind if many parts are needed, but the old lock had double catches, and was spring operated, and was not good because much work has to be done in unlocking. The above has same resistance approx. each way. LOCK BARREL. This must have a stop in R.H. direction for locking, and L.H. for unlocking, exactly one turn even after wear. As the length of the barrel is not limited because part can be inside and part outside, it should be easy to arrange. The barrel is shewn going in from the front, held in by pinion, fixed by 2 screws, (high tensile steel screws because so small). Tapping depth should be moderate - 2 to 3 dias Bosch uses a countersunk even deeper angle than ours (with advantage). The lock body casting goes in from back (inside of bonnet). It can have smooth surface for stop plate to slide upon; projection on pinion can pass into stop plate - SEE ORIGINAL FOR SKETCHES - fig. 2 and 3. contd :- | ||