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 memo proposing two alternative rear spring setups for the 40/50 HP model, specifically for the Australian market.
| Identifier | ExFiles\Box 67a\1\ scan0302 | |
| Date | 10th May 1927 | |
| To DA.{Bernard Day - Chassis Design} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to BY.{R.W. Bailey - Chief Engineer} EP.{G. Eric Platford - Chief Quality Engineer} c. to Pt. Wor.{Arthur Wormald - General Works Manager} c. to CWB. Sg.{Arthur F. Sidgreaves - MD} HM{Capt. W. Hallam - Head Repairs} Hs{Lord Ernest Hives - Chair}/Rml/LG10.5.27. SPRINGS FOR AUSTRALIA ETC. REAR SPRINGS - 40/50 HP. We understand from Pt. that the main trouble experienced in Australia is due to the axle hitting the buffers. He has had no cases of broken rear springs with the exception of the thick leaf type. Therefore we may take it that as at present designed for 12.125" deflection the RR. rear spring is well within the stress limit. We suggest the following two types of rear springs :- (A) 15% Stronger springs. To calculate this spring, the weights over the axles to be estimated as before and having done this a spring 15% stronger than that which would be selected for English conditions to be fitted i.e. spring for Britain 2000 lbs. - spring for Australia 2300 lbs. With this spring the normal buffer clearance will be 5.325" and consequently the static load to bring the axle to the buffers will be approx. 44% greater than with a standard spring. (B) 25% Stiffer spring. The weights over the axles to be calculated as before, and having obtained the spring suitable for Great Britain, a spring should be fitted which is 25% stronger but has 25% less initial camber i.e. British spring 2000 - Australia 25% stiffer - 2500 lbs. - initial camber 1.9". With this spring the normal buffer clearance will be 4.925" and consequently the static load to bring the axle to the buffers will be approx. 50% greater than with a standard spring. The main advantage of spring (B) over spring (A) is that it drops the rear of the car .4" and consequently gives xxxxxxxx better car control at high speeds, reduces the tendency to hit the buffers slightly, and has less tendency to break. Its disadvantage is that it does not give such good riding in towns. We consider that these springs should be sufficiently heavy for cars fitted with balloon tyres and hydraulics and hartfords on the rear, and that if Pt. tries the two types he will be able to decide which is preferable. contd :- | ||