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).
Investigation into the cause of a 'galloping knock' engine noise reported by customers.
| Identifier | ExFiles\Box 47\2\ Scan055 | |
| Date | 23th January 1928 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/GWH.{George W. Hancock - Head Chateauroux} c. to BJ. WOR.{Arthur Wormald - General Works Manager} c. to RG.{Mr Rowledge} H.{Arthur M. Hanbury - Head Complaints} c. to BY.{R.W. Bailey - Chief Engineer} OY. 44117 Hs{Lord Ernest Hives - Chair}/GWH{George W. Hancock - Head Chateauroux}/LG23.1.28. INVESTIGATION OF GALLOPING KNOCKS. 48020 This is a complaint that has been prevalent and complained of by customers for some time. A lot of investigation work has been done by The Production Test Dept. - we took advantage of the information obtained from them. It is a periodic knock which is most noticeable between the speeds of 18 and 24 m.p.h. with a certain load upon the engine, and is accentuated by certain types of bodies. Investigations have definitely proved that it is produced by the firing of the front three cylinders. Tests carried out on the road and in the shop shew that when firing on Nos. 4, 5 and 6, the knock is non-existent, but immediately the front three are fired it is very definite. Further investigations proved that the knock was most pronounced when firing on No.3 cyl. To find what is the knock, a series of tests have been tried. We first tried making the spring drive solid. This did not affect the knock in any way. We then made the slipper wheels solid, which had the effect of eliminating the knock but caused bad rumbling noises from the gears. We got the same effect by taking the slipper wheels off, the difference being less rumbling effect. We then tried various loads upon the slipper wheels and found that when made to slip at 114 in. lbs. the knock was non-existent but crankshaft periods were noticeable. With a friction load of 170 in.lbs. the knock was contd :- | ||