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).
Road tests to eliminate bonnet knocks with Dillmond engine mounting.
Identifier | ExFiles\Box 11\3\ 03-page375 | |
Date | 1st July 1931 | |
To Hs.{Lord Ernest Hives - Chair} From GWH.{George W. Hancock - Head Chateauroux} Hotel de France. Chateauroux. France. Y7941 87360. 87005. 1.7.31. 25-EX. RE. BONNET KNOCKS. WITH DILLMOND ENGINE MOUNTING. A series of tests have been carried out to obliviate the above. The road chosen was of uneven loose surface without pot-holes not quite so severe as the Le CanadelHenry Royce's French residence road. The best solution arrived at is to control the radiator underneath, as at present, to fit medium rubber blocks to locate and damp out the inertia of the radiator sideways, and a soft sorbo rubber pad .500 thick inserted between the medium rubber pads to damp out the inertia endways of the radiator. Replace the standard rubber connection and unions from the cylinder to the radiator and fit a longer and more flexible rubber connection with clips. The front end of the bonnet to fit close to the radiator, or we should prefer wearing pads at the hinges and at the bottom of the side panels. The rear of the bonnet to have a minimum clearance all round of .312. The bonnet clips should be re-designed to allow for a larger dia. longer spring, and higher rating, as they play an important part in holding the bonnet down vertically. The centre control tube as at present. The objections to the Vee control tube is, it has a period of its own which causes rapid oscillation of the radiator. To overcome this very much stronger tubes would have to be used, also the apex of the Vee tubes should be as near the centre of the radiator as possible. The present design tends to swing the radiator round from the apex of the Vee control tube and any small movement at this point is multiplied by the length from the centre. The various tests and conditions are as follows:- 1st. Bonnet clearance round the radiator .031". Bonnet clearance between side panels and bonnet rests .3125" Bonnet clearance round dashboard and minimum .070" Radiator controlled by springs underneath with a load of 45 lbs. Vee control tube from radiator to dash, apex at radiator end. 20-25 MPH. The horizontal movement of the bonnet was rapid with periods of a higher velocity. The vertical movement caused general rattle from the bonnet. The radiator had rapid periods of movement endways as seen by the mascot. 40-MPH. The horizontal movement of the bonnet was rapid but did not cause the bonnet to knock on the dash, a fair amount | ||