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).
The failure analysis of a Wraith bumper chassis petrol tank.
Identifier | ExFiles\Box 10\2\ 02-page27 | |
Date | 18th November 1937 | |
To Da.{Bernard Day - Chassis Design} 651 also 1024 WRAITH BUMPER CHASSIS PETROL TANK. This tank was found to be leaking after 29 hours bumping on the back wheels and 31 hours on the Front. The tank being filled to within 2" of the top with water. On examination a crack was found under the offside strap about 1 1/2" long running in the direction of the strap in the middle of the bottom of the tank lying along the edge of the offside baffle plate. Both baffle plates were cracked as shown on the attached sketch the offside being torn away from the shell of the tank all round the front though the soldered portion was still attached. The near side end plate had a small crack across the bottom end of the rear finger groove. This tank is to Lec.5606 with the thickness of the baffles increased from .018" to .024" and with the addition of finger groove. The new Wraith tank is similar to the above but with the addition of finger grooves in offside end plate and no sump pressed in the bottom. This tank had the sump pressed in the bottom. The direction and position of the crack suggest that the failure of the shell was due to the baffle applying a bending movement to the bottom of the tank which has been brought about by increasing the gauge of the baffle to the same as that of the shell. The sump pressed in the bottom has in all probability localised this stress. The finger grooves pressed in the baffle should have helped but in each case they have failed in the middle there by locating the bending at the top and bottom. On the N.S. baffle there is only one small crack at the top of the finger groove and no damage to the tank shell. The crack on the end plate carrying the filler is placed at the bottom end of the finger groove. Apart from any question of the extreme conditions on the bump chassis not being comparable with service conditions it does | ||