Improving bump rigs and spring testers, with comparisons to Vauxhall's methods.
| Identifier | ExFiles\Box 127\4\ scan0148 | |
| Date | 19th June 1939 | |
| -2- Rm {William Robotham - Chief Engineer} /AFM {Anthony F. Martindale} 4/R.19.6.39. We can adapt this idea to our valve and must try it at once. Our present method is to use damping discs, but these are not always convenient. Vauxhall's say that squawk occurs unless the valve spring poundage exceeds 20 lbs. BUMP RIG. Their rig is so arranged that one can walk around the drums underneath the car. Guards are provided to make it fairly safe. The room can be darkened and lights are provided in the pit. Much interesting information can be learnt with the aid of a stroboscope. The motor they use to drive the gear is a constant speed motor (A {Mr Adams} /C) and a Crofts gear (Manchester) used to get variable speed. The ease of control is splendid. We would strongly recommend modifying our rig to imitate theirs, the cost should not be great. We could throw away the old P.II engine. The only feature we cannot easily imitate is the silence of their bump house. We have air compression cylinders all round ours, the noise is terrific. Noise tests are impossible. This is a great handicap. We have been trying to get noise figures for rubberised front ends, rather unsuccessfully. Olley is building a rig in the open air to get quieter conditions still. (The Vauxhall Works is on the edge of the downs, they don't have test beds running nearby). SPRING TESTER. Olley swears by the Olsen spring rate tester, and says it is only 2/3rds the price of the Avery machine. The only point to watch is that when testing springs upside down, two-thirds of the weight of the spring must be added to the mass. Olley is, of course, incredulous that we have no spring rate tester, work on shackle angles is practically impossible. The Management's refusal to let us buy a tester is a great handicap. Their weighbridge apparatus has a convenient chassis sub frame enabling them to pull cars up and down more easily than we can. This is made from channel by welding (We should see that as much as possible of our Millwright's stuff is welded). They do measurements of steering geometry on this rig. Both wheels are moved simultaneously, thus they can differentiate between steering and "toe in". | ||
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).