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).
Visit to Vauxhall Motors regarding their suspension and shock damper mechanisms.
| Identifier | ExFiles\Box 127\4\ scan0147 | |
| Date | 19th June 1939 | |
| 1097 By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale} Da.{Bernard Day - Chassis Design} Hdy.{William Hardy} Ev.{Ivan Evernden - coachwork} Rm{William Robotham - Chief Engineer}/AFM{Anthony F. Martindale}4/R.19.6.39. VISIT TO VAUXHALL MOTORS 16.6.39. ------------------------ The following information relative to suspension mechanism was learned at Vauxhalls. SHOCK DAMPERS. Vauxhalls get incomplete replenishment unless the poundage necessary to open the refill valves does not exceed 2 ozs. We must check our figure on B.V. front dampers. Olley states that viscosity change of the oil only affects the damping load if the leak by the pistons is excessive. They keep the clearance down to .001", and find this satisfactory. The deliberate leak they use is about .0007 to .001 sq. ins., varying with damper capacity. We have instructed leaks up to .0015 for B.V., but have later found .00045 better, probably because of excessive blow by.{R.W. Bailey - Chief Engineer} The Vauxhall shock damper test rig does not give an indicator diagram, although they admit an indicator diagram has certain advantages. They use a torsion bar as a spring and keep the radius of torque constant at 10" by moving the damper relative to the axis of the torsion bar. They keep the strokes per min. constant during a test and vary the length of stroke; thus giving different piston speeds. Olley claims that this has considerable advantages, approximating more to car conditions. Speed of lever arm end (10") varies from 5 to 25 inches per sec. on their rig. Cranking speed appeared to be 35 r.p.m., although spring frequencies are more like 70~/min. An interesting point was learnt about valve squawk, which is troubling us at the moment. They say the noise is due to the valve lifting, and then owing to pressure drop, chattering back on to its seat. They overcame the trouble by having what is in effect a double valve opening. One opening is the actual seal and gives a big orifice area for a small lift: this alone squawks. A second valve, in one piece with the first, is a leaky piston valve, and so arranged that it has to open a long way before it is fully open, this preventing valve chatter. | ||