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).
Engine testing, detailing issues with oil feed, valve operation at high RPM, and cam/gear noise.
| Identifier | ExFiles\Box 123\3\ scan0101 | |
| Date | 17th January 1934 | |
| -2- Hs{Lord Ernest Hives - Chair}/Swd1.1/KW17.1.34. The oil feed arrangement, at least with very good fitting plungers, does not appear ideal, as the oil has to force its way past this fit in order to reach the oil reservoir above the plunger. As each individual plunger clearance in its housing varies, so does the oil supply; likewise varying height from the oil hole to the top of the plunger would cause the same trouble. Whilst carrying out the power curve on this unit we were going from 3250 r.p.m. to 3500 r.p.m. when the engine started to lose power. On slowing down it was found that almost all the valves were open. By holding down the ball valve and sending the plunger to the bottom of its stroke and then tapping the eccentric down to follow the plunger, the valves were closed. It was only necessary to tap the eccentrics whilst loaded by the valve springs, for when not loaded these were perfectly free. This trouble was repeated several times and became noticeable at 3250 r.p.m. on several valves. Valve bounce would produce this but it is unlikely at 3250 r.p.m., as the valves are fitted with double springs which on a Phantom head puts the valve bounce speed to above 3500 r.p.m. and other than this the trouble is experienced on exhaust valves as well as inlet valves. This trouble goes to point that the leakage factor is so small that the auto adjustment only copes for increasing tappet clearances as the oil does not squeeze past the plunger quickly enough when the engine is slowed down to enable the valves to seat. Large Capacity Oil Pump. This pump is 25% larger capacity than the standard Phantom pump, and obtained by the use of longer gear teeth. With this pump the oil pressure is considerably higher than standard at the high speeds and with an oil temperature of 70°C. inlet the pressure is 50-60 lbs/sq.in. at 3000 r.p.m. In order to correct this it means tests being carried out on the restrictions offered by the relief valve and spring strengths on the ball valves. Balancing Cam & Gear Noise. After having the gears quietened for whine, they are almost perfect when on dynamo charge throughout the speed range. "Off" charge there is a bad rattle from the dynamo pinion which can be cured completely by slacking off the nuts on the fabric coupling. The rattle occurs above 750 r.p.m. and though the backlash between the dynamo pinion and the cam wheel is not excessive, we are convinced Cont'd.{John DeLooze - Company Secretary} | ||