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).
Wear, noise, and required clearances in the tappet mechanism.
| Identifier | ExFiles\Box 35\3\ scan 016 | |
| Date | 6th August 1920 | |
| BY.{R.W. Bailey - Chief Engineer} from EP.{G. Eric Platford - Chief Quality Engineer} c. to Wr. c. to Sft.{Mr Swift} c. to Hs.{Lord Ernest Hives - Chair} g.F.C. X.2764 EP{G. Eric Platford - Chief Quality Engineer}29/F6.8.20. RE. WEAR ON TAPPET MECHANISM. X.2764 With reference to my recent complaint on the above, EP{G. Eric Platford - Chief Quality Engineer}23/F20.7.20, I notice you have instructed that .020" clearance shall be allowed between the fixing and tappet lever and flat on the pin, U.385. I am anxious to bring forward the point that as far as the running of engines is concerned, the absence of movement of this pin and the general absence of slack in these parts does make a manifest difference in the running of the engine as regards quietness. I have been able to demonstrate that tappet mechanism which is distinctly noisy has, when being dismantled, been found to have less than .020" slack between the faces as above described, and when replacing these rocker arms with other rocker arms which do not have slack in this respect, we find that the quietness is then quite satisfactory. I must therefore appeal that the clearance should be reduced, as being necessary in order to obtain satisfactory engines. I should be glad if you will further consider and give further instructions on this matter, letting me have a copy of same so that I can see that they are carried out accordingly. I am returning to you the rocker arm roller pin returned to us from America, under cover of Mr. Caswell's memo. EWC2/AM22.7.20, reading as follows:- "Further to my memo. ref.EWC2/AM19.7.20, I am sending you under separate cover one pin, piece No.U.385, which was removed from the valve tappet lever of the above chassis after 1700 miles' running. This is the car that was formerly owned by Col. Vincent of the Packard Co. Although these pins are quite hard they show considerable wear which may have been caused by running short of oil or being too tightly fitted in the first place which would prevent the parts receiving oil. They also show signs of having been loose in the tappet lever". EP.{G. Eric Platford - Chief Quality Engineer} | ||