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).
Instructions for checking piston clearances and performing easing to prevent engine seizing.
| Identifier | ExFiles\Box 35\2\ scan 145 | |
| Date | 8th October 1919 guessed | |
| -2- so that there is a gradual blending of the present clearance to the present diameter. This easing should not extend any more than about 2" either way from the centre of the gudgeon pin. No easing should take place around the bottom skirt. Easing should be done very carefully, and should be checked by testing the piston in the cylinder, as above described. We have found that the tendency for seizing up generally takes place on the points where we are now recommending slightly further easing. No easing should at any time be made on the piston skirt, in the range at right-angles to the gudgeon pin. 3) The clearance of the [handwritten: piston] gudgeon pin in its [handwritten: at right-angles] respective cylinder should be checked by feeler gauges. [handwritten in margin: to gudgeon pin.] Measurement should be made for clearance at the top of the skirt and the bottom of the skirt. X The top of the skirt can be measured by inserting the piston in the cylinder upside down, the piston being fixed in position to the top part of the skirt, just inside the mouth. The clearance should then be checked by a feeler, and a .009" feeler should enter tightly or not at all, but a .008" feeler should enter freely. Similar measurements should be made on the bottom part of the skirt, the piston then being fixed with the head to the top, so that the base of the skirt is flush with the mouth of the cylinder. Feeler measurements should then again be made, and a .007" feeler should not enter, but a .006" feeler should enter freely. A rough check should also be made around the piston so that in case of slight distortion, a mean average is obtained. I am recommending the above, as I am anxious to avoid the present colossal amount of work which we are having to undertake, of continually dismantling and refitting pistons Contd. [Footer:] N R 111 C.R.H. 1324. A.C.D.(T)497(T/F)193 | ||