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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).
Report with a graph detailing oil consumption tests on various piston ring configurations.

Identifier  ExFiles\Box 132\4\  scan0099
Date  19th October 1937
  
-7-
FIG. IV
Fig. IV again shows the unreliable nature of 4 ring stopped piston.
Curve (1) shows the effect of fitting Wellworthy 'Simplex' type of ring to a standard piston, this ring is very flexible and has a flat wire spring behind it to give it an exceedingly high wall pressure. The ring is also compressed into its groove so that there is no up and down movement.
In parallel with the above tests we also carrying out tests on a Bentley Unit using low viscosity oils and high oil pressure, endeavouring to follow American practice as near as possible of flooding the bores with oil and using high pressure rings to control the oil consumption.

Graph Text:
25/30 OIL CONSUMPTION TESTS.
R.R. SPLIT SKIRT PISTONS
MOTORINE 'C' OIL. PRESS - 26 LB/SQ"
OIL VISCOSITY = 70 SECS. REDWOOD N°I SCALE AT 100°C.
28,000 " " " " " 0°C.
Y-Axis: OIL CONSUMPTION (PTS/HR.)
X-Axis: HRS. RUN

Legend:
CURVE ① WELLWORTHY "SIMPLEX" IN 2ND COMP. RING GROOVE OTHER RINGS STANDARD.
② 4 RING, STOPPED, PISTON.
③ 2ND & 3RD COMPRESSION RINGS 'L' SECTION & STOPPED OTHER RINGS AS ②
④ AS ③ BUT 'L' SECTION RING IN 3RD GROOVE ONLY.
⑤ PLAIN COMP. RINGS AS IN ②
⑥ STD. PISTON (3 RINGS) WITH 'L' SECTION RING IN 2ND COMP. RING. GROOVE, NO STOPS.
MTHS{Reg Matthews} 8.1.37
  
  


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