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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).
Technical drawing of a Specialloid Y Alloy piston for a 6-cylinder engine.

Identifier  ExFiles\Box 148\4\  scan0308
Date  26th September 1941
  
SPECIALLOID PISTON R88
ROLLS-BENTLEY 6 CYL. DRG No EB.025
ROLLS-ROYCE LTD
SPECIALLOID Y ALLOY HEAT TREATED
ALL RING GROOVE WIDTH LIMITS ± .002
.8255 (3 1/4) DIA SEE LAND TABLE
.7575 DIA ± .10
68.5 DIA
1/8 FILLETS ON HEAD & SIDE OF WEBS FROM JOINT UP TO HEAD
REMOVE SHARP EDGES
12 - 5/32 DIA HOLES X SPACED AS SHOWN IN PLAN VIEW
6 - 1/8 DIA HOLES Y SPACED AS SHOWN IN PLAN VIEW
WEBS TAPERED 3 TO 1 1/2
* FOR OVERSIZE PISTONS THESE DIAS TO BE INCREASED CORRESPONDINGLY
* 82.00 DIA AXIS TT, 81.87 DIA AXIS PP
FOR BALANCING WT TOLERANCE ± 2 DRAMS
2 - 1/8 DIA HOLES DRILLED THRO BOTTOMS OF BOSSES
PIN TO BE ROUND & PARALLEL WITHIN .0001" ENDS TO BE SQUARE.
BORE TO BE SMOOTH & FREE FROM SCALE OR FOREIGN MATTER TO BE DRILLED & REAMED AFTER CARBURISING.
MATERIAL 3S15 (3% NICKEL) CASEHARDENED DEPTH OF CASE .020"
CLEARANCES TABLE:
DEDUCT FROM CYLINDER BORE
LANDS | AXIS T.T. | AXIS P.P.
A | .40 | .53
B | .30 | .43
E | .23 | .36
LMT ON DIA D | ± .012 | ± .012
TAPERED TO D1 | .13 | .26
LIMIT ON DIA D1 | .09 | .22
OVALITY OF PISTON .13
13. M.M. = 5.2 THOUS
.09 M.M. = 3.6 THOUS
RINGS TABLE:
| TYPE | WIDTH | DEPTH
1ST | PLAIN | 3/32 | 108/116
2ND | " | " | "
3RD | " | " | "
4TH | RAD. SLOTTED | 3/16
CIRCLIPS 204 AX 1c
DIES TABLE:
BODY | C 253 M.{Mr Moon / Mr Moore}
TOP RING
BOT. RING
TOP | C 28
BOTTOM | C
CROSSHOLE BRUSH | C124
CORE BOX | R88
CYL BORE +.001/-.000
SEE STD. CHARTS FOR LIMITS ON MACHINED DIMENSIONS UNLESS OTHERWISE STATED
ALTERATIONS
SPECIALLOID PISTON (bottom left)
BRITISH PATENTS: No. 227641, No. 364787, No. 399801, No. 2739/32
REG. DESIGNS: No. 685933, No. 775780
STAMP: SPECIALLOID LTD. * 10 OCT 1984 * DRAWING OFFICE
DRAWN 26/9/41
CHECKED 26-9-39
APPROVED
  
  


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