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).
Engineering drawing for a Specialloid R88 piston for a 6-cylinder Bentley engine.
| Identifier | ExFiles\Box 148\4\ scan0301 | |
| Date | 26th September 1934 | |
| SPECIALLOID PISTON R88 ROLLS-BENTLEY 6CYL ROLLS-ROYCE LTD ALL RING GROOVE WIDTH LIMITS ±.001/.002 82.55/3¼ DIA SEE LAND TABLE 75.75 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 FOR BALANCING WT TOLERANCE ±2 DRAMS PATTERN PURPOSES CROSSHOLE DIA .17 2 - 1/8 DIA HOLES DRILLED THRO BOTTOMS OF BOSSES 38 CIRCLIPS B178A M.L.&P.P SPECIALLOID Y ALLOY HEAT TREATED TABLES: CLEARANCES - DEDUCT FROM CYLINDER BORE LANDS | AXIS T.T. | AXIS P.P. A | .40 | .53 B | .30 | .43 E | .23 | .36 LIMIT ON DIA ±.012 D (.0005") | .13 TAPERED TO .26 D1 (.0055") | .09 TAPERED TO .22 OVALITY OF PISTON .13 RINGS RING | TYPE | WIDTH | DEPTH 1ST | PLAIN | 3/32 | .108/.116 2ND | " | " | " 3RD | " | " | " 4TH | RAD. SLOTTED | 3/16 | " CIRCLIPS 204 AX 1 C DIES BODY | TOP RING, BOT. RING, TOP, BOTTOM CROSSHOLE | BRUSH CORE BOX | R88 SEE STD. CHARTS FOR LIMITS ON MACHINED DIMENSIONS UNLESS OTHERWISE STATED ALTERATIONS STAMP: SPECIALLOID LTD. DRAWING OFFICE 26 SEP. 1934 BOTTOM LEFT BLOCK: SPECIALLOID PISTON BRITISH PATENTS | REG. DESIGNS No. 227641 | No. 364787 | No. 685933 No. 399801 | No. 2739/32 | No. 775780 DRAWN: 26/9/34 | TRACED | CHECKED | APPROVED | ||