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).
Tank engine clutch specifications and recommendations from Ferodo and Borg & Beck.
| Identifier | ExFiles\Box 130\3\ scan0137 | |
| Date | 2nd December 1940 | |
| SECRET. 1110 To Ba. From Rm{William Robotham - Chief Engineer}/GB. Copy to Ev.{Ivan Evernden - coachwork} Rm{William Robotham - Chief Engineer}/GB.6/IT.2.12.40. TANK ENGINE CLUTCH In connection with this, visits have been made to Ferodo and Borg & Beck. Reports on these visits follow. FERODO Ltd. For the unblown Merlin engine having a torque of 1203 (110 M.E.P.) Messrs Shelton & Longley recommended a twin disc clutch using 400 m.{Mr Moon / Mr Moore} x 160 (15.75" x 6.3) liners in R.A.D.11. London busses (A.E.C.) use a single disc of this size. Ferodo are not worried about high pressures, but recommend that the work absorbed by each square inch of liner should not exceed 6000 to 7000 lb. ft./min:t. When this value rises above 16,500, liner wear will increase rather fast. Double this figure will result in very rapid wear. They assume that half the power developed by the engine is dissipated by the clutch when starting. The maximum torque on our engine should be developed at 1000 to 1200 r.p.m. Therefore the power dissipated by the clutch will be 1100 x 2π x 1203 / 2 = 4,160,000 ft./min:te. The lb. ft./min./sq. in. of liner which would be dissipated in a clutch of the size recommended by Ferodo and by the various sizes of Borg & Beck clutches is given below. TABLE DATA: Clutch size: 14" twin Area of fabric: 403 sq.ins. lb.ft./min./sq.in.: 10,300 NOTES: Not recommended: Could not be made for: 3 months: Clutch size: 16" twin Area of fabric: 490 sq.ins. lb.ft./min./sq.in.: 8,480 NOTES: Recommended by Borg & Beck Clutch size: 18" twin Area of fabric: 580 sq.ins. lb.ft./min./sq.in.: 7,170 NOTES: Recommended by Borg & Beck Clutch size: 18" single Area of fabric: 290 sq.ins. lb.ft./min./sq.in.: 14,340 NOTES: Used on: 25 ton: Vauxhall: tank 340: lb. ft.: torque. Clutch size: 15.75 x 6.3 twin Area of fabric: 654 lb.ft./min./sq.in.: 6,360 NOTES: Recommended by Ferodo. | ||