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).
17,000-mile test report on a B.56 BN. Bentley engine, detailing performance and issues.
| Identifier | ExFiles\Box 83\4\ scan0223 | |
| Date | 27th May 1936 | |
| X 264a Hs{Lord Ernest Hives - Chair}/GWH{George W. Hancock - Head Chateauroux}/I/JAB. 27.5.36 GRY{Shadwell Grylls} WMN F.T.H. CP. Smith (Handwritten, crossed out) SWDL{Len H. Swindell} MARTINDALE RADCLIFFE (Handwritten) To. Mr. Sx. from Hs{Lord Ernest Hives - Chair}/HWH. (Sx. and Hs{Lord Ernest Hives - Chair}/HWH. are crossed out) c to. Mr. (crossed out) cbto. Mr. c to. Mr. Py (crossed out) c to. Mr. De. (crossed out) c to. Mr. Pr (crossed out) c to. Mr. Hx. (crossed out) c to. Mr. Dx. (crossed out) c to. HHC (crossed out) c to. Hs.{Lord Ernest Hives - Chair} SPECIFICATION OF B.56. BN.{W.O. Bentley / Mr Barrington} BENTLEY. STF (Stamped) To. RHC{R. H. Coverley - Production Engineer}/CP. from 18.2.36 to 3.4.36 17,000 MILES TEST REPORT IN ENGLAND & FRANCE ENGINE UNIT B.20. With the high axle ratio fitted, the maximum speed obtained was 92 MPH. A standard axle ratio was fitted before proceeding to France. 4,500 revs were easily reached. Acceleration good up to 4,000 revs. The engine became rough & thumped after 6000 miles and has become gradually worse. Swell. (Handwritten in margin) At 11,800 miles it was decided to examine the bearings. The connecting rods showed no sign of cracks but bedding was poor. The main crankshaft bearings were in a poor condition. They had become grooved, the crankshaft in a similar condition. An oil pressure test showed excessive leak of oil from these bearings. After refitting, N° 5 Connecting rod bearing suddenly broke up after a 50 mile run. The only indication that could be observed after dismantling, was a slight amount of metal on the crank pin, which indicated a seizure. This seizure is caused by insufficient oil to the connecting rods due to the escape of oil via the main bearings. New rods have since been fitted but we are not happy with the state of the main bearings. With a large escape of oil from crankshaft bearings, there is a definate starvation of the rocker shaft supply, as well as timing gears. Oil temperatures have been high; a maximum of 134°c was reached during the day's run of April the 12th. 120°c has been frequently reached. The water loss has been negligable. ENGINE MOUNTING. WYMAN. (Handwritten in margin) We found that the front centre mounting had more than standard end clearance, the bearing having worn. This locates the engine. The increased clearance causes a knock & is a source of clutch jaggers. This was washered up & reduced to .005" clearance. VALVES & FITTINGS. LOP EB.2708. The valves have been on the noisy side during the whole of the mileage. There has not been any serious loss of clearance, .003" maximum. The seatings of the valves were not in a bad condition when examined. | ||