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).
Failure tests conducted on Bentley fans to ascertain the cause of failures on customer cars.
| Identifier | ExFiles\Box 86\5\ scan0046 | |
| Date | 29th May 1935 | |
| To E.{Mr Elliott - Chief Engineer} c. to Hy.{Tom Haldenby - Plant Engineer} c. to Elt. c. to Hx. c. to RHC.{R. H. Coverley - Production Engineer} Report on Bentley Fan Failure Tests. These tests were made with a view to ascertaining the cause of the failures of Bentley fans which have taken place on customers' cars. In these cases the failure has resulted in so much destruction that it was impossible to decide which part had failed first, only one fan returned to the Repair Department having its blades intact. Calculations indicate that the fan blades, rivets and fan flange are not overstressed. The fan spindle, however, can be quite highly stressed by over-tightening of the belt. These remarks apply to a balanced fan. The one fan whose blades were undamaged was checked for balance and found to be 2.0 oz.ins. out of balance. Tests carried out :- (1) Tensile load at which the fan blade left the flange was determined by means of the tensile testing machine in the material testing Laboratory. Two opposite blades of a completed fan blade assembly were gripped and pulled until failure took place. This occurred at approximately 2 tons load, with each pair of blades, the inner two rivets elongating their holes and the outer ones shearing. This load is approximately four times the calculated centrifugal load at maximum engine revs. (2) A new standard Bentley fan assembly was run at a speed corresponding to 5,000 engine r.p.m. for 10 hours. No failure took place. (3) A new Bentley standard fan assembly was run for 30 minutes at various speeds up to 6,400 r.p.m. (neglecting slip) = 7,100 engine r.p.m. No breakage took place. | ||