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).
Issues of the Wraith fan fouling radiator bracing stays and proposed modifications.
| Identifier | ExFiles\Box 135\1\ scan0270 | |
| Date | 20th December 1938 | |
| 1135 also 624 To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Std. c. Hs.{Lord Ernest Hives - Chair} c. Da.{Bernard Day - Chassis Design} c. RHC.{R. H. Coverley - Production Engineer} c. LA.{L. A. Archer} WRAITH FAN FOULING RADIATOR BRACING STAYS. Two cases have now occurred of the fan blades touching the cross bracing of the radiator, causing noise and damage to the fan blade. In each case the cause is suspected to be due to engine movement caused by deceleration and is due to the small clearance between the fan leading edges and the radiator cross bracing, being also aggravated by any distortion of the fan blades. The drawings cater for .475 clearance at the nearest point and our experimental cars (including Hs{Lord Ernest Hives - Chair}' car and Sg{Arthur F. Sidgreaves - MD}'s car) have approx. .500" clearance at this point - from an idling cooling point of view it is important to keep the fan as close to the radiator as practicable. However, most of the production chassis have only a clearance of .200-.250 at this point and although we asked RHC.{R. H. Coverley - Production Engineer} to let us know the reason for this in Rm{William Robotham - Chief Engineer}/Std.5/WH.15.11.38, we have not had a reply - we presume therefore, that with the limits which the works find practicable it is not possible to work to .250" at this point. We think, therefore, that the nominal clearance of .475 should be increased to .725 at least by moving the fan blades back or modifying cross bracing of radiator or both. This should be done on both future cars and chassis already built. In the case of future cars ample clearance should be obtained by modifying the cross bracing and if necessary shortening the fan hub and spindle. In the case of chassis already built, because of cost considerations, it should be done by machining .250 off the face of the hub flange, fitting a special hub front cover with a flange .250 thicker than standard and revising bolts which secure the flange to the hub. Alternatively if cheaper, a new shortened spindle and distance piece could be used in place of the special hub front cover. | ||