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).
Design modifications for a Roots-type Bensport blower, including rotors and gearing.
| Identifier | ExFiles\Box 140\1\ scan0036 | |
| Date | 27th October 1932 | |
| 8204 To R.{Sir Henry Royce} from E.{Mr Elliott - Chief Engineer} E.6/HP.27.10.32. ----------------- c. Sg.{Arthur F. Sidgreaves - MD} Wer. Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} re Bensport Blower - Roots type. ---------------------------------- In reply to your memo R.3/M24.10.32 concerning the design of blower we showed at WW. during our last visit, we should like to make the following remarks: The scheme, as we remarked at the time, was not fully worked out, and we ourselves did not like the drive as arranged, but nevertheless we still think it will be necessary to include some permanent drive, as well as the spring drive, between the blower and the engine to avoid fracture of the latter when the engine is accelerated on the lower gear ratios, or opened up light. With regard to the rotors altering their shape with centrifugal force, taking into account the smaller radius of our rotors compared with the Allison and debiting for some increase in revolutions together with the much smaller and chubbier proportions of the lobes of the rotor we calculate that we shall be eight times as good as the Allison blower in respect to this point, even if no special provision is made such as a central web in the section of the rotor. The form used by David Brown has a central hole, but this could be modified. We propose to make the rotors in steel which, in conjunction with an aluminium casing should give slight increase in clearance with increased output. The D.B. rotors are also made of steel. With regard to the gearing, we feel that if it is necessary to use straight gears this will wash the blower out as the noise could not be tolerated. We had considered the use of double helical, but rejected them as we thought they would not be sufficiently silent, being equivalent to single helical of reduced width. For this reason we did mean to use single helical gears of the same width as our timing gears. We since find that the David Brown design has very wide single helical gears of about 30° tooth angle. E.{Mr Elliott - Chief Engineer} | ||