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).
The inspection of an S.B.V. engine unit after a 15,000-mile test, detailing the performance of the crankshaft and main bearings.
| Identifier | ExFiles\Box 97\4\ scan0250 | |
| Date | 7th December 1938 | |
| To Ry. from Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} c. Hs.{Lord Ernest Hives - Chair} c. Da.{Bernard Day - Chassis Design} c. RHC.{R. H. Coverley - Production Engineer} c. Ex. Hoob. S.B.V. ENGINE UNIT. 15,000 MILES. Based on the inspection of the above unit after its 15,000 miles test, we give herewith our report on the special parts which were incorporated. Most of the cheapened parts were run with a view to incorporating on B.60 if satisfactory, however, there are certain parts which we consider should be standardised for Wraith III and included on Bentley V.{VIENNA} CRANKSHAFT. The .4 carbon crankshaft which was hardened up to give a Brinell of 321 has performed very satisfactorily, the maximum wear figures being .001 on the journals and .0005 on the crankpins. Considering the running which includes 20 hours endurance on the test bed and 18,000 miles on French test, the above wear figures are very good; a soft shaft, however, can only be used where whitemetal main bearings are employed. Although these wear figures are in excess of that of a VCM shaft with whitemetal main bearings they are appreciably less than a VCM shaft (640 Brinell) with AC (Hall's alloy) main bearings, which combination is standard Bentley II practice. From these results combined with the fact that the material cost of the .4 carbon shaft is £2 less than the VCM shaft, we should certainly introduce it on the cheaper engine in the event of whitemetal main bearings being used. Actually, with more experience we consider it could be introduced on Wraith. MAIN BEARINGS. These were of strip type of Vandervell bearings, whitemetal lined, which fit straight into the crankcase without any reaming or fitting etc., actually as the makers deliver. From this point of view, and for service replacements, they are excellent, and from the sets we have had we can vouch for their accuracy. Each bearing gave a dead .002 clearance on the crankshaft and with their cost of 15/- per set as compared with our own standard of 45/- per set, represents an attractive proposition. | ||