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).
Rig tests comparing the performance and stretch of 1/2 inch and 7/8 inch drive belts.
| Identifier | ExFiles\Box 55\2\ Scan012 | |
| Date | 7th January 1913 | |
| The 1/2" belt is not a satisfactory drive because it has to be kept so tight to get the max: output from the dynamo and if the max output is not obtained one is soon in trouble with the lights. With the 7/8" belt it is possible to run & get the max output with a comparative slack belt. The stretch in the belts after they have been run on the rig is mostly due to the holes in the leather links elongating by the wear, this is not so great if the belt is oiled. sample herewith. Summary of Rig tests. Weight on lever. Stretch. Remarks after 24 hrs. After 48 Hrs. 16 lbs. .531" .656" 20 " .562" .625" 24 " .687" .875" stretched to 1.25" after 140 hrs. 32 " 1.25" 2.0" broke after 86 hrs. 48 " 2.0" 2.75" " " 56 " EA 7/1/13 | ||