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).
Testing the stretching of 1/2 inch dynamo belts before use.
| Identifier | ExFiles\Box 3\1\ 01-page060 | |
| Date | 4th February 1913 | |
| TBB2/L4213 February 4th 1913. For Wormald. Mr Johnson for Mr Royce Re Stretching 1/2" Dynamo Belts before use. Some time ago Mr Royce suggested that since we proposed to use 1/2" dynamo belts until series 2500, we should run these belts on a rig under tension to take out the stretch. In order to save the design and manufacture of a special rig I utilised the fan belt testing rig which was then in course of construction. A number of belts were tested under different tensions and for various periods of time, with the following result:- Weight on end of lever. | Stretch of belt after 24 hours run. | Stretch of belt after 48 hrs run | Remarks. 16 lbs. | .531" | .656" | 20 " | .562" | .825" | 24 " | .687" | .875" | 32 " | 1.25" | 2.0 | Extended to 1.25 after 140 hours. Broke after 86 hours 48 " | 2.0" | 2.75" | Broke after 56 hours. All of these belts were soaked in engine oil prior to running on the rig. The stretch in the belts which | ||