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).
Specification of inspection and test for the R.R. Goshawk Dynamo.
| Identifier | ExFiles\Box 51\1\ Scan182 | |
| Date | 20th July 1923 | |
| X.3604do. R.R. GOSHAWK DYNAMO X.4383. SPECIFICATION OF INSPECTION AND TEST. (1) Inspect the brush mechanism and make sure that all brushes have the necessary freedom without being slack, and that the spring pressures are suitable. Also inspect that the lower edge of the brush holder (near the commutator) and the lower edge of the terminal plate, which is a projection of the brush holder plate, are at the same distance of about 1/16" from the surface of the commutator. Also that the flat faces of the brush holder are parallel to the mica insulations of the commutator. Further, inspect that the brush springs are clear of the sides of the slots of the brush holders, so that the full tensions of the springs are exerted on their respective brushes. Test the springs for cracks by forcing these back as far as possible, when they should not become cracked. Also make sure that neither the insulation or the connection of the pig-tail conductors are in any way damaged. Note:- (1) It is possible that a spring which is noticeably weak is cracked and requires replacing. Note:- (2) It will usually be found that a spring which is good, has a uniformly expanding spiral. (2) The insulation resistance of the machine should be taken and should not be less than 1 megohm. (3) The dynamo in a cold condition but not lower in temperature than 18°C shall be driven at a speed of 600 R.P.M. when the open circuit voltage shall exceed 12.4 Note:- Before taking this reading, the dynamo should momentarily be speeded up so as to reach an open circuit voltage of about double the voltage at which it operates normally. | ||