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).
Dynamo testing and running-in procedures, including brush bedding and performance checks.
| Identifier | ExFiles\Box 168a\3\ img097 | |
| Date | 23th May 1938 guessed | |
| 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. (e) The connections of the pigtail conductors are not in any way damaged. (f) The bedding of the brushes is such that the surface shows signs of making contact, right across its thickness for at least 80% of its width. (2) The insulation resistance of the machine should be taken and should not be less than 1 megohm. N.B. For the running tests it will be necessary to insert a variable resistance in the field circuit of the dynamo. This should be connected between the field terminal and the negative (earthed) brush. A second variable (carbon) resistance is used in the main circuit with which to adjust the terminal volts. (3) The machine complete shall then be placed in an oven, which should be maintained at a temperature of 150°C. In this it must remain for a period of 30 minutes. (4) The machine shall now be removed from the oven, and immediately placed on a rig prepared for running. With the end-cover removed and the field resistance short circuited, it shall be run on load for one hour, at an output of 20.0 amperes at 13.0 volts. During this run the commutator should be frequently wiped if necessary, to ensure that it is free from a grease or varnish deposit. Notice should also be taken of the brushes in respect of noise. Any undue noise should be investigated and rectified, if necessary re-skimming the commutator. This run should render the brush-bedding finally satisfactory, and allow time for the temperature of the machine to settle down. (5) Immediately after the termination of the above run, the speed and voltage shall be carefully adjusted until the output of the machine is 20.0 + .2 amperes at 13.0 volts when the speed should be measured. This should not exceed 1440 r.p.m. (6) With the dynamo still in the same hot conditions it should be verified that running on open circuit it shows a voltage of 13.0 at not more than 940 r.p.m. | ||