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).
Switchbox life tests for a 20 HP vehicle.
| Identifier | ExFiles\Box 65\2\ scan0176 | |
| Date | 23th February 1929 | |
| February 23rd, 1929. X5730. A.D. 28. SWITCHBOX LIFE TESTS. A 20 h.p. switchbox has now been tested out for contact life under each of the four arrangements described in report A.D.8. The switchbox was connected up in a standard chassis charging circuit with dynamo running at 1500 R.P.M., switching being performed at about 30 operations per minute by means of a wire attached to a revolving crank. A counter was also attached to record the number of operations before failure. Each test was started with a new set of standard charging contact fingers and switch blade. The armature and field wires were connected according to which was required to break first; the lower contact breaking first in all cases. The results are summarised below :- Cut-out connected to terminal B. (1) Field break first. Failed after 42574 operations. Flash at cut-out points on opening; points burnt. Groove burnt in under-side of contact blade. Lower contact finger (field) burnt. Top side of blade and top finger as new. (2) Armature break first. Failed after 16843 operations. No spark at cut-out on opening. Points not badly burnt. Small groove burnt in under-side of blade. Also slight groove in top side. Top finger (field) slightly burnt; lower one badly. Contd. | ||