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).
Installation and adjustment notes for a U.S.A. Auto Switch.
| Identifier | ExFiles\Box 59\1\ Scan321 | |
| Date | 30th April 1928 | |
| U.S.A. AUTO SWITCH. Notes re installation and adjustment. Fix on a vertical support with contact points downward. The switch may be used as a three or four terminal device. As a four-terminal unit the bottom R.H. terminal is connected to the dynamo armature. As a three terminal unit it is connected to the top R.H. terminal which in either case is connected to the dynamo field supply. The top L.H. terminal goes to the dynamo field and the bottom L.H. terminal to frame. Fine adjustments of the opening voltage may be made by screwing the fixed point in or out and locking. The re-closing voltage may be set by means of the armature travel stop adjustment. These two adjustments are independent of one another. For large alterations of the opening voltage, the spring screw should be adjusted with the fixed point so as to keep the armature near to the spring adjusting screw in the on-contact position. This will secure maximum armature travel for given voltage limits between opening and closing. Adjusting the spring screw and the fixed point together, in effect varies the distance of the armature from the poles without altering the spring pressure. The re-closing voltage however will need re-adjusting afterward. The switch has been set on the bench as follows :- Cold. Points open 8.3 volts, close 6.0 volts. Hot. " " 8.5 " , " 6.1 " Hot condition attained by running at 8.5 volts continuously (Voltages measured at distribution board). This setting is estimated to be about correct for operation on the car. The field resistance has a value of 5.16 ohms. Shunt circuit resistances :- Copper 1.45. Eureka 4.47. Total 5.92 ohms. | ||