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rig. 199. — Technical Wiring Diagram Showing Circuits of Gray & Davis
Tiro Unit, Two Wire Starting and Lighting System.
be noted that the generator and battery circuits to the lamps are independent, so that should anything happen to the battery,
the lights could be operated by the generator alone.
Diagrams of Gray & Davis 1915 systems will be found on diagrams, Figs. 196 to 199 inclusive, in both non-technical and technical form. A number of parts comprising the 1915 Gray & Davis starting system is shown at Figs 200 and 201. The construction of the type Y motor used in connection with engines of the open flywheel type is clearly shown in the part sectional view at the top of the illustration. As the Gray & Davis systems may be had in either the one wire or two wire type, two forms of switch are provided. One of these, which is shown at B, Fig. 200, is used in a two wire system and has both terminals insulated. This must be wired up as shown at E. The heavy leads from the storage battery are connected as indicated. One of the storage battery terminals is connected to the terminal on the starting motor, while the other starting motor terminal wire goes to one of the insulated switch terminals. The other insulated switch terminal is connected directly to the remaining storage battery terminal. When used in connection with the one wire system the starting switch has one terminal grounded, as shown at C.
The approved arrangement of the starting switch is as depicted at the top of the illustration, in which the contact is not established until the sliding pinion has been meshed with the gear of the flywheel. The construction of the overrunning clutch used with the Gray & Davis system is shown at D. This functions the same as the overrunning clutch previously described, the drive being secured between the member 4, which is keyed to the intermediate shaft, and the reduction gear 2, which is turned by the motor pinion 1 through the medium of the clutch rolls 3. Light coil springs are employed to push plungers, designed to make more positive the engagement of the rolls of the overrunning clutch.
The fuse block, which is an important adjunct of the one wire system, is combined at the rear of the lighting switch, as shown at A, Fig. 201. The function of the fuse is to burn out should an overload occur in any circuit due to damaged insulation. The fuses are readily renewable, these being shown at D. The fuse con
sists of a glass tube, which contains a piece of fusible alloy wire that joins two metal caps, these caps being used to establish contact with the clips on the sides of the connectors at the back of the switch. The fuses should be handled carefully, and in removing same for examination it is well to do this with a sharp piece of
wood, which is used as a pry back of the fuse instead of attempting to remove them with pliers or a screwdriver, which may break the glass or otherwise damage the fuse. An important adjunct to assist in locating trouble is a six volt lamp, such as shown at C. This is of material assistance in tracing circuits.
The latest form of Gray & Davis dynamo, which dispenses with