Fig. 197.-Technical Wiring Diagram Showing Circuits in Gray & Davis Two Unit Starting and One Wire Lighting System.

through wire A to the motor, where it passes through the series field and the armature and from thence through the wire T to the starting switch and from there through the wire C to the negative pole of the battery.

Below 9 or 10 miles an hour or when the motor is at rest the cutout is open and therefore current for the lights must be furnished by the battery, and its path is as follows: It runs out through wire A to one terminal of the starting motor, where it goes to the frame through the ground wire Z. From thence it runs to the lamps. From the lamps the current passes to the junction switch, where all the lamp terminals are connected to the terminal P, and from here the current flows through the series field of the generator and on out through wire F to a terminal on the cutout, and from thence to the ammeter over the short wire E. From the ammeter it goes via wire D to a binding post on the starting switch, from which it connects with the other pole of the battery by wire C. At or over 12 miles per hour the cutout contact points are closed as previously described. Current is then supplied to the storage battery if it needs charging and also to any of the lamps that are in circuit.

If the battery needs recharging it is of course below the voltage of the generator and therefore current will flow to it until its voltage becomes equal to that of the generator, when the flow will automatically stop because the electrical pressure at the two points is the same. The current passes from the positive terminal of the generator through wire G to the series coil of the cutout and from thence through wire Y to the frame. It flows through the frame up through wire Z to one terminal on the motor and from thence through wire A to the plus pole of the battery. The return circuit is through wires C and D to the ammeter and from thence through wires E and F back to the generator. The flow of current from the generator to the lamps is as follows: Through wire G and the series coil of the cutout and wire Y to the frame. This part of the circuit is identical with that for charging the storage battery. Then the current goes through the frame and up through the ground wires to the lamps, from whence it passes to the terminals on the junction switch and on through wire P to the generator. It will

Fig. 198.-Non-Technical Wiring Diagram Showing Arrangement of Parts of Gray & Davis Two Unit, Two Wire Starting and Lighting System, Utilizing Centrifugally Governed Generator.

Fig. 199.-Technical Wiring Diagram Showing Circuits of Gray & Davis Two 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