Another type of drive mechanism used by the Navy is the Sprag overrunning clutch. This type

Figure 10-6.-Dyer drive operation.

of drive is similar to the Dyer drive in that the pinion is engaged by the action of a lever attached to the solenoid plunger. Once engaged, the pinion will stay in mesh with the ring gear on the flywheel until the engine starts or the solenoid switch disengages. To protect the starter armature from excessive speed when the engine starts, the clutch "overruns" or turns faster than the armature, which permits the starter pinion to disengage itself from the ring gear.

The solenoid plunger and shift lever, unlike the Dyer drive, are completely enclosed in a housing to protect them from water, dirt, and other foreign matter. An oil seal, installed between the shaft and lever housing, and a linkage seal, installed around the solenoid plunger, prevent transmission oil from entering the starter frame or solenoid case. The nose housing of the drive mechanism can be rotated so that a number

The General Motors hydrostarter system, as illustrated in figure 10-7, is a complete hydraulic system used for the cranking of internal-combustion engines. The system is automatically recharged by the engine-driven hydraulic pump after each engine start. The starting potential of this system does not deteriorate during long periods of inactivity. Continuous exposure to hot or cold climates also of solenoid positions can be obtained with respect to the mounting flange.