Now that we have seen the basic components of a hydraulic system, let's take a look at a hydraulic mechanism. Up to now, we have pumped the hydraulic fluid from the reservoir through the filter and have it regulated to the desired pressure. Now, let's have it do some work.

Glance back to figure 4-8. This is the illustration of the 5"/54 carrier ejector mechanism we used as an example of a mechanical ordnance device. The

Figure 4-23.-Solenoid housing and valve block.

linkages in the ejector are operated by hydraulic pistons. The pistons extend and retract to operate the ejector. The fluid that moves the pistons is controlled electrically by solenoids. Figure 4-23 shows the inside of a solenoid housing and valve block.

Notice that there are two solenoids attached to the same linkage at opposite ends. The linkage has a pivot point in the middle. The pivot is actually a shaft that extends through the solenoid housing into a hydraulic valve block. The linkage is keyed to the shaft so that when one of the solenoids is energized and moves the lever, the shaft will rotate. Inside the valve block (fig. 4-23), the shaft is attached to a valve. As the shaft is rotated, it positions the valve. One position allows fluid to be ported to one side of the piston, extending it. The other position ports fluid to the other side of the piston, retracting it. When fluid is ported to either side, the other side is opened to allow the trapped fluid to return to the tank. A newer configuration of this same device has the solenoids and valve all in one component. It is used on the newer Mk 45 gun mount. This configuration is also discussed in chapter 5.

For more information on hydraulic systems operation, see the Navy training manual Fluid Power, NAVEDTRA 12964, and system maintenance publications.

THE HYDRAULIC-MECHANICAL OPERATION OF A LAUNCHER COMPONENT

LEARNING OBJECTIVES: Identify the major hydraulic-mechanical components used in GMLS and describe the operational function of each component.

Now that we have covered a typical accumulator type of power drive, the next logical step is to see what its PA can do for a GMLS. In the next chapter we will examine its electrical interlock control circuits. The final object for the various extend and retract signal paths was to energize a solenoid. The solenoid initiated the hydraulic-mechanical actions that actually moved the center guide.

We will first discuss the hydraulic components associated with the center guide. We will then extend the unit from its normally stowed position. As we describe these hydraulic-mechanical operations, you may find it helpful to compare the two hydraulic schematics in figure 4-24

Figure 4-24.-Center guide extend; hydraulic schematic.

(extend cycle) and figure 4-25 (retract cycle).