The slide assembly (fig. 4-47) is suspended between the two trunnion supports. The slide serves as a support structure for the gun mount components that elevate and depress. The main components of the slide are the following:

1. Breech mechanism

2. Recoil/counterrecoil system

3. Recoil/counterrecoil dampers

4. Cold recoil jacks

5. Gun port shield

6. Elevation arc

7. Trunnions

8. Firing cutout mechanism

Figure 4-47.-Slide assembly.

9. Counterrebounding mechanism

Only the recoil/counterrecoil system and cold recoil jacks will be discussed in this chapter. For a detailed description of the MK 75 slide assembly, refer to

Technical Manual for 76-mm 62-Caliber Gun Mount Mark 75 Mods 0 and 1, Description and Operation, SW314-AO-MMM-A1O series.

Recoil/Counterrecoil System

The recoil/counterrecoil system (fig. 4-48) controls movement of the gun during the recoil and counterrecoil strokes. The system consists of two recoil cylinders, connected hydraulically to a recuperator, and performs five functions:

1. Absorbs gun recoil force to ensure prescribed recoil lengths

2. Maintains a nearly constant recoil force throughout the recoil stroke

3. Stores energy to return the gun to battery

4. Regulates the counterrecoil stroke to keep it within the prescribed rate-of-fire limits

5. Brakes recoil and counterrecoil movement at the end of their strokes

The recuperator is a hydropneumatic device having separate chambers for hydraulic fluid and nitrogen.

Figure 4-48.-Recoil/counterrecoil system.

During the recoil stroke, the energy developed by the recoiling gun is absorbed by the recuperator and the recoil cylinders. The energy absorbed by the recuperator is stored as pressure by compressing the nitrogen. The energy absorbed by the recoil cylinders is dissipated by the resistance to the flow of hydraulic fluid through throttling grooves between the stationary and moving parts of the cylinders.

During counterrecoil, the energy, stored in the recuperator as pressure, moves the gun from its maximum recoil position to the gun-at-hooks position. When the gun is released by the gun releasing mechanism, the pressure stored in the recuperator moves the gun to the in-battery position. In this phase of counterrecoil, the recoil cylinders act as stroke regulators and release energy stored by the recuperator at a regulated rate.

Cold Recoil Jacks

Two hydraulic cold recoil jacks (fig. 4-49) are on the forward part of the slide. The recoil jacks are primarily for maintenance work to move the gun in and out of battery. They also move the gun to the hooks position in preparation for firing.

Figure 4-49.-Location of cold recoil jacks.