Electrical cabling and barrel cooling piping extending into the gun mount are routed through the slip ring assembly. The slip ring assembly, through the use of rotating electrical contacts and a rotary pipe joint, allows unlimited training of the gun mount.

SLIP RING ASSEMBLY

The slip ring assembly (fig, 5-48) provides continuous electrical connections between the cabling of the stationary structure of the gun mount and the cabling of the training mass. The slip ring assembly also contains a rotary joint for the barrel cooling system piping.

The slip ring assembly extends up the center of the gun mount. The lower end of the slip ring assembly contains plug-in connectors for the cabling on the stationary structure. The lower end of the slip ring assembly is prevented from rotating by guides mounted to the deck which engage a retaining lug on the slip ring.

The shaft and upper end of the slip ring assembly rotate with the gun mount in train. The upper end contains plug-in connectors for the electrical cables on the rotating structure. When the gun mount moves in train, the upper end and the shaft of the slip ring rotates

Figure 5-48.-SIip ring assembly.

on bearings mounted on top of the lower end of the assembly.

Brushes inside the shaft of the slip ring assembly rotate around stationary ring-shaped conductors as the gun mount moves in train. The ring-shaped conductors maintain continuous electrical contact with the brushes as the gun mount trains. Each wire going into or out of the slip ring has its own ring and brush assembly.

AUXILIARY SYSTEMS

The three electrical auxiliary systems of the Mk 75 gun mount are the ventilation system, the lighting system, and the telephone system.

Ventilation System

Ventilation in the ammunition handling room is provided by the ships ventilation system. Ventilation inside the gunhouse is provided by an exhaust fan mounted in the weather shield above the entry hatch (fig. 5-49). The fan motor operates on 115 VAC 60 Hz power. The fan is controlled by the mount exhaust fan on switch 2S4. Switch 2S4 is located on the outside of the lower feed system support next to the train-securing pin-operating handle,

Figure 5-49.-Exhaust fan (inside view).

WARNING

Fumes resulting from gun firing contain hydrogen, carbon monoxide, and other toxic gases which are potential health hazards. The proper operation of the gun mount ventilation system is imperative when firing the gun.

Lighting System

Illumination inside the gunhouse is provided by two fluorescent light fixtures (fig. 5-50) mounted on the inside of the weather shield. One fixture is on the left side of the gun mount; the other is on the right side. Each light fixture contains three fluorescent tubes. The two outer tubes are connected to the white light supply of the ship. The center tube has a red sheath over it and is connected via the GCP to the red light supply of the ship. The red lights are on at all times. The white lights are on when the white light supply of the ship is on and when two interlock switches are actuated. Circuit protection for the gunhouse lighting system is provided by circuit breaker CB4 in the bottom compartment of the GCP.

One of the interlock switches, the mount hatch closed switch 4S 1, is a manually actuated switch located inside the entry hatch. In normal operation, however, switch 4S 1 is actuated when the entry hatch is closed. The other interlock switch, mount white lights, on switch 4S2, is a manually actuated switch located inside the weather shield on the right side

Figure 5-50.-Light fixture.

of the entry hatch. When both switches are actuated and ships power is on, all lights (white and red) are turned on.

In addition to the light fixtures, the gun mount has a 115 VAC convenience outlet located on the base of the right trunnion support. This outlet provides power for use inside the gunhouse. Circuit protection for the convenience outlet is provided by circuit breaker CB3 in the bottom compartment of the GCP.

NOTE

The convenience outlet provides only a limited amount of current. Equipment requiring more than 3 amps should NOT be connected to this outlet.

Telephone System

Shielded cable for two telephone lines is provided from the GCP to the gunhouse for use with sound-powered telephones. The telephone connector jacks are located on the right side of the GCP (refer to fig. 5-33 and table 5-7) and on the right trunnion support (fig. 5-51). The telephone lines are routed through slip ring assembly 2C1 and signal junction box 2JB1.