The lower gun loading system supplies ammunition to the upper gun-loading system. A revolving magazine and a screw feeder are the principal parts of the lower gun-loading system.

Revolving Magazine

The revolving magazine (fig, 4-40) stows ammunition and delivers it to the screw feeder. Ammunition stowage cells in the magazine are arranged in two concentric circles-an inner circle and an outer circle. The circles hold 70 ready-to-fire rounds of ammunition. As the magazine rotates, ammunition passes from the outer circle to the inner circle.

Screw Feeder

The screw feeder (fig. 4-41) receives ammunition

from the revolving magazine and hoists ammunition to

the last station screw feeder for delivery to the upper

fun-loading system. A hydraulic motor, driving through a hoist reduction gear assembly, rotates the screw feeder and drives the hoist lift pawl assemblies. The revolving magazine is geared to the screw feeder so both the screw feeder and the revolving magazine _{rotate in unison.}

Figure 4-41.-Screw feeder and related components.

Figure 4-42.-Upper gun-loading components.

UPPER GUN-LOADING SYSTEM

The upper gun-loading system (fig. 4-42) positions and holds ammunition for ramming into the gun barrel chamber. A pair of rocking arm assemblies, a loader drum assembly, and a transfer tray mechanism assembly are the principal parts of the upper gun-loading system.

Rocking Arm Assemblies

Right and left hydraulically operated rocking arm assemblies (fig. 4-43) transfer ammunition from the last station screw feeder to the loader drum. The two rocking arms differ somewhat in configuration but function in the same manner. Both arms pivot on a shaft that passes through the left trunnion of the slide assembly.

In operation, the rocking arms have a swinging motion and move alternately in opposite directions. When one arm is at the end of its upward travel to

^{Figure 4-43.-Rocking arm assemblies.}

Figure 4-44.-Location of loader drum assembly.

deliver a round to the loader drum, the other is at the end of its downward travel to take around from the last station screw feeder.

Hydraulically and mechanically operated clamps at each end of the rocking arms hold ammunition while in transit between the screw feeder and the loader drum. When a rocking arm reaches the loader chum, the clamps on the raised arm open to release around to the loader drum. Simultaneously, the clamps on the lowered arm close to take a round from the last station screw feeder.