The hydraulically operated loader drum assembly (fig. 4-44) is synchronized with the operation of the rocking arms. The loader drum has two shaft-mounted disks (star wheels) with U-shaped cutouts to receive ammunition from the rocking arms. A round received by the loader drum is moved, one position at a time, through four stations. From the last station, upon completion of the firing circuit, a round is deposited in the transfer tray for ramming into the gun barrel chamber.

A set of star wheels below the loader drum accepts ammunition from the rocking arms and transfers it to the loader drum. Another set of star wheels (not shown) is geared to the loader drum. These star wheels receive ammunition from the loader drum and deposit it into the transfer tray.

Transfer Tray Mechanism Assembly

The transfer tray mechanism assembly (fig. 4-45), within the slide, receives ammunition from the loader drum and positions it for ramming into the gun barrel

Figure 4-45.-Transfer tray mechanism assembly.

chamber. The transfer tray is connected to the upper part of the slide and, through linkages, to the breech housing support. During recoil and counterrecoil actions of the gun, the transfer tray moves in an up and down swinging arc.

As the gun moves in recoil, the transfer tray swings from the DOWN position to the UP position. In the UP position, the transfer tray is aligned with the loader drum to receive a round.

The empty case tray is attached to the lower part of the transfer tray frame. As the gun recoils, the empty case tray moves up into alignment with the breech end of the barrel to receive the spent cartridge case. As the gun moves in counterrecoil, the loaded transfer tray swings from the UP position to the DOWN position to align the round for ramming into the barrel chamber.

The rammer assembly is within the transfer tray mechanism assembly. Movement of the transfer tray operates the rammer assembly. As the tray moves to the DOWN position (in counterrecoil), the rammer assembly extends, performing two functions: (1) it rams a round into the gun barrel chamber and (2) it pushes the ejected spent case of the previously fired round out of the empty case tray into the empty case ejector chute. The spent case then ejects through the chute and out of the gun mount.

EQUILIBRATOR AND COMPENSATOR ASSEMBLIES

The equilibrator and compensator assemblies (fig. 4-46) operate together to perform three functions:

1. Counterbalance the gun.

Figure 4-46.-Equilibrator and compensator assemblies. 4-36

2. Compensate for the shifting center of gravity of the barrel and breech assemblies that occurs during recoil/counterrecoil and during elevation/depression movements.

3. Stop counterrecoil movement of the gun if a short recoil fails to eject the empty powder case from the gun barrel.

The equilibrator is attached to the bottom of the carriage and extends down inside the revolving magazine assembly. It consists of an equilibrator cylinder assembly and two sets of coil springs. A steel cable extends from a spring seat at the bottom of the equilibrator to the elevation arc. In operation, the coil spring tension pulls on the steel cable to counterbalance the gun as it elevates and depresses.

The compensator assembly is a hydraulic cylinder attached to the slide above and parallel to the gun barrel. A hydraulic line connects the compensator assembly to the equilibrator cylinder assembly in the equilibrator.

As the gun recoils and counterrecoils, the porting of hydraulic fluid between the compensator assembly and the equilibrator cylinder assembly changes the position of the upper spring seat in the equilibrator. This, in turn, varies the counterbalancing spring tension on the steel cable attached to the elevation arc. As the gun moves back in recoil, less counterbalancing force is needed; conversely, when the gun moves forward in counterrecoil, more counterbalancing force is needed.

The compensator assembly prevents the flow of hydraulic fluid into the equilibrator cylinder if a short recoil fails to bring the gun back to the hooks position (or if the hooks fail to engage the gun). This prevents counterrecoil of the gun.