The Mk 26 GMLS hoist assembly (fig. 7-22) is an integral part of the RSR and is very similar to other hoist assemblies. The hoist chain is a link-connected, roller type about 31 feet long with magnet actuators mounted to various links. They activate proximity switches on the chain stowage track that indicate the raised, lowered, and intermediate positions of the hoist.

A hoist pawl and latch, an adjustable link, and a buckling link are on the forward end of the hoist chain. The hoist pawl and latch connect the hoist chain to the pusher bar for hoisting operations. The adjustable link makes possible the proper positioning and alignment of missiles on the launcher guide arm. The buckling link compensates for any overtravel of the chain on an extend cycle.

The curved and retractable chain tracks extend from the hoist speed reducer and drive sprocket assembly to the hanger rail. The curved chain track is stationary. The retractable chain track is a pivoting track that aligns the curved track section with the hanger rail for hoisting operations. When the retractable chain track extends, it actuates a mechanical linkage that releases the pusher bar retainer latch.

SYSTEM NUCLEAR LOCK.- The system nuclear lock (also known as the RSR lock) is a device similar to the hanger rail nuclear locks (fig. 7-23). It is mounted to the retractable chain track of the hoist. Both locks work together to prevent unauthorized loading of nuclear warhead missiles.

Both locks must be locked to perform their intended function. Figure 7-23, view A, shows how the retractable chain track is prevented from aligning with the hanger rail. If the locks are in the conditions displayed in views B, C, and D, hoisting can be accomplished.

One key fits all the rail locks of one RSR, while a different key fits the system nuclear lock. According to nuclear weapon security regulations, the commanding officer or a designated representative (must be a commissioned officer) maintains custody of these keys at all times. To load a nuclear ASROC round, personnel must enter the magazine, prepare the missile, and (according to ship's doctrine) unlock at least one of the locks.

FIXED RAIL.- The fixed rail section is mounted to the top of the RSR's hoist end section. (See figs. 7-19 and 7-22.) This 4-foot rail bridges the gap between a hanger rail and the span rail assembly. All three rails

Figure 7-22.-Hoist components, general arrangement.

Figure 7-23.-Hanger rail and system nuclear locks.

Figure 7-24.-Fin opener assembly.

are locked together by hydraulically operated aligning rods extending into appropriate alignment guides.