The launch shaft of the UGM-27A Polaris A-1 SLBM consists of the following main elements:
- sturdy launch shaft lid;
- lid opening mechanisms;
- the inner cylinder of the starting shaft;
- external launch shaft cylinder;
- inspection hatches;
- flange connections of mine cylinder sections;
- shock absorbers;
- compressed air cylinders for rocket launches;
- centering device and axial support of internal mine cylinder;
- junction box of the starting air system;
- electric compressor of the compressed air system for missile launch.
The starting shaft is a double-walled, cylindrical steel structure closed from above with sturdy lids. The height of the shaft is 8.7 m, diameters of cylinders: internal - 1.45 m, external - 2.1 m. There are three necks in the walls of the shaft for access to the rocket service systems, which are closed with lids. Through the upper neck provides access to the instrument compartment of the rocket, and through the two lower necks - to the junction of the first and second stage engines. The submarine's sturdy hull accommodates the inner cylinder of the launch shaft mounted on 20-30 boots supported by hydraulic shock absorbers. The missile is mounted in the shaft on a special oscillating support and attached to it by a clamping ring. Inside the launch shafts, the set temperature and humidity are maintained by means of air conditioning systems.
The rocket is launched from a depth of 25-35 m with high-pressure compressed air, for which each of the shafts is equipped with an autonomous air system. The air is stored in 1.2 m diameter spherical cylinders. The cylinder capacity, designed for a pressure of 315 kg/cm2, is 0.9-0.95 m3; the total supply of firing air on a submarine (such as George Washington) is 14 -15 .
The launch shafts are equipped with a special blocking system that excludes the possibility of issuing a "Launch" signal if the missile is not yet ready to be launched (e.g. with the mine covers closed; if the pressure in the mine is not equalized or the lock rings are not removed from the missile, etc.). The locking system prevents the engine from starting up in the mine or igniting itself.