Quantcast System Alignment

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Shipyard personnel initially install equipment using precision methods in a newly constructed ship. They take into account stress caused by operational loading and adjust for accurate alignment when the ship is waterborne and contains 90 percent of the total load

(builder yard only). When alignment procedures are undertaken thereafter, the ship should contain 80 percent of the total load of fuel, water, armament, and stores, distributed normally. The greater part of the work will consist of checks and small adjustments unless the equipment has been damaged or moved out of alignment.

System alignment requires orienting and adjusting several components to each other so that they function properly together as a whole. No alignment work should ever be undertaken without first making careful tests to make certain that adjustment is necessary. An incorrect or unnecessary adjustment can cause serious problems in the system.


The alignment requirements for a weapons system include the internal alignment of each of the components and system alignment of the different components or equipment with each other. The internal alignment of an ordnance component is established by the manufacturer. A high degree of machining and fitting of structural parts assures good internal alignment. If any basic alignment is necessary because of faulty manufacture, overhaul at a shipyard usually is required. Each director should be internally aligned with the ship's References. All the parts of the weapons system are aligned to the reference while the ship is being outfitted or in dry dock, and the whole system is tested. When the ship is afloat, you must recheck the operation of the system. If there are serious distortions, the ship is returned to the shipyard for adjustments.

The launchers and gun mounts must be aligned to the directors in train and elevation.

Before any alignment work is undertaken afloat, you should perform a transmission check. Synchro and dial errors corrected at this point will keep you from compounding the errors or from introducing errors into the ensuing alignment procedures. Initially undetected errors would be revealed before the alignment was completed. At this point, you could be faced with the task of redoing one or more of the alignment phases.

You should not proceed with synchro alignment unless the preliminary checks show a misalignment. If the synchro is close to zero, you should make only the fine adjustment.


Precise mount alignment requires extreme accuracy in the performance of alignment checks and adjustments. These checks should be made with the ship moored to a pier or anchored in calm seas.

Train alignment checks provide an accurate method of determining the degree of parallelism between the zero train lines of all the components of the system. When the director is trained to any point and the mount dial pointers are matched with zero settings, the director and mount lines of sight are parallel in train.

Because the ship is afloat, it is impracticable to use multiple targets to obtain parallelism between the mount and director. However, if the lines of sight of both the director and the mount are aligned on a target at infinite range, they will, for all practical purposes, be parallel. The most accurate method of alignment is to use a celestial body.

When train alignment is performed simultaneously for several components, the train dial readings from all the stations should be transmitted to a central station (such as CIC) for systematic recording. The recorders at the individual components should cross-check all the readings to eliminate possible errors in recording the readings. Rotation of the earth and ship's motion may cause the line of sight to drift from the target, but this drift is not detrimental as long as the line of sight is on the target when the reading is taken.

The mount is aligned in elevation to the director. It is elevated in manual control to bring its bore (or launching rail) into a position parallel to its roller path plane (at a point of known inclination) within 3 minutes of arc. All the elevation indicators are adjusted to indicate zero elevation.


LEARNING OBJECTIVES: Discuss the importance of firing cutout mechanisms.

It is hard to overstate the importance of checking the firing cutout mechanisms after making the original alignment or after doing any work or repair on the mount that would disturb the firing cutouts. Every casualty caused by the ship's firing into their own superstructures testifies to the seriousness of any misalignment of the firing stop mechanisms. In every case, these casualties could have been prevented. These casualties have resulted from negligence on the part of ship's force personnel-the cams were cut improperly (in some cases misaligned) or the firing cutouts were inoperative through a lack of preventative or corrective maintenance.

As you may remember, firing cutout mechanisms are designed to interrupt electrical firing circuits and firing mechanism linkages whenever guns and launchers are trained or elevated to position where firing the mount would endanger personnel or cause damage to the ship. They should not be confused with the limit-stop assemblies that are used to limit the movement of some mounts to a safe firing zone. Firing cutout mechanisms do not interfere with the free movement of the gun or launcher.

The Naval Sea Systems Command has issued definite instructions for personnel responsible for plotting, cutting, installing, and checking firing cutout cams and mechanisms. These regulations are to be complied with in all cases. In addition, special instructions govern particular installations. The computations for the safety clearances of the mount relative to the ship's structures and equipment are complicated and extensive. A high degree of precision and skill is required to make these computations and to prepare and install the cutout cams in the mount. The computations are now done with computers at the Naval Surface Weapon Center (NSWC), who prepares the cutout data for the requesting ship. NSWC also prepares the cutout cams and assists in their installation and adjustment.

When anew cam is installed, it is essential that the two train reference points be reestablished. These are the train B-end stopped position and the nonpointing zone cam arrested position. The nonpointing zone switches must be set accordingly. NSWC personnel will assist in performing this task

The firing cutout cams are plotted, scribed, and cut during the final stages of the initial installation or overhaul period. This is accomplished after all the installation and alterations to the topside, superstructure, masts, and rigging are completed.

Procedures for scribing and matching the firing cutout cams are outlined in the applicable system OPs.

Performance of the cams should be checked before each firing, whenever new cams are installed, and as prescribed by the PMS schedule of your system.

The train and elevation limit stops restrict mount movement under certain conditions. When activated, the limit-stop system neutralizes the associated power drive, thus limiting the movement of the mount. The limit-stop cam controls the deceleration rate of the power drive of the mount. Train and elevation require different rates of deceleration, so their cams differ in contour. The actuating cams are identical. When the mount approaches a nonpointing zone, the actuating cams start the limit-stop system.

An adjustment screw is secured to the bottom of each limit-stop cam. As an aid in alignment, scribe lines are scored into the cams. The cam-stacks, which indicate position-plus-lead to the automaticpointing-cutout and automatic-firing-cutout systems, have a vernier that permits simultaneous adjustment of all of the cams in the stack, and each cam can be adjusted to a vernier in its base.

Firing cutout cams, limit-stop cams and associated shafts, switches, and components are preset by the manufacturer and checked by the installing activity. These cams do not require routine adjustment. They should be checked periodically and reset only if they are not within plus or minus 1 of actual mount settings.


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