Conflict Special Study 1

Glossary of Terminology

by TP Schweider

TURRET -- Rotating armored superstructure housing the principal armament, the gun crew and commander in main battle tanks. Essentially fighting compartments, turrets undergo significant design trade-offs between the requirements of allowing enough room and protection for the crew to successfully operate the gun and vehicle, and the need to restrict the size, shape, and weight of the superstructure to a minimum.

TURRET BASKET (or CAGE) -- Lower section of the turret inside the hull and rotating with the turret. Although a:iding weight to the tank and complicating the interior design, the turret basket is a standard feature of Western tanks as it allows the gunner and loader to be constantly in position to service the main gun. Soviet tanks lack turret baskets, requiring the loader to walk around on the hull floor to keep in position with the main gun (and prevent being struck by a traversing gun).

MANTLET (or MANTLE) -- Armored housing protecting the main gun in the turret. Because the mantles and the mount, i.e., the fixture holding the main gun in the turret, are frequently integral components, "mount" is often synonymous with "mantlet." Due to its vulnerability to hostile fire, the armor protection afforded by the mantles is an important factor in determining the battleworthiness of a tank.

GLACIS PLATE -- Front section of the tank hull carefully designed to provide protection against hostile fire. Heavy armor at an incline to the vertical constitutes most front plates, although, however thick and sloped, they cannot be impervious to well-placed, shaped projectiles.

VISION BLOCKS -- Direct viewing ports complementing the periscopes and other vision devices of the tank. Mounted usually around the hatches, especially on the turret, they are considered ballistic in function, i.e., small arms fire will not penetrate their thick laminated glass.

RETURN ROLLERS -- Dead-axle dual idler wheels which support the upper span of the track. Common to Western tanks, return rollers are usually advocated to promote uninterrupted operation of the tracks and a smoother ride, although they do add to the overall weight and maintenance. Communist tanks have, until recently, shunned the return rollers, and some experts claim they are unnecessary if the road wheels are large enough.

HARMONIC VIBRATION -- The effect in which that part of the tread not in contact with the ground, between the front idler and the drive sprocket, vibrates like a taut rubber band. This vibration occurs at certain speeds and is determined bY the size of the road wheels and idlers. As return rollers maintain proper tension on the track, harmonic vibration occurs only in track systems having no return rollers. If the track achieves a vibration of a foot or more the tread will break at a connector or jump off the front idler.

POWER/WEIGHT RATIO -- Relationship between the horsepower provided by the engine and the gross weight of the vehicle which determines speed, acceleration, and gradient-climbing ability of the tank. While high power ratios are sought, actual performance is not constant, and the power available is degraded by the losses to other systems (cooling, transmission, etc.), suitable engines of minimum size, and restrictions of the environment (temperature, terrain, etc.).

GROUND PRESSURE (PSI) -- Specific pressure on soft ground, at approximately one inch penetration, and measured in pounds per square inch (psi). A low load per unit of track contact area is desired, and Soviet tanks are generally superior to their Western counterparts in this regard, although actual cross-country performance of any tank is also determined by the shape of the tracks and the soil under them.

MAIN GUN -- Mounted in the turret, it is the principal armament of all battle tanks and primarily designed to destroy other tanks. As armored plate has increased in thickness, the calibers of main guns have increased, combined with greater muzzle velocity to improve the armor-piercing capability of the projectiles. However, larger guns demand more of the limited turret space because of the bigger firing mechanisms and bulkier ammunition, so alternatives have been sought in new types of projectiles and in weapons mounted externally on the turret.

GUN CALIBER -- Minimum diameter of the bore of a gun. The length of tank guns is usually described in calibers (e.g., "L/56"), determined by dividing the length of the barrel (minus muzzle attachments) by the diameter of the bore. European measurements include the breech ring, but those of the United States do not.

GUN TUBE -- Inner wall of the bore of a built-up gun, extending usually from the breech to the muzzle and made of one piece. Also used to designate the barrel of a large caliber gun, e.g., one mounted in a tank.

GUN BREECH -- Mechanical device for sealing the rear end of the chamber of a gun after loading the round of ammunition which was inserted for firing. The breech of the main gun is important in tanks because of the central position and space it occupies in the turret and because the speed and ease with which it operates is critical to the battleworthiness of the vehicle.

COAXIAL MACHINEGUN -- Heavy caliber machinegun mounted adjacent to the main gun to provide, in modern tanks, the range of targets for the gunner who observes the fall of tracer bullets fired in short bursts. Simple to use and maintain, the coaxial machinegun takes into account the tilt of the tank and the direction and strength of the wind which optical range finders cannot do. However, the effective range of heavy machineguns falls short of the maximum range of most tank guns and firing the weapon can inform the enemy of the tank's presence and location.

STADIAMETRIC RANGE FINDER -- A telescope having horizontal gradations etched on the reticle so that the height of the target is used to determine the range of the target. This system requires the gunner to have a fairly exact knowledge of the heights of all possible targets. Employed by the Soviets, it is a fairly simple system and effective when used by very well-trained crews. However, it is not as precise as more sophisticated Western rangefinding systems.

HULL-DOWN (IN DEFILADE} POSITION -- Chassis of tank hidden by concealment and/or cover with the muzzle of the main gun being the lowest portion of the tank exposed to the front. Used for maximum protection while engaging targets with direct fire.

DESTRUCTIVENESS -- A tank's ability to acquire, engage, and destroy a hostile tank. While basically a factor of the range of the sights for the main gun and penetrability of its ammunition, the rate of fire, general vision blocks, and crew training are also important in determining a tank's destructiveness.

SURVIVABILITY -- This is primarily a factor of a tank's armor protection: the armor thickness and slope of that armor. However, a tank's height (silhouette), mobility, and crew, ammunition and fuel location within the tank are vital in this calculation.

AVAILABILITY -- A tank's capability to be where it is required when it is required. Both cross-country mobility and crew habitability (for combat endurance), as well as combat range (fuel capacity) determine a tank's availability.

More Arab-Israeli Armor 1973

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© Copyright 1975 by Dana Lombardy.
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