TECHNICAL INFORMATION
REPORT 3-1-3P1

OFFICE, CHIEF OF ORDNANCE
(11) April 1954

DEVELOPMENT
OF
155-MM GUN TANK, T58


155-MM GUN TANK, T58

Although the Army Equipment Development Guide of December 1950 called for the development of a heavy gun tank mounting a gun of 120-mm caliber "or one of greater effectiveness," it remained for the Tripartite Conference on Armor and Bridging of October 1951 to recommend a specific requirement for a 155-mm gun tank. The Conference proposed development of a 155-mm gun tank capable of firing HEAT and HEP rounds of high armor-defeating capabilities. Army Field Forces previously had suggested a study of the feasibility of mounting the T80 155-mm gun, normally used on the T97 self-propelled carriage, on the chassis of a T43 120-mm gun tank. Working with both proposals, Ordnance decided that, because chemical energy rounds do not require high velocities, the low-velocity T7 155-mm gun of World War II could advantageously be modified for installation in the new tank. A project for that purpose was opened, and the modified gun desired was designated T180.

The project for development of the T58 155-mm gun tank was formally opened in July 1952, but the work is still in the engineering design stage. Two pilot models are being built, one for engineering tests, the other for service tests. The engineering tests are to be completed by December 1954.

The T58 tank, like the T57 120-mm gun tank, is to have an oscillating turret and power ammunition handling equipment mounted on a T43E1 120-mm tank chassis (for a description of which, see TIR 3-1-3M1). The T180 gun is much shorter in length than the T179 120-mm gun of the T57 tank, and therefore, although of larger caliber, weighs some 1,200 pounds less. Even so, the over-all weight of the T58 will probably be about 66 tons, as compared with the 59 tons of the T57 and the 60 tons of the T43E1.

The T180 low-velocity gun will fire separate-loading ammunition, two rounds of which are now under development. They are as follows:

155-mm HEAT shell, T267
155-mm HEP shell, T152

The former is expected to perforate 16 inches of homogeneous armor at 0° obliquity and 8 inches at 60°, while the latter will probably perforate 7 inches at all obliquities.

The fire control equipment for the T58 155-mm gun tank has not yet been finally determined, and no information is available as to when the tank itself will be released for service use.

TENTATIVE PRINCIPAL CHARACTERISTICS

155-mm Tank Gun, T180

Caliber

155 mm

Length, over-all

no information

Length of bore

40 cal

Travel of projectile in bore

218 in

Rifling

no information

Weight of complete gun

5,100 lb

Chamber capacity

800 cu in

Density of loading

0.65

Rated maximum chamber pressure

32,000 psi

Breechblock, type

vertical sliding

Breech mechanism

semiautomatic

Firing mechanism

no information

Ammunition, type

separated

Muzzle velocity

2,300 fps

Maximum effective range

2,000 yd

Perforation of homogeneous armor
      HEAT shell @ 0°


16 in

Rate of fire

to be determined

Combination Gun Mount, T170

Weight

no information

Recoil mechanism, type

hydrospring

Number of recoil cylinders

4

Recoil length


      Normal

12 in

      Maximum

14 in

Equilibrator, type

no information

Elevating mechanism, type

electrical and manual

      Maximum elevation

15°

      Maximum depression

-8°

Traversing mechanism, type

electrical and manual

      Maximum traverse, right or left

360°

Fire Control Equipment

Commander's range finder

T50

Commander's range drive

model not determined

Gunner's periscope

M20 or M16 type

Gunner's telescope

elbow type

Ammunition Stowage

155-mm rounds

32

155 Gun Tank, T58

Length


      With gun forward

426 in

      With gun to rear

no information

Width

144 in

Height

125 in

Weight, over-all

132,179 lb

Ground clearance

16.125 in

Tread, from center to center of tracks

155 in

Length of ground contact

173.437 in

Ground pressure

12.4 psi

Suspension, type

torsion bar

      Wheels

26 in

      Tires

26x6 in

Tracks


      Type

steel and rubber

      Width

28 in

      Number of shoes (both tracks)

164

Armor

same as 120-mm gun tank, T43E1, See TIR 3-1-3M1

Armament


      Main

155-mm tank gun, T180

      Secondary


            Cal .30 machine gun, coaxial

to be determined

            Cal .50 machine gun, on turret

to be determined

Communications


      Radio

as selected by Signal Corps

      Interphones

5

Engine


      Type

air-cooled gasoline Continental AV-1790-7

      Cylinders


            Number

12

            Bore

5.75 in

            Piston stroke

5.75 in

            Piston displacement

1,791.75 cu in

            Arrangement

V-type

      Drive from crankshaft

direct

      Induction system

natural aspiration

      Ignition timing

automatic advance

      Horsepower


            Gross

810 @ 2,800 rpm

            Net

690 @ 2,800 rpm

      Torque


            Gross

1,600 ft/lb @ 2,300 rpm

            Net

1,330 ft/lb § 2,100 rpm

Electrical system


      Number of batteries

4

Transmission


      Type

CD cross-drive

      Range selector control box


            Type

mechanical

            Linkage to transmission

mechanical

      Torque converter

single-stage polyphase

      Gear shift and steering mechanism


            Internal

hydraulic

            External

mechanical

Oil system


      Capacity

72 qt

      Pumps


            Type

gear

            Number

5

            Drive

2 input, 3 output shafts

      Filter, type

air maze, double

Coolant

air

Fuel capacity

280 gal

Brakes


      Service brake, type

wet, multiple disk

      Parking brake, type

lock on service brake

Crew

5

Performance


      Maximum speed on level

22 mph

      Maximum grade climbing ability

60%

      Maximum trench crossing ability

90 in

      Height of obstacles that can be crossed

27 in

      Fording depth

48 in

      Turning radius

pivot to infinity

      Cruising range

80 mi