The SU-122 (from Samokhodnaya Ustanovka 122 mm) was a Soviet self-propelled howitzer or assault gun used during World War II. The number "122" in the designation represents the caliber of the main armament—a 122 mm M-30S howitzer. The chassis was that of the T-34.

Class Vehicle
Type Armoured Fighting Vehicle
Manufacturer Factory No.9 Ural Heavy Machinery Factory (UTZM)
Production Period 1942 - 1944
Origin Russia (USSR)
Country Name Origin Year
Russia (USSR) 1942
Country Name Operational Year Retirement Year
Russia (USSR) View
ManufacturerName Production From Production To Quantity
Factory No.9 Ural Heavy Machinery Factory (UTZM) 1942 1944 1148 View

Soviet High Command became interested in assault guns following the success of German Sturmgeschutz III SPGs. Assault guns had some advantages over tanks with turrets. The lack of a turret made them cheaper to produce. They could be built with a larger fighting compartment and could be fitted with bigger and more powerful weapons on a given chassis. However, assault guns could aim their cannons in high degree only by turning the entire vehicle, and were thus less suited for close combat than tanks with turrets.

In April 1942, design bureaus were asked to develop several assault guns with various armament: 76.2 mm ZiS-3 divisional field guns and 122 mm M-30 howitzers for infantry support, and 152 mm ML-20 howitzers for breaking through enemy strongholds.

A prototype assault gun, armed with the 122 mm howitzer and built on the German Sturmgeschütz III chassis was developed designated SG-122. Only 10 of these were completed. Production was halted when the vehicle was found to be hard to maintain and judged to be unsuccessful.

Simultaneously, a SPG based on the T-34 medium tank was also developed. Initially the T-34's chassis was selected for the 76.2 mm F-34 gun. This vehicle, the U-34, was created in summer 1942 at the design bureau of UZTM (Uralmashzavod – Uralsky Machine Building factory) by N. W. Kurin and G. F. Ksjunin. It was a tank destroyer with the same armament as the T-34, but because of the absence of a turret, the vehicle was 70 cm lower, had thicker armour, and was 2 tonnes lighter. It did not enter production.

UZTM then worked on combining features of the U-34 and the SG-122. Initial design work was completed between July and August 1942. The project emphasized minimizing modifications to the platform and the howitzer. It used the same chassis, superstructure, engine and transmission as the U-34 and was armed with a new 122 mm M-30S howitzer from F. F. Pietrow's design bureau. This vehicle also used the same gun bed cover and mountings as the SG-122, to keep costs low and simplify production. It had 45 mm thick frontal armour. The M-30S howitzer could be elevated or depressed between -3° and +26° and had 10° of traverse. The five-man crew consisted of a driver, gunner, commander and two loaders.

On 25 November 1942 the first U-35 prototype was ready. Trials ran from 30 November to 19 December 1942, and uncovered various faults in the design including insufficient elevation, a flawed shell transfer mechanism, poor ventilation for the crew compartment and the fact that the commander had to assist in operating the gun which made him unable to successfully carry out his other duties. The U-35 entered service with the Red Army as the SU-35 (later renamed SU-122) despite these faults.

Production SU-122s were based on an improved prototype built after trials were conducted. They incorporated several modifications including slightly less sloped front armour to ease production, modified layout of the fighting compartment (the location of crew member stations and ammunition racks were changed), fewer vision slots, and a periscope for the commander. The first production vehicles were completed before 1943.

The first SU-122s produced in December 1942 were sent to training centers and two new combat units, the 1433rd and 1434th self-propelled artillery regiments. Initially, each of these mixed regiments consisted of two batteries with four SU-122s each and four batteries with four SU-76 tank destroyers each. Each regiment had an additional SU-76 tank destroyer as a command vehicle. It was planned to raise 30 self-propelled artillery regiments operating within armoured and mechanized corps.

In January 1943, the 1433rd and 1434th self-propelled artillery regiments were sent to the Volkhov Front near Leningrad as part of the 54th Army. On 14 January they saw combat for the first time in Smierdny region. After that it was decided SU-122s should follow between 400 m and 600 m behind the attacking tanks; sometimes this distance was shortened to between 200 m and 300 m.

The use of SU-76 tank destroyers together with SU-122s proved unsuccessful. Based on combat experience, the organization of self-propelled artillery regiments was changed; the new regimental organization consisted of two batteries of SU-76 tank destroyers and three of SU-122s, for a total of 20 SPGs. In April the organization of self-propelled artillery regiments was again changed. Separate regiments were created for SU-76 tank destroyers (light self-propelled artillery regiment) and SU-122s (medium self-propelled artillery regiment).

The medium self-propelled artillery regiment consisted of four batteries of four SU-122s each. Each regiment was also equipped with either an additional SU-122 or a T-34 for the commander and a BA-64 armoured car. This organization remained in place until the beginning of 1944 when the SU-122 started to be replaced by the SU-152, ISU-122 and ISU-152 heavy SPGs and SU-85 tank destroyers.

The SU-122 proved effective in its intended role of direct fire on strongholds. The massive concussion of the 122mm HE round was reportedly enough to blow the turret off even a Tiger I if a direct hit was scored at close range, although longer range penetration against heavier German armor remained poor, a trait shared with the larger 152mm howitzers. The new BP-460A HEAT projectile was introduced in May 1943; however its primitive warhead design was only minimally more effective than brute concussive effects of the old HE shell at close range.

At least one SU-122 was captured by the German Army.

A small number of SU-122s survived the war. Currently, only one example remains, on display in the Kubinka Tank Museum.

Formal DesignationSU-122
Manufacturer(s)Factory No.9 Ural Heavy Machinery Factory (UTZM or Uralmash)
Production Quantity1148Production PeriodDec. 1942 - early 1944
TypeAssault GunCrew5
Length overall6.95 m (22' 10")Barrel Overhang1.03 m (3' 5")
Width3.00 m (9' 10")Height2.32 m (7' 7")
Combat Weight30900 kg (68000 lbs)Radio Equipment9R
Primary Armament122mm Howitzer M-30SAmmunition Carried40
Traverse (degrees)Manual (10°L - 10°R)Elevation (degrees)-3° to +25°
Traverse speed (360°)-Sightn.a.
Secondary Armament-Ammunition Carried-

Engine Make & ModelV-2-34Track Links72/track
Type & DisplacementV12, 38.9 litersTrack Width55.0 cm (22")
Horsepower (max.)500hp@1800rpmTrack Ground Contact372 cm (146")
Power/Weight Ratio16.2 hp/tGround Pressure0.75 kg/cm2 (10.7 psi)
Gearbox5 forward, 1 reverseGround Clearance0.40 m (1' 4")
FuelDieselTurning Radius7.6 m (24' 11")
Range on/off road270+/165+ kmGradient35°
Mileage on road155 l/100kmVertical Obstacle0.8 m (2' 7")
Fuel Capacity420 (+ 270 external)1 lFording1.3 m (4' 3")
Speed on road55 km/hTrench Crossing2.5 m (8' 2")
Armor DetailFrontSideRearTop/Bottom
1In general, one of the four 90 liters external fuel tanks was reserved for oil.

TWWII, PV, T-34IA, ST, RTAV, George R. Bradford

End notes