SU-76 Variants

SU-12 (SU-76)

On October 19 1942 Governmental Committee of a Defence (GoKO) issued the decision N2429ss "About development and preparation of mass manufacture of artillery self-propelled guns of all necessary calibres". By the responsible executors of support SP gun and tanks destroyers were nominated Kolomensky factory #38 imeni Kuibyshev and GAZ imeni Molotov.

In November 1942 Factory #38 and GAZ began tests on an assault SP gun, armed by 76-mm divisional gun ZIS-3Sh ("Shturmovaya" -" assault") on the chassis with parallel paired engines GAZ-202. The machine from Gorki city had an index GAZ-71, and machine of Factory #38 - the SU-12.

On December 9 1942 the GAZ-71 was rejected, as not adequate technical project working unreliably. The machine SU-12 was recommended for acceptance on a service under the name "assault self-propelled gun of support of infantry and tank divisions SU-76 ". Serial manufacture SP gun began since January 1 1943.

SU-76M (SU-12M)

From the very beginning of operation SU-76 (SU-12) in army, mass cases of breakages of gearboxes began. It occured because of bad synchronization of work of two in parallel connected engines GAZ-202 on the common axle. Torsional fluctuation arose in a mode of a movement cross country. On March 21 1943 manufacture of SU-12 was stopped pending elimination of defects.

In April 1943 in Kirov city a tests of the new machine SU-12M were finished. This sample had an improved design. Between motors and gearboxes were established two mainspring sockets, and between two main transfers on a general axle - friction connection. Motors were given special shake-absorbers. The SU-12M began to work more reliably, but the failures had not completely stopped.

In May 1943 manufacture SU-12M was begun and they went on to service under the index SU-76M. These machines participated in battles on the Kursk Salient.

SU-15, SU-16, SU-38

In the summer 1943 DB GAZ and DB of Factory #38 proposed improved SU-76 projects. In the project of Gorki factory's GAZ-74A the engine ZIS-16F, ZIS-80 should be established with an american diesel "Giberson" engine with power 110 hp. The arming of GAZ-74A was by 76-mm gun S-1. This project was not carried out in time. Factory #38 made three SP gun: SU-15, SU-16 and SU-38, in which use of the consistently connected motor GAZ-203 from the tank T-70 and arms of 76-mm of a gun S-15 (SU-15) was supposed.

• SU-15 used a body and chassis of SU-12, but equipped by engine GAZ-203 with new configuration and cannon SU-15. The battle cabin had the large sizes, than SU-12.
• SU-16 differed that in it the engine, transmission and chassis of the tank T-70 were used. The battle branch was openly from above. Because of small length of the machine the commander could sit in cabin only by a side.
• SU-38 was similar on SU-16 (were too used the chassis and engine of T-70). But in it there was the thick armour (45 mm) and completely closed battle branch in the middle of the machine. It was made for improvement of distribution of weight on road wheels and tracks. The commander sat in it by the right side ahead (over engine).

In July 1943 tests of these machines were carried out. Tests had shown that for shooting the SU-16 was more successful, but its configuration is unsuccessful. SU-15 and SU-38 appeared very heavy, because of that their road wheels and tracks were broken.

SU-76 (SU-15M)

After comparative tests SU-15, SU-16 and SU-38, decision on development new SP gun from SU-15, but from the thin armor and open from above battle branch (as SU-16) was accepted. The governmental tests of the new machine were finished on 23 August 1943. The self-propelled gun received an index SU-15M and was accepted on a service instead of SU-12M and SU-S-1 under an index SU-76. The SU-15M had in army service an index SU-76 (not SU-76M).

As all basic units of SP gun (engine, gun, the transmission) were made in Gorkij city, and the tanks T-70 were gradually removed from manufacture, main factory on manufacturing SU-76 was nominated GAZ. But serial production of SU-76 began here only since 01 October 1943.

OSA-76 (OSU-76)

In the summer - autumn 1943 the Artillery Directorate of Soviet army for increase of speed of approach has at the front offered the project of motorization of all army artillery. This project received the conditional name «OSA » (All-army Self-propelled Artillery). OSA was not the predcessor, or development of family SU-76, but represented a new class of artillery systems, intended for use in structure of infantry formations. The project supposed the creation the following self-propelled guns:

• OSA-76 - self-propelled 76-mm gun of partial armoring;
• OSA-57 - self-propelled 57-mm anti-tank gun of partial armoring;
• OSA-23 (or OSA-12) - self-propelled 23-mm (12,7-mm) A-A automat of partial armoring.

The responsible executor of the project «OSA » with tracks chassis nominated Factory 38. OSA-76 represented the small light machine with the motor GAZ-MM, armed by 76-mm gun ZIS-3. The chassis OSA was assembling from standard units of the chassis of tanks T-60 and T-70. Armor protection of OSA-76 was weak, as at a shield of a gun ZIS-3 (6-mm) and protected from a simple way and light splinters. The tests were finished successfully and OSA-76 was recommended for acceptance on a service, but because of a cancellation of realization of the project OSA, serial manufacture of this SP gun did not begin.

Assault gun of factory 37

The work to creation Soviet SP gun began after the order NKTP on March 3 1942. In a design of machines wanted to use a standard units of tanks T-60 and trucks GAZ. The experimental machine, assembled at Factory 37, was delivered to tests in May 1942. The new battle machine received the name "The Assault 76-mm Self-propelled Gun for supporting". The tests were finished unsuccessfully. Supreme head-quarters recommended to continue work with new SP. But in the summer began the battle for Stalingrad and work stopped.