Wheel self-propelled gun PCB-76 (GAZ-68)
In the summer of 1943 at the Gorky Automobile Plant started preparations for mass production of self-propelled guns SU-76M. Track self-propelled gun had a good cross in off-road, but had a little speed on the highway. And since the Red Army was advancing, the designers of the plant the idea to create more and wheeled self-propelled guns to use as a mobile means of fire support of infantry, reconnaissance for an active and maneuverable as a tank destroyer.
Focusing on the prototypes 1940-41 period the truck GAZ-63, October 19, 1943, VA Grachev started the layout of "plant products 63-SU" after the designation of GAZ-68. Together with the designers worked IV Gavalov, AL Ivanov, BD Kirsanov, IG Szymanowski, and others. By the end of 1943 was made a wooden model, which convinced some skeptics of the reality of the project, February 7, 1944 approved the draft GBTU Red Army. By the spring, without waiting for completion of the design cycle, finished drawings had been sent to the shops, and May 4, 1944 the first copy of wheeled self-propelled guns taken out of the GAZ factory gates.
Low, open-topped mass of 1140 kg bronekorpus was made of rolled armor plate thicknesses 4, 7 and 16 mm, so that the front part of the body armor formed a box with a jack for attaching the tip of the gun ZIS-3. The thickness of the armor gun shield was 12 mm. Armored plates with rational angles (developed by N. Sorochkin and AN Kirillov) protect the crew from small arms fire, the front armor withstand falling debris and heavy armor-piercing bullets. Inside bronekorpusa as low as possible - to ensure stability in the shooting - was located 76.2 mm divisional gun ZIS-3 - line-height of the fire was 0.7 m lower than the SU-76M. Horizontal angle of fire weapon was 37 °, the angle of elevation ranged from -3 to +15 °. When shooting panorama used Hertz. Rate of guns reached 8 rds / min. In the ammunition consisted of 54 shots from armor-piercing and high-explosive shells. The initial velocity armor-piercing projectile was 662 m / s, high-explosive - 680 m / sec. In addition, in the fighting compartment installed stacked two 7.62mm machine pistol with ammunition PCA 852 rounds. Right of the gun was the driver's seat, watching the situation from the front and side viewing bulletproof devices. On the other side of the gun was commander-gunner in front of him in a particular niche radio station established 12-RT. For charging back hinged seat there.
In the stern self-propelled guns placed at 276 mm offset from the axis of the machine to the right four-cylinder petrol engine GAZ-202 (version tank car engine GAZ-11 with enhanced cooling system and oil cooler) with a capacity of 85 hp (63 kW) at 3600 rev / min. To the left of the engine, in isolated compartments, located 140-liter fuel tank and bulk ammunition.
The structure consisted of a manual transmission: Chief dry friction clutch, gearbox with four forward gears and one reverse gear, transfer case with demultiplicator three driveshafts and two differential. Transfer case and transmission shafts placed in a special tunnel, located along the axis of the body. The original design of self-propelled installation was that the lead was always the front axle. This greatly increases the stability of self-propelled motion at all speeds with the rear axle off, as the rear wheels in this case were less loaded with forces in the horizontal plane of the road, increasing their ability to keep the car from skidding.
Wheel self-propelled gun PCB-76
Cushioning system included four car semi-elliptic leaf springs and hydraulic shock absorbers four piston type. In the running of the machine used in bullet-proof (gusmatik) lean-large diameter tires with advanced tread.
Electric cars have been performed on a single-circuit. The voltage onboard network was 6 V. The sources of electricity used two batteries FTA-112.
Wheel self-propelled gun PCB-76
When combat weight 5340 kg GAZ-68 developed at highway speed 77 km / h. At the factory tests in the summer of 1944 self-propelled climbing to 30 °, fords depth of 0.9 m and half-meter wall, confidently held in the pits, gullies and loose soil. The new wheel was twice ACS lighter Su-76M and at the same firepower had better mobility and quiet running. However, when in November 1944 resulted in trials of this machine, which received the designation Army SPC-76 (wheel self-propelled gun), the urgent need for it by the army was gone, the war was unnecessarily and reset the end of production to the production of PCB-76 was it's too late.