Development

Given the climatic and road conditions in USSR it's surprising the Red Army never fielded half-tracks in alternative to its trucks already in the mid-1930s. Famous French Engineer Adolphe Kegresse (1979-1943) came to Russia to provide the Tsar an half track already in 1912. But nothing came out of it apart some flexible tracks that could be installed on regular roadwheels on many vehicles, expecially 6x6 armoured cars. Bu there was still no cross-country transport available as both ZIL and GAZ until then produced until licence simple 4x4 and 6x6 trucks derived from US patterns, Ford in particular.

Nevertheless, the Russians saw the French Army equipped with several models of the Citroen-Kegress and consider it as a possible idea for a licence production. However instead the patent for the Kegresse track itself alone was purchased. From there, NATI in 1936 worked out a prototype based on the GAZ AA called the NATI-V3. It was tested and accepted for conversion at the Gorkiy Auto Zavod (GAZ) from late production GAZ-AA with a Kegresse halftrack suspension for further testings in 1937. They went on with many modifications, until production was greenlighted in 1938 as the standardized GAZ-60.

Mass-production was completed by late 1939 with 700 produced, just in time for the Russo-Finnish "Winter War". This war proved a crucible in which the vehicle was seriously tested. It showed the GAZ-60 was far from optimal in real combat condition. The added weight of the track system meant the truck was underprowered, but also frequently broke down due to track problems. Still, 200 more were built, in part as replacements, delivered in 1940 with improvements such as a new rear sparewheel mount.

Production was terminated, just as the competiting design from ZiS, the ZiS-22 2½-ton Halftrack. The latter was given the same track system on the ZIS-5 base, with 200 produced from 1938 to 1940, equally unsatisfactory in Finland, leading to an improved model, the ZiS-22(M) and ultimately to the ZiS-42 with a beefier 76 hp engine and a frontal brushguard protection, 5000 made from 1942 to 1945 as the ZiS-42(M). But yet again, it was never satisfactory as as much as 6,000 M5 Half Tracks came in lend-lease and were far more satisfactory.

Design of the GAZ 60

General layout

The GAZ-60 was not more than a regular truck half-track version of the GAZ-AA, which was used for the initial production. So, apart the rear twin axle, the remainder of the truck, its chassis, cabin, forward axle and equipments were identical to the regular GAZ AA. The GAZ AA, the legendary "Polutorka" (one million built 1930-38) was derived from the 1929 Ford AA, with a licence acquired at the time. It became the primary civilian and military Russian truck, until better arrived in lend-lease from 1942. The next, simplified GAZ MM of 1941 was used for extra tests but it went nowhere.

The vehicles still uses the classic FR layout ("Front engine, Rear drive") but the rear axle with paired roadwheels was replaced by the main rocking bogie supporting the full tracked ensemble. Dimensions were unchanged, 5,335 mm (210.0 in) orverall bumper to bumper, 2,360 mm (80.3 in) in width (30 cm larger than the original) but taller at c2,100 mm (78 in). The Curb weight of the original went from 1,810 kg (3,990 lb) to 3,520 kgs, almost double. The original Ford AA licence was for an SWB (short wheelbase), 131 in (3,327 mm) originally. It was now to centre of bogies 3,340mm, but road clearance at the rear was better at 30 cm.

The forward cabin was a two-seater with simple manual folding glass windows, profiled cabin roof with roof sun/rain deflector and removable vinyl cache. It was not amphibious. The flatbed was the same also, with had a maximal load capacity above 1,500 kg (although still 1.5t nominal). Indeed the tracks were able to better support heavy loads than the original single axle, but the main issue was the unchanged engine. There were stamped fenders forward but no winch.

The flatbed was surelevated on two sets of wooden framing and four supports, made in two layers of wood and surrounded by wooden panels assembled by four riveted braces, mounted on hinges so to be lowered down just as the back panel. Five frames were mounted in sockets over it, to strap a tarpaulin. The cabin also had a small rear window. There were also two headlights welded on a simple bar running across the fenders. Under the right one was situated the horn. Standard light were fitted at the rear and a hook for towing light payloads.

Engine and performances

The GAZ engine was a copy of the Ford 201 CID coupled with a 4-speed manual geabox and one reverse gear. This GAZ-M was 4-cylinder gasoline engine, 3.285 liters, for an output of 50 hp at 2,800 rpm (engine weight 248 kgs). Tank capacity was 40 liters gasoline for 215 km by road, less cross country of course. Top speed for the original truck was 70 km/h but fell down here due to the immense drag caused by the rear track to a mere 35 kph in the best of times. The engine also kept its dynamo with preheater for winter, plus backup handcrank. Orignal maximum torque was 16.5 kGm (162 Nm) but consumption was 57 liters per 100 km compared to just 22 for the GAZ AA. The gearbox had a cone worm and 2-ridge roller, the main gear ratio was singular with a pair of bevel gears without spiral teeth, the clutch was single-disk and dry.

The rear Kegresse style track system comprised two central bogie axles installed where the former rear axle was installed to ease production, and this bogie frame extended forward and rear to two main driving roadwheels. The upper track was supported by a single return roller placed at the centrer, offset from the axis, and close to the leaf-spring suspension unit. The lower track was rolled over by two smaller bogies suspended under, but offset to the main axle, at the same height of the top return roller. Each comprised a 4-wheels articulated bogie for eight in all. The Rubber tracks were 390 mm wide with metal spurs, interior ridge. It went in between doubled rollers that prevented the track from sliding off. The suspensions comprised one transverse inverted semi-elliptic leaf spring forward and at the rear two longitudinal cantilever leaf springs. The brakes were of the drum type without mechanical drive to transmission. Front wheels were of the 6.5-20 type.

⚙ GAZ 60 specifications
Weight	3,350 curb, 4,825 gross
Dimensions (mm)	5300 x 2400 x 2085
Suspension	Leaf springs
Propulsion	GAZ M carb., 4-tact, 4 cyl., sv cyl. 50hp @ 2800 rpm
Speed	35 kph
Range	2x B-66 Gazoline 20L tanks: c80 km
Armament	None.
Payload	1,300
Wheelbase	3350 (to center of bogie)
Crew	1 driver

The GAZ 60 in service

The flexible tracks were of the central pin type, passing through the doubled main roadwheels for an aft and smaller bogie wheels. Since the bogie was taller than the former rear axle, the vehicle had a "nose down" allure. It was not uncommon also to add two skids maintained by chains to the forward axle for deep snow driving. It's clear overall however given the general specs, weight and same engine, that the added weight of the tracks made the vehicle sluggish at best, especially compared to the original GAZ AA, for better traction and half the range (70-80 km, 60km fully loaded). It was usable when the road was unpracticable to deliver goods at the "last mile" to the frontline, up to c30 km.

These vehicles were pushed hard in the winter war, through walls of snow and mud, and often overloaded as customary at the time. Mechanically underpowered, they thus often broke down, engines failing completely, leaving many vehicles to be retreived and sent back to depots. It is not known how much were captured by the Finns, but if tried, they were certainly not impressed. By 1941, there were still perhaps 500 in circulation, including the 200 of later production, sometimes called GAZ-60M. It was definitively retired in 1943 and the remaining vehicle were likely kept for spares of converted back to a regular GAZ-AA or MM.


The related BA-30 armoured half track, equally unimpressive.

The BA-30 armoured car was the only known adaptation for an armoured vehicle of the GA-60 track system. Developed at the NATI Institute as the GAZ-60 it was developed from the BA series on the NATI-3 half-tracked transporter (GAZ-60 prototype) but with a BA-20 armoured hull with turret. Like the GAZ-60, two skis could be added to the front wheels. It had good performance over varying terrains indeed, but the original engine was again not sufficient to cope with the extra weight, and if it was tested in few numbers n the Winter war, production was not approved.

Gallery

GAZ-60 of early production in early 1939

GAZ-60 in Finland, December 1939

Camouflaged GAZ-60 summer 1941

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Technical (the blueprints)






ZIS-60M

The very similar ZIS-22M

Sources/Read More

o5m6.de
veneraud.ee
sovavto.net
autogallery.org.ru

WW1 Vehicles

Allied ww2 Vehicles

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Sd.Kfz 2, 6, 7, 8, 9, 10 and 11 were half-tracks designed just before the war as prime movers, to carry supplies, ammunition, personal, and tow artillery. Many were also converted during the war as armored versions carrying AA FLAK guns (Flakvierling, 37 mm, or the legendary 88 mm Rheinmetall als used as tank hunters), or were converted as nebelwerfer (rocket launching armored vehicles). They were built by Hanomag, Steyr, Mercedes-Benz, Bussing and many other manufacturers until 1945, over 20,000 half-tracks.

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