Skoda-706RT

Škoda 706 RT: The Czechoslovak “Trambus” That Defined an Era

The Škoda 706 RT is one of the most important trucks in the history of Czechoslovak road transport. Known simply as the “Trambus,” it transformed the familiar Škoda 706 formula by replacing the traditional bonneted cab of the 706 R with a modern cab-over-engine design. Introduced in the second half of the 1950s, the 706 RT combined a new cab, revised chassis and a considerably improved 11.8-litre diesel engine, creating a truck that was better suited to the rapidly changing demands of post-war freight transport. Its importance was not limited to Czechoslovakia: the vehicle was exported throughout the Eastern Bloc and became a familiar sight on roads in countries including East Germany and the Soviet Union. Production of the broader 706 RT family ultimately continued into the 1980s, long after the truck had ceased to be a cutting-edge design.

The story of the 706 RT is also the story of LIAZ, the Liberec-based Czechoslovak truck manufacturer that grew out of the industrial reorganization of the early 1950s. The first RT prototype appeared in 1955, followed by a definitive pre-production vehicle in 1956 and the first series production in 1957. The new truck represented a major change in philosophy. Instead of placing the driver behind a long bonnet, engineers moved the cab forward and positioned it above the engine, shortening the vehicle and creating more usable space for cargo or specialized equipment. At the same time, the 11.8-litre diesel inherited the basic dimensions of the 706 R engine but received direct fuel injection, raising output to approximately 160 horsepower.

From the Škoda 706 R to the 706 RT

Why the old bonneted design had to change

The Škoda 706 R had been a highly successful post-war truck, but by the middle of the 1950s its traditional bonneted layout was beginning to look increasingly conservative. A truck’s overall length was an important consideration, and a large engine compartment extending ahead of the cab consumed considerable space that could otherwise be used for cargo or bodywork. The cab-over configuration offered a solution by placing the driver directly above the front axle and engine.

LIAZ’s newly established development organization began work on the replacement during the first half of the 1950s. The first prototype appeared in 1955 and was based partly on existing 706 R components, including its axles. A more definitive pre-production example followed in 1956, incorporating the technical changes that would characterize the production 706 RT. Series manufacturing began in 1957, with full-scale production accelerating rapidly during the following years.

The name RT is commonly explained as referring to rekonstruovaný trambusový, essentially “reconstructed cab-over.” It therefore reflected both the vehicle’s relationship to the earlier 706 and the most visible feature of the new generation: its cab-over-engine configuration. The change was much more significant than a simple alteration to the cab. The frame, axles, engine installation and other components were also revised to create a coherent new truck.

The Famous Trambus Cab

A modern shape for the 1950s

The most obvious characteristic of the 706 RT was its cab-over-engine cab, or trambus layout. At the time, this gave the truck a distinctly modern appearance. Instead of looking like an enlarged traditional lorry, the 706 RT had a compact front end with a large, upright windscreen and a broad radiator grille integrated into the cab structure.

The new arrangement had practical advantages as well as visual appeal. By moving the cab forward, the designers could achieve a relatively short overall vehicle while maintaining a useful wheelbase and cargo area. For a heavy truck, this was particularly important because it allowed operators to carry substantial loads without making the vehicle unnecessarily long. The same basic chassis philosophy could also be adapted to a wide range of specialist bodies, from tippers and tankers to municipal and emergency vehicles.

The cab was not especially luxurious by modern standards. Noise, vibration, mechanical controls and limited insulation were all part of the experience, while access to the engine required opening service panels rather than simply tilting the entire cab forward. Nevertheless, compared with the older 706 R, the Trambus represented a substantial change in driver environment and vehicle packaging.

The 11.8-Litre Direct-Injection Diesel

More power from a familiar engine

One of the most important technical changes was hidden beneath the new cab. The basic dimensions of the six-cylinder diesel were retained from the 706 R, with a 125 mm bore, 160 mm stroke and 11,781 cm³ displacement, but the combustion system was extensively revised. The earlier precombustion-chamber arrangement was replaced by direct fuel injection, producing a major improvement in performance and fuel efficiency.

The production engine developed approximately 160 hp (118 kW). Automobil Revue’s period specifications give maximum output at 1,900 rpm and maximum torque of approximately 687 Nm at 1,200 rpm. This was a substantial increase over the 135-horsepower engine of the 706 R and gave the new truck considerably more flexibility when hauling heavy loads or towing a trailer.

The relatively low engine speed at which maximum torque was produced was particularly appropriate for commercial transport. The 706 RT was not designed as a fast vehicle in the modern sense. Its large diesel was intended to produce strong pulling power at low revolutions, allowing the truck to maintain progress under load without constantly operating at high engine speeds. This characteristic became one of the defining traits of the 706 family.

The engine remained water-cooled, with the radiator positioned at the front of the cab ahead of the engine. The cooling system held approximately 45 litres of coolant, while the standard fuel tank capacity was around 175 litres. Historical technical material gives fuel consumption of approximately 24 litres per 100 kilometres, although actual consumption naturally depended on load, gearing, terrain and driving conditions.

Transmission and Chassis

A five-speed mechanical drivetrain

The 706 RT retained a fundamentally conventional drivetrain despite its modern appearance. Power was transmitted through a five-speed manual gearbox, with a dry twin-plate clutch. Depending on the selected final-drive ratio, the truck could be geared for different operating requirements, with period specifications listing maximum speeds ranging from approximately 55 to 85 km/h.

This flexibility was important because the 706 RT existed in many forms. A vehicle intended for urban refuse collection had different requirements from a long-distance tractor unit, while a construction tipper needed yet another balance between pulling power and road speed. The choice of final-drive ratio allowed the same basic powertrain to serve these different applications.

The chassis itself used a steel ladder frame, with two rigid axles suspended by longitudinal leaf springs. The front suspension incorporated hydraulic dampers, while braking was provided by compressed-air drum brakes. Steering remained entirely mechanical, using a worm-and-roller system. In other words, although the 706 RT looked modern in 1957, it remained a fundamentally mechanical machine, with relatively little of the complexity that would characterize later generations of trucks.

Built to Carry Heavy Loads

A serious seven-ton truck

The standard 706 RT platform truck was rated for a useful payload of approximately 8.6 tonnes, according to period material, with a gross vehicle weight of approximately 15 tonnes. This was a significant capability for a truck of its era and made the Trambus suitable for both domestic freight work and demanding industrial applications.

The standard truck measured approximately 7.6 metres long, 2.35 metres wide and 2.5 metres high, with a wheelbase of around 4 metres. Its standard cargo platform was approximately five metres long and 2.245 metres wide. Ground clearance was about 280 mm, providing useful capability on poor roads without making the truck a dedicated off-road vehicle.

The combination of dimensions and payload explains why the 706 RT became so widespread. It was large enough for serious freight work but sufficiently compact to operate on the road infrastructure of the period. Its cab-over layout also made the vehicle easier to package than the older 706 R, particularly when manufacturers needed to install specialized bodies.

A Whole Family of Trucks

From flatbeds to tippers

One of the greatest strengths of the 706 RT was that it was never restricted to one body style. The standard 706 RT served as a flatbed or chassis for specialized bodies, while the 706 RTS became a three-way hydraulic tipper. There was also the rapidly operating RTS 1 tipper, designed for applications in which unloading speed was particularly important.

Other derivatives included the RTD long-wheelbase flatbed, the RTK refuse-collection vehicle, the RTH chassis used for water-spraying and municipal applications, and the RTTN tractor unit for semi-trailer work. There was even the RTP, a four-wheel-drive version intended for situations where the standard rear-wheel-drive arrangement was insufficient.

This enormous variety was central to the success of the platform. Instead of developing an entirely different truck for every industrial application, Czechoslovak manufacturers could adapt the same fundamental engine, chassis and cab to many roles. The result was an extensive family of vehicles recognizable by their shared mechanical and visual identity.

The 706 RT and the Škoda 706 RTO Bus

The truck that also became a bus icon

The influence of the 706 RT extended into passenger transportation. The related Škoda 706 RTO bus used the same basic LIAZ/Škoda mechanical foundation, while body construction was associated with Karosa and other manufacturers. The RTO became one of the most famous Czechoslovak buses of the twentieth century and was produced in several forms, including urban, interurban and touring versions.

The relationship between the truck and bus is a good illustration of the engineering philosophy of the time. A robust heavy-vehicle chassis and powertrain could provide the mechanical foundation for vehicles with radically different bodies and purposes. The 706 RT therefore influenced not just freight transport but also the appearance and operation of public transportation across Czechoslovakia and its export markets.

Production and the Rise of LIAZ

From a new truck to an industrial institution

The 706 RT became one of the foundational products of LIAZ, whose factories in the Liberec region developed into a major centre of Czechoslovak truck manufacturing. Production increased dramatically after the initial series. According to historical production data, approximately 4,070 vehicles were built in 1958, followed by 5,359 in 1959. Production of the RT series reached a reported peak of 9,142 vehicles in 1968.

The longevity of the design is perhaps even more remarkable than the production numbers. Although newer generations such as the 706 MT and later LIAZ models gradually appeared, the 706 RT family remained in production in various forms into the 1980s. Historical sources place the final production period around 1985, demonstrating that a design introduced in 1957 could remain commercially useful for almost three decades.

The truck also became an important export product. It was especially significant in other socialist countries, where Czechoslovak heavy vehicles were used extensively in freight transport, construction, municipal services and industry. The 706 RT’s reputation therefore extended far beyond its domestic market.

What Made the Trambus So Successful?

Practical engineering rather than technological excess

The 706 RT’s long career can be explained by a combination of factors. Its cab-over layout was modern and practical, its engine delivered substantially more power than the preceding 706 R, and its ladder-frame chassis could accommodate an unusually broad range of body types. At the same time, the mechanical systems remained sufficiently conventional to be repaired and maintained by workshops without sophisticated electronic equipment.

This simplicity was particularly valuable in the operating environment of the 1960s and 1970s. A truck could spend years working in construction, agriculture, municipal services or long-distance transport, and operators needed vehicles that could be repaired rather than simply replaced. The 706 RT’s heavy-duty construction made it well suited to this philosophy.

The vehicle also benefited from standardization. Once workshops and drivers were familiar with the 706 RT, the same knowledge could be applied to many derivatives. Parts, maintenance procedures and driving techniques could therefore be shared across a substantial fleet.

The End of the 706 RT Era

From Trambus to later LIAZ trucks

The appearance of the 706 MT marked the beginning of the next major stage in LIAZ development. The MT family introduced further engine and chassis improvements while retaining the general cab-over philosophy established by the RT. Later LIAZ trucks would become progressively more modern, with improved engines, cabs and drivetrains, but the basic transition had already taken place with the 706 RT.

That is why the Trambus occupies such an important position in Czechoslovak truck history. The 706 R had been a successful traditional bonneted truck, but the 706 RT changed the visual and technical language of the country’s heavy vehicles. For several decades, the sight of its distinctive cab became synonymous with commercial transport in Czechoslovakia and throughout much of Central and Eastern Europe.

Škoda 706 RT Technical Specifications

The figures below refer primarily to the standard 706 RT flatbed configuration and period specifications; individual derivatives, production years and final-drive ratios could differ considerably.

The Škoda 706 RT was therefore far more than a replacement for the 706 R. It represented the moment when Czechoslovak heavy trucks entered the cab-over era and established the technical foundation for decades of LIAZ production. Its 11.8-litre direct-injection diesel, five-speed transmission and adaptable ladder-frame chassis gave it the versatility required by a rapidly industrializing economy, while the distinctive Trambus cab made it one of the most recognizable vehicles on the roads of the period.

Perhaps the most remarkable aspect of the 706 RT is its longevity. A truck introduced in 1957 remained relevant through the 1960s and 1970s and continued to be manufactured in derivative forms into the 1980s. It served as a freight carrier, tipper, tractor unit, municipal vehicle, emergency vehicle and the mechanical foundation for the celebrated 706 RTO bus. Few Czechoslovak commercial vehicles demonstrate so clearly how a well-conceived platform can adapt to changing requirements.

Today, the 706 RT “Trambus” is remembered not only as a workhorse but as a symbol of an entire era of Czechoslovak engineering. Its broad cab, unmistakable grille and deep diesel note are instantly recognizable to enthusiasts, while surviving examples preserve the memory of a time when heavy trucks were predominantly mechanical, deliberately overbuilt and expected to remain in service for decades. The 706 RT may have been conceived as a practical industrial machine, but its combination of distinctive design, technical importance and extraordinary longevity has transformed it into one of the classic trucks of Czech and Slovak automotive history.