In 1969 Tatra decided to modernize the existing T138 model with a number of improvements and design changes. The new model series was designated T148. Designers were tasked with the requirements of increasing engine power, vehicle speed and reliability as well as meeting stricter noise and emission regulations.
Yet again design continued with the proven central backbone tube construction and power train integrated into the central backbone tube as a modular concept in 4×4 and 6×6 configuration. A new feature was the inter-axle differential. The main advantages of the central load carrying backbone tube are in its high torsion and bend strength, which protects the truck body against load stresses. The secondary advantage is that it houses all important parts of the drive train as well as it enables a concept of modular construction where designers and customers can specify 4 and 6 wheel drive, as well as various length wheelbase combinations.
The improved powerplant had its stroke lifted by 10 mm while the bore remained the same. The displacement was lifted to 12.6 litres which resulted in increased horsepower and torque. For military variants the engines were capable of running on alternative fuels (mixtures of diesel fuel, gasoline and or aviation kerosine fuel), albeit with a performance loss. The air cooling system was retained once again with the cooling fan driven via hydraulic clutch and engine oil temperature controlled. The fuel injection pumps featured different types variable or combination governors depending on the vehicle application.
