The man behind the modular system

While it is impossible to credit any single individual as the originator of Scania’s much-admired modular product system, there is no doubt that the company’s first technical director Sverker Sjöström played an important role.

During the early 1950s, Scania-Vabis’ component and material deliveries from Germany and elsewhere left much to be desired. The situation became so critical that the company was forced to suspend much of its new vehicle and engine development work. Components were incorrectly dimensioned and materials were faulty or not fully tested, which led to under- or over-dimensioning of parts and components.

To tackle these quality problems, Scania-Vabis turned to newly recruited Sverker Sjöström, a 27-year old Licentiate of Technology in engineering physics from the Royal Institute of Technology in Stockholm and an expert on strength of materials.

Sjöström began systematically reviewing the stresses that trucks were subjected to in practical operation. “The results of these measurements often turned upside down then-prevailing perceptions of how to calculate the strength of a given component,” Sjöström said in an interview in 2004. “In those days, computational practices were based on calculating the strength of a component under static loads without reference to actual use. We were forced to re-assess this.”

“The prevailing view at that time, for example, was to have one axle gear for each engine size, regardless of application. According to our new findings, this was totally wrong. Engine power was of negligible importance. It was the gross vehicle weight and the topography of the transport route that were the main dimensioning factors.”

In 1961 Sjöström became Scania-Vabis’ first technical director. From the 1960s onward, truck production rose dramatically and Scania-Vabis exported a growing share of its products. Meanwhile, trucks were becoming more complex. Customers became increasingly demanding and trucks often had to operate in completely new settings.

“This created a need for classification of different truck applications,” Dr Sjöström said. “With carefully balanced strength steps in the various component types, we could then satisfy varying customer needs with a limited number of components. This also led to a reduction of the weight of the final product.”

Scania’s competitors argued that it was impossible to create an effective modular system, but Scania’s focus on heavy vehicles was crucial. Subsequent progress was based on constructive teamwork within the company’s Research & Development units.

“Together we worked out the GPRT range, with our own cab and frame production units. The concepts began emerging in the late 1960s when we were working with new cabs. We reached a consensus: if we could produce an entirely new range, how would it look?”

The first model in the new fully modularised truck range was the bonneted T truck, unveiled in April 1980.

The complete GPRT range, based on four cab types, was also called the 2-series and was unveiled in December 1980.

The new range was divided into three main duty classes: M (medium duty), H (heavy duty) and E (extra heavy duty) based on the use of the truck.

The new truck range achieved what can almost be called perfection when it comes to modularisation. From a limited number of main components, Scania was able to create an almost limitless number of truck variants, adapted to the special needs of individual customers.