Fork lift trucks: cleaner and quieter thanks to computer simulation

The increasing integration of new functions and components into fork lift trucks poses a challenge for engineers as they need to use existing installation space intelligently. This was also the case at Linde Material Handling (LMH), where the Fork Lift Series 392 and 393 were to come onto the market with upgraded models. To make this possible, the engineers had to replace the resonator in the combustion engine to make room for additional components. LMH sought assistance for this project from TECOSIM, the specialist in numerical calculation and simulation.



Use of computational fluid dynamics
A clean air resonator is used to minimise noise and absorb sound. This sound absorber was to be housed in a smaller installation space in the future fork lift models. It was only permitted to be a third the size of its predecessor, but needed to be equally efficient at reducing noise and, what’s more, over a large frequency band of 30 to 200 hertz. 

Such development would have been tedious and costly using conventional methods. That’s why Linde Materials Handling commissioned TECOSIM to design the new resonator with the aid of computer-aided engineering (CAE). LMH was already familiar with the engineering company’s expertise, which it valued highly, due to previous projects involving the optimisation of air ducts for engine cooling and heat removal.

Computational fluid dynamics played a major role in the development of the new resonator. As sound basically consists of air molecules moving and the changes in pressure that this movement causes, such methods were highly suitable for this project.

Development of a special method
TECOSIM engineers developed a special method to verify the effectiveness of the resonator over the whole frequency range quickly and reliably. The simulation involves vibrating the intake system on the engine side over a wide range of frequencies. On the other side of the intake system, the ‘environmental side’, the incoming data is reconverted into frequencies with their corresponding oscillations (sound levels). 

When this process was verified as part of an undergraduate project, it was shown that the system’s natural frequencies can be determined precisely to within one hertz.  

A small, dedicated team of TECOSIM engineers produced a design which met specifications within three months. 

The initial tests on a prototype which followed the successful resonator simulation confirmed that the computer calculations matched the characteristics of the finished product exactly. The resonator now only requires a third of its former installation space to provide the same level of performance. This project has enabled TECOSIM to help its customer Linde to make its product cleaner and quieter. What’s more, the new process can be used to simulate complex acoustic systems in a wide range of industries.

Quieter, more efficient and more environmentally friendly for industry, the new clean resonator at a glance:


  • Task: due to new functions and components, the clean air resonator needed to fit into a far smaller installation space
  • Data calculation and interpretation using computational fluid dynamics
  • Result: the new sound absorber is only a third of its previous size and half as heavy, yet just as efficient