From design to final testing: This is how we ensure the quality of every Cojali Parts viscous clutch

June 24, 2026

In a cooling system, the reliability of the viscous clutch is essential for maintaining the engine optimal operating temperature. A fault in this component may compromise the vehicle cooling capacity and lead to serious breakdowns.

That is why, at Cojali, we view quality as an ongoing process that extends from design validation through to the final inspection of the finished product.

Dimensional inspection of each component

Quality begins long before assembly. All components received at our premises undergo dimensional checks using co-ordinate measuring machines (CMM), optical inspection equipment, micrometres, etc., which are capable of accurately verifying the critical dimensions and finish of each part.

This process makes it possible to detect any deviations from the tolerances defined during the design stage and to ensure that all parts fit correctly into the final assembly.

Design simulation and validation

Before manufacturing a new viscous clutch, our engineering team digitally validates its performance using advanced simulation tools.

These technologies make it possible to analyse the mechanical strength of critical components, such as the main shaft, and to study their behaviour under different operating conditions. In addition, we use computational fluid dynamics (CFD) tools to optimise airflow and the interaction between the clutch, the fan and the other components of the cooling system.

Test benches and wind tunnel

Once the clutch has been assembled, the functional validation phase begins.

Using specialised test benches, we verify parameters such as the activation temperature, torque transmission capacity, coupling and decoupling speeds, and the behaviour of the fan control system.

Validation is completed with aerodynamic tests in the wind tunnel, where we analyse the combined performance of the fan and the clutch, assessing variables such as the airflow generated, the power absorbed and the overall efficiency of the fan clutch assembly.

End-Of-Line test and traceability

Verification continues throughout the entire production process. Every viscous clutch undergoes quality controls and End-Of-Line tests to ensure it is functioning correctly before dispatch.

Furthermore, all units are linked to a traceability system that makes it possible to identify the components used, the checks carried out and the parameters recorded during their manufacture, providing an additional guarantee both for our internal processes and for our customers.

Quality checked at every stage

By the time a Cojali viscous clutch reaches the market, it has already undergone metrological checks, structural and CFD simulations, functional trials, aerodynamic validations in a wind tunnel, traceability checks and final operational verifications.

The combination of all these stages enables us to offer reliable, durable components that are designed to perform to the highest standards in the most demanding applications.