Recent technological advances in electronics have strongly affected the medium and heavy duty truck industries. Modern truck engines supply much higher torques over a wider range of rotational speeds than their predecessors of just a few years ago. Drivetrains with “new generation” engines and “old generation” clutches most often have resonances that are spread over the entire operating range. Consequently, these powertrains experience large torsional oscillations accompanied by considerable dynamic overloads. This implies a special responsibility binding clutch manufacturers. New clutches must not only have higher torque capacities, much lower damper rates and longer working travels, but they also must be packaged in the very limited environment allowed by the old designs.
Newly redesigned LTD discs produced by the Meritor Clutch Company meet these new demands. As a modular product the LTD disc has been designed to comply with today's rigorous dynamic requirements. Smoothing dynamic loads while being very robust, it will enhance the performance of the entire drivetrain.
This paper not only describes the modifications and new features of the product, but also chronicles an investigative effort that was undertaken to research deficiencies in existing designs, such as frequent fatigue failures and the excessive wear of the clutch and other drivetrain components. Special considerations are devoted to issues of non-parallel compression of the damper springs and to the design of the spring to pocket interface, including transformations associated with dynamic deflections within the damper. Emphasis is placed on the degree to which computer aided engineering techniques were employed during the design process.
In conclusion, the paper discusses current trends in the truck industry. Especially highlighted is the unquestionable propagation of a systems engineering approach, which will be followed by changes in the way automotive products are designed.