Federal-Mogul Powertrain unveils new Unipiston® technology
Federal-Mogul Powertrain has unveiled its latest development of its Unipiston® technology: the Unipiston with integrated springs. Suitable for clutch packs in Dual Clutch Transmissions, conventional automatic transmissions and limited slip differentials, the new technology builds on the savings in package space and assembly complexity already achieved by the ground- breaking Unipiston, to provide designers of clutch systems with even greater flexibility and performance.
The Unipiston with integrated springs eliminates separate spring carriers, reducing the axial length requirement that is often a crucial constraint in pistons for multi-plate clutch packs. Federal-Mogul is first to bring this technology to market and the additional design freedom it provides allows the selection of a better spring force characteristic, a reduction in the spring count, or the use of a more cost-effective spring material.
“The introduction of the original Unipiston by Federal-Mogul was an industry first that helped make clutch pistons more compact and easier to assemble,” said Gian Maria Olivetti, Chief Technology Officer, Federal-Mogul Powertrain. “Now this innovative Unipiston with integrated springs provides even greater advantages allowing our customers to design even more compact and robust transmissions.”
Integrated construction greatly reduces the quality risk that can arise from separate springs, reducing the parts count and assembly operations and simplify logistic for customer. It also improves the guidance provided during transmission assembly, making the process more robust, which is particularly important for blind assemblies.
“The Unipiston with integrated springs removes the need for our customers to undertake a difficult assembly operation that could introduce quality concerns,” explained Cem Yoldjou,
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Technical Specialist, Unipiston & Dynamic Seals, Federal-Mogul Powertrain. “Many clutch systems are closed off by a welding operation following assembly, making it impractical to rectify any quality issues after that point.”
The Unipiston applies hydraulic pressure to a clutch pack to facilitate torque transfer and can be used as an apply piston or a balancer piston closing a hydraulic chamber avoiding unwanted activation of the apply piston. To ensure good transmission ‘feel’ to the driver throughout the life of the vehicle, very tight tolerances on manufacture are required; by integrating the springs, the number of elements in the tolerance stack is lower, making it easier to achieve the necessary accuracy without increased manufacturing cost.
The stroke available from the Unipiston with integrated springs is typically specified within a range from less than one millimetre to several mm. The technology has already been validated with one customer and is expected to enter series production in the near future.
