Auto Service World
News   January 26, 2004   by Auto Service World

Plastics Making Inroads In Braking System

General Motors’ next generation of mid- size trucks benefit from a new lightweight, highly effective brake system vacuum booster self-retaining spacer made of DuPont Hytrel thermoplastic polyester elastomer.
The spacer sits between a vehicle’s firewall and brake system to help position brake components. The innovative vacuum booster spacer, designed and developed by Delphi Corporation, helps significantly reduce assembly time, dramatically reduces weight and offers performance advantages over the existing spacer. The spacer design and material allows the vacuum booster to be mounted securely and sealed against the engine compartment wall.
“Helping to reduce component weight and improving the design for assembly without sacrificing performance are crucial industry-wide goals, and this application meets all these objectives,” said Michel J. Vermoesen, the senior project engineer at Delphi Energy & Chassis. Retaining tabs made of DuPont Hytrel significantly facilitate assembly by reducing the necessary force to install the spacer while ensuring it is attached correctly.
The tabs, located at the base of four over-moulded metal inserts, align the spacer properly with the booster attachment studs and allow the spacer to remain securely attached to the booster during shipping. This thermoplastic spacer replaces heavier and more commonly known two- piece metal alloy components and eliminates the need for sealing adhesive gaskets.
The one-piece design utilizes the excellent flexibility and strength of Hytrel to incorporate primary and secondary sealing lips to better isolate the passenger compartment from the engine compartment. Hytrel retains its physical properties which reduces dimensional variations, helping to maintain sealing performance while addressing temperature requirements. The compact design of the spacer also meets underhood packaging challenges.
“The outstanding physical properties of Hytrel combined with DuPont material and technical knowledge augment Delphi’s innovative spacer design, demonstrating the value of collaboration throughout the entire development process,” said Ken Hines of DuPont Engineering Polymers.

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