Banded seals for hydraulic automotive shock absorber pistons
27 June 2008
Engineers at Trelleborg Sealing Solutions have come up with an alternative to the traditional method of sealing the pistons of car shock absorbers. In this new process, a flat disc of Turcon PTFE based material is pulled over the piston using a special assembly machine that was engineered and developed by the company.
A car’s shock absorber includes a hydraulic piston, which moves within the absorber housing and damps the vibration from the road. The piston needs a seal to enable the shock absorber to perform. Traditionally a band of PTFE based sealing material is wrapped around the piston manually. The disadvantage of this method is that it tends to be time consuming and it is difficult to achieve high volume throughput.
The machined thin disc of Turcon incorporates a lip, providing enhanced friction characteristics. This improves the resistance to wear and overall performance of the shock absorber.
The bronze-filled Turcon material can operate in temperatures from -40°C/-40°F to above 120°C/248°F at peak pressures of 8MPa/1160 psi with a linear movement of up to 3m/sec/10 ft/sec. This provides long seal life, contributing to shock absorbers that can meet the demands from car manufacturers of one hundred thousand kilometers (sixty two thousand miles) before replacement.
Trelleborg has also introduced a colour coding system for O-rings to improve the identification of seals that may be similar in size but composed of differnet materials. The coatings will not crack or peel and are said to reduce friction during installation.
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