Timing Chain Tensioner Piston

[cda951]

1 hour ago, jimk said:

I believe the name "tensioner" is a misnomer because it can't possible apply any appreciable tension on the chain.  It only keeps the chain from flopping (from the slack) in the non-driven side.

 

It is an elegantly simple device, same principle is used on almost any timing chain tensioner in modern engines. Of course lack of maintenance on modern engines such as the BMW N20/N26 and VW/Audi 2.0T causes a lot of issues with timing chain drives, but that's a different story . . . .

 

The timing belt de-tensioner used on the Busso V6 of my Alfa GTV-6 is operates via a similar principle, but is more complicated because it is attempting to maintain a constant tension on the belt regardless of engine temperature. It also needs a constant supply of pressurized oil, so leaks are commonplace. 

 

US4077272A - Device for the automatic regulation of the tension of a crenellated timing belt - Google Patents

PATENTS.GOOGLE.COM

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In an internal combustion engine having a timing system which employs a crenellated or toothed timing belt and the lubrication is carried out under a substantial oil pressure, a device for maintaining the tension of said belt as close as possible to the initial calibration value, said...

 

 

Edited December 4, 2022 by cda951

[2002#3]

Toby, Jim, and Tommy,

     Thank you for elegant, comprehensive, and clear explanations of TC piston function.  You're right, Toby, "It's kind of elegant." and Jim, Tommy, and Chris, it's really is quite simple.  I expect many FAQers will find the info as useful as I did.  When I install the piston in my rebuild I now will be dangerously educated.

Larry