FYI: How pressure plates work

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theholycow
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FYI: How pressure plates work

Post by theholycow »

I found a couple interesting exploded views.

Image
Image

The second one doesn't seem to show pivots but seems to have a better diaphragm spring picture.
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Re: FYI: How pressure plates work

Post by LHOswald »

the only one that made sense to me was the one on howstuffworks. once you see how it all moves you just go "oooh now it makes sense...duh"
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Re: FYI: How pressure plates work

Post by mtheis »

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Re: FYI: How pressure plates work

Post by LHOswald »

yeah what he said
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Re: FYI: How pressure plates work

Post by theholycow »

That one tells how a clutch system works, but it didn't explain how a pressure plate works.

Here's what caused me to look it up:

After reading HowStuffWorks and every other explanation, I was left with the impression that when you step on the third pedal the release bearing pulls the clutch disc away from the flywheel or pulls the pressure plate away from the clutch disc.

However, while putting together my clutch I could see that when you step on the pedal the release bearing pushes on the clutch cover assembly. I couldn't figure out how that would remove pressure instead of adding pressure. The only thing I could think of would be some kind of pivot but staring at the assembly I was unable to identify it.

The drawings I posted filled in the missing info for me.
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Re: FYI: How pressure plates work

Post by Rope-Pusher »

^ and the straps help pull the pressure plate away from the clutch disk and torsionally link it to the cover.
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Re: FYI: How pressure plates work

Post by theholycow »

Ah, an even better picture:
Image

The same site where I found that also explained what those little coil springs in the clutch disc are. The hub is connected to the friction material via those springs; the springs cushion clutch engagement by compressing.
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Re: FYI: How pressure plates work

Post by Rope-Pusher »

Image

Ready for understanding self-adjusting clutch covers now?

The cover adjusts the geometry of the pivot for the diaphragm spring, so the clutch pedal effort remains fairly constant for the life of the vehicle instead of increasing over time as the clutch disk wears thinner.
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Re: FYI: How pressure plates work

Post by theholycow »

Wouldn't self-adjusting hydraulic clutch actuation make that obsolete?
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Re: FYI: How pressure plates work

Post by Rope-Pusher »

theholycow wrote:Wouldn't self-adjusting hydraulic clutch actuation make that obsolete?
The hydraulic self adjust will make up for any changes to the required range of motion of the release bearing due to clutch disk wear or system component tolerances, but a self-adjusting clutch cover will keep the diaphragm spring geometry relatively constant throughout the life of the clutch. Normally, as the clutch disk wears, the pressure plate moves closer to the flywheel and the diaphragm spring fingers move away from the flywheel and the geometry of the fingers to the release bearing and the fingers to the pressure plate changes and results in increased pedal force being required to release the Kraken.
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