Pneumatic clutch actuator

JasonG

Well-known member
Has anyone put a brake treadle in place of a hydraulic clutch master cylinder. Then used a small brake pot on the clutch lever on the transmission?
By adjusting the size of the brake pot and the air pressure the feel could be made to be decently acceptable.
A stop solenoid, like a high idle plunger, could be used to prevent the clutch brake from being activated.

So, am I crazy or a genius?
 

Truck Shop

Well-known member
Don't know that I have seen that except for operating a PTO. Your not crazy, what are you trying to do?

Truck Shop
 

JasonG

Well-known member
Well, Couple of things.
Lighter clutch, though I float most of the time anyway.
I think it would be cool to have a thumb switch for the clutch on the shifter.
 

Truck Shop

Well-known member
I don't know if the timing would work out, there's something about hand, eye and foot coordination that works too well with a manual trans. Basically what you
would achieve is a semi automatic trans. I don't know other than that. I suppose it could work but it would take a lot of work.

Truck Shop
 

Longhood

Well-known member
Well, Couple of things.
Lighter clutch, though I float most of the time anyway.
I think it would be cool to have a thumb switch for the clutch on the shifter.
Some Crane carriers have pneumatic controls in the crane cab for moving the chassis from the crane cab, they are usually fairly effective, although you have no way to feather the clutch.

if you used a treadle valve you should be able to feather, I really don't think that you would have a lot of luck shifting, but then double clutching is a really fast route to drives hafts on the road anyway.

If nothing else you would have a good theft deterrent.

the only hick up that I see right away is the input shaft brake, how would you prevent full linkage travel??
 

JasonG

Well-known member
Snip/

the only hick up that I see right away is the input shaft brake, how would you prevent full linkage travel??
A stop solenoid, like a high idle plunger, could be used to prevent the clutch brake from being activated.
 

rzucker

Well-known member
A stop solenoid, like a high idle plunger, could be used to prevent the clutch brake from being activated.
The other possibility would be to use a pto opening trans brake to get it into gear and float shift from there. I drove an old IH Fleetstar with a huge gas engine and a 10 spd that had the clutch brake button on the shifter and it worked pretty well.
But I think you would still need an adjustable stop to keep from pulling the center out of your clutch. Or at least a new input shaft clutch brake with the internal tangs ground off as spacer.
 

Longhood

Well-known member
Well I guess the next step would be to measure the force required to move your clutch through it's stroke and then start building a mock up to see how things work, I think that I still have the air pot and some other pieces that I removed from a link belt crane at it's owners request. I have also seen several sizes of air cylinder that could be used as your stroke stop for the input brake.
 

JasonG

Well-known member
Hmm, a small switch at the bottom of where the pedal hits the floor could retract the solenoid allowing the input shaft brake to grab.
The button on the shifter would only disengage the clutch.
Tell me again why I don't just go buy an Autoshift???
 

rzucker

Well-known member
Tell me again why I don't just go buy an Autoshift???
Because the first time that clutch brake won't stop the input shaft, you're stuck... it ain't going into gear. I've rescued about 5 trucks stuck at red lights and stop signs due to clutch brake adjustments. Farmer friend of mine bought 6 Freightliners with auto 10s for field trucks. they lasted one season and got replaced. Told him so.
 

Truck Shop

Well-known member
Because the first time that clutch brake won't stop the input shaft, you're stuck... it ain't going into gear. I've rescued about 5 trucks stuck at red lights and stop signs due to clutch brake adjustments. Farmer friend of mine bought 6 Freightliners with auto 10s for field trucks. they lasted one season and got replaced. Told him so.
You summed up what a pile auto shifts are real well. You ought to see the trouble shooting manual for auto shift, looks like the tax code.

Truck Shop
 

rzucker

Well-known member
You summed up what a pile auto shifts are real well. You ought to see the trouble shooting manual for auto shift, looks like the tax code.

Truck Shop
I have. Never had to deal with one that didn't have the clutch pedal, been told those are super useless.
 
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