Author Topic: Air starter  (Read 7211 times)

fabricator

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Air starter
« on: October 09, 2011, 09:41:10 PM »
This was my weekend project, it's a 4 hp air motor, it won't crank against compression but it beats the hell out of cranking :D The plumbing needs to be a little more elegant but it works for now.
BioDiesel Brewer

Billyrob

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Re: Air starter
« Reply #1 on: October 10, 2011, 01:08:35 PM »
Hi Fabricator,

Interesting set up.  I like the air cylinder arrangement to push the starter against the flywheel.

I am curious.   You say that it will not work against full engine compression.    Where does the weak link occur?   Does the air motor stop, or is there slippage on the drive wheel?

I am curious because I hope to fabricate a similar system using a FORD long shaft electric starter.     

What did you use for a drive wheel?

Best regards,

Bill

fabricator

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Re: Air starter
« Reply #2 on: October 10, 2011, 09:53:00 PM »
The wheel is a three inch rubber caster with a cast iron hub, I had to machine an adapter to fit it to the 3/4" shaft on the air motor. There is no slippage the air motor just stalls out when it comes up against compression, I know there are air starters that will start under compression, maybe I just need a bigger air motor.
BioDiesel Brewer

SHIPCHIEF

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Re: Air starter
« Reply #3 on: October 11, 2011, 04:21:28 AM »
I just blew the nose off my Chevy starter. When I didn't let up on the button soon enough, when engine must have sped ahead of the starter and over ran the starter gear and climbed it. Maybe my starter mount isn't stiff enough?
I really like your set up. Do you mind if we copy it?? :laugh:
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fabricator

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Re: Air starter
« Reply #4 on: October 11, 2011, 11:02:25 PM »
Hell no, it's a copy to begin with.
BioDiesel Brewer

Billyrob

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Starter -- Speed ?????
« Reply #5 on: October 14, 2011, 12:38:09 PM »
Does anyone have any idea of how fast (minimum RPM) that the engine must spin to have enough energy to overcome compression (after exhaust valve is released).

If a drive system can not spin the engine fast enough to overcome the compression stroke (after the exhaust valve is released) the engine can not be started.

I hope to use a similar system with a long shaft FORD starter motor.    Knowing the minimum speed requirements will help determine the size of the drive roller to fit on the starter motor.    Too large and the loading on the starter will be high.   Too small and there may not be enough speed (energy in flywheels) to overcome compression after the exhaust valve is released.

I don't think that any rubber roller starter system is capable of starting an engine without compression release.     That may be a good thing, because it requires you to be at the engine at the time of starting.

Cheers !!!

Bill

xyzer

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Re: Starter -- Speed ?????
« Reply #6 on: October 14, 2011, 02:17:02 PM »
I don't think that any rubber roller starter system is capable of starting an engine without compression release.     That may be a good thing, because it requires you to be at the engine at the time of starting.

Cheers !!!

Bill
Rubber wheel 12 volt starter without compression release. It won't do it if it is against compression but if it has a half revoulusion run it does.
 http://www.youtube.com/watch?v=_QmWXNo-Gmg&feature=channel
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fabricator

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Re: Air starter
« Reply #7 on: October 14, 2011, 02:27:19 PM »
Well without a reliable way to stop the engine so the starter has enough of a run at compression it really isn't much good to somebody who wants to automate a battery charging system, don't get me wrong your system is very cool and works great.
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dieselgman

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Re: Air starter
« Reply #8 on: October 14, 2011, 02:41:00 PM »
The SOM sets also had a compression release solenoid as part of the automatic system.

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AdeV

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Re: Air starter
« Reply #9 on: October 14, 2011, 03:49:33 PM »
The SOM sets also had a compression release solenoid as part of the automatic system.

dieselgman

They do, but the solenoid activates (pulls out) as soon as the S-o-M starts motoring, i.e. the starter system will pull through compression, even if it doesn't have a run-up.

My home-made ring-gear based starter (with the ring gear on the alternator) will also pull through compression without a run-up; in "normal" weather (10 deg C +) it will fire if it gets at least a 1/2 turn run up to 1st compression.
Cheers!
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Billyrob

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Re: Starter -- Speed ?????
« Reply #10 on: October 14, 2011, 05:46:34 PM »
I don't think that any rubber roller starter system is capable of starting an engine without compression release.     That may be a good thing, because it requires you to be at the engine at the time of starting.

Cheers !!!

Bill
Rubber wheel 12 volt starter without compression release. It won't do it if it is against compression but if it has a half revoulusion run it does.
 http://www.youtube.com/watch?v=_QmWXNo-Gmg&feature=channel

Xyzer,
That is excactly what I have mind.  Thank You!   The video gives me a good idea of the diameter of the rubber drive wheel.   The foot operated method is a great idea because is leaves the hands free to operate the compression release lever.

I like the fact that the drive wheel is a form of a "clutch" rather than a gear drive.   I am sure it much more forgiving if the engine races ahead of the starter.

I am too old now to be starting these by hand.  :)

Thanks again,

Bill