Author Topic: Air Motor Starters  (Read 1150 times)

magneto man

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Air Motor Starters
« on: May 21, 2020, 07:54:45 AM »
Has anyone got experience of using an airmotor to start various old single cylinder engines? I have seen a device being used to start F1 cars by shoving it into the engine rear, then applying air the detaching the device. Some thing like this would be great for firing up these engines as one get older, and finds turning them over getting more and more difficult.  It would need to be detachable so that it covered various engines.
What would be a likely HP and torque requirement say to start a Lister CS. As the compression can be removed there should not be too much load initially!
Any comments? cheers

magneto man

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Re: Air Motor Starters
« Reply #1 on: May 22, 2020, 09:40:45 AM »
Thank you GLORT, food for thought.
cheers

MM

multis6

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Re: Air Motor Starters
« Reply #2 on: November 08, 2021, 10:07:47 AM »
I have a Metro 12/2 and have tried to add an air motor to assist on starting. The motor in the photos is a used motor but still serviceable. I had set it up so that the motor was hinged so that lifting the rear of the set up with a 2x4 would engage the motor wheel to the flywheel. With the set up seen the air motor was not strong enough at 100lbs air pressure to turn the 12/2 over. I had high hopes that this would help my aging back, but not so.   

mobile_bob

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Re: Air Motor Starters
« Reply #3 on: November 08, 2021, 04:02:58 PM »
have you tried spinning the motor up with the compression release?
if you use the release you should be able to spin the motor up fast enough, and develop enough inertia to start the engine.

i assume you engine has a compression release?  if not, no wonder your back hurts!

;)

bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

BruceM

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Re: Air Motor Starters
« Reply #4 on: November 09, 2021, 07:52:36 AM »
I've been using a Gast 4AM motor with rubber roller on my Listeroid 6/1, as part of remote start automation.  It has enough power if the engine is decompressed for cranking up to speed.  I run the pressure at 110 psi.  An air cylinder lifts the assembly into the flywheel, while another air cylinder lifts the exhaust valve, and another closes the injector rack.  I used air since running an air compressor was a major role for this C/1.  It has worked reliably for over 12 years and about 3500 running hours.

Air motors don't have great torque at lower rpm like electric motors; they only generate the rated torque at maximum rated RPM.  So they aren't the most powerful starters.  Several forum members have made rubber roller electric starters that are quite powerful. I'd look into that if I was adding a starter to a 12-2,  or a belt driven starter-alternator.

The Gast 4AM motors require 1/2" ID hose, high flow fittings and a very low restriction exhaust.  I use a garden tractor muffer outside my engine shed, a short length of 1/2 hose. They eat a lot of air; 42 CFM at 80 psi and 2000 rpm.  The air requirements of the 6AM and above are so fricking huge (132 CFM at 100 psi and 3000 rpm for the rated 4 hp)) that no normal shop air plumbing would suffice.  I got a real education by putting pressure gauges at inlet and outlet of a 4AM while running.  It demonstrated that due to flow restrictions at standard air fitting, and stock muffler, I wasn't getting even 45 psi differential pressure while starting at 120 PSI from a high capacity regulator but standard 1/4 air fittings,  So I switched to 1/2 high flow fittings and low restriction muffler, and va-voom, the 4AM was not so gutless after all.  The 6AM motors and above aren't useful with normal home/automotive air setups.  They just need too much air flow, and starting torque will still be pathetic. You'd likely do better with a geared version of a 4AM. 

https://gastmfg.com/sites/default/files/2019-07/std132.pdf

I have had problems with air leakage and condensate corrosion with my air system for the Lister.  I solved the condensate issue by adding an oversized water separator.  If I was starting over I'd add a transmisson oil cooler to the air compressor output, followed by a big Astro separator with auto drain at low pressure.  That's what I used on my more recently added electric air compressor and it's been problem free.

Best Wishes,
Bruce





« Last Edit: November 10, 2021, 10:46:41 PM by BruceM »