Author Topic: Greene Automatic Cutoff Steam Engine  (Read 29031 times)

Offline Dennis

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Re: Greene Automatic Cutoff Steam Engine
« Reply #435 on: December 07, 2020, 03:12:42 PM »
Glad to see you making progress again.

Dennis

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #436 on: January 24, 2021, 07:29:31 PM »
After a large number of valve adjustments that resulted in the engine making 1-3 turns at best, I located one problem that may be the key.  The input valve rods are connected to a yoke with a slot in which lives a small bronze slide. The slide has a .125" hole for a pin that is supposed to be threaded 3-48 on each end.  The pin is rotated by a clevis on the actuator rod.

As it happens, I was apparently fooled by the SW model showing the 3-48 nut that I used a 3-48 pin.   :hammerbash:  This results in significant lost motion meaning the input valve moves only a fraction of the distance it should.  Apparently I did it corrctly on the head side valve.  Short term, I'll use a 5-40 screw that "ought" to fix it, and hopefully I'll someday get a run video.

I found a local woodworker who's committed to making me a base from some brown stuff, and I hope to get it in the next week or so.

Offline Admiral_dk

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Re: Greene Automatic Cutoff Steam Engine
« Reply #437 on: January 24, 2021, 08:20:16 PM »
It will be great if it turns out to be the solution  :cheers:

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #438 on: January 25, 2021, 01:24:43 PM »
Alas it wasn't.  But that valve's motion is now much smoother.

Offline Dennis

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Re: Greene Automatic Cutoff Steam Engine
« Reply #439 on: January 26, 2021, 05:04:01 PM »
Kirk, good to see you back on line, I was beginning to worry.

It sounds like you have checked and rechecked the valve mechanism many times,  have you looked at the eccentrics?  I remember early on a  builder of this model found his eccentrics were off by 180 degrees.  Also, the two eccentrics are out of phase by 90 degrees because of the motion to open and close the exhaust. 

I know you are very meticulous in tracing the valve movements so if I am stating the obvious, I apologize.  The Green Engine valve mechanism is fussy to get adjusted correctly, however, I haven't heard of any problems from other Green engine builders getting their models to run.

Dennis


Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #440 on: January 27, 2021, 12:56:16 PM »
Dennis,

The reverse eccentric is either at the top or bottom of its lift when the input eccentric is at the end of the stroke, but I don't see it matters which way.  Since the exhaust clevises have one above the bracket and the other below, the reverse valve motions are opposite.

I've found that the angle of the clevis with the bracket has a big impact on the valve travel, and with the angle set pretty close to 30 degrees, I needed to adjust the length of the valve rod as well. 

I'm only going into the shop one day a week as we have a lot of home renovation in the works.