Author Topic: Bob Herder's Meyers side shaft hit and miss  (Read 5817 times)

Offline Dave Otto

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Re: Bob Herder's Meyers side shaft hit and miss
« Reply #45 on: October 26, 2018, 11:03:13 PM »
Nice work Craig, you have been busy.

Dave

Offline Craig DeShong

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Re: Bob Herder's Meyers side shaft hit and miss
« Reply #46 on: October 29, 2018, 11:32:47 PM »
Thanks for all who have made comments; I really appreciate your responses. 

Iíve had a request from a fellow Mem member, asking me to further explain the governor lock-out mechanism.  Rather than just answer him privately, I thought Iíd post my response here incase others are interested.

The engine incorporates a flyweight governor as I showed above.  This is a photo with the flyweight cover off so you can better see the mechanism.  On the top is the weight hanger and directly below is a doughnut shaped part that is pinned to the weight hanger; Iím pointing to it with the pencil.  It is free to move up and down on the shaft but is carried around with the flyweight hanger by the vertical pin that fits loosely in the weight hanger.



Below the indicated doughnut above is a thin fiber washer that acts as a thrust bearing and below it is another doughnut, similar to the one above.  Iím pointing to it with the pencil in this picture.  It has a pin that points down and is trapped in the bell crank casting below to prevent it being carried around with the flyweights.


The fiber washer transitions the rotary motion of the above doughnut to non-rotary motion in the lower doughnut.  I believe this is done so that the lugs of the bell crank do not excessively wear.  Both doughnuts are free to more vertically, and they do as youíll see.  In the following photo Iím pointing to the bell crank, specifically to the bell crank pivot.  As the bell crank rotates, the lockout lever moves in and out,  trapping the exhaust lever and holding the exhaust valve open when it is in the ďoutĒ position.
 


In this photo, were the engine running, the governor is positioned be at low RPM and the spring on the far end of the bell crank holds the two doughnuts up against the governor weights and the lockout bar in the retracted position.

 

In this photo, Iím holding the governor flyweights out as they would be at high RPM.  The flyweights, through the flyweight holder has driven the two doughnuts down the shaft and this has caused the bell crank to rotate and move the lockout bar in the advanced position where it would hold the exhaust valve open.
   


As you can see, there isn't a lot of movement in this mechanism.
« Last Edit: April 28, 2019, 02:50:18 AM by Craig DeShong »
Craig

Offline MJM460

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Re: Bob Herder's Meyers side shaft hit and miss
« Reply #47 on: October 30, 2018, 08:58:59 AM »
 Hi Craig, I am one of Iam sure many who wanted to know but hesitated to ask.

Thanks for posting such a clear explanation, it all makes sense at last and I feel I now have a better understanding f of how the fascinating mechanism of the hit and miss actually works.

However, I suspect thre is always a lit of fiddling around to balance the force from tiny flyweights and that return spring at an appropriate speed.

Thank you

MJM460
The more I learn, the more I find that I still have to learn!

Offline Brian Rupnow

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Re: Bob Herder's Meyers side shaft hit and miss
« Reply #48 on: October 30, 2018, 02:10:57 PM »
So--the lockbar slips under the tail end of the rocker arm to do it's job.---Right?

Offline Roger B

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Re: Bob Herder's Meyers side shaft hit and miss
« Reply #49 on: October 30, 2018, 05:49:10 PM »
Excellent progress and a good explanation of the valve/timing operation  :ThumbsUp:  :ThumbsUp: Your local miniature railway group seem to offer the passengers much better seating than I remember from England.
Best regards

Roger

Offline Craig DeShong

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Re: Bob Herder's Meyers side shaft hit and miss
« Reply #50 on: October 31, 2018, 12:36:32 AM »
So--the lockbar slips under the tail end of the rocker arm to do it's job.---Right?
Yup
Craig

Offline Brian Rupnow

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Re: Bob Herder's Meyers side shaft hit and miss
« Reply #51 on: November 08, 2018, 08:49:17 PM »
Craig--Maybe I missed it--Did you make those helical miter gears between the crankshaft and sideshaft from scratch or did you buy them?--If you bought them can you tell me where please.---Brian

Offline Craig DeShong

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Re: Bob Herder's Meyers side shaft hit and miss
« Reply #52 on: November 13, 2018, 01:25:45 AM »
Brian, the gears were supplied with the 'KIT'.  They came in packages labeled 'martin', made in USA.  The crankshaft gearcpackage is labeled BS1612-2. The cam gear is labeled BS1624-2.

Btw- i'm making progress on this model... finishing up a bunch of odds-and-ends.  Hope to have it running- sans paint- in a few more days.  When that happens i'll post a video.
Craig

Offline Brian Rupnow

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Re: Bob Herder's Meyers side shaft hit and miss
« Reply #53 on: November 13, 2018, 01:38:41 AM »
Yesterday I ordered a set of helical miter gears from ebay, listed as having a 2:1 ratio. They were metal, and didn't cost much, and appeared to be about the right size. Buying from ebay is a lot like buying a "pig in a poke", so I'll know what I have when they get here.---Brian

Offline Brian Rupnow

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Re: Bob Herder's Meyers side shaft hit and miss
« Reply #54 on: November 14, 2018, 09:16:07 PM »
Craig--I'm going to drive you a little crazy asking questions. Have you got part numbers and/or tooth-counts for the gears that run your governor?--Something is a little strange. The part numbers you gave me are for bevel straight tooth gears, not helical gears. I checked with martin gear using the part numbers  you gave, and I think perhaps those part numbers were for the governor gears. Do you have any other part numbers?---Please---Brian
« Last Edit: November 15, 2018, 01:20:04 AM by Brian Rupnow »

Offline Craig DeShong

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Re: Bob Herder's Meyers side shaft hit and miss
« Reply #55 on: November 16, 2018, 01:38:29 PM »
Brian.  Life has pulled me away from the forum for a few days.  I had saved the gear packages, thinking some future project  might need gears and I was saving for the Martin name only.  I hadn't come across that name in my past searches for gearing.  I had thought these were the camshaft drive gear packages, guess not, sorry for the confusion it caused.  Looks like you have it sorted out from your other post.
Craig

Offline Brian Rupnow

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Re: Bob Herder's Meyers side shaft hit and miss
« Reply #56 on: November 16, 2018, 03:29:45 PM »
Craig--I keep posting questions about your project, then putting on my detective hat and figure them out from all the pictures and videos you have posted. Thank you so much for that.--Brian
« Last Edit: November 16, 2018, 11:47:41 PM by Brian Rupnow »

Offline Craig DeShong

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Re: Bob Herder's Meyers side shaft hit and miss
« Reply #57 on: November 19, 2018, 10:47:04 PM »
Brian- I too usually figure things outÖ after Iíve asked the question.  :-[

Thanks to yíall who have been following along with this build and the interest youíve shown.  Iím about to wrap-up this build; only a few items remaining.

Iíve been busy with non-shop related items over the past week or so; still I managed to get the engine together and running as the video shows.  The engine has a crankshaft pulley, connecting rod oil shield, and tag to be fabricated and attached to the engine as yet before I can call it completely Ďdoneí. 

Along with that is dis-assembly, cleaning, and painting before final assemblyÖ so there are still some items to complete before I can put this model on the shelf and move on to the next project.  :cartwheel:

Craig

Online b.lindsey

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Re: Bob Herder's Meyers side shaft hit and miss
« Reply #58 on: November 19, 2018, 10:57:52 PM »
Wow Craig. That looks and sounds great. Seems like you just started on this one and now it's almost done.  What will the color scheme be?

Bill

Offline zeeprogrammer

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Re: Bob Herder's Meyers side shaft hit and miss
« Reply #59 on: November 19, 2018, 11:08:06 PM »
That looks great. And the base seems to set it off too.  :ThumbsUp:
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