Author Topic: Chris's Marion 91 Steam Shovel  (Read 317352 times)

Offline Kim

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Re: Chris's Marion 91 Steam Shovel
« Reply #480 on: January 08, 2018, 05:45:37 AM »
I came up with 8:1.  Lever D looks like about 4:1, and cross bar connected to the latch (A) looks like 2:1.  That gave me 8:1.  Is there something else I'm missing? Or maybe I miscalculated?

Still, that's a pretty good advantage!

And how was the chain pulled?  Was it on the end of a lever also, to give some additional help?
Kim

Offline 10KPete

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Re: Chris's Marion 91 Steam Shovel
« Reply #481 on: January 08, 2018, 07:17:36 AM »
8 to one is shorter stroke for the guy pulling the rope but 12 to one means he doesn't have to pull as hard. If you assume the latch bolt moves an inch then the 8 to 12 inch distance to pull the rope is very reasonable.

There's some pretty cool engineering exhibited there.

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Offline Farmboy

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Re: Chris's Marion 91 Steam Shovel
« Reply #482 on: January 08, 2018, 09:20:18 AM »
Hi Chris. I am an avid follower of your work, although a novice in model engineering. However I do have a lifetime's experience in using various farm machinery.

Looking at your amazing 3D drawing of the bucket latch I wonder if there is a link missing at point B. On the photo of the full size bucket I had the impression of a short link which would allow the bolt to be drawn without any sideways movement which would be induced by the arc of the first lever if it pivots from a fixed point. I may well be wrong as it is not easy to see the detail clearly on the photo, in which case I hope you will forgive my intervention. I feel a bit like I'm telling God he made a mistake  :NotWorthy:

Mike.

Offline Admiral_dk

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Re: Chris's Marion 91 Steam Shovel
« Reply #483 on: January 08, 2018, 11:25:25 AM »
I would dare to say that you have lever F fixed in each end and therefore not doing anything .... one end should be point B that isn't fixed - if I interpretere the picture right ....

Best wishes

Per

Offline scc

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Re: Chris's Marion 91 Steam Shovel
« Reply #484 on: January 08, 2018, 11:54:40 AM »
The Lombard was epic enough, but I am enjoying this build even more!  Chris, how do you find the time to make such rapid progress?

Excellent thread     Thank You.           Terry

Offline Farmboy

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Re: Chris's Marion 91 Steam Shovel
« Reply #485 on: January 08, 2018, 12:16:42 PM »
Per,

Going back to the original photo (full size bucket) my impression was that Link F was actually a fixed guide bar for Lever D but there appears to be a short link, mostly concealed by Link F, which acts as a floating fulcrum for the lever connected to Latch Bolt A to prevent it binding due to sideways pressure.

Mike.

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #486 on: January 08, 2018, 03:30:08 PM »
That looks like about 12:1 total. How far into the latch hole does the bolt go??

Pete
It only goes in an inch or inch and a half.

Online Flyboy Jim

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Re: Chris's Marion 91 Steam Shovel
« Reply #487 on: January 08, 2018, 03:32:16 PM »
Did the release rope go directly to the cab? It occurred to me that, if it went up to a pulley on the boom, the bucket could be tilted such that the bottom moved somewhat vertical which would reduce the load that the "puller dude" had to work against.
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Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #488 on: January 08, 2018, 03:32:34 PM »
I came up with 8:1.  Lever D looks like about 4:1, and cross bar connected to the latch (A) looks like 2:1.  That gave me 8:1.  Is there something else I'm missing? Or maybe I miscalculated?

Still, that's a pretty good advantage!

And how was the chain pulled?  Was it on the end of a lever also, to give some additional help?
Kim
The chain goes back to lever E, at the bottom of E, which just hangs from the boom, would be a rope going back to the operator.

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #489 on: January 08, 2018, 03:38:10 PM »
Hi Chris. I am an avid follower of your work, although a novice in model engineering. However I do have a lifetime's experience in using various farm machinery.

Looking at your amazing 3D drawing of the bucket latch I wonder if there is a link missing at point B. On the photo of the full size bucket I had the impression of a short link which would allow the bolt to be drawn without any sideways movement which would be induced by the arc of the first lever if it pivots from a fixed point. I may well be wrong as it is not easy to see the detail clearly on the photo, in which case I hope you will forgive my intervention. I feel a bit like I'm telling God he made a mistake  :NotWorthy:

Mike.
There was no short link at B, they just had that pin be a loose fit in the hole. Can't tell from that picture, but I checked that when I was there, that last hole was an oval to allow the slight side movement. You are right that it would bind if it was a close fit. What looks like a short bar in the photo is where the main bar narrows to the first link b.

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #490 on: January 08, 2018, 03:40:05 PM »
I would dare to say that you have lever F fixed in each end and therefore not doing anything .... one end should be point B that isn't fixed - if I interpretere the picture right ....

Best wishes

Per
Bar F is just a guide to keep bar  D from sagging down out of line, it is not part of the linkage itself.

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #491 on: January 08, 2018, 03:40:57 PM »
The Lombard was epic enough, but I am enjoying this build even more!  Chris, how do you find the time to make such rapid progress?

Excellent thread     Thank You.           Terry
One word. Retirement!!

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #492 on: January 08, 2018, 03:54:46 PM »
Per,

Going back to the original photo (full size bucket) my impression was that Link F was actually a fixed guide bar for Lever D but there appears to be a short link, mostly concealed by Link F, which acts as a floating fulcrum for the lever connected to Latch Bolt A to prevent it binding due to sideways pressure.

Mike.
Hmmm... just went back to the photo sets, and I think you are right! I had not noticed that short link before, with all the lumps of the tar that they sprayed it with. I'll go update the 3D model on that! Thanks, that is a sharp eye to pick that up! I had thought it was just the mount post under bar F, but there is another layer there.
 :cheers:

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #493 on: January 08, 2018, 04:23:26 PM »
Here is the 3D model updated with the new link - thanks for picking that up guys, took me a while to find what you guys were looking at!

Offline b.lindsey

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Re: Chris's Marion 91 Steam Shovel
« Reply #494 on: January 08, 2018, 04:31:00 PM »
I think you have it now Chris. That small link does make some sense. Even back in the day those designers were pretty sharp. It actually amazes me how much of that we have lost over the years.

Bill