Little Engines "old" Atlantic?

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Harlock
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Little Engines "old" Atlantic?

Post by Harlock » Thu Aug 18, 2016 11:10 pm

Was there ever an 'old' Atlantic casting set that was different or more complete / expensive than the current one?

I've got an engine here finished in the late 70s that someone is claiming is different / better than the current offerings. I have no idea if there is any truth behind that so I'd love to hear your input. If the answer is 'no' then OK. If it's 'yes' then I'll post some pics of it to verify.

-M
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Miserlou57
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Re: Little Engines "old" Atlantic?

Post by Miserlou57 » Thu Aug 18, 2016 11:32 pm

Can't say with any certainty, but I think from prior discussion hearing the Atlantic/Pacific line changed from inside to outside admission (or vice versa), perhaps in the 80s?. Possibly related, I thought these engines had slide valves disguised in there, but the castings nowadays sure look piston valve.

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Trainman4602
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Re: Little Engines "old" Atlantic?

Post by Trainman4602 » Fri Aug 19, 2016 5:59 am

They are outside admission piston valves. This was done in order to keep the original valve gear. The thing is that there is pressure on the valve steam was as with conventional piston valves the stem has exhaust pressure or no pressure on it.

I may add the outside admission valve has less pressure them a slide valve as the pressure is equal all around the valve rather then pushing down on top of it.
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Re: Little Engines "old" Atlantic?

Post by Soot n' Cinders » Fri Aug 19, 2016 1:07 pm

If what Dave is saying is correct about the current LE Atlantic, then they have changed since the 70s. I have a friend who started his in '75 and it has slide valves with the steam chests cast to mimic the look of piston valves.
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Highiron
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Re: Little Engines "old" Atlantic?

Post by Highiron » Fri Aug 19, 2016 2:27 pm

Okay...lets set this straight

The Atlantic was the second designed 1-1/2" scale Little Engines loco in the 50's

as many know it ha a 1 piece cylinder block with "D" valves and a steam chest that when jacketed gave it a piston valve appearance

This remained this way until about 1983 to 85 (I have been unable to clarify the actual change date) when Moody Braun decided to opt for a 3 piece cylinder block with OUTSIDE admission piston valves.
eeThis block is a direct replacement/upgrade from the original block.e
The original valve liner design was flawed and had corrections made in the late 80's

With all the records I have there is no indication or evidence of there being a more complete or more expensive 4-4-2

the original 4-4-2 was based on the 3000 class SP Atlantics as was the 1" scale version

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Harlock
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Re: Little Engines "old" Atlantic?

Post by Harlock » Fri Aug 19, 2016 2:27 pm

Soot n' Cinders wrote:If what Dave is saying is correct about the current LE Atlantic, then they have changed since the 70s. I have a friend who started his in '75 and it has slide valves with the steam chests cast to mimic the look of piston valves.
Is there a way to tell without opening the chest? Perhaps by looking at the travel of the valve? A real piston valve should have a shorter travel, yes?
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JKreider
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Re: Little Engines "old" Atlantic?

Post by JKreider » Fri Aug 19, 2016 2:52 pm

Outside admission valves on a locomotive with outside valve gear require that the eccentric crank be set 90 degrees from where it would be with inside admission valves. The eccentric rod pin therefore leads the main pin instead of following it in forward motion. To me this gives the eccentric crank and eccentric rod kind of a lop-sided motion compared to the prototype, and a model equipped with inside admission valves.
Martin Lewis started this because he had inexperienced builders trying to fit round valves liners in a round hole without the proper fit and thus making the liner egg shaped. You were never going to get a piston valve to seal under those conditions. His idea was that a flat slide valve was easier to make seal. His point that the valves would wear in is true but at the expense of the valve gear wearing out much quicker because, as was pointed out, the greatly increased forces required to move the unbalanced outside admission slide valve.
Also on the slide valve, the radius rod on Walchearts gear (or valve rod on Baker gear) connects below the valve crosshead pin on the combination lever instead of on top as per the prototype.
Moodie Braun simply converted the slide valves to an outside admission piston valve with his three piece design, thus requiring no change to the valve gear.

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slsf1060
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Re: Little Engines "old" Atlantic?

Post by slsf1060 » Sat Aug 20, 2016 4:47 pm

Harlock wrote:
Soot n' Cinders wrote:If what Dave is saying is correct about the current LE Atlantic, then they have changed since the 70s. I have a friend who started his in '75 and it has slide valves with the steam chests cast to mimic the look of piston valves.
Is there a way to tell without opening the chest? Perhaps by looking at the travel of the valve? A real piston valve should have a shorter travel, yes?

Try looking at the front or back of the cylinder casting inside of whatever jacket liner you see. Examine the area between the round decorative covers for the main piston and "valve piston". If you have a slide valve engine you will see a horizontal part line between the halves. If you have a piston valve engine the block casting will be one piece.
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kenrinc
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Re: Little Engines "old" Atlantic?

Post by kenrinc » Sat Aug 20, 2016 6:50 pm

Mike,

It's tough to tell without removing at least the outside jacket or at least removing a few of the jacket screws and peering in. The chest design on the D-valve cylinders is very distinctive and easily identified. If you have or can get a hold of a pre-80 LE catalog there are some good pictures in there showing what the valve chests look like. There is a small seam between the valve chest and the lower cylinder.

$.02

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kenrinc
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Re: Little Engines "old" Atlantic?

Post by kenrinc » Sat Aug 20, 2016 7:09 pm

Mike,

I found a photo in my library that shows the D-valve block. May be tough to see with these 1024 px requirements.

Ken-
LE442.jpg

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slsf1060
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Re: Little Engines "old" Atlantic?

Post by slsf1060 » Sat Aug 20, 2016 7:46 pm

kenrinc wrote:Mike,

I found a photo in my library that shows the D-valve block. May be tough to see with these 1024 px requirements.

Ken-
LE442.jpg

There 'ya go.
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Harlock
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Re: Little Engines "old" Atlantic?

Post by Harlock » Sat Aug 20, 2016 11:04 pm

Hi all,

thanks for the enlightening feedback. Words from elsewhere also bolstered what was said here about the timeline of the slide valve vs. piston valve at LE.

Today I pulled one of the covers off and confirmed that it is the slide valve. Here it is. Quite clever really.

-M
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