Which one would you buy???
Light Mountain
Heavy Mountain
I would go for light mountain with UP lettering. I hear they’re strong pullers & are easy to convert to DCC.
I have to disagree (sorry!). The N scale light 4-8-2 is almoost universally lamented for its lack of pulling power. I know; I have one. A decent fix involves adding a 0.005" shim above the traction tire driver bearing block; this more than doubles its pulling power.
Out of the box, though, it’s a little weak. Just 5 or 6 cars before slipping. After I modified mine I can get 15-18 cars; much better. Part of that was because I also added a new (PRR-style) boiler that allowed room for more weight over the drivers.
Okay. Then get the unlettered Heavy Mountain!
ok dumb question. What is the difference between a light and a heavy mountain. I have a light mountain spectrum but it looks the same as a heavy. Any help here.
mike
Looking at the posted pics in this thread I’ll throw my 2 pennies in…The light unit has the driving rods attached to the driving wheels a bit closer to the outer edge of the wheel while the Heavy has the rods closer to the center. This would apply more mechanical advantage (leverage) to the Heavy’s wheels for harder pulling on steeper terrain.
This was basically a guess though…probably the differnece was the Heavy was more of a heavy duty loco while the Light was …light duty.
The heavy also has a bigger boiler. Guessing that means more power to the wheels.
The USRA designed several wheel arrangements in ‘light’ and ‘heavy’ versions - the key difference being axle loading. The ‘light’ versions were intended to operate on all but the most lightly engineered contemporary railroads, while the ‘heavy’ versions were designed for use on the more heavily built railroads of the coalfields and heavy industrial regions.
In the case of the 4-8-2, the ‘light’ version had a lengthened version of the heavy Pacific boiler, while the ‘heavy’ 4-8-2 used the boiler designed for the light 2-10-2.
Neither engine was widely used. Only nine railroads had the light version, while the heavies were only used by the C&O, the N&W and the FEC. When rebuilt by Roanoke in later years, some of the N&W USRA 4-8-2s were streamlined in a manner similar to the Js.
For more specifics and a lot of photos, check plans 88 and 89 in Model Railroader Cyclopedia, Volume 1, STEAM LOCOMOTIVES.
Chuck (modeling Central Japan in September, 1964)
Another difference was axle load. The USRA “light” designs were held to 50,000 pounds per axle, with heavies at 60,000 per axle iirc (may have been 55k and 60k, and of course i cannot seem to find my loco cyclopedia atm). The light design was meant to be just what it said, literally a “lighter” loco for use on lines who’s track or clearances may have limited the size of the power they ran.
As an afterthought, that heavy looks like a nice starting point for a T-3…
I’ve got a Spectrum Southern Pacific N scale light version. It’s a nice looking loco and all as far as I’m concerned, but the rotten thing won’t stay on the tracks. I have a UP Challenger that runs just fine on the same tracks…
Tracklayer
Tracklayer,
There are a couple of things you can do to improve its tracking qualities. Most of the problems stem from the drivers being out of balance. If you’re brave you can remove the plastic strip that holds the drivers in place. Then carefully lift the drivers out of their journals and rotate the bearing blocks. You may hav to do this several times in order to get the drivers in balance. This is a good time to shim the TT driver. Shim thickness should not exceed 0.003" to 0.005", or the whole thing will be out of balance again.
If you do this, be prepared to have the entire valve gear come apart on one side. That happened to me. Took about 45 minutes to put it all together again and tune it. But then, I’d already voided the warranty when I chopped it up to turn it into a Pennsy M1. So I was stuck doing it myself anyway.
Also, and this is equally important (and a whole lot easier)… Make sure the pilot truck is nice and loose and doesn’t push down too hard. Too much upward pressure by the pilot truck can lift the front driver and cause tracking problems.
I should caveat that I made the possibly erroneous assumption that the OP was referring to the N scale locos and not the HO… This is because I had thought I’d seen in previous posts that he was N scale. But I might well be wrong.
If the OP is refering to the HO Spectrum Mountains, please disregard my advice. I can’t attest to their pulling power or operation.
No, they don’t. Both engines have the same piston stroke - 30", and the same diameter coupled wheels - 69". The crankpin throw is the same on both engines.
How do you figure that?
Cheers,
Mark.
If it’s HO, I have a light mountain and it’s an excellent runner. I don’t have one yet (but I am planning to get one soon) but the heavy mountain is supposed to have a pulling advantage in that it has a metal boiler instead of plastic, so has more weight. AFAIK both are “plug and play” for DCC conversion with an 8-pin plug so that’s not an issue.
BTW an interesting this about the USRA is they designed “heavy” and “light” engines in several categories, but not always with the same wheel arrangement. For example they did both heavy and light versions of the 2-8-2, 4-6-2, 4-8-2 and 2-10-2, but for switchers the “light switcher” was the 0-6-0, the “heavy switcher” was an 0-8-0; and the “heavy Mallet” was a 2-8-8-2 and the “light Mallet” was a 2-6-6-2. Originally they were just going to make one design, a 2-8-2.
Note too that in many cases, more “copies” were made of USRA engines than there were of the original USRA engines. The USRA only existed a few years, but copies continued to be produced into the early fifties.
Here’s a chart of the USRA designs: http://orion.math.iastate.edu/jdhsmith/term/slususra.htm
It has some good basic info. As far as the pictures posted, the light looks like it was made by Baldwin and the heavy by Alco, if that matters to you.
To add to what Stix said, the USRA designs are good fodder for “close enough” models. If I wanted a model of a Frisco 1500-class mountain, I’d probably buy a light mountain and add a few details and reletter it (I do want one; my wife says I don’t need it). [:P] See http://www.frisco.org/vb/showpost.php?p=10193&postcount=17 for an example.
Mark, a couple of years ago a post like this one dealt with the Heavy vx. Light difference(s), and I seem to have come away with a memory that one of the big differences was that a heavy had a super-heater. Now, with this thread, I am shaking my head and wondering what is the real diff.
-Crandell
The major difference is the size of the boiler. Just look at the cab roof vs. the boiler top, or the height of the stacks. The heavy Mountain is a beefier loco with greater weight on drivers and therefore more tractive effort (in real life).
As for me, I would buy the light Mountains, but only because the New Haven had the very first USRA light Mountains and did not get any heavy USRA Mountains. But that’s just me. I would also buy the long Vandy tender to give it a more modern appearance, and then maybe add an Elesco feedwater heater, Golden Glow headlight, etc…
Paul A. Cutler III
Weather Or No Go New Haven
So are you talking HO scale Spectrum mountains?
If so, I’d say the answer is ‘neither’. They both of phosphor bronze wipers for the inner rims of the drivers for electrical pickup. When the light mountains were introduced the wipers on the first unit were bent up pretty good (and they’re were in a place where they could relatively easily snag on stuff). The second unit had a shorted motor.
When the Spectrum heavy mountains came out they had the same wipers (plus the one in the store had a narrow driver set).
So although they’d be ok for my location and era I own none of the buggers.
Quite different from the Spectrum 2-8-0’s I own (first gen) which have been pretty good runners.
YMMV.
Of course if you’re talking USRA mountains in general then none of the above applies.
Regards,
Charlie Comstock
I’ll admit to three mistakes on my post here…
the first was I assumed the pics shown were relatively accurate scale reproductions
second was I should have said it APPEARED as though the driving rods had different locating points on the wheels
third was I had my interpretation of the wheel/rod mounting points worded backwards. To me in those pics it appears as though the heavy unit has the rod mounted closer to the outer edge and the opposite for the light unit. IF the rods were closer to the perimeter of the wheel on the heavy it would give more leverage to turn the wheel (same as having a longer wrench for a tight bolt…less effort needed to turn it)
Apparently all the info I supplied is/was incorrect…my mistake[#oops]
Crandell, both engines were superheated. The Heavy had a bigger boiler than the light and carried a greater axle load. The light produced 53,900 lbs TE, the Heavy 58,000.
Andre
My N scale light mountain required the traction tire shim already mentioned to pull more than five cars up my 2.5% grade. Now it pulls twelve [or more, but that’s my limiting rule]. However, it does not like to stay on track. The front pilot wheels like to jump the track. I taped a weight on them and they stay on track, but of course it shows.