Which one would you buy???
Light Mountain
Heavy Mountain
- Luke
Modeling the Southern Pacific in the 1960's-1980's
New Haven I-5 wrote: 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.
Modeling the Rio Grande Southern First District circa 1938-1946 in HOn3.
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
alco's forever!!!!! Majoring in HO scale Minorig in O scale:)
rs2mike wrote: 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.
Vincent
Wants: 1. high-quality, sound equipped, SD40-2s, C636s, C30-7s, and F-units in BN. As for ones that don't cost an arm and a leg, that's out of the question....
2. An end to the limited-production and other crap that makes models harder to get and more expensive.
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 wrote: 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.
concretelackey wrote: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.
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). See http://www.frisco.org/vb/showpost.php?p=10193&postcount=17 for an example.
Gary
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
marknewton wrote: concretelackey wrote: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.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.this would apply more mechanical advantage (leverage) to the Heavy's wheels for harder pulling on steeper terrain.How do you figure that?Cheers,Mark.
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
selector wrote: 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
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
Dave Vollmer wrote: Tracklayer wrote: 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.
Thanks for the advice Dave. I may just try what you've prescribed. Like I said, it's a nice little loco, and I only paid about $65.00 for it on eBay. It would be great if it ran better...
selector wrote: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.
Thanks very much, Mark. I'll have to gash that erroneous file on my "hard drive" and replace it with this new one.
Mark, I couldn't be absolutely certain about your late friend's use, but the term as used in the Canadian Armed Forces is derived from the French verb "gacher", or to throw away as waste, to spoil. In order to progress in rank, one of the requirements is to become proficient in the "other" official language, so for me it was French.
Like you, I can recall with warmth, and regret for their passing, others who had an effect on my life. I am sure that you also pass it on.
Regards to you.
Hey guys.
Stop the presses!. I just came up with a quick, cheap fix for my Lt. Mt. using a small piece of foam rubber that I wedged between the boiler and front guide wheels and it works great. So far it's ran about an hour pulling twelve cars without any problems - which is a first for that particular loco...
I have one of Bachmann's HO Light USRA Mountains which I modified to represent a Mohawk on my free-lance road.
It ran okay when I got it, but was rather noisy - a .010" shim where the superstructure attaches to the frame at the rear seemed to help quiet things down. I lengthened the frame at the front end slightly, to accomodate the air pumps and shield, and installed a Commonwealth cast steel pilot, from Cal-Scale, along with a new headlight and a Worthington fwh system. The running boards were raised, and new air tanks added, made from lead-filled brass tubing. Working from a photo of a NYC Hudson, I added the shrouding over the turret piping in front of the cab, and reworked the wind deflector on the cab roof. The tender was modified to follow my road's practice, including an open bunker for a loose coal load. With the added weight, she's a good puller and runs well with my Athearn Mikes and remotored diesels.
Wayne
Tracklayer wrote: Hey guys.Stop the presses!. I just came up with a quick, cheap fix for my Lt. Mt. using a small piece of foam rubber that I wedged between the boiler and front guide wheels and it works great. So far it's ran about an hour pulling twelve cars without any problems - which is a first for that particular loco...Tracklayer
Clever! I would not have thought of that. Can you see the foam from the side or do the cylinders hide it?
I was able to keep the pilot truck on the rails by loosening the screw that retains it. But even so, I can't get my 4-8-2 to stay on my 13.5" radius curves (not enough driver side-play)... So she stays on my 15" radius curves.
Here she is, having been completely rebuilt as a Pennsy M1 (I extended the frame as well).
But if Bachmann Spectrum's new heavy 4-8-2 ends up being a better puller, I'm willing to rebuilt this engine with the mechanism from the heavy 4-8-2. I need her to be a big puller, and right now she's not.