Leave it to me to come up with weird ideas. [:-^] On my layout any single GP can pull far more than is realistic over the hills and mountains. I’ve been pondering the idea of disconnecting one truck and removing the gearing on each GP. That would effectively halve the pulling power of the engines and thus create a real need for adequate power-to-train load ratios and for helper engines. Real stalls could even happen.
Has anyone ever tried this? What are the possible pitfalls involved?
What makes you think you GP can pull more than the real one could? I doubt that is the case. While model diesels pull better than model steam, few if any model locos pull as much as the real ones do.
How many cars are you talking about? What brand and exact model loco?
Sheldon
You need more cars or a steeper grade! One of my favorite things about the 4% grade on my layout is running a 10 car train up with a single GP7 or GP18 - you really have to charge the hill at track speed (40 mph accelerating out of Link Siding on the west end and 25 mph on the east end coming out of Ogden Siding and going through a sharp curve) and once near the summit, run at full throttle with a lot of wheelslip or you WILL stall!
But if you can’t do prototypical length trains, disconnecting one truck would work for you. BUT, assuming you kept electrical pickup on both trucks (you’d be a fool not to!) having one truck unpowered would make cleaning wheels that much harder. It’s hard to spin wheels on a rubbing alcohol soaked paper towel when some of the wheels don’t spin…
You might try experimenting with resistors on one of the motor leads. It will decrease maximum speed which I assume is not a problem on your shortline, but it should also decrease pulling power. OR you could program your decoders to have a slower maximum speed - it will pull just fine at the lower speed ranges but if you are stalling, you can’t just crank up the throttle some more and power over the hill.
We used to have a saying in the Army that fit this situation: “Hey, you thought of it, you do it!”
Let us know how it works out. Personally, I think your idea is a little crazy. Manufacturers have spent thousands of dollars designing a better drive system and now you want to revert to the old Tyco or Bachmann one powered truck drive system? Just go out and buy one of those junky models.
perhaps you need to be looked after.
seriously, though, when there was a temporary shortage of replacment axle gears for proto 2000 geeps i cut the teeth off some of the offending gears and would up with 2 or 3 axles powered on some of them. this was not an operational problem since i mu’d road power anyway. sort of like having a traction motor cut out on the real thing.
on our model railroads, wheel slippage is usually the deciding factor on locomotive ratings where on the 12’ to the foot ones, you can burn up the electrics by overloading the engine. most real locomotives can pull a great load at a slow speed but not for long. i remember watching the old GM&O throw out bad orders 50 cars deep in coal trains at Venice Illinois with ancient alco S-1’s or S-2"s. i don’t know the exact model but they were so old they had wooden cab interiors. they must have had a hold of 5000 tons or more which would in itself be a respectable road train back then. a great show with huge amounts of smoke and sparks but very little wheel slip as long as the hogger kept the sanders on. they never got over walking speed.
on the other hand, you can literally burn the ball out of the rail trying to start a heavy train if you ignore that stupid white wheel slip indicator light. (don’t ask how i know this)
grizlump
It still wouldn’t mimic the real world in the scense that it could pull the same number of each time before slippage and mandatory helper power is needed. You could keep those locos with all the factory parts together and mimic real world situations by putting some loads in the cars. Varying the weight between many different cars would mean that lone geep may pull many empties on it’s own, but would need some help with varying cars and numbers of cars. You would have to somewhat keep track of weights and exactly what the loco can pull and make operating decisions based on that. Every so often, change the loads around and throw in a couple heavy machinery cars in to mix it up.
Sorry if I am not interpreting what your proposing correctly but why give an engine a reduction in power? As we all know these are"Scale Models" of the prototype but the misinterpreted part of it is the word scale. Yes it’s scaled as far as dimensions and details go and now even sound is scaled to fit a particular locomotive but when it comes to power that part of it is up to you the operator. I am not a dcc expert but perhaps thee is a way by altering or adjusting CV’s to change the amount of pulling power an engine has to be more prototypical. By cutting off one truck I fell will accomplish nothing more then maybe shortening the life of the motor by changing the resistance value and then again maybe not. More likely it will just cut down on the efficiency and reliability of the motor. passing through unpowered frogs comes to mind.
A simpler solution would be to just have your locomotives pull what the prototype normally does If lets say a GP38 would normally pull a maximum of say 20 cars and your model can pull 30 then only pull 20 cars and call dispatch for a helper when you want to pull more.
On the railroad that I operate on thats pretty much what we do. We know that a locomotive can pull 30 empty’s up a grade just outside the yard, but make up a train of 30 full 100ton coal hoppers and dispatch is sending in the yard helper. Once the trade has reached the summit of the “big hill” the helper(s) are cut off and return back to the yard and await their next assignment.
Send it to me, I will break it for free!
You will not lose power pick up my removing the center gears. Power comes the wheels and then the side frame, not the gears. If it did there would be a short!
I all so don’t see why it would shorten the life of the motor, if the wheels are spinning the motor is not working as hard. Now, if the train is not moving fast enough to get cool air into the shell, that could be a different story.
Cuda Ken
Hi,
if you would like to reduce the pulling power of your diesels, just remove the weights. Less weight inside the body of the locomotive reduces the pulling abilities and all it takes is to loosen a couple of screws in the P2K and Atlas geeps. This way you have not altered the locomotive drive gear and you can fine tune how much each engine can pull.
In my case the spiral easily reduces the pulling ability of every engine, as for stalling out at a certain spot, I just cut the power to a section of flex track. At the same time I make sure that the coupler from the first locomotive is above the insulators (running in DC) so that I can hook a helper unit at the front and continue along the route.
Hope it helps.
Frank
A little more info on the prototype and diesel pulling power.
An EMD GP7 has about 50,000 lbs of continuous tractive effort;
Skipping over a buch of math about rolling resistance, etc, that means on straight level track it should be able to pull a 2500 ton train with no problem.
This equals 50, loaded 50 ton twin hopper cars typically used in the 30’s, 40’s and 50’s.
Three GP7’s would/could easily handle a train of 100 to 120 of such cars through normal trackage with grades of 1% or less. Steeper grades would likely require helpers or simply more power.
My Proto 2000 GP7’s will each pull about 40 free rolling 4 oz cars on level track - so they barely come close to pulling what their prototype would have pulled.
NOW, in model form there is little difference between a GP7 or a much newer more powerful loco Like a GP30 or GP38-2 - it too is likely to only pull 40 cars but its prototype would have pulled even more than the GP7.
So whatever your diesels are pulling, up whatever gardes, it is likely less than the prototype.
On most model layouts two or three diesels, pulling 25 to 50 cars looks very realistic. Very short trains, with too much power, look very unrealistic to me.
As others have suggested, why not simply operate as you desire with modifying any locos?
Sheldon
sheldon, you forgot to include the tare weight of the cars. a 50 ton hopper would probably weigh over 20 tons empty. around 25 tons per car allowance for empty weight was our standard for years.
single unit gp-7’s and 9’s could easily shuffle more than 50 cars around but you would never make track speed with that much tonnage once you got out of the yard… it would also be difficult to “kick” that much weight and it would be hard stopping them with the independent only. as best i can remember, a cut of 20 or 25 cars was about right for an old geep or sw when flat switching. we just went back and got another bite after that.
i never worked with steam, but i am under the impression that if a steam locomotive could start it, then it could run with it. diesels could start more than they could comfortably work with.
grizlump
I understand, but I did not forget about the tare weight. My single loco model was based purely on theoretical math and ideal conditions.
My later 3 loco model allowed for a real world operating conditions, hence it allowed for 25% to 33% more power.
And maybe hoppers where a bad choice since they are generally loaded right to their max, but I simply allowed a 100,000 lb total weight for an “average” loaded car back in the days of 50’ and smaller rolling stock.
The detail variations of this “question” are endless, but the fact remains, our model diesels just barely come close to pulling what their real life counterparts pull and even that is subject to careful selection of era, prototype, car type, and theoretical loading.
Regarding steam, or compairing it to diesel is easy to some degree if you look at specific examples of what diesel power replaced what steam.
On the B&O, 50-70 car manifest freights would leave Baltimore headed west with two Mikado’s, usually Q-3’s or Q-4’s. One of each
If you want a 3-unit lash up for 25 cars, just do it.
Two Athearn RTRs will not pull 25 covered hoppers around my canyon grade (between 1.5% and 2%) at prototypical speeds. If I take a run at the grade and curve at non-prototypical speeds they can do it. So I add a third locomotive and it allows me to crawl up grade at realistic, slow speeds.
As the original poster, perhaps some more background is in order. The engineers with the Great Smoky Mountains RR tell me that one older GP can only pull three loaded freight cars over the mountain. For each additional set of three cars, another engine is required. Likewise, reading and watching videos of other true mountain shortlines reveals the same, as in the case of the Georgia Northeastern. A lone GP can’t manage more than a small number of cars on the grades. This is the effect I’m seeking and not just by pretending.
I use mostly rebuilt Athearns with can motors and Ernst gearing. My decoder of choice is the Lok Sound 3.5 due to the downloadable sound and the fine motor control. These decoder allow the user to notch up the prime mover while still creeping. I’ve already downgraded the speed significantly.
You’ve all given me much to consider. I like the idea of adding weight to the loads. Adding weight to the cars, however, tends to create derailments and string-line accidents. I’d like to keep the cars themselves close to the NMRA standard.
My idea is off-beat and so am I. But I assure you that my psychiatrist says I’m sane (with a straight face). [:o)]
That’s true and fine - some more background:
Are you taking about present day? Todays freight cars are much heavier than when GP7’s were new, often twice as heavy. So three cars today is 6 cars in 1949 when the loco was new.
How steep are these grades? That has a lot to do with it.
On the prototype:
A 1% grade reduces pulling power by more than half, I had already allowed for that.
A 3% grade reduces that number by 80% - so that loco that I said can handle 50 of those 1950 freight cars (or 25 of todays cars) on 1% or less grades - can only handle 10 1950 cars (or 5 of todays cars) on a 3% grade.
Add into that curves, age of the loco (no mater how well maintained) and you have exactly what they told you, 3 cars.
Our models pull less on level track, but don’t loose as much pulling power to the grades as the real thing.
Had I known the shortline/steep grade situation I would have explained that part sooner.
Sheldon
Good info, Sheldon.
I’m modeling 1970, give or take a decade. My grades are mostly 2-2.5% with 4% max.
If you were to disconnect the drive on one truck, you would not end up with less power applied to the driving wheels, but you’d have less useful traction because only part of the engine’s weight would be applied directly over the remaining powered truck. With all the motor’s power now being applied to the one truck, and no weight gain applied to ensure traction for that power, you’ll soon scrub the metal plating off the drivers if you impose a sufficient trailing ‘tonnage’ on the engine. I’m pretty sure that, under those circumstances, you would not want such an outcome.
-Crandell