hi all 

i have been wondering lately how much rolling stock behind a loco is too much 

i seem to see references all the time in mags and on forums that some loco's will "pull anything you put behind them"

but what is the limit before you start to damage motors , gears , etc 

i am asking this as anytime i put more than 20 wagons or 7 coaches behind a loco all i get out of my father is
"you'll burn the motor out"
he's the same when we go to exhibitions all i get is
"they are going to damage something"

so i decided to put this out on the forum to try and get an answer to my question and put my dad's mind at ease 

dave 

Depends on the loco and how free running the stock is really...

For example...   Dapol 9F and 25 mineral wagons = optimistic !   
                         Union Mills G2 0-8-0 and 25 mineral wagons = not even breaking a sweat...

                                                                                                   

Depends on the individual loco really, some can almost literally pull anything you put behind them, others would struggle to pull the skin off even the runniest of rice puddings! 

Usually it's limited by traction rather than motor power though, if the wheels aren't slipping and the loco isn't struggling then I'd say it should be OK. The only other point is the length of time it's running like that - it WILL heat up if run continuously without being allowed to coo down, and eventually will damage something which is what happened to my Farish HST, but that was after nearly six hours of pulling eight coaches and a trailing car with hardly a break 


Paul

Well designed mechanisms can and will take what you can give them, although there are some I would trust more than others, and some I wouldn't trust to leave running light engine for 10 minutes. I left three Intermountain SD40T-2s running for 6 days with 40 Microtrains freight cars in tow on my layout, with its ruling 1:60 gradient, purely to test something someone said about underset couplers bending when under heavy load. You could see the units straining up the grade on every lap, and yet after 6 days they were running just as well as the day I opened the parcel containing them. My Kato, Atlas and Union Mills are the same, they can be left running for hours with the kitchen sink hanging off the drawbar, some of which have over 300 hours worth of running on them. Most of my Farish models have done well, although I have killed a few ex-Poole models that have seen over 150 hours use. My old class 20s do seem to like getting very hot on even moderate loadings so only get used for short periods, the same can be said for what remains of my Dapol fleet...except for an Ivatt I crammed with weight to try and improve its traction and pickup; that one will run all day long with 8 on the drawbar without breaking sweat and has mounted up nearly 220 hours.

Very good information here 

Quote from: davieb on February 09, 2012, 09:13:43 PM
I have been wondering lately how much rolling stock behind a loco is too much 

Do you mean in real life, or in N gauge?

I have tested various N gauge motors and have managed 24 foot of rolling stock without any problem on a level surface
However, introduce a gradient and the limit is about 15 coaches / bogie wagons
Equally, some models perform slightly better than others, even though they have the same chassis design

The InterCity style trains I have are typically 8, 9, or 10 coaches
The heavy freight are typically 12 to 15 bogie wagons
However, these start off very slowly and the speed is built up
The main issue is if you go from off to full speed continuously (and the wheels on the motor spin)

Quote from: mjkerr on January 10, 2013, 12:25:13 PM
The InterCity style trains I have are typically 8, 9, or 10 coaches
The heavy freight are typically 12 to 15 bogie wagons
However, these start off very slowly and the speed is built up
The main issue is if you go from off to full speed continuously (and the wheels on the motor spin)

To over come the wheel spin issue which works for dc and dcc is a digitrax DZ125 decoder, you can set the acceleration rate and deacceleration rate. The only difference is the deacceleratiopn wont work on dc as your shutting off the power.

I have tested somw locos that can pull 15 coaches plus, but i think its down to the stress on the motor, if it will cause damage long term. For example if you have a large layout say 10ft x 10ft with operators well, using R3 and R4 curves this would put less strain on the motor than a 3ft by 6ft with R1 and R2 curves

To over come the wheel spin issue which works for dc and dcc is a digitrax DZ125 decoder, you can set the acceleration rate and deacceleration rate. The only difference is the deacceleratiopn wont work on dc as your shutting off the power.

I have tested somw locos that can pull 15 coaches plus, but i think its down to the stress on the motor, if it will cause damage long term. For example if you have a large layout say 10ft x 10ft with operators well, using R3 and R4 curves this would put less strain on the motor than a 3ft by 6ft with R1 and R2 curves
[/quote]

Wouldnt adding a digitrax decoder just make the loco DCC?

Most locos can pull anything i have a very early Dapol class 66 which would run with a dummy class 66 and 25 bogie tankers on a 20ft by 5ft layout that had very noticeable gadients the powered loco was happy with it no slipping and can still do it many ears on

i'm no expert but will the wheels start slipping before gears are stripped or the motor stalls? I can understand the need to keep the motor cool if running extended periods.

Dave

In a word, yes 

The motor and mechanism will easily overpower the available traction so I wouldn't worry about 'strain' on the powertrain. As said, extended running periods are more likely to damage something due to excessive heat build-up 


Paul