Pulling power

[tatmaninov]

Hi there, I am completely new to the world of model railway and considering to purchase my first set. Had my eye on the Santa’s Express, I would like to add to the set with more carriages over time but really have no idea on the limitations of the loco that comes with the set? How does one determine the pulling power/torque/capability of a loco? I am wondering if I should future proof myself and start with a beefier loco?

The tech specs in the online Hornby shop, don’t really seem to provide much technical information at all.

[96RAF]

Most folk just hang on more and more trucks until the loco fails.

Measuring then publishing the pulling power in newtons or some other value may be accurate but not something a layperson can relate to.

[tatmaninov]

Thanks for the reply @96RAF, yes maybe hoping for specific pulling power mentioned in product specification is a little optimistic, but there must be some way to tell if one loco is more or less powerful than another otherwise I would just be blindly buying locos until one works for specific scenario. As previously mentioned I am completely new to the scene, so please don’t hesitate to point out what might be blindingly obvious to everyone else.

[96RAF]

OK - pulling power is the product of engine power x traction.

One of our forum members does measure his locos’ pulling power using scales, so he has actual measurements for comparison loco to loco.

In the model world given the electric motor drive and gear train are similar, this basically boils down to number of driven wheel and friction gained either by vehicle weight or rubber tyres.

So the more driven wheels a loco has the better and if it is heavy that also helps. Do not confuse total number of wheels on a steam or diesel loco with driven wheels.

Traction tyres are moot as they hinder power pickup but on lightweight locos with small wheels such as EMUs they may be essential to get even basic short train running.

[ntpntpntp]

Measuring loco pulling power is all very well but in the real world the train it can handle is greatly affected by the weight of the stock and how free running that stock is, whether or not there are gradients and / or tight curves etc.

Personally I wouldn't expect much of the very basic 4-wheel chassis of the Santa Express loco compared to a larger heavier steam loco with a better engineered chassis and more driven wheels, or a diesel with both bogies powered.

[Tony57]

Hi

Best guess a maximum of 5-6 small wagons or 4 wheel coaches. More than that the drag weight of the rolling stock will over power the tractive effort of the loco.

That also applies to new large locos some can only pull 5 large coaches.

[Rallymatt]

It’s a combination of many things, however weight of the loco can be a good indicator of its potential pulling power. If it’s light and inexpensive it’s unreasonable to expect great things. As already mentioned the resistance in what you are pulling makes a huge difference, the weight and free running is key but don’t forget gradients and in particular curves. Tight radius curves (usually associated with train set packs) can kill the performance of many locos

[atom3624]

I find that there are so many 'variables', as mentioned above it can be difficult to accurately relate.

Loco weight is one, number of driven wheels, motor condition, track type, level and condition ... coach / wagon condition if based on number hauled ...

Motors invariably lose performance - weakening magnets, dirty commutator, etc ... all add to this - over continued use, particularly at higher power settings.

Al.

[Brew Man]

I think it's reasonable to say though, that expectations of Railroad 0-4-0 locos should not be high.

[M. Matthews]

We have this set under our Christmas tree. With the added weight of the moulds from the Christmas wagons, it tops out at 7 wagons.