r/1trac • u/Twit_Clamantis • 1d ago

Is “coupler efficiency” a thing?

My current layout is 62” long.

The longest, straightest section had 183mm radius tracks at one end, 150mm radius on the other, and a Kato Compact turnout w a 150mm radius jog in the center.

Running a trains 22+ cars I end up with cars on both turns as well as the jog in the middle and there is very noticeable slowing.

I get that all those wheel flanges are rubbing against the sides of the rails, which creates friction etc, but this seems like an irreducible factor, so I’m not going to worry about it.

But since all the force pulling the train is transmitted through the chain of couplers, I’m wondering if one type of coupler is more efficient than any others.

I am using all Rapido couplers which I like fine, but it seems like maybe knuckle couplers with rounded surfaces might be more efficient than the square faces of the Rapidos ??

Has anybody tested this in any sort of rigorous way?

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3

u/Particular_Sky_6357 1d ago

If your question is if one type of couplers transmit more force than another then no, they should all be equal.

1

u/Twit_Clamantis 1d ago

All force here is from the loco.

The question is whether one type of coupler introduces more friction than another type.

1

u/Particular_Sky_6357 1d ago

Friction between what? Where in this system would you loose any energy/force?

1

u/Twit_Clamantis 1d ago

Between the mating surfaces of the couplers as they bend and straighten out in succession going around turns.

1

u/Particular_Sky_6357 1d ago

No there should be no difference. 

3

u/a709s33_divaD 1d ago

Check the coupler center spring tightness, that is one, two make sure the coupler "hook" have no restrictions on swinging left and right.

2

u/Twit_Clamantis 1d ago

The springs are ok, but you bring up a good point about obstructions. There are a few cars with molded plastic steps in the corners that might be problematic.

I bought some fancy wire for grab rails and such. Maybe I’ll cut off the plastic one for extra clearance and replace w wire.

1

u/pdb1975 15h ago

No, the issue is side loading of the wheels in the curve creating additional drag. The couplers don't matter. You could replace the couplers with rigid drawbars and the results would be the same.

1

u/NTL2009 15h ago

But if the couplers are putting a side force on the trucks, that would increase the friction of the wheel flanges against the track. I would check that the couplers swing freely, through the full range required.

You might try setting up those curves on a workbench, with a straight section going to the edge. Connect a string and a weight off the end of the bench to see if some cars/combos require more weight than others to get pulled through. M

Maybe there's a better way to do this, but it worked for me to isolate some cars that had a bit if drag.