Losing power on curves [DCC Loco]

[Eddie-684739]

DCC - Loco losing speed when going round curves.

One of my locos slows down considerably when navigating curves - is there a CV setting in DCC to compensate for this?

Many thanks

[Chrissaf]

No CV specifically designed to detect curves can fix this as loosing speed on a curve is almost certainly a physical mechanical drag issue.

Try lubricating the drive mechanisim and check the wheels for correct 'back to back' measurement between the rear faces of the wheels [14.5mm +/- 0.05mm]. If the loco is a Steam loco with 6 driving wheels in the mid section, check that there is sufficent sideways play in the middle wheel axle.

The tighter the curve, the more drag there will be. What radius is this curve, ideally it should be R2 or higher [R3 R4 etc].

[ellocoloco]

@Chrissaf,

I agree that this is not a CV issue and probably due to the drag effect on the curve, but could this be compensated for by using a decoder with BEMF?

[Chrissaf]

Just to add to 'ellocoloco' reply, BEMF [back Electro Magnetic Force] acts a bit like a car "Cruise Control". BEMF detects motor speed and tries to keep this constant if it detects a slowing down by automatically increasing the voltage, but this assumes that the drive train is operating at optimum efficiency and may not be able to provide adequate compensation for a dragging drive train.

[RDS]

@Eddie

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[ColinB]

What loco is it? If if has six wheels and a solid con rod, as in the case of a lot of Railroad A3 locos it might be worth buying the A1 split con rods option. Someone on EBay even said that they were the same as Duchess ones (I must measure mine). With the single long con rod the centre wheel cannot move freely. When Sam tests locos he regularly has them slowing down on bends, but we need to know which one it is. I must admit I have never noticed it on mine but I do run DCC.

[ColinB]

Sadly edit button still doesn't work, I just noticed you are running DCC, so ignore my comment about running DCC. I am not an expert on these as I don't have one, the Hornby Prairie supposedly has an issue with bends according to reports, whether it is true I have no idea.

[morairamike]

My 2-6-4 4MT slows on bends. adjusting the centre drivers back to back helped.

[ColinB]

That seems weird, it is basically the same wheel arrangement as an A1 which in my case doesn't slow down. I will have to try my 2-6-4 4MT, I recently changed the chassis as the old one had an issue with its pickups so it was constantly stopping. Sadly I could not find any as spare. I wonder if it is the valve gear.