Highest Speeds

[electronicvin]

I have just managed to install decoders into several of my Lima locomotives. Nearly all of these locomotives run slower than they did using DC. I knew that this would happen but some are unacceptably slow in my estimation.. Even my Hornby two-coach HAL electric train runs too slowly.
CV 5 seems to control the maximum speed but no matter what value I assign to CV 5 it does not improve matters.
Is there any way in which I can improve the highest speeds? (Both my Hornby Select and Gaugemaster Prodigy give the same speeds so I assume that the controllers are working correctly.)
Many thanks!

electronicvin

[Rog (RJ)]

This is a feature of DCC. The voltage to the motor can be a bit lower than many dc controllers which supply rather more than 12volts to the track. You can't increase a DCC locos speed beyond it's maximum by altering CVs, except possibly by turning off Back EMF.

There are some controllers that allow you to increase the track voltages, which will increase the speed but may not be good for the longevity of the motor if you take it too far.

[Mountain Goat]

I was going to say that (Not sure if all DCC systems can do this) that one can usually increase the DCC voltage. I can do this on my system (Lenz) though it requires opening up the case and altering these tiny switches as per instructions. Is the only manual setting on my system as everything else is via the usually programming methods. I think if memory serves, I can have a track voltage output of anything from around 6.5v to 24.5v? (Or maybe higher) I think they can be set to the nearest 2 volts.

Some systems like the starter DCC sytems may not be able to change the voltage.

I am trying to remember the default setting. I think on mie it is about 18v or 20v? Seem to recall 18. (18.5?) I tried it on 12.5v just out of curiosity and everything ran slow so I put it back to its origional setting.

[Brian]

Neither any of the Hornby DCC systems or the Gaugemaster Prodigy range which the OP has asked about, can have the rail voltage altered. They are set by their mains to low voltage power supplies. Using the supplied Power Supply Units the rail volts produced by the GM Prodigy is typically 15 volts and Hornby use nominal 15 volts too

The NMRA give specifications for various scales of models and these can be viewed here... https://www.nmra.org/sites/default/file ... l_2021.pdf Item 85 OO/HO Nominal 15volts on the rails but can be in the range 8.5 to 22 volts, but caution needs to be exercised when increasing rail volts on systems that allow such.

[GeoffAlan2]

One of the issues is that each modeller has their own idea of the correct top speed. Go to any exhibition and you'll see some layouts which have locos whizzing about at double or more their prototype's top speed, and also models showing mainline operations running at little more than scale walking pace.

I have a continuous run of half a (scale) mile, so at 60mph the train should complete a lap in 30 seconds. at 120mph in 15 seconds. That looks incredibly fast, partly due to the necessarily tight curves.

The N gauge society Hunslet DH shunter has, on DC, a top speed of about 25 scale mph, rather more than the prototype's 15mph or so. Yet some members commented on how slowly it ran, implying that for them it was too slow.

It's all a matter of opinion.

[Steve M]

Some seem confused when they realise model locos aren’t Scalextric cars.

Let’s see if I get slapped down on here for that comment.

[brian1951]

Totally agree Steve, now my cars speedo goes up to 155mph, does that mean i should drive at that speed.

[Steve M]

Totally agree Steve, now my cars speedo goes up to 155mph, does that mean i should drive at that speed.

Only when no one is looking.

[jamespetts]

It is possible to measure the speed of a locomotive to see whether its top speed is lower than the scale top speed of the real locomotive: there are various commercial devices that can do this, automation software, if you have an automated model railway, will do this for you, or you can just measure two points at a set distance apart and film your locomotive passing those points exactly side on and calculate the speed mathematically from the time that it takes the locomotive to traverse the known distance.

If you find that the locomotive's maximum speed is lower than the scale maximum speed of the real locomotive, you can try, as others have suggested, increasing the DCC voltage to the track, but be careful to ensure that this voltage remains within the standard DCC voltage tolerances. How to adjust the voltage and whether this is possible will depend on the manufacturer of the command station or booster supplying the track section in question.

I should note that Lima models are not renowned for the quality of their motors; there are, I believe, people who produce replacement motors for these models.

[Walkingthedog]

If the speed looks right it is right. I once worked out that one of my locos at full power was travelling at a scale speed of well over 200mph. I like running them nice and slow.