GP9 on a go slow

I recently purchased a second hand Proto 2000 GP9 in UP livery. It is in 'as new' condition. Although it is very powerful and smooth, it runs quite slowly (about half the speed of an E or F unit). Can anyone tell me if this is deliberate, i.e. it is geared down by the manufacturer, or have I got a duff one? (and yes, I know my controller is ok because all my other locos run fine). Thanks in advance for any advice. Paul Francis, Surrey, England.

Reply to
Paul Francis
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Lifelike, bless their hearts, have geared their engines to run at about scale speeds, so your engine is just fine. Most model engines run much too fast. I recall the Athearn Hustler, a 4-wheel industrial diesel, which ran at around 400 scale mph at 12 volts. Not bad, eh?

60 mph in HO/OO works out to about 1 foot/second, which looks slow. I could explain why, but I won't impose on you. :-). GP9s were geared to run a little faster than that, but not by much. The E units were geared to run up around 80-90mph, and Fs intended for dual service could do that too, if they had too. I rode in the cab of an F unit some 30 years ago - rode a like dinghy in a rough sea, though we were only doing about 40mph.

If you have an oval track, it should be easy for you to time your engine and calculate its scale speed. You don't need a stop watch, just a watch that shows second. Since your reading error (strat and stop time) will about 1 second, let the engine do about ten laps, which will reduce the error per lap, and so give you better accuracy.Have fun!

But beware - if you get bitten by the scale speed bug, you'll do all sorts of expensive things, like regearing engines, or installing DCC (which allows you to limit top speed electronically). And you may start criticising the speed at which fellow modellers operate their engines, which is Not Nice. :-)

Reply to
Wolf Kirchmeir

All Proto engines use a directional constant lighting circuit that reduces voltage to the motor and as a result they run slower than most engines.

Most Proto 2000 circuit boards use 8 diodes for this circuit.(Some earlier units only used 6)

The current passes through 4 diodes running forward and

4 diodes running backwards before going to the motor.

This results in a voltage drop of 2.8 volts to the motor. (.7 x 4=

2.8)

To make it run faster, you could remove the circuit board OR.....

You can bypass the entire board easily by simply putting a jumper wire from P8 (grey wire on top of motor) to P4 (black wire to trucks).

This will put track power directly to the motor.

The end result is no lights forward or backwards, but will give full voltage to the motor .

It should then run pretty close in speed to an Athearn. (P2K gearing is the same as Athearn)

Mike Sowsun Oakville, Ontario

Reply to
Mike Sowsun

Paul

As Mike Sowsun has said it is all due to the voltage reducing (to the motor) curcuit board that is slowing your loco. The gearing is the same as Athearn "blue box" at 12:1 reduction. In fact the 12 tooth axle gears of the Athearn and Proto2000 are interchangeable. For DCC folks this curcuit board is unplugged and the decoder is plugged in. With some decoders you are required to replace the 1.5volt bulbs with

12volts bulbs while other specific for Proto2000 decoders do not (Digitrax DH 163LO) Anyway, there is nothing wrong with your loco.

Nigel

Reply to
Nigel Nichols

Many thanks to all of you who kindly responded to my question - you have all been most helpful. As you can probably tell, I'm fairly new to American outline Diesels (I've bought a few U.S. steam locos over the last few years to add to my British stud). Its nice to be reassured that this model loco was actually designed to run at 'scale' speed. Thanks again, Paul.

Reply to
Paul Francis

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