SD45 SPECTRUM

[altorrman]

I have a Spectrum SD45 DCC onboard that runs very slow.  I have tried to reconfigure the max speed "CV", but this has not helped.  The loco will only pull 3 cars up a moderate grade.  Does anyone have any ideas to get it to run faster, pull more?  I am using an NCE Power Cab system.  My other locos run fine.  This is my second attempt to post this, I hope I haven't repeated myself.

Thanks,  Dave

[hrose52]

Dave I have the same problem I have 2 new SD45 loco that do not run well at all. I hope someone can help Henry

[Yampa Bob]

When I buy a new DCC equipped locomotive, the first thing I do is break it in on a DC powered track for at least 30 minutes.  During that time I check for any sluggishness, binding, noise, lack of lubrication, and check the current draw of the motor with a digital multimeter.

I also do a drawbar force test, an SD45 should typically have about 5 to 6 ounces of drawbar force, which equates to about 50 easy rolling cars before stall, or 25-30 at a good speed.

Only when I'm completely satisfied with the performance do I put the loco on DCC power.

Every modeler needs an inexpensive DMM to troubleshoot electrical problems. Testing of the locomotive is more easily accomplished with DC power.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=90899

Rolling stock should be fine tuned by reaming the truck journals and replacing any plastic wheelsets with metal.  An essential tool for checking required pulling force of cars is a simple spring force gauge. An easy rolling car should require only .08 to .1 ounce of pulling force.

http://www.delta-education.com/productdetail.aspx?Collection=Y&prodID=1973&menuID=

[WGL]

  My Spectrum GN SD-45 pulls 16 cars at a top speed of 92 HO mph.  My Spectrum UP SD-45 pulls 15 cars (including two 75' well cars with loads) at a top speed of HO 78 mph.  My layout is level.

[Yampa Bob]

That seems realistic, when the coal trains come through here with 100 loaded cars, there are 2 locos up front, 2 at mid train and 2 at the rear, or about 16 cars per loco. When they return with empties, we have clocked them at about 70 on the straights.

Back to the problem locos, with or without the benefit of a DMM, another good indicator is your hearing.  Listen closely to the loco and slowly turn the throttle up from zero. The motor should start humming at or before 1/4 throttle.

If it does, and the humming gets very loud at full throttle with no or low speed, there could be binding in the mechanism. If using a meter, the current will be higher than normal, as in a full stall.

At the opposite side, the motor might not be receiving the full available current, due to poor wiper contact, dirty wheels, brushes not aligned on the motor armature, or a resistance connection in the wiring.  In this case the current will be lower than normal.

A small DC motor, running at full RPM with no load, draws very little current. I did current tests on all my locos, typical current was .12 to .15 amp at crawl speed,  .19 to .25 amp full throttle, at stall (wheels spinning) .35 amp, at full stall .70 amp.  A DMM is your friend.

[hrose52]

Thanks Bob I will get a draw meter and check and see what I get. I have some gp38 engines that do real good as far as pulling. I just got 2 spectrum sd45 and one runs ok I guess but the other is a DOG.(I am running a 5 amp power supply on 18v) I have run both for 30 min. about 10 min forward and the reverse and then forward again and I have not seen much improvement. One will catch the other in about 8 laps (about 55') I have check lube in both axles as well as the gear. Now I have also just got a sd45 athearn now that one is awesome but these Bachmann run slow but look great.

How do you check scale speed for HO? 

Thanks Henry

[Yampa Bob]

Hi Henry,
Please read this page, lots of scale information.

http://www.spec2000.net/rr_site_pages/rr_scale_dfn.htm

Scale Speed (mph)= 1/88 X speed (feet per minute) X scale ratio (87 for HO).
The "1/88" is a derived mathematical constant that applies to all scales.

Note in the speed formula that for HO scale, the 1/88 constant and 87 scale ratio practically cancel each other out, so for HO all you need to do is determine speed in feet per minute.  Feet per minute ~= Scale MPH.

Use a stop watch or sweep second hand to time a lap around your layout.  Say it takes 30 seconds to make one of your 55' laps, that's 110 feet per minute, or close to 110 scale mph.  If you use the complete formula it would come out to 108.75 mph.  Ross Crain is a Professional Engineer so you can trust his equation.

Some modelers develop their own conversion/mathematical system, but I am a believer in the "K.I.S.S." approach. 

If if takes 8 to 10 laps for one loco to catch another, consider the two to be speed matched close enough to run in consist. Continue to break them in and you should see a big improvement.

[WGL]

  I also use Bachman's 5 amp power booster set to 18v. 

  Here's the link to a speed calculator, which I've bookmarked in My Favorites for easy access:  http://home.cogeco.ca/~trains/rrsoft.htm#cal

[hrose52]

Well after checking time and distance I get 95mph on one and 78mph on the other. Track voltage is 18v. I can rig up dc on one of my loops and will run them for awhile and see if that does any good on the slower one.

WGL: great link this is simple for the simple man like me

Thanks Henry

[Yampa Bob]

I keep a stop watch at the layout, and since I know the length of one lap, it's very simple to convert the time to feet per minute ~=mph. 

I also made a chart based on various time intervals for a quick reference.   

[WGL]

  I just bought a cheap watch partly because it has a stop watch feature that is easy to use.  It's certainly easier than looking from loco to watch & back, remembering what time I started counting, & then subtracting o'clock from o'clock! 

  Henry, you're welcome.  I'm glad to pass along something I learned from another member of this forum.

Bill

[RAM]

Your cheap watch is your best buy.  For 5 to 10 and they last for years.  Just don't buy cheap locomotives.

[hrose52]

Ok here is what I found out so far:

This was done in DC voltage

Start voltage is [email protected] forward and 2.7v @ .11a backwards
7 volts .13a forward and .15 backwards
10 volts .17 forward and .18 backwards
Full [email protected] and backwards .2a
After 5 laps (41.5 feet per lap) [email protected] forward and [email protected] backwards

No load on track 15.2volts

Stall wheels spinning [email protected]

Time after 1 lap 33sec at 41.5 feet =75 mph

Time after 5 laps 30sec at 41.5 feet =82mph

My meters are fluke 88 and fluke 87. Time was with stopwatch, power supply Athearn 16v dc out

Total time on engine about 45 min.

Engine is a Bachmann Spectrum EMD SD45 82715

Is this is good as it gets with this engine?

Thanks for all your help and input guys

Henry

[Yampa Bob]

Hi Henry,
Very thorough test, the results coincide closely with tests I made on 6 various Bachmann diesel locomotives, all DCC equipped on DC power.  If you get similar results with the faster one, I think you have a very healthy locomotive.

The only difference is the speed, my diesels run about 95 - 102 mph. This is splitting hairs, as that's only a difference of 1 second or less per lap.  However, when I first bought my diesels, they averaged about 85 mph.  All of them have at least 2 hours or more running time.

An important element of break-in is seating the brushes on the motor armature. Typically factory installed brushes are not pre-formed the entire width of the brush. As the brushes wear a bit, the "period of commutation" increases with a slight increase in motor performance.

Electric motors exhibit the best efficiency under load. At no load, the generated back-emf has a greater bucking effect against applied voltage.  Motor torque is proportional to current, and is greater at low rpms. Motor speed (rpm) is proportional to applied voltage.  Don't be surprised if your loco actually runs just as fast with a light to moderate load.

Add a few cars and continue break-in for another hour or so. In short, just run it and have fun.  I have several good links to sites with DC motor theory and operation if you like to read a lot.