Athearn Genesis SD45-2 - Wheels not slipping

Model Railroader General Discussion (Model Railroader)
1

I have an Athearn Genesis SD45-2 - and I’ve noticed that the wheels don’t slip at low speeds if the locomotive is unable to pull the weight.

Initially I installed some weights because it was a lighter locomotive to begin with - now it just has the decoder (a Tsunami 2), an iphone speaker, and about an once of extra weight in the fuel tank. To troubleshoot, I removed the extra weight from the fuel tank - and I still doesn’t see much slippage until I get the throttle pretty high.

I’ve also applied Liberty Synthetic Lubricant to the gears in the trucks and the worm gear - same result.

Overall the locomotive runs fine, and generally runs at the head of a consist, my overall concern is that if the wheels aren’t slipping at lower speeds - I may burn the motor and the decoder over time. The other locomotive that it generally runs with is mostly speedmatched - though sometimes there’s a bit of a mismatch at lower speeds that may cause the SD-45 to slip a bit until the other “catches up.” While I intend to fine tune that a bit more - I also don’t want to damage the SD45 if it can’t get traction and I don’t immediately catch it.

2

The heavier the engine, the more power it will take to overcome the friction between the wheels and the track. What you are seeing is normal. To easily demonstate this, increase the throttle to where the wheels are slipping. By pressing down on the engine with your hand, you will easily lock the wheels up again. Obviously, there is a point where this is not good and the motor will draw excess current, which in turn could damage the decoder if the motor is drawing more current than the decoder is capable of supplying.

Mark.

3

What do you mean by “slipping?”

Perhaps you can call Athearn about it before damaging the loco.

4

That’s what I assumed - it was weight related. What confuses me a bit is that I feel this loco has been heavier before I had the decoder and the speaker in there - or at least pretty close to the same weight. And even then - if it was pulling a train it would slip if it hit a grade or if I was asking it to pull too much. I don’t feel like it will do that now - and while some of the internal components have changed (Ie - taking a wheel balancing weight out and adding a decoder/speaker), it is still around the same weight. It doesn’t even get close to what my Proto 2000 SD60 weights in at.

5

I’m thinking it means the loco doesn’t move nor do the wheels turn, with the throttle cranked up. Nothing about that sounds good.

6

I apoligize for the delayed replies - my posts still require approval.

The loco does move - I’m just referring to the wheels not slipping when the locomotive is either tied to a heavy load it can’t pull at low throttle. The obvious answer would be that it’s related to weight - but this seems to be a new problem and the weight has stayed mostly consistent throughout some part change outs.

Essentially I’m trying to determine if there would be any other possible causes for a unique issue like this other than weight.

7

I recently replaced five genesis motors that exhibited very weak torque and very high current draw.

A few years ago I decided to beef up my F3 and F7 roster and over a period of a year or so bought maybe two dozen various Genesis engines, most new, some used. Seems like all the motors go bad after maybe ten hours running time or thereabouts.

They mostly had the open-sided Roco motor but a few had a Buhler flat can motor. Fortunately I caught most of these before they damaged the decoders, some were Tsunami and T2, Lok pilot and a Loksound Select.

From what I gather these motors had “soft” brushes which eventually clogged the commutators, caused excess current draw and resulting heat which melted the plastic and solder around the armature wiring.

ATH_DC-motor by Edmund, on Flickr

ATH_DC-motor4 by Edmund, on Flickr

If you have roller test stands, I would suggest placing the engine on them and disconnect the motor wires to the decoder. Then clip test leads from a known DC power source along with an ammeter to check average current draw and stall current.

On the motors that I suspected the stall current jumped over 3.5 amps at six volts. Not good. Those little cheap motors go for about $40/each!

Good Luck, Ed

8

3.5 amps is outrageously high.

The Genesis line is not my era. We have had several threads about repowering engines. Is one obligated to replace Genesis motors with Genesis motors?

9

The motor emits volumes of smoke at this point as well.

Google “Genesis Roco bad motor” and there is more information from this MR site and others.

Regards, Ed

10

Hi,

if motor is ok, then maybe CV 212 (BEMF Feedback Intensity) is set too low. Default value is 255, but in normal situations value between 100-150 should be enough (if you have several locomotives in a consist, it is better not to set CV 212 too high, because locomotives will fight each other). Check CV 212 value and correct it if required, maybe it will help.

But if motor is damaged/drawing too much current, than it is just a question of time when it will fail completely.

There are many options for replacement that are cheaper that original Genesis (Roco) motor.

For example, this iron core motor (around 8 USD), according to technical specs, it is strong enough (stall torque 17,7 mNm).

Or, much better option - a coreless motor, like this one. In fact, this motor is new on the market - I finally persuaded one Chinese seller (manufacturer?) to manufacture a test run of these motors (99 pieces) - this motor is widely available with just one shaft, but for many locomotives, a motor with two shafts is required. I have several motors with one shaft, so I know this motor - it is quiet and very strong (stall torque around 20 mNm). It can easily move my Intermountain Cab Forward, so it is strong enough for most of our locomotives.

I am waiting for 2 pieces of this motor to test them, I will report my findings here.

Hrvoje

11

Good info Ed, thanks. I only have a couple Genesis, both from the 90’s, so far, no problem.

Mike.

12

Appreciate it - I’ll mess with CV 212 and see whether that may be influencing what I’m seeing.

Thanks to everyone for the feedback - and I apologize again for the response delay on my end due to the approval. I’ve been following the thread and greatly appreciate the feedback.

13

In fact, if CV 212 does not help, it would be good to reset a decoder to factory default values, and then observe the motor behavior.

Not only CV 212 is in charge of motor control, but also 209, 210, 211, 215, 216 and 217. I think 209, 210, 211 and 212 are the most important. So, if you are not experienced with all these values, maybe it is better to start from standard factory values - they should be fine with most iron core motors.

Then, if you want to fine tweak your locomotive, especially during slow speed and during acceleration and deacceleration (jerkyness), you can use these values for further improvement.

It is also advisable to read/use Tsunami 2 User Manual, section “Configuring Hyperdrive2” (pages 61 - 64).

Hrvoje

14

This seemed to help even out some of the behavior I was seeing. My concern was that I wasn’t seeing the wheels slip until the throttle got above 50, which I generally don’t run that high. Now I’m seeing the wheel slip down in the 20s - which gives me some more comfort that I’m not risking burning up the motor if I hit a point at low throttle where the other loco in the consist isn’t 100% matched up and the SD45 attempts to take up the slack.

15

Try now to decrease CV 212 until you still have wheels slipping, but CV 212 is lower than 255 - then locomotives in a consist will not fight each other so much.

Furthermore, check motor temperature for some while, because if it is very hot, then motor is not good. If motor is warm but not hot, that is fine.

But I am little confused, because usually, wheels slip if I put a finger in front of a locomotive practically immediately after start, i.e. at speed step 1, 2 or 3.

Did you check the whole drivetrain for any binding (gears, trucks)? It is not easy to do that - you should first remove both worms and then observe if locomotive chassis with both trucks is rolling with very little resistance. Or if there is any unusual noise (e.g. univrsal joints rubbing to something inside locomotive)?

I do not say you do it now - but this could be your next step, if you observe unusual locomotive behavior. But in that case I would first take motor out, hook it to plain DC and see how it works (listening also helps), and measure how much current it draws. Commutator should be free of “fire” ring - if it is present, it should be cleaned, together with brushes and brush holder.

I think Roco/Genesis motor during normal idle running shold not draw more than 0,5 - 0,75 A, maybe even less (it was long time ago I measured that, but if you need that value for comparison, just write - I have a pile of these motors that I replaced with coreless ones, so I can measure again).

Hrvoje

P.S.

CV 10 is also very useful, you can have full motor control at SS 1 but zero at full speed. To achieve this, set CV 10 to 126 or 127.

16

Again, this is not a unique issue. Try tying your car to a small tree and pulling. Under light acceleration, the wheels aren’t going to spin because there isn’t enough power to overcome the friction between the tires and the ground. Keep giving it more throttle. You still aren’t going to be able to pull the tree, but you will attain enough power to oversome the friction and the wheels will begin to spin. Exactly the same thing.

In a nutshell, you are simply trying to pull too much train. Period. Try adding more power (engines) to the consist.

Mark.

17

Locomotive wheels slipping at speed step 1, locomotive stopped with finger (at 0:16 - 0:20)

Decoder is ZIMO MX 600, motor coreless Maxon.

Cars have rubber tires rolling on asphalt/earth (not very slippery), while locomotives have iron/metal wheels running on metal surface (very slippery). So it is not a good comparison, friction in these two is not the same at all.

Hrvoje

P.S.

I tried to insert video directly, but it does not work.

18

I have checked the drive train - but I haven’t completely disassembled it. I didn’t see anything super obvious - if I have the shell off and spin the motor the wheels move without issue. I can’t say whether there was a ton of wheel slipping below the 20s prior to me noticing this issue. I might take a deeper look into the drive train as you said after running it a bit.

19

Thanks Mark - I definitely understand what you’re saying. What caused me to create this post was that I noticed a change in behavior - whereas previously I’d see the locomotive stall but slip - my observation was that the barrier was suddenly much higher for it to slip, which caused me to do a deep dive, search around, and ultimately make this post.

This loco generally does operate with another - my concern is that in the event something hapens with the other locomotive (a speed mismatch, etc) - I didn’t want the SD45 to burn up if it was running at a lower speed, suddenly had to pull a lot more, and wasn’t slipping.

20

If motor is just warm and not hot, do nothing - it is fine.

Hrvoje