# 474 Diesel Rocket just doesn't want to go!



## chrisallen21 (Sep 1, 2016)

Well I thought the source of my problem was the finger units on the top and bottom of the eunit in my 474 Diesel Rocket. I replaced them with new ones and while I know power is being fed to both engines (I checked with a meter on the front and back engines and both had equal amount of power as what I see when I test against the wheels themselves), she doesn't want to turn either of the worm gears. I made sure to clean the drum with contact cleaner and ensure that the fingers on both the top and bottom are touching the drum. The little metal tab that sticks out the side engages each time so I would guess that the eunit is functional in terms of direction although I noticed that the eunit hums louder when I adjust the lock lever different positions for some reason. Both worm gears turn easily when I move the drums by hand (which in turn moves the wheels and both directions are equally easy) so I think that part is fine but am wondering what to check next. The eunit does hum louder as more power is applied so I think it is ok but who knows. The engine light shines bright so I know it is getting power to the front at the very least. 

Here is a picture of the new finger units. I took pictures of the existing finger units before I removed them so I am pretty sure it is connected correctly.


















Any suggestions on where to look next?


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## AmFlyer (Mar 16, 2012)

Only two of the four fingers on the reverse unit are visible. Those two look fine. Verify the two fingers on the bottom of the reverse unit are also in correct contact with the drum. 
In the bottom picture part of one of the brush springs is visible. The commutator should be clean, brush spring ends seated in the groove on the brush holders and the brushes in firm contact with the commutator. Hopefully that will get it running.


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## chrisallen21 (Sep 1, 2016)

Here are some pictures of the bottom finger unit:
























The brushes are tough to get a good picture of but here are the front ones:















Here are the back ones:


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## flyernut (Oct 31, 2010)

Double-check to make sure the fingers are touching the drum, and check your wiring diagram.. The repo fingers with the white fiber-board usually must be adjusted as they are stiff, and are not at the appropriate angle. Make sure the brushes are indeed touching the armature face.


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## chrisallen21 (Sep 1, 2016)

I did adjust the springs downwards on both finger units after installation as I noticed the same thing. The boards definitely are not as flexible as the original ones.

Perhaps something else to consider is the wiring near the top of the field clamp assembly. I did notice a little arcing once when I was probing around to see if I could coax it into running. I am not sure the existing pictures show it well enough to comment though.

When I started out to recondition this engine by cleaning the truck and wheel assemblies right down to the worm gear, both engines did run for a short period of time albeit a bit erratically. I noticed one of the top fingers was extremely brittle near the end curl and I figured the finger units were the source of the problem so I replaced them. Unfortunately, neither engine wants to turn now so either that wasn't the source of the problem or I have done something incorrectly (which is completely possible!)


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## AmFlyer (Mar 16, 2012)

I see nothing obviously wrong in the pictures. If there were a bad field or a bad armature the second motor would still run. This indicates power is not getting to the motors. The reversing unit coil hums so there is continuity to that point. Verify the reverse unit is not in the neutral position then with the power on spray some contact cleaner at the commutator-brush point and press the brushes against the commutator. If the motor does not spin then the problem is at the fingers on the reverse unit or the wiring from the fingers to the motor.


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## chrisallen21 (Sep 1, 2016)

Spent a fair bit of the day troubleshooting with some progress. I noticed that I can get both engines to 'feel' like they want to start (I can hear them hum) but I have a couple questions on the picture I have below (this is a picture of the front motor of the 474 Diesel):








I played a little bit with the red wire (which may be a ground?) and think maybe this may be a loose connection causing a short as both engines would hum periodically if I wiggled this wire. It looks like this wire is attached to a wire from the coil and soldered together but I am not sure if this is just to keep them from coming apart and staying connected to the hold in the black board. What is the purpose of this wire along with the black one on the other side of each motor? Is it supposed to be soldered to anything or is it just to keep the wires together? Should these wires ever touch the gold bracket (field clamp assembly?) as it looks like it has in a few cases in this picture may from my troubleshooting.

Second, there are set screws that seem to attach the gold bracket/field clamp assembly to the field assembly/motor. I noticed that if I set these screws loose and then moved the field clamp assembly up and down while power is going to the train, power would sometimes come to the motors and I think even one time the worm drive turned. Should the field clamp assembly be in the middle of the field assembly/motor away from the red and black wires or should they be able to touch each other? 

Finally, how tight should the set screws be against the field assembly/motor? It is meant to keep the field assembly/motor from moving at all or should the set screws be free so the field assembly/motor can move on its own up and down.

I think I am close to solving this problem and am confident that both motor can get working again but just need a little help from the veterans to seal the deal! Any help/comments are definitely appreciated.


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## flyernut (Oct 31, 2010)

chrisallen21 said:


> Spent a fair bit of the day troubleshooting with some progress. I noticed that I can get both engines to 'feel' like they want to start (I can hear them hum) but I have a couple questions on the picture I have below (this is a picture of the front motor of the 474 Diesel):
> View attachment 240585
> 
> 
> ...


Those set screws are used to center the armature in the field. Be sure the armature is centered by adjusting each screw either in or out.The armature should not touch the field coil. Tom Barker has a book that details exactly how to do this. Tom can be reached on facebook, and I'm sure he can/will help out.


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## chrisallen21 (Sep 1, 2016)

Thanks. I have his books on order but will drop him an email as well.


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## chrisallen21 (Sep 1, 2016)

Well, I managed a bit more success but not quite there yet. I centered the armature over the field such that there was no grounding out with the red/black wires. I also noticed that the field was touching (ever so slightly) the board that holds the springs. I am not crazy on how the springs attach to the board as the spring ends stick out towards the field and can short it out very easily. Anyways, managed to get both engines to turn the worm gears (albeit always in reverse regardless of the reverse unit setting). I played a little bit with the reverse unit and managed to get it switched for both engines to go forward :thumbsup:

Now my problem is that the engine only runs at about 1/4 of the speed as my other 474 Diesel (even if I turn on full power). I checked that the worm gears turn easily (which they do). I suspect I am still facing an electrical grounding/short of some sort in that all the power isn't being transferred properly. I will say that the fields are VERY hot to the touch even after only one loop of a short track (maybe 10').

My Amazon order of Tom Barker's books can't arrive soon enough


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## flyernut (Oct 31, 2010)

Wish I could help more, but all my diesels run great.


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## AmFlyer (Mar 16, 2012)

I rarely run the Gilbert diesels. I have a 370 I use for light duty on the Christmas layout. To get it to run well I completely disassembled the motors and drivetrain, cleaned and lubed, put on new brushes and brush springs. Before I did this I verified the axle holes in the truck were not worn. I have no other recommendations.


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## chrisallen21 (Sep 1, 2016)

Thought I would post a bit of an update. I ended up tearing both engines down again to the armatures and cleaning them. This time I focuses on the three slits and cleaned them out with a pin as suggested on other posts in this forum. They did look like they were clogged up which I missed on the first cleaning. Anyways, I was able to get her running back to full power  (and man does it book it around the track) but it doesn't switch from forward to reverse. I played with the reverse unit a little bit and can get it to switch but it never does it on its own after stopping and starting. I have the lever set to the same position as my other 474 Diesel which switches fine (completely opposite side of the locked position) so I suspect I need to clean/lubricate the reverse unit and that should solve my last problem. Other than spraying it with electrical contact cleaner, what else would you recommend? The metal tab isn't bent at all and engages right away if I have it set in the bottom position once I add power to the engine so I am confident that it works as expected. I am wondering about the bottom plate on the reverse unit and whether something needs cleaned out there. The drum unit is also clean and the finger units are making good contact (as evidenced by the train racing around the track!)


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## chrisallen21 (Sep 1, 2016)

Found this post and wonder if this might be the issue:
http://www.modeltrainforum.com/showpost.php?p=753321&postcount=4

Could it be that the pawl (I referred to it as a 'metal tab' in the previous post) is magnatized when it should not be? I don't have the cool tool that is mentioned in the post so I am wondering about other methods to demagnatize.


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## flyernut (Oct 31, 2010)

I usually clean out the drum axle holes with a rolled up piece of sandpaper, and polish the insides of the e-unit itself with a bright-boy. Make sure there is a good tension on the fingers, and I would tweak that small brass tab a little. It always helps my e-units. Use very little oil on the brass tab and the drum axle holes.


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## chrisallen21 (Sep 1, 2016)

Well, finally a happy ending to this Diesel story. My final problem did end up being a sticky reverse unit. It turns out that the bottom plate that moves up and down when engaging/disengaging was getting stuck on the metal sides of the unit and not releasing fully down properly each time when the train came to a stop (and hence why it didn't switch direction). I used a small amount of 3 in 1 oil on the area and voila, forward and backwards at will:thumbsup::thumbsup::thumbsup:

Thanks for all the help and suggestions. 

Next up, a 370 diesel where I am replacing the field coil and finger units. Now that I know what to look for on the reverse units, I will add it to my list when servicing them on all my engines.


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