# New Design Track-Cleaning Engine Under Development



## toddalin (Jan 4, 2008)

Those of us who run track power are well aware of the ability of the drywall sander to clean track. I've been using one setup as a railcar pulled by an engine on the Tortoise & Lizard Bash for years with great success. But the problem I have is that I can't reliably _push_ the car with the engine as it "hangs" and derails in some curves. This then makes it fairly worthless for cleaning my sidings where I run point-to-point. As always, I knew there had to be a better way.

I determined that if the sander sat _between_ two motor blocks, the front block would pull out the slack preventing this derailing. So how it this really different that just mounting it to an existing engine? None really. The trick then is to use a BIG engine that can support the sander between the motorblocks.

A standard pole drywall sander head is 9-1/2" front-to-back. That's certainly more space than any of my engines have between the trucks, but just barely more than on the U-25B, that sits on the shelf as a spare. But, I found that my dry-wall _hand sander_ was only 8-3/4" front-to-back, and that can fit between the trucks on the U-25B.

I also noted that the U-25B has two screws on the bottom to hold the air tanks. These screw holes have already been centered for us and are just the right distance to accept complementary screws in the sander once the handle is cut off. I'll probably let two screws protrude down though these two holes, and nut them in place. Then I'll drill the holes in the sander and run two countersunk screws upwards to engage a threaded spacer. I'll drill the threads out of a portion of the spacer, or grind them off of the screws that protrude down, and this will let the pad "float." Some weight, or springs to push against the bottom of the engine will tension the pad to the track. I will have to remove the inside brake assembly and tips of the sideframes from the trucks.

I'll outfit the engine with a 12 volt gel pack and there will be a switch to allow for this battery or track power.

The engine will be fitted with reed switches front and rear. When operating under battery power, the engine will have the option to automatically reverse should a reed switch be triggered. Then I can just put two magnets anywhere along the track and the engine will go back and forth between them allowing me to clean my sidings with out running off the track or ramming the platforms.


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## lownote (Jan 3, 2008)

That's a great idea, although personally i think a drywall sander is too aggressive, and I prefer the green scotchbrite pads


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## docwatsonva (Jan 2, 2008)

I did pretty much the same thing a number of years ago and it's still doing a fine job. I made a custom skid out of hardwood and scotchbrite pads. I added some flat sheets of lead to help the skid work a little better. Hope these pictures help. Good luck with the project.






























Doc


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## Dennis Paulson (Jan 2, 2008)

There are many products and devices , but I prefer to keep it " simple " , purchase an Aristo track cleaning car , or two if your in a hurry , and remove it from the box , set it on the track , either in front , or behind a locomotive , run the loco and clean the track . OR , couple it behind the train and pull it as you operate . I have years of pushing them or pulling them with no problems . Its pad is not aggreassive , it just polishes the railhead nicely . Clean the pad with denatured alcohol , or water .
Its really simple







, and it works .


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## Greg Elmassian (Jan 3, 2008)

I haven't had problems pushing a "scotchbrite" car myself either, but in the above design, I think you may have problems on tight curves, with parts of the block going "inside the rails" 

Of course it could be due to magnetic repulsion ha ha. 

Greg


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## docwatsonva (Jan 2, 2008)

Gregg,

If you're referring to my design, I have not had any problems with the pads dropping down between the rails on curves as tight as 9 ft. dia. The cool thing about the design is that the front an back of the pad is connected to the trucks so, as the trucks turn the curves, the pad follows them and therefore the rails. In addition, having 2 cleaning strips, you avoid catching anything between the rails such as switch frogs. Also the pad rides freely up and down on the front and rear pins which allows for slight variations in track level.


Doc


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## toddalin (Jan 4, 2008)

Using my current cleaner, the outter edge doesn't leave the rails, but the inner edge does come in quite far and also sands down my LGB turnout motors. I would expect the engine to do pretty much the same, because the block is only slightly shorter.

I can't reliably push this, though it does a great job. Other than an LGB track cleaning loco, I've not seen any of the blocks do better or usually as well. Yes. it's agressive, but works for me. I'm hoping the engine does as well.


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## toddalin (Jan 4, 2008)

Posted By docwatsonva on 28 Aug 2012 02:37 PM 
I did pretty much the same thing a number of years ago and it's still doing a fine job. I made a custom skid out of hardwood and scotchbrite pads. I added some flat sheets of lead to help the skid work a little better. Hope these pictures help. Good luck with the project.
















Doc


I like your idea of using the motion of the trucks to your advantage. I need to look further into if this is feasible using what I have. Luckily, I haven't started drilling or cutting yet. 

Thanks


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## Greg Elmassian (Jan 3, 2008)

No Doc, was referring to Todd's. I can see that you made the block plenty wide, and now that you have given further explanation, (and I looked more closely at your pictures) it's even more clear. Nice design, like the trackman 2000 that also pivots. 

Greg


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## bdp3wsy (Mar 14, 2008)

Doc, looks great. Can you post a pic with the pad removed and give some dimensions. How does it piviot are the holes in the pad for the pins elongated? Thanks Jack


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## docwatsonva (Jan 2, 2008)

Todd, First off, I'm not trying to pirate your topic I'm just trying to provide you and others with some of my experiences with building one of these track cleaners. I hope you understand.

Below are a few additional photos to help explain my design. The skid/cleaning pad is 6" long x 3" wide x 1" high. The weights and scotchbrite pads add about another half inch.

It turns out that the mounts of the U25B trucks have enough slop in them that I didn't have to elongate the holes. However, it couldn't hurt to elongate them a little. Here's a photo of the bottom of the engine showing the trucks rotated as far as they can without elongated holes. As I mentioned, they can negiotate 9 ft. dia. curves.










The next 3 pictures are of the skid.





























The last photo is a side view of the truck without the skid.

















As Todd noted, on top of the trucks are 2 holes that can be used to attach the pivot plates. I made mine out of 1/16" fiberglass.


Hope this helps.


Doc


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## toddalin (Jan 4, 2008)

Thanks Doc,

You're not pirating anything. This is excellent information and exactly what I wanted to know.

At this point I've removed a truck and found that I could do it using the two unused screw holes on the top of the truck, just as you have done. I've already made the motorblock extensions (similar to yours but still rectangular) from brass and also made a cardboard template to get the screwholes and spacing right. It was the slots that were giving me concern, and I still may need to do a bit as I run a minimum 8' diameter curve.

I used a wood saw to remove the hard rubber handle from the sanding block and milled it smooth using a Dremel mill bit chucked in the drill press. Because of the relatively slow speed, this does an excellent job of milling the hard rubber without melting it into a gooey mess.


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## toddalin (Jan 4, 2008)

Voila!

Should be _just enough_ clearance with the pad mounted. Now I just need to replicate the holes onto the other piece of brass, mount the trucks, and check the "slotting" for curves.


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## toddalin (Jan 4, 2008)

Okay, the "articulation" is completed and the pad will now follow the track. I did it a bit different than Doc in that I have the "posts" on the pad, rather than on the pivot pieces.

I was able to push this through though my 8' LGB turnouts. When the pad moves out, the posts flex in a bit as the body on which they are mounted is made of resin rather than metal. The flex of the body replaces the action of the slot, but if I find this to be a problem (e.g., any binding), I'll revist it as need be.

Note that the pad _just_ fits, but like most things on the T&LB, we operate "on the edge."


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## toddalin (Jan 4, 2008)

An LGB 1100 (2-foot radius) curve between two, 2-foot straights. Didn't see any binding. Nothing on the railroad is less than LGB 1600 (4 foot radius), so I should be good to go.


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## bdp3wsy (Mar 14, 2008)

Thanks Doc, That was exactly what I needed. I have my u25 apart and should have it done by the end of the week end. I am also using a spare SP unit that I got off Ebay for 50 bucks last year and was wondering what I would use it for since I dont model that road. I have a spare roof beacon flashing light from RAM electronics and flashing ditchlights also from RAM that will add to the overall look of the unit. Thanks again. Jack


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## bdp3wsy (Mar 14, 2008)

Ok, changed my direction, still going to do Doc's cleaner, but I looked up and found a better engine. I have a Aristo class 66 freightliner that this will also work on with the Ram roof lights on both ends and the unit will be painted as a track maintenace unit which is what it will be. Add a revo and you can fit a ton of batteries in it and away you go..... this will be cool. A friend suggest to add black styrene to the sides of sled to hide the pad a little more and to mimic the fuel tank.... maybe cut the sides off the tank and fit those.... Jack


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## toddalin (Jan 4, 2008)

Work continues.

At this point I've tapped into the existing circuit board so that the engine can select from track power, or the internal battery. When my reed switches and relays arrive, I'll include an "automatic reverse with relay momentum" circuit (2 reed switches, 2 diodes, 2 relays, 2 capacitors, and 2 resistors) that will allow the engine to slow, then stop, then wait before automatically reversing when encountering a magnet on the ties. This will allow me to clean my sidings using the internal battery power, unattended.

I'll also add polyswitches between the rear pickups and circuit board to keep the engine from frying its wiring, or popping the circuit breaker on the Train Engineer, in the event of a rerailment while under track power. I do this to all my diesel engines if I have occasion to open them.

Rectangular brass was added to the sheets that center the pad to strengthen them and to bear against the motor blocks, which will also keep the sheet from bending down over time under the weight of the pad as the engine is lifted.



The sheets were shortened and contoured to better fit the undercarrage, allow easier access to the charging jack, and keep me from cutting my fingers on the brass in use. These have now been painted black.



The floor of the engine was modified with the addition of various Plastruct shapes, milled on the drill press with a Dremel mill bit, to hold the battery, centered over the pad. The battery actually sits on plastic just above the floor and allows the existing wires to pass below. Some of the internal "bumps" were milled so that the battery could sit flush. The switch forms the fourth side and pins the battery in-place.



A piece of foam and double-sided tape keep the battery from shifing even if the engine is jostled while held upside down. The foam will be taped to the inside of the plastic shell above the battery so is not in the way when the train is opened for any reason.


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## toddalin (Jan 4, 2008)

Brass has been painted and the extensions installed.


Polyswitches added and now ready to run off track or battery power. The autoreverse feature will come later when the parts arrive, but this will work for now in case they don't come by the time we run operations.


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## toddalin (Jan 4, 2008)

It wasn't too hot this afternoon so I took the track cleaning engine out for its maiden voyage. This thing works great!

With my track cleaning car, the pad hangs "inward" too far from the rails on inside curves and this then hits ballast and rock (and flings ballast and rock onto the rails) leading to the wheels derailing and "flopping" behind the engine. Trains don't hit this ballast and rock because they don't have that much "overhang" at the level of the rails.

After a few passes, the the track cleaning car's pad clears this material, but for the first couple laps, I usually expect some derailments. With this arrangement, the pad stays with the rails and I didn't get a single derailment over run (about 40 minutes on the battery)! Furthermore, this thing has so much torque, it easily pulls my track cleaning car if I really want to get the job done fast.
Here you can see how my track cleaning car (and pole sander) take their toll on my LGB turnout motors.



The culpret!



But with a bit of fabrication:



With lots of power to spare.


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## toddalin (Jan 4, 2008)

I've worked out the electronics to make the engine automatically decelerate to a stop, pause, then accelerate in the other direction whenever it encounters a magnet between the rails. This is far easier on the motor and gears than simply reversing current at full stride!

This is nice for cleaning spurs and point-to-point lines. This will work with any 12 volt on-board system, but can be adapted to other voltages. It uses very common (i.e., cheap) parts that can be had from the 'bay. Furthermore, we are only dealing with a few "larger" parts, and there are no microchips or semiconductors other than common rectifier diodes involved.

The actual list of parts includes:

Two 12 volt, 5 amp, 4pdt relays,

One 12 volt, 1 amp, spdt relay,

Two (or three) 47,000 mfd, 16 volt capacitors,

Two 2.5 ohm in-rush thremistors, *OR* two 3-ohm resistors (5 watts or more), 

Six 1-amp rectifier diodes, and 

Two N/O reed switches

Basically, when the engine encounters a magnet, it disengages the battery, it flips the polarity and engages the capacitor that drains through the motors slowing the engine to a stop. This capacitor has to be of the opposite polarity as the incoming current because its polarity will be flipped when the train encounters the magnet and you want the train to continue on it current heading as it slows to a stop. A capacitor holds this relay closed and determines how long the engine has to slow down and wait before it restarts in the other direction. When the engine does start, the motors "compete" with the capacitors for the current and this provides start-up "momentum."

This would make an excellent beginner's project with basic soldering skills. If there is interest, I can draw up a schematic. Here you can see the completed unit. The two larger 10,000 mfd caps in the back will be replaced by one of the smaller 47,000 mfd caps as shown in the front when the part arrives on Monday.


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## steam5 (Jun 22, 2008)

Great informative thread, i'd be keen to see a schematic 

Alan


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## toddalin (Jan 4, 2008)

Here you go. Let me know if you have any questions.

This would have been far easier to design if 5pdt relays were available for the relay on the left (Relay 1) that changes the polarity of the motor (using 2 poles), changes the polarity of the cap (using the other 2 poles), and self energizes through the spdt relay only when the relay is in the reverse mode (usually requiring 1 pole in itself). The beauty/trick to this circuit is that because the same power supply is used for the electronics and the trains, we can "trick" the relay into thinking it has a fifth pole, by using a diode that only lets the current flow to hold the relay open when it is in the reverse mode.

I was going to do this with a single reed switch (energize once for reverse and again for forward, but 1) with the track cleaning pad in the middle, the reeds could only be mounted at the ends so I would end up using two reeds anyway so I don't have to worry whether my engine was going forward or reverse down the siding, and 2) using this method,_ in testing,_ the circuit is subject to "bounce." That is, if you try to physically touch a wire to the contact, you may actually touch it many times in close succession and each time you do, the relay changes state so you don't really know where it will end up. I imagine that when using the reed/magnet, this isn't a problem, but why make it a problem if it need not be?

So we have front and rear reed switches where the front reed reverses the engine and the rear reed puts it right again. If the engine is going forward and the rear reed is activated for whatever reason (rather than the front), the engine will just slow and wait, but restart in the same direction it was going. If the engine were going reverse and you wanted it to go forward without a magnet handy, you would simply turn it off (i.e., select to run off track power) and turn it back on resetting the electronics. If you wanted to defeat the magnetic reverse (maybe you use sound magnets on your track), simply disable the +12 volts to the reed switches (or everything for that matter EXCEPT the + and - 12 volts on terminals 1 and 2 on Relay 1) with a spst switch on the + 12 volt feeds.


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## steam5 (Jun 22, 2008)

Thanks for that, really great solution.


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## toddalin (Jan 4, 2008)

The track cleaning engine got a work out and a couple problems became evident that I didn't encounter on the work bench. 

The first problem was that after the engine passes the magnet, stops, and reverses, the first thing that it encounters is the magnet it just passed before making it to the magnet at the other end.

So we must make the circuit "direction sensitive." Rather that just use the +12 volts to feed the two reed switches, we will use a diode in the same position as the diode that feeds from Relay 1 to Relay 2 and instead of going to Relay 2, it will go to the +12 volts for the rear reed switch. Similarly, we will add a diode to the very top contact of Relay #1 (N/C) placed in the same direction as the other two noted diodes, that goes to the +12 volts to the front reed switch.

Now the engine can only trigger the front reed switch when going forward and the rear reed switch when going backwards. When the engine passes over a magnet, stops, and reverses, the reed switch on the other end is inoperable so the engine doesn't pause as soon as it reverses, starts moving, and passes over the magnet.

The other problem was the momentum. While this works great, if too much capacitance is applied, both sides of the engine proceed past the magnet, and the magnet that it just passed becomes the first thing encountered by the reed switch on the appropriate end (after fixing the above). The answer (other than going to electronic timing ala 555 chip) is to use just enough capacitance so that the both reed switches don't pass the magnet. I ended up removing capacitance to appeviate this problem. On a short engine, you may not be able to use any capacitance or you may coast both ends past the magnet.


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## toddalin (Jan 4, 2008)

I've beaten the problem with the momentum and can now run as much momentum as I like without worry about re-crossing the same magnet triggering the system for a pause or reverse or engine length placing the reeds so close that momentum would not be possible without sliding past the other reed switch.

Once we add the two diodes to make the reeds direction sensitive (described in the post above), it is just a matter of the placement of the reed switches. Instead of just putting one at the front center and one at the rear center, we just put the switches toward the right side, regardless of direction (i.e., one on the right facing forward and one on the right facing backwards).

Now when the train crosses the magnet it slows and stops and changes direction. When it changes direction, it will select the other reed switch and of course the magnet that was just crossed is now on the wrong side, so it is now ignored and the engines proceeds to the other magnet which will be on the right side.


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