Aristocraft Mikado Modifications & Repair page:






Drivers turning on axles and getting out quarter:


Even before running my Mallets for the first time on the layout, ~20+ drivers (out of 48) could be turned on the axles fairly by hand easily allowing them to get out of quarter.  I eventually determined the main cause was that the inside taper surface of the driver that mates against the axle taper surface was tighter at the end near the outside portion of the driver than was the axle.  If you clean the unmodified taper surfaces of both the axle and the driver with alcohol and then press and twist the driver on the axle end by hand, you will get this....  A rub ring around the end of the axle which shows where the inside of the driver taper is making contact.  In every single case where a driver could be turned on the axle, performing these steps showed the same rub ring.  The problem is clearly with the wheel casting die at the factory being out of spec.  Note: that this ring is NOT caused by the star-lock washer under the axle screw. 


To resolve, it necessary to use a small fine modelers file to file out the inside outer end of the driver taper so it would sit secured on the axle end.  Pictured here the outside end of the inside taper has been filed down.



Another issue is the axle end was extending out too far from the inside of the driver such that tightening down on the end screw would result in the driver not securing tightly to the axle.  The solution is to file down the end of the axle so it will be slightly recessed into the driver axle hole.



After these two modifications are done, ensure again both surfaces are complete clean of oil and grease by cleaning with rubbing alcohol.  Then take and push the driver down on the axle and twist the driver back and forth till they fit perfectly tight.  (To assist you can use a rubbing compound.)  (Note: for added insurance you can choose to add blue or red Loctite to the taper surfaces.  Just be aware that later removal of the driver will be very difficult.)  Once the surfaces are properly mated adjust the driver's quartering by placing the rods temporarily back over the driver pin holes.  Once the driver is in position, reinstall the axle screw and star washer.


The combination of these two modifications results in a very secure driver on the axle.



Note:  In order to get the axle screws out of the axles without them snapping off, use a blow torch to heat the tip of a Philips head screwdriver very hot then use on the screw-head.  When you fit the screw driver tip in the screw head, the heat will transfer from the screw driver head to the screw and will soften the Loctite (used to secure the screw) and allow the screw to back out.  Be careful and don't apply too much torque as it is very easy to snap the screws off in the axle end.  You may need to repeat the heat and unscrew process more than once per axle as there is a short window of time the Loctite is softened as the heat transfers from the screw tip into the screw and then cools back down as it's fully transmitted through the entire axle and driver.  Also note that this process of heating the screwdriver tip will eventually ruin the screwdriver tip so use one with a lifetime warranty so you can exchange it out.







Drivers out of quarter fix: rework connecting rod holes: (*CHECK THIS ON ALL NEW ENGINES BEFORE RUNNING FOR THE FIRST TIME!*)


Another issue I've found with virtually every Mallet I've seen is individual drivers being out of quarter causing driveline binds.  This leads to erratic running performance and eventually the strain can break a driver loose on the axle causing it to spin.  The fix can include trying to re-adjust the driver on the axle but this can involve a bit of time and effort to get re-secured back on the axle properly... and even still you are still likely to have a tad bit of resistance.  One fairly quick and easy way to address this problem is to simply oval out the holes (with a Dremel) in the connecting rods to allow more play in the driver pins.  Because the drivers are all powered via internal drive gear blocks and flywheels, opening up the rod holes does not negatively impact the running characteristics in any way. 



Here is an example video of a new Mallet with driveline binding because of out of quarter drivers.  In this video I'm trying to start the engine by slowly applying track power... it should start moving slowly but it goes from stopped to moving at a good clip quickly.


Note: if the video skips, right click on the link and select "save target as" and save it to your local drive, then play it.

                                              Select the version / quality you want to download:


        - Video #1 - 3:48 mins  -  Demo of a Mallet with drive-line binding

                       -  87MB/3000kbs   -  30MB/1000kbs - 11MB/400kbs








A more refined way to tell if your drive line has binding is to tip the engine on it's side and run the drivers around slowly and stop in many positions per revolution.  Check and wiggle the each section of the rod assembly, you should have some play in the rods in all positions and in all sections.  If you don't you may need to open the holes up a bit.  Another test is with the engine still on it's side and watch the rods as they complete each revolution.  If you see certain joints push up this is evidence of binding from an out of quarter driver which means one or more drivers are loose on the axle and/or installed out of quarter from the factory.


It should be noted that it took many hours reworking the drivers and axles on my 3 Mallets so the drivers were properly secured to the axle and were quartered right.  Even still, I had to go back and oval out the rod holes to alleviate minor binds.



Here is an example of how far out of quarter this driver is from the factory on this new engine.  If not fixed, this would eventually lead to a driver spinning.




With some ovaling out of the hole you can allow for the driver being out of position (in both positions) as it completes a full revolution:



After rework, you usually can't see the additional rod ovaling in most cases and if it is visible you have to really look close to see it.  I used a dremel with a small drill bit on the end to do the work.  It's relatively quick and easy and after spending so many hours reworking drivers and trying to get them quartered right, this is my new method of resolving binding issues. 




Note:  Here are the socket sizes need to remove the rod screws:



**  Caution: When trying to remove the rod screws, (especially the smaller 4mm screw head) if you encounter too much resistance they may have Loctite on the threads.  Use a soldering iron to heat the screw head up to soften the Loctite, then try to remove.  You can break the screw-head off in the driver/rod if you aren't careful.  **





**** NOTE:  Running an engine that has driveline binding to "Break it in" WILL NOT properly resolve the issue and will if anything lead to one or more drivers spun loose on the axle ends.  The only way the binding can go away is for you to correctly adjust the driver by loosening the screw (see other write-up sections for more info) or by working the rod holes as I've noted.  If the driver gives and turns on the axle as a result of the driveline binding, you will most likely have a problem at some point with that driver coming completely loose on the axle and locking the entire drive train.  So in other words, if you have binding, DON'T RUN IT.  Fix it first!!! 


In many cases, the owner may not realize that they have driveline binds from the very beginning.  I highly recommend you watch the video and take the time to thoroughly check both engine sets for any binding before running.  Don't assume it doesn't have binding just because it looks like it runs ok. ****




Also, once you eliminate All binding from the rods you should be providing added insurance that you will be much less likely to have a driver spin on the axle in the future.






Rod pins impacting main rod as engine runs: (unexplained 'clinking' sound)

This is an issue I've found when running the Mallet was that the motor block has too much side to side play on the axles.  This results in the engine making a metal 'clinking' sound as it runs around the track because the #2 or #3 driver rod pin (don't remember which) could actually impact the main rod as the engine ran.  This is a big risk as if it catches too bad it would likely lock the drive train, cause a driver to spin on the axle or something to break.  I'm not certain if this would be an issue on the Mikado but it is something to consider.


The way to fix this was the same method I used on the MTH Big Boys and that was to add a 5/16" Nylon washer (can be purchased from Home Depot) to each of the #1 drivers on each engine set.  (Pictured is a 1/4" washer)



Here is an example of them installed on the MTH Big Boy:






Connecting rod pins screwed in crooked:

I found this on a couple of engines I was trying to perfect the quartering on.  While seemingly very minor, they can increase the resistance at certain points in the revolution of the driver that can lead to the pin coming loose or cause/accentuate minor binding.  Fortunately, backing them out and re-screwing back in straight up and down can correct the problem.






Painting the drivers:

To get an overall better look, I painted the Mallet drivers black.  To get as precise a job as possible, I disassembled each motor block and removed each axle set and masked the surfaces I didn't want painted.  One part of this process that is very important is to mark on the bottom of each gear box the direction and location position order.  Also, it's important to draw a center line down the side of each flywheel to note it's original orientation, direction and order.  This is critical in order to maintain the quartering!


The paint I used was Krylon Fusion - Satin Black.


First, here are the socket sizes need to remove the rod screws:


Here are the almost completely masked drivers.


This is what the drivers look like when completely masked.  (Note in these photos, it documents the original method of not removing the gearboxes from the block.)

Images of the disassembled pieces of the Mallet motor block and other images:


Images of the just painted drivers:


Final end result reassembled and back on the engine:





Defective motor:

I noticed when one of my Mallets ran that the front engine set turned noticeably slower than the rear set which mean the front set was being pushed/slid around the track by the second engine set. (This was at all speeds)  After eliminating the possibility that it was out of quarter/loose drivers, crooked rod pins, motor hex shaft too far out on the end of the motor or a wiring problem, I turned my attention to the motor itself.  I eventually determined the motor itself was the problem.  A replacement was ordered from Aristocraft and the results are in the below video, the new motor worked much smoother than the original and once installed the engine ran as it should.  On an engine like the Mikado with only one engine set, you may not notice a difference, but if the engine is running much slower than others this may the the reason.


(Right-click and save-as the video before you play and it will run smoother.)

                                              Select the version / quality you want to download:


 -  Video #1 - 1:45 mins 

                       -  26MB/2100kbs - 13MB/1000kbs - 2MB/150kbs


 -  Video #2 - 1:31 mins 

                       -  23MB/2100kbs - 11MB/1000kbs - 2MB/150kbs





Power pickup problems from some drivers: (missing power transmission strips)

On 3 axles (out of 48) I found that no power was being picked up from the driver.  The cause ended up being the power transfer strips that ran down the inside of the motor block was missing on all three axles.  Aristocraft was good enough to provide replacement strips to me.  


You can see in the second photo that the power transfer strip is there in the top right location, but in the other three, they are missing. (Below and the top and bottom in the gear box area on the left.)








Drive train (Gearbox) failures

If you get a good amount of run time on your engine you may encounter this issue where either a gearbox fails or the entire drive-train fails to operate. 


The failure will be either one of two things(or both):

  • Plastic axle gear or plastic worm gear strips in one or more of the gearboxes

  • Hex shaped hole on an individual gearbox's worm gear will strip out


If the plastic axle/worm gear strips out that drive-wheel will no longer spin with the rest of the wheels and will allow that driver set to get out of quarter with the rest of the drivers.  This will cause the entire drive train to lock-up. 


If the Hex shaped hole on a worm gear strips out that gearbox and all others driven off of it will no longer turn.  If it's the first gear box (attached to the motor) then the entire drive train will fail to operate.   If it's a second, third or later, then that gearbox's wheel set and all others after it will fail to turn causing them to get out of quarter with the gearbox wheels that are still operational. 


In either case you will need to to either replace the gearbox or send the drive-train in to Aristocraft for replacement.  Aristocraft engines have a 5 year warranty and will replace it for free if still under warranty.








Power pickup problems from some drivers: (power pickup ball missing on axle to ball power pickup)

On one axle I found that power was not being transferred to the engine.  After doing continuity tests and disassembling the gear box, I found the very small ball bearing that is installed on the bottom side axle hole (through the side of the gearbox) was missing.  Aristocraft did appear to keep these in stock so I had to find a third party supplier for them.  After a few hours I found a place that sold them and ordered a few.  Once replaced the axle transferred power fine. 


If I remember correctly, they are a 2mm ball and I ordered them from:  I believe they were the "Standard Commercial balls" - 316 Stainless steel.










Adding a real coal load to the coal tender


Aristocraft coal tenders do not have any form or type of coal to simulate a coal load.


Original from mfg




The first step to add coal is to tape off all nearby surfaces that you do not want to get glue on.  Next take a brush and apply the desired adhesive (in this case 50% Mod Podge 50% Water with few drops of rubbing alcohol) over all the surfaces you want covered with coal.





Next, place the tender/cover over a box and sprinkle the coal on and add enough to create the desired form and height.




Then using a dropper, drip additional adhesive over the entire top surface of the coal load.  Be sure to add enough so it works it's way to the bottom.  (You need to try and find a right balance between too little and too much.)  Let the glue dry for 12-24 hours and be careful to not tip or shake.





Here is the finished product. 










Sealing the Aristocraft smoke unit fluid reservoir tank to prevent leaks: 

I've found most of the Aristocraft smoke units leak around the inside wall when fluid is added.  To keep this from happening, I run a bead of superglue along the outside corner of the inside wall to seal it.  Once sealed it won't leak anymore.  I usually let it sit overnight to fully dry before reassembling. 

Before sealing

Before sealing






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