Tomix 'TN' couplers

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The 'TN' couplers, made by Tomix recently have become rather popular among modellers modelling Japanese railways. The 'TN' couplers are close reproductions of the couplers used by the prototype and come in a variety of styles. 'TN' couplers are a bit of the opposite of the Micro-Trains magnetic action coupler. These magnetic action couplers are meant for realistic shunting operations, 'TN' couplers are less suited for shunting, but offer close-coupling of fixed rakes. 'TN' couplers are made of a durable plastic and need some assembly. Assembly of 'TN' couplers is generally spoken easier than assembling an 'MT' couplers and thus suitable for less experienced modellers. An overview of the various TN couplers can be found here.

A few manufacturers other than Tomix offer provisions on their models to fit 'TN' couplers on their models, Micro Ace in particular. Most recent Micro Ace models (MU's only!) can have 'TN' couplers fitted. I have done so on a few of my models. A description of each conversion can be found below.

Tools needed:

- Flush cutter to cut off the plastic parts from the sprues

- Needle files

- Scalpel or small X-Acto knife and blades

- Tweezers

- Small needlenose pliers

- Small Phillips screwdriver

- Patience

Model: Tomix 14 type sleeper coaches

TN coupler used: 0391 ( 'S' coupler )

Conversion by: Mark Veneman

Skill level: easy / intermediate

My 14 type sleeper train has Micro-Trains couplers on the outer vehicles and I fitted TN couplers between the coaches to reduce coupler slag, for which TN couplers are perfect. Assembly of the TN couplers is easy, just cut off two coupler halves (upper and lower part) from the sprue, cut / file off any burrs and press the two halves together, you must feel a clear 'snap' just before the coupler halves are in their correct position.

Then remove the metal lid from the coupler pocket by prying off the lid with a small screwdriver or knife, take care to keep the lid as you need to put it back on the coupler pocket after the conversion. Remove the Rapido-style coupler and keep the spring. Then fit in the TN coupler assembly, put the spring back in its original position. Put back the coupler pocket lid and you're ready! Test coupler operation. Couplers are normally at the correct height without any adjustment and should snap together with positive action. Uncouple by just pulling two cars apart. This conversion applies to all Tomix coaches.

Model: Micro Ace KiHa 400 DMU (Rishiri) ref. A-5931

TN coupler used: 0371 or 0374 ( you need 2 sets )

Conversion by: Mark Veneman

Skill level: easy

This conversion uses the 0371 type TN coupler, which has an integrated short-coupling system. In tight curves the couplers slide outward to provent the coach bodies hitting each other.

It is best to do this conversion coach-by-coach. Micro Ace provided mounting notches for the TN couplers, they are at the right locations. Assemble the TN couplers first. Start the actual conversion by removing the coach body from the chassis and removing the bogies (trucks). Use a small Phillips type screwdriver, mine came from a shop which sells parts and tools for electronics etc. Expo Tools (UK) and others have suitable screwdrivers in their range. Remove the Rapido coupler from the bogie and put this aside as a spare part or just discard the old coupler.Then clip the TN assembly on the mounting notches. Repeat this for the other end of the car. Then reassemble the car, be careful with the front skirts (pilots). The power car needs a slightly different appraoch. Take the body off the chassis, remove the front skirts and the remove the Rapido couplers from the bogies. Then clip on the TN couplers. Then reassemble the power car. Check coupler height with a car already converted.

Model: Micro Ace 701 type EMU ref. A-4920 or E127 type ref. A-4970

TN coupler used: 0331 and 0334

Conversion by: Mark Veneman

Skill level: easy

This conversion is very similar to the one described above, but you need two different TN couplers: # 0331 and # 0334. Coupler # 0334 have to be placed at the cab ends of 4 of the 5 cars in the set, the 0331's fit under the non-cab ends and on both ends of the centre coach. Althoung the mounting pads look similar, they are not, so please do not mix up the couplers. Assembly is again very easy, but you need a little more care as with the KiHa 400 set. Normal procedure is: unscrew the bogies from the body (not with powered car), remove the rapido couplers by clipping these off the coupler pocket. Then clip the TN couplers to the floor of the car, mounting pins are provided. Removing the upper part of the body is not necessary, apart from the driving cars. These have a front skirt that should be removed before you clip on the TN coupler. Pry off the body, take care with the electrical contacts for the front/rear lights. Then remove the front skirt and rapido or dummy coupler, these are mounted on the same pins as the TN couplers would fit to later. Then clip on the TN couplers, place the front skirt in its original position and put back the body. Then screw on the bogies and you're ready!

The power car (car in centre of the 5-car set, with cab) needs a little different treatment: remove the body and front skirt, remove the rapido couplers. Clip on the TN couplers and reassemble the car in the reverse order of the disassembly. Again very easy. The table below shows which TN coupler fits which car. At the cab ends you should use TN #0334 and on the non-cab ends TN #0331 is the right choice.

Car number

TN coupler left

TN coupler right

KuMoHa 701-104



KuHa 700-104



KuMoHa 701-101 (motor)



SaHa 701-101



KuHa 700-101



Model: Green Max MU and coach kits

TN coupler used: ref: 0391 (diesels and coaches) or 0381 (electrics)

Conversion by: Jeroen Braamhaar

Skill level: Intermediate

If you have Greenmax EMU's (either Precolored or Economy) you're probably aware the inbetween cars are fitted with Rapido's.
Well, you *can* change them for something better quite easily.
Greenmax bogies
Tomix 0391 or 0381 couplers (600 yen, 24 couplers/package)
A small screwdriver
LOTS of patience

Remove the Rapido from the Greenmax truck, leaving the spring in place. Best way I've found is to twist the Rapido sideways out of the coupler box. Be careful to NOT damage the coupler box and that the centering spring remains in place.
Assemble the Tomix coupler per the instructions, but leave the "U" shaped clip that goes over the T piece off.
Now for the tricky bit (you'll need three hands here - I used a little soldering stand with two alligator clips to hold the truck)
Put the bogie in a solid stand (aforementioned soldering aid helps A LOT), with the coupler box pointing up. Now, use a small screwdriver to compress the sping onto its retaining pin . Slide the new coupler into the coupler box sideways, then, keeping the spring compressed, rotate the new coupler into place.
Gently release the spring so it catches onto the protrusion at the back of the coupler's T-shank.
Even though it's still a truck mounted coupling, you will get MUCH better car distances (closer together) and much more prototypical looking couplers! (and much less slack in the train!)

Model: Micro Ace KiHa 281 'Heat' / 283 'Furico' DMU sets ref. A0342 and A0344

Skill level: easy

TN coupler used: 0334 (2 sets needed)

Tools needed: small Philips-type screwdriver, tweezers, patience

More or less a standard conversion for a Micro Ace multiple-unit. It is easiest to start with the non-powered cars. Remove the bogies (trucks) from the car's body by unscrewing the black screw on which the bogie s pivoting. Unclip the Rapido-style coupler and keep it as a souvenir or discard the old coupler. Nowadays, TN couplers come preassembled, so Tomix took out the fiddly work. Clip the TN-couplers in place. Put the bogies back under the car's body, take care that you also put back the springs that unsure electrical contact. If these have fallen off the bogie, put them back using a pair of tweezers.

The power unit is a bit harder, as you cannot take off the bogies easily. Use a very small Philips-type screwdriver to loosen the tiny screws that hold the coupler pocket in which the Rapido coupler is mounted. Put the old couplers aside and clip in the TN coupler. If you're not sure the TN couplers fit well, then take of the body shell and assure that the TN coupler fits on all mounting pins. If not, correct this. This final step is usually not necessary.

Model: Micro Ace KTR-100 'Tango Explorer' ref. A2770 and A2771

Skill level: easy

371 334 TN Coupler used: 0371, 0374 or 0334 (1 set needed, leaves 1 pair of couplers)

Tools needed: small Philips-type screwdriver, tweezers, patience

This train is a recent (late 2007) release and a few things are changed when compared to the Kiha 281 set described above. It's easiest to start with the end cars. I put a TN-coupler only at the inner end, which couples to the power car of this 3-car set.. Remove the rearmost bogie and twist off the Rapido coupler, this provides room for the TN-coupler. Now clip the TN-coupler in place, the mounting tabs are on the underside of the body. Re-fit the bogie. I used TN-coupler ref. 0334, which I had on hand, but it is not of the correct type. For optimal realism you should use ref. 0371 or 0374. In practice it is very hard to notice that the couplers are of the wrong type. There's no difference in how to fit ref. 0334 or ref. 0371. The power car is also easily converted: remove the Rapido couplers by twisting them off. Micro Ace have used a new method of mounting Rapido-style couplers on powered bogies; the very small screws are gone. After removing the old couplers, the new TN-couplers simply clip into place.  Test if all couplers fit well, and put your train were it belongs: on track and do a final test run. Bon Voyage!

KTR 'Tango Explorer' (photo: Micro Ace)

Model: Tomix Suha 32 Coach and similar models

Skill level: fairly easy, non-reversible

Tools needed: Tweezers, small Phillips screwdriver, jeweller's saw or piercing saw, patience

TN-coupler used: 0373

0373 Tomix 0373 TN-coupler

First thing to do is to remove the bogies from the bottom of the coach, use the screwdriver to do this, take care not to lose the springs that provide electrical contact between the pick-ups in the bogie sides and the brass strips in the bottom of the coach. Then cut off the Rapido coupler with the jeweller's saw, be careful not to damage the bogie sides! Then simply clip on the TN-couplers. Then put back the bogies, take care to put them back into their original orientation. Finally: test coupler operation and free-rolling of the bogies. At this time you could also put on the rub-on coach numbers. Job done!

coach Tomix coach model, ready for conversion to TN-couplers, photo by author.

bogie 0373 The bogie (left) and the conversted coach (right)

Text & scans by Mark Veneman

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