Coping with Couplers
There are two primary types of couplers available on Z-scale locomotives and rolling stock.
Marklin couplers (shown left), introduced with Z scale in 1972, are standard on all Marklin products (except for the TEE and ICE sets, and the Railex/Marklin offerings).
Micro-Trains (Kadee, a.k.a. MT or MTL) couplers (shown right), come with products from most US-based Z-scale manufacturers (such as Micro-Trains, American Z Lines, and PennZee).
Given the frequency of popular questions, such as, "Which couplers should I use?" and "How do I switch couplers?," I thought I'd put in my own $0.02.
As a warning, this article represents my opinions and experience on the subject, but by no means will every Z-head agree with what I've written here.
In this article:
Feel free to write me if you have any additions or corrections to this page. Click on any photo to see more detail.
What's the Difference?
Micro-Trains (MT) Magnematic "knuckle" couplers (shown right) are much more prototypical in their appearance and operation (at least to modern couplers), and are much smaller and less obtrusive, than their Marklin counterparts.
On the down side, MT couplers are also much more fussy, requiring adjustment to get them to work properly.
And if you ever are stupid enough to take a MT coupler apart, you'll find out how frustrating it is to put it back together (trust me).
Hint: buy MT couplers pre-assembled.
Marklin "fish hook" couplers (shown left) are larger, and therefore more sturdy and forgiving than their MT counterparts.
While MT couplers are comprised of five parts (including the casing, spring, knuckle, lip, and trip pin - see picture), Marklin couplers are only made of two parts: the single piece hook, and the spring.
Marklin couplers require no adjustments, and require virtually no maintenance.
I have Marklin rolling stock that is over 25 years old, and the original couplers are still trouble-free.
The down side, of course, is the unrealistic appearance.
There's actually a third type of coupler: Marklin-style couplers made by Micro-Trains.
Every Micro-Trains car and F7 locomotive is available with either MT Marklin-style couplers or MT couplers (a "-2" after a MT model number means it comes with MT couplers).
Although it may seem like a good idea to get only Marklin-style couplers to work with the Marklin cars and locomotives you already have, Micro-Trains Marklin-style (MT #907 & #908) couplers, in a word, suck.
They have most of the disadvantages of standard MT couplers (such as the complexity of all the parts), they don't work very well, and are even uglier than Marklin couplers.
Avoid them if at all possible.
While I'm at it, I should also mention the Marklin drawbar, a permanent coupler designed to connect two F7 units. For more information, see this section of Making Your Own Wired Multi-Unit Locomotives.
Aside from the more obvious differences, there's still the matter of their day-to-day operation to be considered. Aside from looking good, couplers have to do three things.
AUTOMATIC COUPLING
Since Marklin couplers are large, their ability to automatically couple in nearly every circumstance is excellent.
This photo shows two cars, one four-axle boxcar with truck-mounted couplers, and one two-axle container car with chassis-mounted couplers, about to mate on a curve.
Note that despite the different mountings, they are still perfectly aligned.
The only time I've seen Marklin couplers fail is when the train collides with a car at rest at too high of a speed.
Instead of coupling normally, the two hooks get caught in each other, a condition that must be manually rectified.
MT couplers don't seem to have this problem.
The solution, of course, is to s-l-o-w d-o-w-n.
Here, a Micro-Trains 50' boxcar with chassis-mounted couplers and a PennZee 3-bay hopper with truck-mounted couplers are about to mate on a curve. Since they are not aligned due to the different mountings, the automatic coupling will fail.
Note that the alignment of couplers is more important than just their ability to couple automatically on a curve. When these two cars are coupled, they will exert excessive force against eachother when traveling around a curve, which can very easily derail these lightweight cars. Here's another example of this problem (a American Z Lines C44-9W and a PennZee hopper); notice when they're coupled, the coupler on the locomotive must bend substantially to stay coupled with the hopper.
The problem is due partly to the different coupler mounts, and partly to the inherent pitfalls of mounting couplers to the chassis.
While chassis-mounted couplers are more prototypical (i.e. like the real world), their mounting causes them to point outwards on a curve, away from the center of the track.
The tighter the curve, the further away from center they point.
One solution is to convert all cars with chassis-mounted MT couplers to truck-mounted MT couplers so that the couplers automatically pivot in the correct direction on a curve.
The photo shows three cars: a Marklin boxcar, a MT boxcar with a chassis-mounted coupler, and a PennZee hopper with a truck-mounted coupler.
Essentially, the conversion involves removing the old trucks (held in with a plastic peg) and the coupler (mounted with a tiny brass screw), and installing new MT trucks with couplers (Micro-Trains #954 "Bettendorf", #955 "Archbar", or #956 "Roller Bearing").
The style you choose should match the ones you're replacing and/or the historical protoype - see truck styles for details.
This will help with coupling on a curve, and may even help reduce derailments.
The downside is the cost (over $5.00 a pair) and the minor compromise in prototypical operation.
It has been suggested that chassis-mounted couplers are better for operations and when going in reverse, although I haven't seen any difference between pushing cars with truck-mounted couplers and chassis-mounted couplers. Another solution that will reduce derailments, while retaining chassis-mounted couplers, is to add weight to the more troublesome cars. Two small lead weights, placed inside the boxcars, directly above the trucks, will help the cars stay on track; the downside is that your locomotives will be able to pull fewer cars. I, of course, invite any opinions on the subject.
STAYING COUPLED
Marklin couplers usually do a better job of staying coupled than MT couplers.
If a train accelerates and slows down rapidly, such as going down a hill, MT couplers can easily let go.
This is due to the way MT couplers are automatically uncoupled (see below); Marklin couplers do not appear to be susceptible to this.
Since they're smaller, MT couplers are also more susceptible to uneven track, which can raise one coupler significantly higher than another, causing them to loose contact.
Lastly, sharp curves and chassis-mounted MT couplers are not a good mix: in addition to derailing, the sharp bending can cause MT couplers to unhook (Marklin couplers and truck-mounted MT couplers don't have this problem).
Remote Uncoupling
To uncouple two cars without manual intervention, you'll need to install a device specific to the coupler type:
Marklin
A Marklin 8587 or 8597 uncoupling track section must be installed in any location you wish to uncouple cars with Marklin couplers, usually in a yard. Since they are electric solenoid mechanisms, they must be wired to a switch and a power source. To uncouple Marklin couplers, a train must be in motion over the uncoupler. Push and hold the button when the desired coupling is almost over the uncoupler, which will cause the uncoupler to rise about 1/8th-inch to mechanically trip the couplers, and the train will separate. The reliability of this procedure, in my experience, is about 80% (assuming ideal conditions). The down side is that Marklin uncouplers are expensive, ugly, and installation requires wiring.
Micro-Trains
To uncouple MT couplers, the train must be stopped with the desired coupler directly over a permanent magnet installed under the tracks (such as MT #921). Briefly put the train in reverse, and then move it forward again. The magnet will cause the two magnetic trip pins to separate, which will release the knuckles. It's an absolutely ingenious mechanism, although good reliability requires careful selection and installation of magnets. The magnets must be the right type (the rare earth magnets I've tried don't work at all), and must be strong enough to uncouple the cars, yet small enough to be hidden under the track (see this for what I've done). The benefit is that magnets are much cheaper than Marklin uncoupling tracks, require no wiring of any kind, and are completely invisible once installed.
If you have rolling stock with both MT and Marklin couplers, you'll most likely end up installing both types of uncouplers in your layout. I've installed magnets under my Marklin uncouplers so the single section of track serves double-duty; see Converting Turnouts to Under-table Drive for details.
There are also tools designed especially for manually uncoupling two cars with MT couplers without removing either of them from the tracks, but I've never used one. A standard awl does the trick nicely, and works for Marklin couplers equally well.
Lastly, there's the matter of manually removing cars from the tracks when they're coupled to other cars. When I lift a car with Marklin couplers, it usually doesn't give me a fight. However, lifting a car with MT couplers usually takes its neighbors with it.
Coupler Coping Tips
If you're like most of us, and haven't already committed your collection to only one coupler type, you have a combination of cars and locomotives with Marklin couplers and MT couplers. You can either switch them all to the same type (see below), or find ways to cope. Here are some tips to help deal with differing couplers:
Changing Couplers on your Locomotives and Rolling Stock
The procedure for changing couplers depends on the specific upgrade path you wish to take:
PUTTING MICRO-TRAINS COUPLERS ON MARKLIN LOCOMOTIVES
While there are several different designs of locomotives, each with a different procedure for removing the couplers, they all have one thing in common: the couplers can be removed fairly easily and without permanent damage.
The photo to the right shows a Marklin 8880 on its head. This chassis is very common, used in many European diesel and electric locomotives as well all American diesels. To remove the old coupler, just bend back the plastic cover (gently), and pull out the old coupler and spring. Most other designs are similar, although some require more disassembly. The exceptions are the moving trucks on steam engine tenders - see the tips on rolling stock, below.
When the old coupler has been removed, install Micro-Trains 901 or 902 replacement couplers (medium or short shank, respectively), according to the overly-lengthy instructions included with the couplers.
PUTTING MICRO-TRAINS COUPLERS ON MARKLIN ROLLING STOCK
The photo shows the three common coupler mounts for Marklin rolling stock.
All Marklin cars accept Micro-Trains 901 or 902 replacement couplers (medium or short shank, respectively), and all, unfortunately, require a little surgery to be opened up.
The left-most boxcar has a truck-mounted coupler; the metal plate is removed by cutting the three plastic spots with an X-acto knife. The plate is re-attached by re-melting the plastic spots with a fine-tipped soldering iron. I shouldn't have to tell you to be careful not to permanently destroy the coupler housing here.
The middle car is a three-axle passenger car with chassis-mounted couplers. The coupler housing design is actually very similar to the left-most car, except that the metal plate is on the top rather than on the bottom. Just pop the shell off the chassis, and then follow the procedure above.
Lastly, the right-most car (an 8610 gondola) has a chassis-mounted coupler held by a common single plastic weld.
Carefully cutting the red plastic with an X-acto knife will allow the body - and the coupler pin - to be lifted upwards, releasing the coupler.
Once the new coupler has been installed, just push the pin back in, and re-weld it with a soldering iron.
Obviously this can't practically be done more than once or twice without rendering the pin unusable.
PUTTING MICRO-TRAINS TRUCKS ON MARKLIN ROLLING STOCK
You've probably noticed that the trucks on Marklin boxcars, gondolas, cabooses, and tankcars are located too far from the ends of the cars to look realistic.
Unfortunately, Marklin trucks are too large to move them closer to the edges, and the couplers get in the way.
To make Marklin US rolling stock look more prototypically accurate, you'll need to remove the Marklin couplers and trucks, drill new holes, cut new bolster pins, and mount Micro-Trains couplers and trucks.
Harald Freudenreich has provided some excellent instructions for this conversion on his website.
REPLACING COUPLERS ON MICRO-TRAINS LOCOMOTIVES AND ROLLING STOCK
Fortunately, exchanging couplers on almost any product that uses Micro-Trains brand couplers (either MT or Marklin style) is quite easy, since they all share the same form-factor.
You can put MT Magnematic couplers in MT cars that came pre-installed with MT Marklin-Style couplers, or if you only have a few MT cars, you can put MT Marklin-style couplers on them (Marklin doesn't make any couplers for this purpose, though).
Aftermarket Couplers and Trucks
Here are the different kinds of couplers and trucks Micro-Trains makes. Except for the #901, #902, and #949, all of the trucks and couplers are interchangeable (that is, they all share the same mount).
| MT Model Number | Description | Assembled? | # Included |
| 901 | Medium-shank couplers for use with Marklin locomotives and rolling stock (picture) | no | 2 pair |
| 902 | Short-shank couplers for use with Marklin locomotives and rolling stock (picture) | no | 2 pair |
| 903 | Standard couplers for use with MT locomotives and rolling stock (picture) | no | 2 pair |
| 905 | Same as 903, but come pre-assembled (picture) | YES | 2 pair |
| 907 | Marklin-style couplers for use on MT rolling stock with truck-mounted couplers (picture) | n/a | 3 pair |
| 908 | Marklin-style couplers for use on MT rolling stock with chassis-mounted couplers & F7 locomotives (picture) | no | 2 pair |
| 951 | "Bettendorf" style trucks (no couplers) | n/a | 1 pair |
| 954 | "Bettendorf" style trucks with couplers | YES | 1 pair |
| 952 | "Archbar" style trucks (no couplers) | n/a | 1 pair |
| 955 | "Archbar" style trucks with couplers | YES | 1 pair |
| 953 | "Roller Bearing" style trucks (no couplers) | n/a | 1 pair |
| 956 | "Roller Bearing" style trucks with couplers | YES | 1 pair |
| 970 | "Andrews" style trucks (no couplers) | n/a | 1 pair |
| 971 | "Andrews" style trucks with couplers | YES | 1 pair |
| 961 | "Diamond Archbar" style trucks (no couplers) | n/a | 1 pair |
| 962 | "Barber Coleman Archbar" style trucks (no couplers) | n/a | 1 pair |
| 904 | passenger coach trucks (no couplers) (picture) | n/a | 1 pair |
| 949 | F7 truck side-frames with couplers, for use with Marklin F7 locomotives (picture) | YES | 1 pair |
| 950 | 33"-diameter wheelsets (picture) | n/a | 1 dozen |
| 957 | 36"-diameter wheelsets (picture) | n/a | 1 dozen |
| 702 | Assembly fixture for #903 coupler (picture) | n/a | 1 pair |
| 915 | Replacement spring for #903 and #905 couplers | n/a | 1 dozen |
| 916 | Replacement spring for #901 and #902 couplers | n/a | 1 dozen |
First, determine if the coupler is attached to the chassis or the truck - see the second and third examples in this photo, respectively. Essentially, MT boxcars and flat cars have chassis-mounted couplers, and MT locomotives and tankers have truck-mounted couplers. PennZee hoppers have truck-mounted couplers, too. The Rogue GP38-2 has truck-mounted couplers, and the American Z Lines C44-9W has chassis-mounted couplers, although both use standard #903 couplers.
If you have truck-mounted couplers, you may have to replace the entire truck, depending on what you need to do and what's available. If you want to save money, you could disassemble the coupler on the truck, although I really don't recommend it. Remove the old truck by pulling out the pin (held by a friction fit or a snap-fit) with a pair of needlenose pliers. Find the appropriate truck style listed above (#954, #955, #956), and install it in place.
If you have chassis-mounted couplers, simply remove the screw that holds in the old coupler, and screw in the new one - the procedure is the same regardless of the coupler style (MT or MT Marklin-style).
Choosing a Truck Style
The different Z-scale truck styles offered by Micro-Trains differ only in their appearance.
Click on the photo (from the Micro-Trains catalog) to see what each of the styles looks like.
The criteria used to choose a style for any paritcular application is simply historical accuracy. (Thanks to Micro-Trains for some of the historical info.)
Archbar
Archbar trucks were common on early double-sheathed wood box cars, flat cars, and reefers, but were completely phased out by the end of the steam era (circa 1938).Bettendorf
Bettendorf trucks were the most widely used during the first 50 years of this century, appearing on steel boxcars into the 70's wood boxcars into the 60's.Roller Bearing
Roller bearing trucks started appearing in the 30's, and were required on all new cars starting in 1966 and rebuilt cars starting in 1970. By 1978, more than 70% of North American rolling stock was roller bearing equipped.Andrews
A contemporary of both the Archbar and the Bettendorf trucks, its cast frame design was less prone to failure and allowed the use of expensive, serviceable journal boxes left-over from retired Archbar Trucks. The two main spotting features are the bolts that attach to the journal boxes and the tie-bars from the bottom of each journal box to the diagonal of the casting.
Most, if not all Micro-Trains boxcars come with Bettendorf trucks.
FR hoppers typically have Bettendorf trucks, and Pennzee hoppers typically have Roller Bearing trucks.
Alan Curtis Models' 48ft spine car uses Roller Bearing trucks (1 pair #956 for the ends, and 2 pair #953 for the pivots).
That about covers it!
If you have any comments, additions, and corrections to this page, I welcome your email.
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