Brick Model Railroader is proud to bring you our latest product. Our Brick Train Compatible Knuckle Coupler. BMR, in partnership with BrickForge, has been work- ing on a replacement for the old LEGO® 9v era magnetic train couplers. These new couplers are now available for sale in our BMR online store.
Shipping will begin Monday.
Connecting LEGO® Trains In A New Way
The heart of our new couplers is the Kadee® Magne-Matic Knuckle Coupler. Kadee’s couplers are the industry standard for model railroaders. They have provided reliable, trouble free operation. The specific couplers we are using are the no. 743 and no. 747 O-scale couplers. We feel these two couplers give us the best possible options for adapting to LEGO trains. They are die-cast metal couplers offering exceptional strength and durability as well as reliable operation. They are also true O-Scale, 1:48 scale couplers, which translate very closely to 8-wide LEGO scale for North American trains.
The second half of the equation for these new couplers are the draft gear boxes designed by BMR’s own Glenn Holland and produced by BrickForge. Draft gear is the equipment that connects the coupler to the rolling stock. These draft gear boxes are injection molded in ABS plastic. We have worked hard to make sure the quality of the fit meets all expectations.
We have designed four different draft gear boxes, two for each style of coupler. These four draft gear boxes give a wide range of mounting options for your trains. The offset height of the 747 coupler is one plate higher than the 743. The S gear box has top studs for mount- ing, while the Z variant, named for the Z shape of the bottom gear box half, has a tile top with anti-studs on the thinner end.
These couplers are also self-centering, meaning they are spring loaded to return to the center position when uncoupled to make coupling easier.
Backwards Compatibility With All BMR Models
In introducing these new couplers, we wanted to ensure they were backward compatible with all previous BMR Premium Instruction Models released. To make converting your BMR cars easy, we have produced a manual for converting all 14 of our first regular Premium Instruction models. Included are detailed assembly steps for each truck style, a parts list, and tips and build notes. You may buy a printed copy of this book or download the digital version for free.
All BMR models from here forward will include instructions for upgrading the model to the new knuckle coupler in addition to the old LEGO 9v era magnetic train couplers.
Using The New Couplers In Your Trains
The four coupler designs give a pretty wide range of mounting options. Of course in LEGO trains, because of the extremely tight radius of R40 curves, the most common mounting point for couplers has been on the trucks. And our new couplers work very well for this. The two Z variants are excellent options here, but the 747S also works well in some truck mounted situations.
But what about body mounting couplers?
For real rail cars, standard practice is to have the couplers mounted to the body/frame of the car. This is the strongest mounting point and also transmits the pulling and pushing forces through the center frame of the car, and not the trucks.
The transmission of pull/push forces is most evident when backing a long train. When backing long trains with truck-mounted couplers, you are shoving the couplers together, causing the trucks to skew and potentially making the wheels want to climb the rails. With body-mounted couplers, the wheels are free to find their own way and the pushing forces are efficiently transmitted from one car to the next.
Typically in the LEGO train hobby we’re not running trains long enough to see this much. But if you are running very heavy cars, or need to back up a very long train on a large club layout, you may have encountered this problem.
The reason we use truck mounted couplers in our LEGO trains and not body mounted comes down to the extremely tight R40 radius curve that LEGO has given us. Truck mounting give us more room for the couplers too swing in order to cope with these super tight curves. Body mounted couplers just can’t swing far enough.
But with the introduction of larger radius curves from the likes of BrickTracks, body mounted couplers can be a viable option. And our new knuckle couplers, and the 743S and 747S couplers in particular, are very good at this. Cars of 32 studs in length (the equivalent of a 40ft car in 1:48 scale) can negotiate R72 radius curves while coupled using body mounting. 40 stud cars could negotiate R88 with minimal issues. Of corse the wider the curve the better the performance, but this does show that body mounting can be a viable option in your models.
Coupler Mounting Height
In traditional model railroad scales, coupler mounting height is set at an agreed upon standard that all manufacturers and model makers follow. This ensure that every ones models will work seamlessly with any other model in that scale. For our couplers, we have come up with a recommended mounting height that we thing best fits the average LEGO train model. Two help modelers with checking their coupler height on their models we have come up with a convenient hight gauge that you can build.
Instructions for this coupler height gauge are also included in the Knuckle Coupler Conversion Book, we talked about earlier. We also have LDraw and Studio model files available. Speaking of……
Coupler CAD Files
To aid builders in designing digital models to use our new knuckle couplers we are providing part files for all four coupler types to the community. These are free to download from our BMR store. Also included are the LDraw and Studio model files for our coupler height gauge.
Note that these parts are not officially endorsed by LDraw.org or Studio and are provided as is. Use at your own discretion.
We hope you enjoy these new couplers. It’s been quite an adventure for us getting to this point, but we are excited to see the final product, and see how you use them in your trains.