Kadee Body Mount Considerations

Kadee Coupler Body Mounting Considerations: Car Height & Attitude, Floors, Trucks, Wheels & Prototypes
Ted Doskaris
June 17, 2016
Rev GE-A

June 21, 2016
Rev GE-B  Added supplemental material, Illustrations and Kadee wheel measurements

July 6, 2016
Rev GE-C  Added supplemental prototype illustrations

August 13, 2016
Rev GE-D  Corrected wrongly identified brand for SP 40 ft. box car example (was AML, corrected to USA Trains) 

December 29, 2016
Rev GE-E  Added info. about Kadee coupler box types; Updated Roller Bearing Truck Types Image

February 21, 2017
Rev  GE-F  Added info. about modifying an LGB truck; added Other Rolling Stock reference vignettes

April 3, 2019
Rev GE-G Added alternative coupler box mounting method for Aristo lowered floor; Added Custom coupler box options

July 10, 2019
Rev GE-G1 Updated Illustration for 3-D Print CamPac BoxTM offerings

August 4, 2019
Rev GE-H  Added AML coupler box adaptation info. and other rolling stock reference to Aristo 50 ton 2 Bay Hopper Car

August 19, 2019
Rev GE-J  Added other rolling stock reference to AML Stock Car

February 23 & 24, 2020
Rev GE-K  Added AML coupler box illustration; updated Illustration for 3-D Print CamPac BoxTM offerings; added missing links

May 19, 2020
Rev GE-L  Added Kadee 100 ton truck to roller bearing truck comparison illustration

November 13, 2020
Rev GE-M  Updated CamPac 3-D print coupler box offerings illustration

February 16, 2021
Rev GE-N  Added hybrid Aristo floor info.; Added material with several illustrations concerning trucks' bolster heights; Updated CamPac 3-D print coupler box offerings illustration

March 6, 2021
Rev GE-P  Added info. for USA Trains 50 ft reefer & boxcars, including cushion frame types employing 3-D printed coupler boxes & updated CamPac box offerings illustration

June 13, 2021
Rev GE-Q  Added method for making Kadee metal truck slack ring; and updated CamPac box offerings illustration

July 27, 2021
Rev GE-R Added USA Trains 60 foot boxcar Info.; and updated CamPac box offerings illustration




Prototypes & Reference Material
Some History and Compromises
Freight Car Truck Selections
More About Trucks
Using a Kadee Truck
Car Floors
Various Methods for Body Mounting Kadees
Aristo-Craft 40 foot Car Examples
USA Trains Car Examples
American Main Line (AML) 40 foot Car Examples

Adapting AML coupler boxes to accept Kadees

Custom Coupler Box Prospects
Other Rolling Stock




This vignette (article) will describe issues with respect to body mounting Kadee coupler boxes having centerset couplers and using various trucks on selected cars.  Moreover, the advent of affordable 3-D printing offers some interesting prospects, particularly with regards to direct fit (devoid of spacers) when body mounting couplers.  Compromises may be made according to what is reasonably practical to implement with attention paid to prototype rolling stock being tempered by  functionality and operation.  Accordingly, examination of the physical attributes and livery of prototype rolling stock is considered in the mix.  Examples will be shown with methods used for selected brand car types, and references will be provided for existing vignettes that may describe different car types or differing methods with specific information.

Prototypes and Reference Material

My approach is to make a practical and reasoned tradeoff for operational performance while trying to best replicate a prototype car or loco's attributes.  In some case a car is so far afoul, like Aristo-Craft's fluted side streamliner passenger cars and Refrigerator cars, both of which are out of proportion, the best thing to do is to mitigate their appearance.  I strive for worst case Loco and rolling stock operation down to 8 foot diameter track curves so that operation on 10 foot curves of my outdoor layout are assured.  Accordingly, examination of prototype material is first done to see how accurate a particular 1/29 scale car or loco is (including its dimensions and livery) before doing any modifications or installing couplers or changing trucks.

The following books are just a few I use for reference:

Books include:

The Best of Mainline Modeler's Freight Cars, Volume 3
By  Robert  Hundman
Published by Phoenix Publishing
P.O. Box 3260 Friday Harbor, Washington 98250

Locomotives and Cars Since 1900
By Walter A. Lucas
Published by Simmons - Boardman Books
30 Church Street, New York 7, New York
Library of Congress No.: 59-9485

Pullman-Standard Freight Cars, 1900 - 1960
By Edward S. Kiminski
Published by Signature Press
ISBN 978-1-930013-17-9

American Car & Foundry Company, 1899-1999
By Edward S. Kiminski
Published by Signature Press
ISBN 0-9633791-0-0

Pullman-Standard Color Guide to Freight Equipment
By James Kinkaid
Published by Morning Sun Books
ISBN 1-878887-42-4

Southern Pacific Color Guide to Freight and Passenger Equipment, Volume 2
By James Kinkaid
Published by Morning Sun Books, Inc.
ISBN 1-58248-155-5

Rio Grande Color Guide to Freight and Passenger Equipment
By Jim Eager
Published by Morning Sun Books, Inc.
ISBN 1-878887-64-5

Some History and Compromises

When body mounting couplers, there are a number things to be considered.

Typically, for 1/29 "G" scale rolling stock, there are some compromises to make.  This scale started out to be toy like with emphasis placed on operation in a garden setting likely having undulating track work and very tight radius curves.  This may explain the prevailing tall locos and rolling stock employing hook & loop truck mounted couplers with an excessive amount of coupled separation.  In this regard, LGB brand equipment earned a good reputation for their operational prowess on such layouts.  
The LGB truck with  plastic wheels (illustrated below) that is typically fitted to LGB's American standard gauge rolling stock exhibited silky smooth operation.

However, over time rolling stock evolved into fairly realistic replicas of prototypes, but many offerings still included trucks with plastic wheels and legacy truck mounted couplers, though in some cases using knuckle couplers in place of hook & loops.

Likely due to the scale's historical roots, rolling stock tends to sit tall off the railhead or a car's sides or length are disproportionate when compared to prototype rolling stock.  One example shown below is the  REA / Aristo-Craft  brand Refrigerator cars having overly tall sides with respect to the car's length.   Also, the car sits too high off the railhead and employs truck mount couplers.
(Note:  The Aristo-Craft company predecessor name was "REA", and its successor company is / was Polks GeneratioNext, all now defunct)


Another example is the Aristo Budd streamliner fluted side passenger cars being notably short in length at about 2/3 the length of what it should be when scaled up to a prototype car.  Also, the car sits too high off the railhead and employs truck mount couplers.  However, the more recent production runs of the streamliners had improved lower car height and lessened coupled car separation, but they are still less than optimal.

In this regard, further refinements that make for a more plausible streamliner car are described in a Vignette, title:
Aristo Streamliners - Lowering & Body Mounting Kadee 907 Centerset Couplers


When deciding how to body mount a Kadee coupler, it's behooving to choose a centerset coupler (straight shank coupler having no vertical offset) for not only appearance, but for its improved physics (avoids potential pull apart from leverage action when operating heavy trains).  In this regard, best practical choices include the Kadee 906 or 907 assemblies.  While Kadee offers #1 scale couplers, its smaller size intended for 1/32 scale rolling stock, is not as operationally forgiving in some outdoor layouts as the lager "G" couplers scaled for narrow gauge rolling stock using the same 45 mm wide track that both 1/32 & 1/29 scales employ.

Note: The black finished aluminum boxes shown above I had custom made for me a long time ago by Datum Precision, Inc.  The motivation to do this was to afford a favorable coupler height whilst having a super strong coupler box (that accepts Kadee couplers and lid) for mounting on mostly Aristo Locos.

These are described in Vignette, title:
Custom Made Coupler Boxes & Kadee Centerset Couplers for Selected Aristo-Craft Locos

and Vignette, title:
USA Trains GP 38 - Kadee Centerset Coupler Install, Abandoning Traction Tires & Various Mod's

The "G" scale 907 small footprint box coupler has evolved from its predecessor over time - illustrated below.


The "G" Kadee 906 box is wider than the 907 and has a single spring loaded coupler that may be operationally better than the 907 in some applications.

The Kadee 906 design can offer better overall operation on a layout, particularly when backing up a train, though the Kadee 907 assembly intended for truck mount application (with two coupler springs for self centering) can work well for body mounting when tight fitment clearance is needed owing to its smaller box footprint.

Coupler Selection Issues for Short & Long Cars:

Another consideration with respect to body mount coupler box choice is car length.  For cars that are very short, such as the Aristo 2 bay hopper and especially for cars that are very long, such as USA Trains passenger cars, the Kadee 906 with its bigger / wider box opening is preferable to the Kadee 907.  This is because of how the coupler projects from the end of the car with respect to track on curves.  This is mostly a concern for train operation on smaller 8 to 10 diameter track.  Looking down from the top of a car toward the track, a very short car's coupler is more toward the center (between the rails) on curves (which is OK for the most part), whereas, a very long car's coupler can project near or somewhat beyond the outside rail.

Coupling a long car to a short car is the extreme case where the Kadee 906 on both type cars is more tolerant so the cars won't tend to be pulled off the track around the curves.   Some cars like Aristo's heavyweight passenger cars with 3 axle trucks have offset asymmetric mounted trucks, whereby, the truck's pivot point on the car is closer to the car end.  To good effect, this minimizes the amount of coupler projection for body mounted couplers.  (Aristo-Craft, also, used this technique on the U25B Loco.)  Because of space limitations, the smaller footprint of the Kadee 907 will fit on this car having 3 axle trucks and yet still works OK when coupled to other cars and Loco down to 8 foot diameter curve track. 

More detail about the Heavyweight 3 axle car is described in Vignette, title:

Aristo Heavyweight Passenger Car & Body Mount Kadee 907s


Freight Car Truck Selections

Based on observation and reference material, an American freight truck's wheel base and spring pack configuration (typically multiple coils) is related to a car's load capacity for both friction bearing Bettendorf / Ride control and roller bearing Barber type trucks.

A wheel base of 5 foot, 6 inch is the most common truck for car capacity of 100,000 lbs. (50 ton).  A wheel base of 5 foot, 8 inch is typical for car capacity of 140,000 lbs. (70 ton).  Less common is 5 foot, 4 inch for a car capacity of 80,000 lbs. (40 ton) that may be found on flat cars with friction bearing type trucks.  A wheel base of 5 foot 10 inch is common on 200,000 lbs. (100 ton) cars with roller bearing type trucks.

As to commonly available "G" trucks when scale up to prototype, the Aristo Bettendorf truck wheel base is close to a 5 foot 8 inch 70 ton truck, but its 2 coil per side spring pack resembles a 50 ton truck.  This truck is universally common to Aristo products that include 40 foot Box, Reefer, Stock cars and 37 foot tank cars, and 2 bay hopper  cars (covered & open).  The USA Trains Bettendorf truck wheel base is close to 5 foot 6 inch, but its 4 coil per side spring pack resembles a 70 ton truck.  This truck is universally common for USA Trains products that include 40 & 50 foot cars and 3 bay hopper cars.

The following illustrations describe commonly available Roller Bearing type  trucks:

The following illustrations describe commonly available Friction Bearing ("Hot Box") type  trucks:

The following illustrations describe additional attributes that may be helpful for selecting a truck to retrofit on a car:







Wheel diameter is a factor with respect to car height from the railhead.
For Example, wheels from Aristo-Craft/Crest, P/N 29111 with suffix Blank/S/B/D, have a diameter that is about .040 inch more than an AML wheel, P/N R2093.  Thus, a car height from the railhead would differ by 1/2 x 0.040 inch = 0.020 inch when wheels are installed in the same trucks.

The example wheel set illustrated below is an Aristo 29111D (Currently with the CREST brand name).  The "D" version has machined down axle tip hubs to specifically fit Aristo's Barber truck.  The wheel itself is virtually the same as the Blank, "S", or "B" version with the difference being finish. The Blank suffix version is brass; the "S" version is bright metal plated; both the "B" and "D" versions are bright metal plated but have a black smoked finish to dull the appearance.  Most other brand wheels are painted black like USA Trains wheels.


Greg Elmassian has descriptions and tabulated measurements for various brand trucks and wheels. Topic Title,
Wheels & Trucks

Comment about Kadee Wheels:

My experience with Kadee's wheels supplied with the Kadee 970, 971 & 973 trucks is that they are gauged to a back to back value at minimum NMRA specification.  While it's tempting to re-gauge them a little wider to the "target" value, the prominent wheel's fillet & flange slope can present operational problems on Aristo-Craft's notoriously under gauged No. 6 turnouts where the truck's wheels would ride up on both fillet and flange!  To mitigate this affect, I ground the No. 6 turnout point rails and stocks rails where they mate so that the Kadee truck wheels (retaining their minimum back to back value) would traverse the turnout without excessively riding up.

Kadee wheels like equipped in the Kadee trucks can be purchased separately in a 4 axle group, Kadee P/N 960.

These wheels can be installed in various brand trucks.  An example Aristo Truck is illustrated below.


Kadee Wheel Measurements:

Example measurements of the Kadee 960 wheels are depicted in the following illustrations.  
Because the Kadee wheel includes a prominent fillet, values shown in this area are predicated on determining where the fillet transitions are located with respect to the wheel tread and flange.

With respect to Kadee wheel operational problems on the Aristo No. 6 turnout (previously described in "Comment about Kadee Wheels"), the dimension between the wheel backside and the flange periphery would appear to have a profound affect on back to back gauging.  If the backside area were machined to a lesser thickness (like  AML wheels having a similar profile) the back to back gauging would conform to NMRA specifications which they don't appear to as they come from the factory.

The Kadee packaging indicates the wheels are applicable for both #1, 1/32 Scale, as well as 1/29 Scale applications having deep flange wheels.   
The Standard S-4.3 applicable to 1/29 scale has more tolerant values for some of the dimensions which appears to prevail over Standard S-4.2 for what is discussed herein.
Shown below are S-4.2 & S-4.3 specification excerpts pertaining to this discussion.


Wheel Angle of attack (Axle skew):

The attitude of a wheel flange with respect to the railhead is known as its angle of attack that can result from axle skew.  Axle skew does not affect car height for mounting trucks and body mounting couplers but does affect car operation.  It's discussed here because axle skew can be mitigated before mounting trucks on a car.

How much lateral play axles have within a truck affects its operation on curve tracks resulting in drag and possible car derailment when traversing into a turnout's point rails.  This is because the axles "walk" to opposite sides within the truck as it traverses along a curve track.  This results in a couple of wheel flanges pointing more so toward the inner side of the outside railhead; thus, the axles are skewed such that its wheel flange is at an angle that "attacks" the railhead.
The example shown below is an Aristo-Craft Bettendorf truck with ART-29111B metal wheels.

Axle skew can be mitigated by adding spacer washers on the axle tips that was done on the truck as shown below.
It's behooving to correct axle skew before mounting the truck on a car.

Other brand trucks may exhibit excessive axle skew, too.  The AML short wheel base Bettendorf type truck is probably the worst offender of any brand I have seen to date.  However, the wheel sets in the latest production version of this truck shown in prior examples have a profile with prominent wheel fillet and flange slope that significantly reduces operational problems.  The Kadee brand metal wheels are esthetically superb and have an excellent profile, too.  However, the thickness of the Kadee wheels near the outside periphery of the flange takes up more space that seems to limit what can be done with gauging with regards to operational problems on Aristo's No. 6 under gauged turnouts (out of NMRA spec.) as previously described.

More detailed information with respect to axle skew is covered in Vignette, title:
Aristo-Craft Metal Wheel "train accessory" kits and wheel issues
(Only Aristo trucks are described.)


More About Trucks

Car height from the railhead can be profoundly affected by its trucks. Some brands of cars as they come from the factory are way too high. Selecting a different truck to lower a car will not only make it look more realistic but also facilitates body mounting coupler boxes with minimal or no spacers.

Though out of business, the Aristo-Craft freight car trucks are fairly realistic and a choice if available, with the friction bearing truck being a bit long in wheel base, and the 100 ton "roller bearing" wheel base being more like a 70 ton prototype.

For the majority of the most common applications, the readily available Kadee aftermarket trucks and USA Trains trucks represent the better selections with respect to prototype replication with some of them having the best potential to lower a car the most.


The USA Trains truck is comprised of the truck parts only so a user could choose a different brand wheel set; however, available choices may be limited.


The USA Trains Intermodal Car "roller bearing" truck with actual springs can be used as a replacement truck with spacers or can be used to lower a car just the way it is without spacers.


Another truck is the USA Trains Bettendorf "hot box" truck with molded-in spring pack that also lends itself to be modified to lower a car even more than the Intermodal truck.

The USA Trains Bettendorf truck (P/N R2033) with separately sold USA Trains wheels (P/N R2093) at a relatively low cost offer the most pragmatic choice for modifications when needed.  The bolsters & side frames can be readily modified for lowering a car's height to be more prototypical whilst at the same time minimizing or possibly eliminating the use of coupler box spacers when body mounting Kadee couplers.  Since this USAT truck is made of plastic (apparently Nylon) it can be cut where needed using a razor saw and cleanup using a file.

The following illustration includes dimensions for an example modification:


Depending on a car's chassis bolster design, the USAT Bettendorf truck could have its "ribs" trimmed off to lower a car a bit more.



Another comparison of roller bearing type trucks is illustrated below.

As can be seen the LGB roller bearing truck has the tallest bolster from the railhead which means replacing this truck can be easiest thing to do to lower a car having that truck to a more prototypical height that's also advantageous to body mounting centerset (no offset) couplers.


Visually, too, the LGB Roller Bearing freight car truck is the poorest choice since, at best, appears to be an obscure replica of a prototype truck.  The following illustration includes Roller Bearing trucks:

Moreover, unlike most other brands, the LGB truck bolster is high up and level with the tops of its side frames.  This limits its practicality as a retrofit truck with other brand rolling stock since it would raise up the car.  (Trucks from most other brands have truck bolster recessed from the tops of the side frames.)  
In this regard, substituting  Aristo Roller Bearing trucks to lower an LGB car and body mount Kadee couplers are described for an example car in Vignette, title:
LGB Modern Tank Car - Lowered, Body Mount Kadee 907 Centersets & Added Weight

That said, the LGB truck can be modified, albeit with time and effort, to lower an LGB car rather than using a substitute truck.  Modifying the LGB truck is described in vignette, title:
LGB's American Standard Gauge 1/29 Scale Trucks & Mods for Car Lowering.


As to the LGB Roller Bearing truck used in the American standard gauge 40 foot type box cars, it's mostly inappropriate with respect to prototypes.  Substituting another brand's Friction Bearing trucks can be done while at the same time lowering the car to a scaled prototypical height from the railhead.

Substituting USA Trains and Aristo Friction Bearing trucks and body mounting Kadee couplers are described in Vignette, title:
LGB American Standard Gauge 40 foot Box Car & Body Mounting Kadee 906 Couplers

Using a Kadee Truck

On cars I selected to mount Kadee trucks, I chose to avoid the use of the Adaptor kit base plate as intended by Kadee in order to keep the car height from railhead to a minimum.  USA Trains and AML cars have a rounded floor bolster from which a truck pivots against with minimal contact, so If and when the Kadee truck's side frame should twist by design while the truck is pivoting during car operation on a layout, there would be minimal affect.  An Aristo car can use the USA Trains adaptor kit with the base plate having a bigger hole so when installed it fits beyond the base of floor's mounting post, thus, becomes physically closer to the car floor compared to using the Aristo adaptor.

Using a ring to minimize Kadee truck slack will also tend to stabilize the car when operated on tight curves. The ring can also be applicable when choosing 3-D printed CamPac coupler boxes which include 3-D printed "chassis bolster caps" that take the place of Kadee base plates.



Car Floors

A car's under frame or floor design affects how body mounting Kadee couplers are done and how retrofitting trucks to a given brand car is done (if done).

With respect to Aristo-Craft 40 foot type cars, there are 3 generations of removable floor assemblies that are described in the following illustrations.

The Aristo 2nd Generation floor is designed such that when mounting a Kadee 830/906  box, it will protrude out being more appropriate to a later era "Hydra-Cushion" or "Shock Control" car.  For prototypical appearance on Aristo's 40 foot type cars, the coupler box face should be somewhat flush with the end bulkhead of the car. The factory mounting hole locations for the  Kadee coupler box appears to have been chosen so the Aristo truck (devoid of coupler) could be remounted 180 degrees on the floor bolster so it would not interfere with the Box without having to cut off the truck's coupler tang and tail extension.  
What's more, the mounted height of the Kadee coupler would not align with the Kadee 880/980 Coupler Height Gauge.  

The following illustration describes modifications to correct the floor.

As an alternative, the coupler box can be saddle mounted by its two side ears.



A Hybrid Aristo Floor Alternative

Because Aristo-Craft is out of business, obtaining a lowered floor assembly may be difficult. In this event, a tall bolster floor can be modified using 3-D printed plastic replacement portions of the floor designed by Nico Corbo. Nico offers two 3-D print variation replacement bolster portions of the chassis. Both variants have a lowered bolster portion resembling the later Aristo generation chassis. This does require making some simple cuts to the once removed existing floor assembly.

See Nico's Youtube video for Replacement Bolster only

See Nico's Youtube video for Replacement bolster with integral body mounting Kadee coupler pad

Keep in mind that the floor is typically factory glued in addition to being screwed to the chassis except for the earliest production runs, so separating it to make cuts can be changeling. Also, the Kadee coupler box mounting pad height may need "tweaking" depending on car height from the railhead affected by trucks used and wheel diameters.

Nico Corbo can be contacted to purchase 3-D prints at:
This email address is being protected from spambots. You need JavaScript enabled to view it.



Various Methods for Body Mounting Kadees

Centerset couplers (no vertical offset of knuckle from shank) are preferential to use, not only for their appearance, but for better tolerating the physical forces when employed in a heavy train.  When body mounting centerset couplers, spacers may be needed, or cars & locos may need to be lowered (rarely raised) from the railhead so couplers will properly align with a Kadee coupler height gauge.  This is important because proper coupler alignment ensures compatibility between different train product brands.

The centerset Kadee 789 & newer 907 type boxes typically used for truck mounting can be used for body mounting, particularly in confined areas of a car's underside because of the box's smaller foot print compared to a centerset Kadee 830 & newer 906.  That said, the Kadee 830 & 906 wider box with extendable coupler when in tension can be more forgiving for some extreme operational conditions on a layout.  I strive for train operation down to 8 foot diameter track curves.  Track "S" bends should have a straight section about the length of the longest car between directional transitions.

The Kadee 830 & newer 906 type assembly is typically mounted using its side ears; however, there are circumstances that inline mounting is better for clearance purposes.  In most cases only two screws are needed to mount the box.  The Kadee 830 and early production Kadee 906 included # 2-56 stainless steel machine screws and nuts. The later production Kadee 906 now includes larger diameter # 4 self threading screws.  The self threaded screw may make it easier to mount the box to a car; however, It can be behooving to use # 2-56 screws because they can serve as "studs" if need be for certain mounting applications, and their smaller diameter allows for more forgiving tolerances given the larger hole diameter in the Kadee box.

Some example cars made by different companies will be illustrated to show how things can be done.


Aristo-Craft 40 foot Car Examples

The  Aristo 40 foot flat car and gondola car are described in Vignette, title:
Aristo Flat & Gondola Car - Lowered, Weighed, and Fitted with Kadee Centerset Couplers

The Aristo Covered 70 ton Hopper Car is unique and described in Vignette, title:
Aristo Covered hopper, Lowering & Kadee Coupler Installation

An Aristo-Craft Refrigerator car will be used in the following example.  Aristo 40 foot Box cars, Stock cars will be similar.  The Aristo Reefer appears to be based on their Box car and as such it's out of proportion having the same height sides as the Box car.  Typically, the sides of a prototype Reefer are not as tall as the Box car.

The Aristo Refrigerator 40 foot Car is an example of compromises.  Again, with respect to a prototype, this car has out of proportion sides (too tall), and as it comes from the factory the car also sits too high from the railhead, which further exacerbates its appearance.  As an alternative to "chopping & channeling" the car's sides (which would be delicate and time consuming to do while spoiling its otherwise good graphics in the process) I chose to mitigate its appearance to make it plausible.  This is done by lowering the car using Aristo Lowered Floor assembly and then ultimately replacing its trucks with modified USA Trains trucks to lower it even more.

The minimal approach is to ensure the car has the lowered floor installed and then mount the Kadee 906 coupler box so it fits without interference with the screw head at the end of the car.  Of course, the floor having been prepared (Ribs trimmed on pad for Kadee coupler box) and screws that hold it to the car body must be installed with a snug fit before mounting coupler boxes and trucks.

The Aristo 1st Generation floor will need to have the rib (or most of it) removed from the pad and a spacer added.  Kadee spacers can be used or an inexpensive spacer the width of the Kadee box and thickness of about 0.110 inch can be cut from a strip of plastic sheet obtained from TAP Plastics. The spacer can be glued to the floor pad and holes drilled and threaded if using 2-56 screws to fasten the coupler box (late production run Kadee 906 kits changed from 2-56 screws to self tapping screws).  Shown below is an example 1st Generation floor with glued spacers.


The 2nd generation floor will only need its surround type ribbing trimmed down to a lower height of 0.110 inch as previously described.

For further information employing the 1st Generation lowered floor and its proper orientation (for many years Aristo floors were factory install backwards), see Vignette, title:
Lowered Floors for 40 Foot Cars

and Vignette, title:
Aristo-Craft's first generation lowered freight car floors & Kadee body mount couplers

and for information employing the 2nd Generation Lowered floor and its proper orientation, see Vignette, title:
Aristo-Craft's 40 foot Double Door Box Car & Kadee Couplers

Aristo Example 1,  The 40 foot Reefer Car with USA Trains Trucks:

Shown below is an example Pacific Fruit Express (PFE) car on the left with lowered floor and Aristo trucks. The car on the right adds Modified USA Trains trucks to lower it even more.

Both PFE cars shown below have flush mounted Kadee 906 coupler boxes (detail to follow). The difference being the brand of wheels sets used in their USA Trains trucks.  The car on the left has USAT wheels (P/N R2093) while the car on the right has Aristo Wheels P/N 29111S ("S" for silver, actually they are shinny metal plated).

As can be seen above, emphasizing the "white walls" on the wheels, as some of the prototype PFE cars exhibited, further mitigates the tall appearance of the car.

Described in the Illustration below is what's done for flush mounting the Kadee 906 box.  In this example, the box is mounted using its two center holes with the longer screw in the front.



Aristo Example 2,  The 40 foot Plug Door Box Car with Kadee Roller Bearing Trucks:

Shown below is an example Fruit Growers Express (FGE) car.  This car is a replica of an Insulated Box Car.  The FGE car in the road numbers that Aristo chose to use is accurate with Bettendorf friction bearing trucks, however, I chose to use the Kadee 973 Barber roller bearing trucks that were used on higher road number cars that looked very much the same.

The car in the illustration below has the 2nd Generation lowered floor. The floor coupler pad ribs were trimmed down to a height of 0.110 inch.  In this example, the Kadee Box was positioned on top of the ribs with the face of the box flush with the end bulkhead, and then mounted using the two side holes. (The pad had to be drilled & tapped for # 2-56 thread for the mounting screws.)

When mounting a Kadee truck, the screw that fastens it to the floor post must be longer than the original Aristo truck mount screw because the surface of the Kadee adaptor "Hat" is somewhat thick. (The Hat not only is the primary means to keep the truck side frames from separating, it's the means to mount the truck, too.)  The Hat's shank is designed to envelope the floor bolster post.  In the event the floor post is split as some floors came from the factory that way, the Hat also serves as a remedy.
The replacement screw thread pitch should be similar to the original Aristo screw as shown below.

As illustrated above & below, the Kadee USA Trains Adaptor including base plate (NOT the Aristo adaptor) is used for truck mounting.  The USAT adaptor base plate hole just happens to be large enough to exactly fit over the truck bolster post's base area.  As such, the car becomes lower to the railhead when compared to using the Aristo Adaptor.



USA Trains 50 foot Car Examples

By design, like the 40 ft. cars, the 50 ft. cars have floor pads with holes intended for mounting Kadee 906 type coupler boxes.

Kadee 906 coupler assemblies are installed on these cars, however, the sides of the coupler boxes must be notched to clear wheel flanges for operation on 8 foot diameter curve truck (10 foot diameter for Mechanical Reefer car when equipped with Kadee truck due to its wheel properties).


USA Trains Example 1, The Mechanical Reefer with Kadee 973 Barber Roller Bearing Trucks

The USA Trains 50 foot Reefer car example described is suppose to be a replica of a Rio Grande car.
Since D&RGW did not actually roster a mechanical reefer car, but did roster a similar 50 foot plug door box car, the replica's livery appears to be modified to be plausible.


Kadee 973 Barber Roller Bearing Trucks are fitted to this example car in place of the USA Trains Friction Bearing Trucks.

So as to keep car height from railhead to a minimum, the Kadee 973 Adapter Kit's base plate will not be used.

Described in the below Illustration is what's involved when fitting the truck to the car.



USA Trains Example 2, The Union Pacific Express Car with Modified USAT Friction Bearing Trucks:

A prototype express car is often lower in overall height than a conventional freight car since it is used as a head end car on a passenger train.  Moreover, Union Pacific railroad paid attention to the esthetics of its streamline trains to the extent of matching its livery to be like the passenger cars as well as the height of the car being similar to the passenger cars. 


To mitigate the tall appearance of the USA Trains car in a passenger train, I chose to lower it to its maximum practical amount which is 1/8 inch.

In order to lower the car to its maximum, the USA Trains friction bearing truck was "lowered" and  the  Kadee 906 coupler box cover plate was eliminated.  
The coupler box, also, needs to be notch on its sides for wheel flange clearance when operating the car on 8 to 10 foot diameter curve track as illustrated below.

To lower the car, its trucks were "lowered" 1/8 inch.  Refer to the previous shown dimensional drawing for specific dimensions to modify USAT truck to lower car by 1/8 inch.



To emulate a car with roller bearing trucks is shown above. In this example the car is lowered by employing the plastic trucks from the USA Trains Intermodal car pretty much as is rather than modifying the Bettendorf "Hot Box" trucks.

Illustrated below is a height comparison of the UP Express car with Bettendorf and Intermodal trucks.


For a more exacting car height match to the car with the Bettendorf truck is to add thin shims within the Intemodal trucks' bolster - illustrated below.
(Caution: Shims should not be too thick as the sideframes can become pigeon toed - go out of parallel - resulting in pinched axle tips causing rolling drag.)


Shown below is what the car looks like in the passenger train (Note the passenger cars were, also, lowered and equipped with body mounted Kadee 907s.)

For a description about body mounting Kadee 907s and mitigating the appearance of the Aristo Streamliner cars by lowering them, see Vignette, title:
Aristo Streamliners - Lowering & Body Mounting Kadee 907 Centerset Couplers


USA Trains 60 foot Car Example
USA Trains Example 3, The Santa Fe 60 foot boxcar with extended "bell mouth" draft gear box

The USA Trains 60 foot boxcar is factory equipped with realistic "bell mouth" body mounted extended draft gear boxes typical of a cushion frame prototype car this long with couplers that can compress on impact.  The factory box includes a removable spacer so it can be directly mounted on the floor to better align with couplers of other brand locos & cars having body mounts assuming the USAT oversize knuckle will mate.  However, for folks desiring Kadee couplers with consistent uncoupling & coupling to locos and cars, a Kadee 906 box can be mounted with custom made adapter or use the now available CamPac 3-D printed direct fit (no adapter/spacer) box that uses the same Kadee slack action coupler (pulls out in tension) that is in the Kadee 906 box kit. The box is designed by me (Ted Doskaris) and implement by Colin Camarillo. To obtain the CamPac BoxTM, visit Colin Camarillo's website.

A comparison of the 3 coupler boxes (USAT, CamPac, & Kadee) is illustrated below.

 A discretely mounted Kadee 906 box, shown above, does require a custom made adapter / spacer.

The CamPac BoxTM uses the same Kadee coupler & spring that's in the Kadee 906 kit but is a direct fit (no spacers or adapters used) and is a slimmer, bell mouth shaped, box.

Illustrated below is the example Santa Fe car shown before & after being equipped with the CamPac BoxTM.

As shown above, the USA Trains typical factory tilted floor & coupler is also taken care of.

See the "USA Trains 60 foot Boxcar Bell Mouth CamPac Box Install Guide", available on Colin Camarillo's website.



USA Trains 40 foot Car Example:

USA Trains Example 4The Southern Pacific 40 foot box car fitted with Kadee 971 Bettendorf Friction Bearing Trucks

Compared to prototypes of this 40 foot car, it's basically OK with the as supplied USAT Friction Bearing trucks.  However, the decision was made to replace the factory trucks with Kadee 971 Bettendorf trucks even though the script on this USAT car's end bulkhead indicated "Roller Bearings".

Examining prototype material showed the road number on the USA Trains car was actually applicable to a longer, later era car having roller bearings.  Though railroad companies are known to renumber equipment , this did not prove out as far as could be determined with respect to the USAT car's number; so here is an example of what appears to be a transitional livery that subsequently did away with the round herald.

From what could be determined, double door box cars seemed to be more prevalent with the livery of the USAT single door car.  That said, a single door car was found with this livery, albeit with Youngstown corrugated door.

Described in the below Illustration is what's involved when fitting Kadee 906 couplers and Kadee 971 Bettendorf friction bearing trucks to this USA Trains car.

Illustrated below is the car now equipped with a smaller footprint 3-D printed CamPac BoxTM having conventional draft gear developed for the USA Trains 50 foot reefer & boxcar.

Note: When operating the car on tight curves should wheel flanges touch screw heads (that fasten box at its wings), the box should be mounted using its in-line holes..


American Main Line (AML) 40 foot Car Examples

AML cars are supplied with truck mount unique AML knuckle couplers.  Coupler boxes that resemble Kadee boxes may also be supplied with the car as a user installable option.  Accordingly, the car's floor already has pads with holes that can be used to mount Kadee 906 type boxes.

AML Example, The Boston & Maine 40 foot box car fitted with Kadee 973 Barber Roller Bearing Trucks

This car is factory equipped with metal AML Friction Bearing Bettendorf type trucks.  Examining prototype reference material with respect to this car's road number indicated it was among a road number series built around 1957 that were early adopters of Roller Bearing Trucks.  Consequently, Kadee 973 Barber Roller Bearing trucks were installed in place of the AML factory trucks.

Described in the below Illustration is what's involved when fitting Kadee 906 couplers and Kadee 973 Roller Bearing truck to the car.

Adapting AML coupler boxes to accept Kadees

AML freight cars typically include a pair of body mountable coupler box assemblies that resemble Kadee 906 or older 830 kits. However, the AML boxes are thinner and have an offset knuckle coupler unique to AML.

That said, the AML boxes can be adapted to accept the Kadee straight centerset shank (zero offset) #900 knuckle coupler that is used in the Kadee 906 kit - or older coupler used in the Kadee 830 kit.

Alterations needed to adapt the AML coupler box with an example stand alone Kadee 900 coupler is illustrated below.






Custom Coupler Box Prospects

Custom boxes have been developed that are made from CNC machined aluminum metal and 3-D printed plastic resin that make for easier mounting, mostly without the need for spacers, hence, direct fit.


Metal Coupler Boxes:

Shown below are direct fit metal boxes designed by me (Ted Doskaris) that utilize Kadee centerset couplers for selected locomotives.  Colin Camarillo has been commissioned to provide them.  Limited quantities may be available from Colin via his Web site.


For specifics and installation information, see vignette, "Custom Made Coupler Boxes & Kadees Centerset Couplers for Selected Aristo-Craft Locos"





3-D Printed Coupler Boxes:

Shown below are direct fit 3-D printed resin plastic "CamPac BoxesTM" that utilize Kadee centerset couplers for selected cars and locomotives - jointly designed by me (Ted Doskaris) and Colin Camarillo who has the 3-D printer and software expertise to implement the designs.


These boxes employ coupler, springs & lid from Kadee 907 kit - except for the USA Trains 60 foot boxcar that uses the Kadee slack action 900 couplers & springs with CamPac lid and American Series Woodside Reefer that uses the couplers & springs from Kadee 789 kit with CamPac lid.


Note: Small footprint boxes are now available for USA Trains 50 foot reefer & boxcars, including the Hydra-Shock variation of the box for cars identified as having cushion underframes - illustrated cars below.

See "USA Trains 50 foot Box & Reefer car CamPac Box Install Guide"
Note: If electing to lower the car 1/8 inch requiring the special order CamPac Hydra-Shock box and choosing USA Trains Intermodal trucks, they are directly mounted so truck spacer washers and mounting post extender washers are not used as shown in the Installation guide.


CamPac coupler boxes can be obtained from Colin Camarillo via his Web site at cost shown.



Early prototype railroad adopters of cushion underframe type draft gears in the late 1950s were Southern Pacific's Hydra-Cushion and Santa Fe's Shock Control.  Southern Pacific is illustrated below.

The CamPac "Hydra-Shock" box is inspired by the SP prototype car draft gear with +, - 10 inch travel that projects somewhat from the car's end sill.  Later prototypes draft gear boxes having a greater travel distance would project much farther - but replicating these can look grotesque and may cause coupled car operational problems on tight curves, such as 8 foot diameter.


Other Rolling Stock

Refer to "Vignette" (article) Titles listed below that are specific to the following brand cars:
(All cars use Kadee body mounted centerset couplers)

Note: CamPac 3-D printed coupler boxes are now available for some of the cars - described in respective vignettes.


American Main Line (AML):

AML Wood Side Reefer Fitted with Kadee 900 Couplers In AML Boxes
(Uses couplers like in Kadee 906 box in AML boxes, but using Kadee 906 or 830 kits should work same way)


AML Stock Car Experiences & Body Mounting Kadee Centerset Couplers
(Uses couplers like in Kadee 906 box in AML boxes, but using Kadee 906 or 830 kits should work same way)


AML Pullman Standard 4750 ft3 Covered Hopper Fixes & Kadee Body Mount Couplers
(Uses Kadee 906 couplers)

AML BETHGONs - Installing Kadee Body Mount Couplers & Squeaking wheel fixes
(Uses Kadee 906 couplers)

AML Hi-Cube Box Cars & Kadee 907 Body Mounts
(Uses Kadee 907 couplers)


Aristo-Craft (aka, REA & Polks GeneratioNext):

Aristo Covered hopper, Lowering & Kadee Coupler Installation
(Fitted with "Lowered" USA Trains trucks and can use either Kadee 830/newer 906 or Kadee 789/newer 906 assemblies) Note: Detailed "how to" information to "lower truck" included

AML Stock Car Experiances & Body Mounting Kadee Centerset Couplers

(Uses couplers like in Kadee 906 box in AML boxes, but using Kadee 906 or 830 kits should work same way)


Aristo's 50 ton 2 Bay Offset-side Hopper Car & Body Mount Kadee Couplers
(Uses Kadee 906; Kadee 830 also applicable)


Aristo 100 Ton Hopper & Body Mount Kadee Couplers
(Uses Kadee 906 and other related couplers)

Aristo-Craft's first generation lowered freight car floors & Kadee body mount couplers
(Includes Aristo 40 foot box cars that uses Kadee 830; Kadee 906 also applicable)

Aristo-Craft's 40 foot Double Door Box Car & Kadee Couplers
(Uses Kadee 830; Kadee 906 also applicable)

Aristo Flat & Gondola Car - Lowered, Weighed, and Fitted with Kadee Centerset Couplers
(These 40 foot type cars use Kadee 907 couplers)

Aristo Tank Car Fitted with Body Mounted Kadee 907s or 789s

Aristo EVANS Car and Body Mount Kadees
(This EVANS 53 foot car uses Kadee 830 or newer Kadee 906 couplers)

Aristo Streamliners - Lowering & Body Mounting Kadee 907 Centerset Couplers

Aristo Heavyweight Passenger Car & Body Mount Kadee 907s

Lehmann Gross Bahn (LGB):

LGB American Standard Gauge 40 foot Box Car & Body Mounting Kadee 906 Couplers

LGB Modern External Post Type 50 foot Boxcar & Body Mount Kadee 907s


LGB Center Flow Hopper Car Lowered with Kadee Body Mount Couplers


LGB Modern Tank Car - Lowered, Body Mount Kadee 907 Centersets & Added Weight

LGB 50 Foot Flat Car, Lowering & Body Mount Kadee 907 Centerset Couplers

LGB's American Standard Gauge 1/29 Scale Trucks & Mods for Car Lowering


USA Trains (USAT):

USAT's SP Hydra-Cushion Boxcar & Kadee 830s Vignette (Also applicable to newer Kadee 906)

USA Trains 60 foot box car Body Mount Factory vs. Kadee Knuckle Couplers

(This car type includes Hydra-Cushion & Shock Control)


USA Trains Golden West Service 4 Bay Hopper Car & Kadee 830s (Also applicable to newer Kadee 906)

Body Mounting Kadee 907s to USA Trains Bay Window & Extended Vision Caboose
(Without using a glued on coupler pad block or cutting the caboose body)

USA Trains Intermodal Container Car - Lowered & Fitted with Kadee 907 Centerset Couplers

USA Trains Streamliner & Kadee 906 Centerset Couplers

USA Trains American Series Woodside Reefer & Body Mount Kadee 789s

Note: Other references may be added at a later date.



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