AML Stock Car Experiences & Body Mounting Kadee Centerset Couplers

AML Stock Car Experiences & Body Mounting Kadee Centerset Couplers

Ted Doskaris
August 17, 2019
Rev. GE-A Initial Release

August 18, 2019
Rev. GE-B Added chassis reinstallation illustration and comments

August 21, 2019
Rev. GE-C Added video showing drawbar measurement of train


Out of the box Car Performance
Chassis Removal
Adapting AML Boxes For Kadees
Mitigating Car Rocking & Leaning
Adding Weights
Installing Weights
Body Mount Coupler Installation





American Main Line (AML) stock cars (aka cattle cars) are available in several road names. Around mid year 2010, I obtained one each in Western Pacific (WP), Santa Fe (ATSF) and Southern Pacific (SP). The AML 1/29 "G" scale stock cars represent early 1900s era prototype rolling stock that were in use for many subsequent decades.



Out of the box Car Performance

These cars are a bit too light weight and exhibit excessive rocking and tendency to severely lean over under some conditions. The cars are equipped with all metal Bettendorf type trucks with metal wheels like used on AML's 40 foot box cars and have the same excessive axle side play that can be corrected with washers as described in vignette, "AML freight car truck problems".


The car's truck sideframes are rigidly attached to the truck's bolster and do not have springs or any means to flex to provide car articulation, so it appears AML chose to use a unique coil spring truck mounting mechanism that results in significant body articulation that would provide operation over very uneven track work. But operation around curves proved problematic, particularly when employing body mount couplers. AML does supply user installable body mount coupler box assemblies of their own design in a plastic bag with the car.

In the Illustration below the severity of a leaning car (when positioned near the front of a long train) can be appreciated. At this point in time the car had been fitted with AML's supplied body mount coupler box assemblies.



Chassis Removal

The car's body shell and chassis are fastened together via mating posts within the car held together by screws within deep recesses.
In order to install added weights, or for other purpose, the chassis can be separated from the body shell as Illustrated below.
(Note: When taking out the chassis, trucks and/or body mounted couplers can be left in place.)


Adapting AML Boxes For Kadees

The AML Stock Car includes a pair of body mountable coupler box assemblies that resemble Kadee 906 or older 830 kits, but the AML boxes are thinner and have an upward offset knuckle coupler with straight shank unique to AML.

AML boxes can be adapted to accept the Kadee straight shank centerset (zero offset) #900 type knuckle couplers that are used in the Kadee 906 kit - or predecessor coupler used in the Kadee 830 kit.

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

While Kadee 906 or older 830 assemblies may be the best expedient to install on the car, the modified AML boxes fitted with Kadee 900 centerset couplers were utilized in the examples that follow. (Installation is later described in section, Body Mount Coupler Installation)


Mitigating Car Rocking & Leaning

Illustrated below is an example method to minimize the ill effects of the car's tendency to rock or lean concerns how the trucks are attached to the car.



Chassis Issues


Adding Weights

The car's operation can be notably improved by increasing its weight by about 1/2 pound.

Plates meant to be bearing surfaces for building foundation bolts that are made by Simpson Strong-Tie* are readily available from big box stores like Home Depot. These plates are about 0.2 pounds each. Two plates are used to weight the car. Illustrated below is an example of what is needed in addition to the plates.

The ABS plastic material for the square washers can be cut in long strips to the width needed by TAP Plastics, so all that need be done is to cut off the length needed and drill the offset hole - shown above.


Weight Plate Attaching Screw

I chose to use a metric M3 by 15 mm self threading screw. (Screws that are supplied with a Kadee kit are #4 self threading, formerly #2 machine types, fit too loosely.)
The screw is used to hold the metal plate with plastic square washer to an existing hole in the car's chassis. The plates will not show since they will be placed above each truck within the interior extremities of the car for a low center of gravity.

How the screw size was determined is illustrated below.

Note: It may be worthwhile to check for your own parts owing to manufacturing tolerance differences. Slight difference can affect screw fit.



Installing Weights

In the illustration below, the screw used to attach the weights is an M3 by 15 mm self threading screw with metal lock washer under its head.

Car Weight with Added Weight

The car's weight was increased by about 0.4 pounds, just enough to make an operational difference.



Body Mount Coupler Installation

AML coupler box assemblies can be installed in place of truck mount couplers. When doing this the truck mount couplers are to be removed, and the truck is to be mounted on the car chassis reversed so its tang faces inward. AML coupler boxes are included in the packaging the car comes in as an option for the user to install. The AML boxes resemble and have a similar foot print of the Kadee 906 and older 830s, but do differ.

In the examples that follow, AML boxes were adapted to accept stand alone Kadee 906 couplers as previously described.

That said, Kadee 906 or 830 assemblies can be used rather than going to the time & effort to adapt AML boxes to accept a stand alone Kadee coupler.

Illustrated below is a better location for the coupler box assembly that is more prototypical.

Note: Coupler boxes can be installed on the chassis with or without the chassis being separated from the body shell.

Note: The coupler box lid (whether using AML or Kadee boxes) needs to have its lid trimmed when installing the box in the new location - illustrated below

Note: An installed unmodified AML box with its factory intended AML upper offset coupler would not be expected to align with the Kadee gauge without using a spacer.


Chassis Reinstallation

When reassembling the chassis & body shell, it does not matter whether trucks and/or coupler boxes had been preinstalled or already installed on the chassis.






A drawbar measurement is done to see how much force it took to pull the long 41 car train around the tree where the AML stock cars had "string lined" before they were modified - though they already had some truck mount spring stiffening with an incomplete set of washers.


Operation of the long train with the AML stock cars at the front of the train include a description of what happened with these cars before and after weights were added along with another truck mount spring stiffening washer.





* Simpson Strong-Tie is a registered trademark of SIMPSON STRONG-TIE COMPANY, INC. CORPORATION CALIFORNIA



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