Rails on Wheels
525 E. Michigan Ave #151
Saline, MI 48176-1588

Founded 1988

A freight car truckRails on Wheels Rolling Stock Standards
Rev. 1.0, 5/3/92

The following guidelines have been adopted by Rails on Wheels to ensure the best combination of operating characteristics possible using common standards.

  1. All cars must be readily identifiable - The method we use is a colored dot on the bottom of each car, often on one of the truck mounting screws or pins on freight or passenger cars. A dot on the bottom of the trucks or frame of any locomotive used on the modules is also recommended. The owner's initials or membership number may also be used. A Testor's paint marker is useful for this.
  2. Wheel gauge and contour - All wheelsets should conform to the NMRA Mark III or Mark IV standards gauge in all critical dimensions as defined by applicable NMRA RPs.
  3. Weight - All cars should be sufficiently weighted to track well. Two common formulae that are used within the club to calculate total car weight are:

    Both methods yield acceptable results for operation on our layout.

  4. Couplers - Standard HO-sized Kadees are preferred, and are assumed. The knuckle must be at a height that matches a Kadee height gauge when the knuckle is relaxed. Vertical knuckle play should not exceed 1/4 the height of the knuckle. The trip pin height must clear the plate on the bottom of the height gauge. The coupler must open properly and not stick open. Trip pins are not mandatory.
  5. Body-mounted couplers are preferable. - In such installations, draft gear housings must be securely attached to the car- glued boxes are discouraged, screws are preferred.
  6. All coupler trip pins should clear all trackwork. - Since the pins on horn-hook couplers are seldom used, it is recommended that they be removed.
  7. Excess height or excess width cars are permitted, but should be tested for clearance. As all trackwork and structures on the modules are to be constructed to clear an NMRA Mark III or Mark IV standards gauge, cars with clearance conforming to these gauges should experience no difficulty on the layout.

Over the past few years, we have used a "rolling stock obstacle course" to determine the conformance of rolling stock to these standards. Ours are built according to the design described by Mont Switzer in the July, 1994 issue of Model Railroader magazine.


Amtrak's Capitol Limited at Ballbach Estates
The eastbound Capitol Limited waits at Ballbach Estates while a coal drag passes
(Ray Martin photo)

Do you have questions or comments regarding this web site? E-mail to
All original contents of this web site are Copyright © 1999-2023, Rails on Wheels, All Rights Reserved.