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
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
The eastbound Capitol Limited waits at Ballbach Estates while a coal drag passes
(Ray Martin photo)
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