(AAR) has promulgated a new Rule 46 in the Field Manual of the AAR Interchange Rules. This new rule represents a comprehensive effort to codify under one umbrella many of the formerly fragmented rules dealing with truck wear limits, maintenance criteria and inspection standards. Specifically, for the first time there are now condemning limits for friction casting (wedge) rise above the top of the bolster when a car is on a repair track.

As explained in earlier Interface articles in dealing with truck warp, harmonic rock and roll, and truck hunting (see related articles in the side panel and the Interface Archives), friction casting wedge rise can be a critical factor in poor truck performance. When friction castings rise to a certain limit above the top of the bolster, it is an indication that the sacrificial wear surfaces have worn to an extreme condition. In this condition, truck damping and truck warp restraint are severely degraded.

Prior to Rule 46, the only AAR standards that addressed wedge rise were found in Rule 88, which was typically applied when cars were going through major maintenance overhauls. If excessive wedge rise was spotted when a car was on a repair track for routine maintenance, such as brake shoe replacement, there was no mechanism to force repair of the friction castings, or to specify billing procedures. The new Rule 46 should go a long way toward improving truck performance in dynamic regimes by allowing earlier detection of impending truck damping performance issues.

When reviewing the new Rule 46, bear in mind that there are two distinct sections. Section 1 presents standards and condemning limits for a car “at any time.” This means that any time a mechanical inspection reveals that one of the condemning limits is exceeded, repairs can be made and billed to the car owner. For instance, if during an outbound inspection in a yard track a condemnable situation is observed, the car can be moved to a repair track for remediation and repair. Section 2 presents standards and condemning limits when a car “is on a repair track for any reason.” This means that a car must first be on a repair track for these standards to take effect.

Rule 46: Section 1

Section 1 of Rule 46 also provides the following standards and condemning limits for a car at any time:

— Truck side friction casting wear plate is missing, broken or loose.

— Bolster wear plate is missing, broken or loose.

— Vertical clearance between the truck bolster center plate rim and the body center plate is less than 1/16 inches at any locations.

— The difference in the diameters of body center plate and truck bolster bowl at the same location exceeds 1-3/8 inches.

— Body Center plate bowl or truck bolster bowl is worn to limits shown in Table 1 (see Figure 4).

— Truck is detected by a truck hunting detector exceeding certain thresholds (see Rule 46 for more detail).