OOSC, Part II, Item 1. Brake Systems - Brake Adjustment Reference Charts

The OOSC, Part II, 1. Brake System Reference Charts are not updated with current industry brake adjustments. The brake chambermate measurement on a Type 16 MGM can indicate a Type 20. The issue of concern is that newer manufacturing standards are not being accounted for in the Out of Service (OOS) Criteria. I recently assisted during a level 2 inspection on a truck that had Type 16 Long Stroke brake cahmbers on the steering axle. One cahmber was brand new and was manufactured by MGM. It was clearly marked as a Type 16 however using a brake chambermate showed it to be a Type 20. The manufacturers rated stroke on the chamber was 3”. The OOS criteria Reference Chart for Long Stroke Clamp Type Brake Chamber Data indicates this would have a brake adjustment limit of 2”. 393.47(e) states that the stroke must be less then 80% of the rated strokes however the OOS criteria does not address these greater lengths. The brake chamber on the same axle on the opposite side was older and had no readable marking on it. This brake chamber was a size 20 according to the chambermate used to measure it. If it was in fact a size 20 brake chamber, according to the OOS criteria, this truck would have been OOS for having mismatched air chamber sizes.

The OOS criteria is a very important reference guide. In order for it to be effective it must contain the most up to date and accurate information to ensure proper enforcement and education is being conducted throughout North America.

Communicate with industry to locate any changes that have been made to brake chamber manufacturing rated adjustments limits and diameter of brake chambers. If standards have been modified, the OOS criteria should be modified to reflect the changes and provide an accurate reference for individuals utilizing this publication. In addition, if the diameter of the Type 16 chambers has been increased to that of a Type 20, it should be incorporated into written text within the OOS criteria. As the chambers are exposed to the elements, the text, such as chamber size, often becomes illegible. When the chamber size can not be determined by reading it off the chamber, often times chambermates or outside diameters are used to measure the chamber and make a determination as to its size.