Brake Chamber Sizes and Markings

I was recently performing a CVSA Level 1 inspection on a "5 -ton" commercial motor vehicle (single steering axle and single drive axle). The drive axle of the commercial motor vehicle was equipped with an air brake chamber that had a type 30 spring brake and a type 24 service chamber. The 24 service chamber was marked with an embossed marking on the chamber that said "TYPE 24L SERVICE BRAKE." By the embossment, I knew it was a long stroke brake chamber, but I was unable to determine whether it had a 2 1/2" rated stroke or a 3" rated stroke. See the attached photos. The three methods for identifying long stroke brake chambers listed in CVSA Inspection Bulletin 2014-02 "Identification of Long Stroke Brake Chambers or Brake Adjustment Limit Markings," did not clearly indicate the rated stroke of this brake chamber: 1. Service instructions embossed or stamped onto the chamber. - The chamber was embossed with an L, but no stroke length. 2. Tags showing the rated stroke of the chamber. These tags are trapezoid-shaped (trapezoidal) with information embossed on the surface. - There was no trapezoid shaped tags on the chamber, that indicated rated stroke. 3. Square-shaped air ports or a square-shaped embossment around the air port. - The ports on this chamber were round. There was also no rated stroke markings (A,B,C,D, etc.) stamped or embossed on the housing that I was able to find. With all this considered, I was still not confident in the stroke length of the chamber (whether it had a rated stroke of 2 1/2" or 3"). To identify the chambers rated stroke, I referenced the manufacturers catalogue and noticed that all the Type 24 long stroke brake chambers with a 2 1/2" rated stroke had round ports and all the Type 24 long stroke brake chambers with a 3" rated stroke had square ports. Finally, I verified the dimensions of the brake chambers with some of the measurements in the catalogue and I was satisfied that this chamber had a 2 1/2" rated stroke.

Correct identification of brake chamber size and stroke is necessary to ensure proper reference to the appropriate brake adjustment charts in the North American Standard Out-of-Service Criteria (OOSC).

I think CVSA should consult with brake chamber manufacturers and review applicable standards to determine the following in relation to Type 20 and Type 24 long stroke chambers: - If a marking of "L" or "LS" is observed on the brake chamber (and no other identifiers of rated stroke are present), and the chamber has round shaped ports, do the round ports indicate a chamber with a 2 1/2" rated stroke from all manufacturers? - If a marking of "L" or "LS" is observed on the brake chamber (and no other identifiers of rated stroke are present), and the chamber has square shaped ports, do the square ports indicate a chamber with a 3" rated stroke from all manufacturers? Depending on the answers, an update to the Inspection Bulletin 2014-02 – Identification of Long Stroke Brake Chambers or Brake Adjustment Limit Markings and potentially the Reference Charts, Long Stroke Clamp Type Chamber Data (pg. 20 of the OOSC) should be considered to provide clarification.