Surge Brake OOS Threshold

Part 393.48(d) Surge Brakes, allows the use of surge brakes on specific size CMV combinations. This section limits the trailer to a maximum GVWR or actual weight of 20000 pounds. The trailers GVWR or actual weight cannot exceed 1.75 times the towing units GVWR if the trailer's GVWR or actual weight doesn't exceed 12000 pounds. The trailer cannot exceed 1.25 times the towing units GVWR if the trailer's GVWR or actual weight is above 12000 pounds up to 20000 pounds. Currently there is nothing in the NAS OOC addressing a situation where these designated ratio's are exceeded.

During a recent CMV inspection it was discovered that a CMV with a GVWR of 14000 was towing a surge braked trailer with a GVWR of 18000. This alone would have violated the FMCSR's. However the actual weight of the trailer which was transporting a large boat (see attached photo's) was 25680 pounds. Which results in the trailer exceeding the towing units GVWR by more than 1.83 times. The actual weight of the towing unit was only 10480 pounds, so the real roadside weight ratio of trailer to towing vehicle exceeded 2.4 times. Vehicles operated exceeding these ratio's will have a diminished trailer braking capability and overburdened towing vehicle braking system. Which creates an imminent hazard and an increased possibility of a crash.

The limits for surge brake ratio's allowed by the FMCSR's is the point at which a violation occurs. Like other parts of the OOSC often place a different threshold for a violation versus an imminent hazard. This system, I feel should have an OOS level that is greater than the level of the violation. I request that the committee include surge brake systems in Part II of the NAS OOSC. The section should be placed just after letter o. Hydraulic Brakes. Suggested language and OOS levels are as follow: p. Surge Brake Systems (1) Trailers with a GVWR or actual weight of 12000 or less. When the trailer GVWR or actual weight, which ever is greater, exceeds 2 times that of the towing unit GVWR. (2) Trailers with a GVWR or actual weight of more than 12000 and up to 20000. When the trailer GVWR or actual weight, which ever is greater, exceeds 1.5 that of the towing unit GVWR. (3). Any surge braked trailer, regardless of the towing unit GVWR, that has a GVWR or actual weight that exceeds 20000 pounds.