FMVSS 121 Reduced Stopping Distance (RSD) Requirements

It’s only been a few years since new FMVSS 121 Reduced Stopping Distance (RSD) Requirements took effect. The amended regulation reduced the previous stopping distance by 30 percent. The update to the previous standard is a safety measure. The National Highway Traffic Safety Administration hoped it would decrease the number of injuries and fatalities linked to semi crashes. The NHTSA also expected the new RSD requirements to reduce the severity of heavy-duty truck accidents. In response to the FMVSS 121 RSD requirements, brake manufacturers changed the way they make brakes, pads, and shoes. The good news is that fleets and heavy-duty repair shops can stock RSD brakes to keep handy for regular PMs.

FMVSS 121 RSD Requirements

Before the new FMVSS 121 RSD requirements, all heavy-duty vehicles were subject to a 355-foot stopping distance. That’s just 5 feet short of the length of a football field. That RSD applied to fully loaded trucks coming to a complete stop from 60 mph. The new rules give the same trucks only 250 feet to stop. However, trucks with 3 axles carrying more than 70,000 lbs and ones with 4 or more axles carrying more than 85,000 lbs get up to 310 feet RSD.

How Are Brakes and Brake Shoes Affected?

Since stopping distance is shorter with air disc brakes, many truck builders and fleets rely on them to meet the FMVSS 121 RSD requirements. Additionally, brake manufacturers began producing RDS drum brakes. These specialized parts typically meet or exceed the RSD. Some of the changes brake companies have made include using advanced friction material to reduce brake fade and resist high temperatures better. Also, most RSD brakes are larger, and include increased wearable lining. In addition to improving stopping distance, larger brakes last longer. That means extended time between relining and brake changes.

What’s more, durable material such as steel go into making RSD brake shoes. Plus, heat-treating super-hardens them, and a powder coating helps them stand up better under extreme conditions.

Safety is the Bottom Line

The FMVSS 121 RSD requirements only apply to brakes on new trucks. Once a semi joins a fleet, it’s OK to install non-RSD parts when brakes and linings need replacing. However, with safety and performance so closely tied to profit margins, it makes sense to use RSD brakes, linings, and shoes certified to meet FMVSS 121 RSD requirements whenever your trucks need brake maintenance, whether it’s after a pre-trip inspection or during regular preventative maintenance. That goes for older vehicles, too, since the certified parts will reduce stopping distance and improve safety.

When it comes to brake maintenance, it helps to have assistance in keeping track of repairs, changes, and parts used. Fullbay is the fleet management and heavy-duty repair software for the job. It manages maintenance schedules and parts, builds estimates and invoices, and, since it operates in the Cloud, you can access it on any Internet-enabled device from anywhere. It’s a versatile tool that helps keep you on top of safety and compliance issues while freeing you up to run your business the way you want to.