Putting brakes to the test

Brakes are at the top of maintenance worries for every fleet, and a solid maintenance program is no guarantee that brakes will perform as needed. Consider a report on the adoption of a performance-based brake testing system in the 205-vehicle fleet operated by the City of Long Beach, Calif. Despite a rigorous maintenance program, this fleet found it had big brake problems. Solving those problems made the trucks safer and cut driver complaints by more than 90 percent. It also reduced overall brake maintenance costs by at least $125,000 yearly because routine preventive maintenance replaced many emergency repairs.

The City of Long Beach’s brake tester consists of a motorized dynamometer, computer and a lot of software. An electric motor rotates each wheel slowly while the operator gradually applies the brakes until reaching maximum apply pressure. The tester precisely measures the torque each brake produces. The technician inputs data on the equipment, and the machine knows what the brake torque values must be to be up to snuff.

Data gathered over a period of 20 months in Long Beach shows that a performance test on every wheel is better than periodic inspections/road tests, says Dick Radlinski, president of Radlinski and Associates. Radlinski’s company produces the RAI in-ground brake tester that Long Beach uses.

The problem with road tests, Radlinski says, is that they don’t reveal much unless the fleet uses an instrument to measure deceleration or unless the driver locks up the wheels – something most fleets don’t want to do on a regular basis. Even if the technician does sense a problem, it’s hard to figure out which wheel or wheels are at fault.

Visual inspections may be even less useful. There are many things an inspector won’t find, such as the wrong type of lining with a lower – or higher – coefficient of friction than the original. Nor would a visual inspection show a lining that is not properly matched to the drum in terms of its arc – a problem when a standard lining is used and the drum has been turned or is greatly enlarged from wear.

Or consider a broken spring in a spring brake. These are difficult to spot visually. Yet, broken springs disable the parking function and often interfere with service brake chamber operation, making it function near the end of its travel rather than at the beginning, where application force is greatest. The tester also determines whether or not spring brake torque is to spec, so broken springs always show up.

A brake tester also might detect a problem that a fault code might not. For example, the RAI system has found ABS hooked up backward so the antilock would induce rather than prevent a skid. No fault code noted the error.

While only medium-size or larger fleets can normally afford such an installation, performance-based brake testers produced by both Radlinski’s company and a competitor called VIS will be sold to dealers and repair outlets. Thus, small fleets could outsource performance brake testing on a regular schedule, getting the same benefits available to system owners.

There isn’t much data yet on crash or cost reduction. But the data on reduced driver complaints certainly hints strongly at an improvement. Plus, using a performance-based tester could pay off in other ways. Dennis Hill, the manager of fleet services in Long Beach, says his system “creates an audit trail for mandated inspections and potential litigation.” You could prove in court that you have kept your brakes safe.

There’s one more reason to consider investing in a performance-based brake tester. Eventually, it may be a common means of enforcing brake performance. As of February 2003, the Federal Motor Carrier Safety Administration has adopted criteria for approving performance-based brake testers for the purposes of enforcement. For more on those criteria, visit this site and search Docket No. 6266.

Radlinski admits that the learning curve may increase brake costs while a fleet gets its trucks up to full braking efficiency. But maintenance costs will ultimately decrease because small problems will get fixed before damage spreads. Further cost reduction stems from the fact that consistent balance of a rig’s brakes makes linings last longer. The benefits in maintenance, safety and driver satisfaction may make a performance-based brake tester a sound investment.