Paul Richards is editor of Commercial Carrier Journal. E-mail [email protected] or call (610) 993-9430.
As you may remember, last year, we reported that the Federal Motor Carrier Safety Administration was considering rulemaking on the use of performance-based brake testing (PBBT) at roadside inspections.
Clearly, the FMCSA had, and has, good reasons for such consideration. According to the Commercial Vehicle Safety Alliance, brake problems still account for about half of all safety defects resulting in heavy vehicles being put out of service at roadside inspections.
And, while the most common brake defect is still misadjusted brakes, adjustment doesn’t tell the whole story. Brake-chamber pushrod stroke, which is the measurement used to determine adjustment, might say very little about how much brake force is actually being applied to the road. That value could be next to zero, for example, if the brake linings were soaked with oil from a leaky wheel seal, or if a brake is “cammed over.”
That’s where PBBT shines. Using a roller dynamometer, drive-on sensor plate, or breakaway torque tester (functional specifications for approved testing machines were established two years ago), inspectors can measure actual brake force at individual wheels. And because that’s what really stops a vehicle, such testing would go right to the heart of the purpose of roadside inspections which, presumably, is highway safety.
The final rule on PBBT was issued last month, and takes effect Feb. 5, 2003. But, unfortunately, from a safety perspective, it’s more permission than requirement. It simply establishes pass/fail criteria for test results. To pass, any vehicle over 10,000 GVW or GCW must have a total brake force equal to 43.5 percent of its weight as tested, which equates to a deceleration rate of 14 ft/sec/sec.
Here’s what the rule doesn’t do:
· Require inspectors to use PBBT;
· Establish pass/fail criteria for side-to-side brake balance;
· Require that failing a PBB test be established as an out-of-service violation at roadside inspections.
“The rule helps,” says Dick Radlinski, president of braking consultants Radlinski & Associates, East Liberty, Ohio. “But it creates no guarantee of widespread use of PBBT.
“States that want to use it can do so,” he continues. But it’s up to them to buy the testing equipment. And even money granted by the Motor Carrier Safety Assistance Program often has other uses that will compete with brake tester purchases – salaries, overtime, that sort of thing.”
Regarding enforcement, “The CVSA is expected to use the new regulation as a basis for developing out-of-service criteria,” says Radlinski. “That will allow inspectors – federal, state and local – to remove vehicles from service if their measured brake force is below the minimum level required. It’s going to be discussed at an upcoming CVSA meeting.”
As it is, “The pass/fail criteria is good for fleet operators,” Radlinski concedes, “in that it lays the groundwork for voluntary use. If asked, say, in litigation, ‘how do you know your brakes were doing their job?,’ they can point to test results that mean their trucks can stop in accordance with DOT requirements.
And PBB testers, especially dynos, have proven valuable in diagnosing hard-to-find brake problems at the fleet level. “Dynos can expose poor drum/lining fit, contaminated linings, broken park springs, broken or out-of-round drums, kinked air lines and defective valves,” says Radlinski.
“Ours has found cross-wired ABS sensors on several vehicles,” he adds. “That confuses the ABS control unit, causing the loss of two brakes under hard application. But it won’t trigger the ABS fault light. I have no idea how many trucks are out there like that.”
If the right brake testing equipment were in the right hands, there wouldn’t be many.
