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Tests confirm knock-off brake components pose risk to safety, durability

Tests completed by Bendix Commercial Vehicle Systems LLC confirm knock-off brake valves to be inferior when compared with genuine Bendix valves

Tests completed by Bendix Commercial Vehicle Systems LLC confirm knock-off brake valves to be inferior when compared with genuine Bendix valves.

Bendix, on the forefront of combating the counterfeit product epidemic, tested knock-off parts, purchased off distributor shelves across North America, against its own design specifications and discovered knock-off products can create safety issues, as well as problems associated with brake feel and durability.

“Our business involves efficiently stopping heavy vehicles, so any compromise to the integrity of vehicle braking systems due to poorly manufactured knock-off components can have serious consequences on highway safety across North America, on our customers, and on our brand in general,” said Dave Schultz, Bendix marketing manager – valves.

After several thousand hours of comprehensive testing and evaluation to assess safety, brake feel, durability, corrosion protection and more, Bendix engineers and brake system experts examined the data to reach a number of critical conclusions. First, knock-off valves create double the allowable OEM specification for pressure differential. Too high a pressure differential means the primary circuit opens long before the secondary circuit, leading to an unstable vehicle, longer stopping distances for both routine and emergency stops, and accelerated wear of other critical brake components such as friction materials, drums, and seals.

Knock-off valves were also found to have inconsistent spring tension, which means loss of the driver’s ability to lightly apply the brakes during normal operation.

Because of the inconsistent or poor-quality spring, these valves act more like an on-off switch instead of providing the expected gradual braking capability, Schultz said.

Tests also revealed knock-off valve bodies cracked before durability testing was complete.

Most failures occurred well in advance of the halfway mark during extended durability testing designed to simulate normal operating wear and tear.

“This is troublesome because the valve is more susceptible to cracking and valve rupture due to weak or thin body castings.

This type of failure can pose a major safety hazard for both the vehicle driver and others on the road, including brake actuation while the vehicle is at full highway speed,” Schultz said.

About Bendix Commercial Vehicle Systems LLC

Bendix Commercial Vehicle Systems, a member of the Knorr-Bremse Group, develops and supplies leading-edge active safety technologies, air brake charging, and control systems and components under the Bendix® brand name for medium- and heavy-duty trucks, tractors, trailers, buses, and other commercial vehicles throughout North America. An industry pioneer, employing more than 2,000 people, Bendix is driven to deliver solutions for improved vehicle performance, safety, and overall operating cost. Bendix Commercial Vehicle Systems is headquartered in Elyria, Ohio, with manufacturing plants in Acuña, Mexico; Frankfort, Ky.; and Huntington, Ind. For more information, call 1-800-AIR-BRAKE (1-800-247-2725) or visit

NOTE: This content is supplied by manufacturers, associations, and others in the trucking industry. It is neither written nor edited by FleetOwner.

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