A new air-disc brake pad friction material from TMD Friction of North America, Textar T3070, is first TMC approved replacement option for newer tractor designs with air disc brakes on steer axles and drum brakes on drive axles.

TMD Friction says its premium aftermarket lining material meet FMVSS 121 dynamometer requirements of the Technology & Maintenance Council's Recommended Practice #628 - "Aftermarket Brake Lining Qualification," as verified by SAE's Performance Review Institute. As a result, TMD's friction material for 225 size calipers is the first and only air-disc pad listed on TMC's list of approved replacement linings, the company says.

In addition, TMD's premium drum brake lining, Textar T5000, has also passed RP 628 qualification testing for standard 16.5x7 drum brakes.

Compatibility issues facing operators of vehicles with different brake designs on front and rear axles were a major reason TMD developed and certified to aftermarket standards a disc brake pad formulated to replicate the performance of drum lining material.

"The driving force behind our pursuit of TMC's approval is that we believe the growing number of air disc brakes in the North American market could trigger a rash of disc/drum brake compatibility issues, including rotor cracking and pre-mature wear," explains TMD's general manager, Tom Green.

Also of concern is the entrance of potentially inferior aftermarket disc-brake pads. The key to TMD's T3070 air-disc pad formulation is that its high energy performance "matches" the high energy performance of typical North American drum brake linings. That assures compatibility between two types of brakes that can cause problems for truck operators.

"Unfortunately, North America has a higher probability of these issues than Europe -- where air disc is the dominant brake -- due to the lack of aftermarket lining regulations here," Green says. "That is why TMD supports RP 628, and the inclusion of air disc aftermarket pads on this approval list."

The inherent difficulty in mixing air-disc and air-drum brakes is that the disc brake will often do a disproportionate share of the work, resulting in premature pad wear compared to the lining of a drum brake.

"Disc and drum brakes differ in both the way they mechanically react to higher temperatures, and the type of linings that are typically used on them," says Jim Clark, director of engineering for TMD. "Disc brakes generally have metallic-type linings that continue to produce friction at high temperatures, while drum brakes typically use non-metallic linings that lose torque, or fade, at high temperatures.

"The T3070 pad chemistry is formulated to give significantly longer life, reduced rotor scoring and cracking, and improved compatibility to North American drum brakes, when compared to other available disc brake pads," Clark says.

TMD Friction of North America has offices and manufacturing facilities in Troy, Mich., and Queretaro, Mexico. TMD Friction, a Luxembourg Group company, is a global manufacturer of brake friction materials for the automotive and commercial vehicle industry.

More info: www.tmdfriction.com.