Heavy Duty Trucking, April 2019

aftermarket friction in a fatal collision case The friction material may not have made a functional difference in the outcome of the collision but no attorney worth his or her salt is going pass up asking why you chose a cheap and unproven aftermarket brake lining rather than the more expensive OE lining or high quality aftermarket product Lining characteristics Brake friction material has to accomplish several things to be effective It has to stop the vehicle within a reasonable or prescribed distance It has to wear at a reasonable rate so it is cost effective And it has to do all this without adding undue stress to the brake drum or rotor For example an aggressive lining might offer a shorter stopping distance but it could chew up the drum or rotor in the process Since drums and rotors especially rotors are much more expensive than linings or pads going for the aggressive lining wouldnt be cost effective at all Linings that offer long life might be characterized as hard and therefore potentially damaging to the drum or rotor Linings that claim to be quiet might be relatively soft and therefore short lived Anybody can make a pad to last long so theyll tout the wear performance and or stopping distance if theyve tested it but no one ever talks about what impact that has to the rotor McComsey points out In a lot of cases that weve tested those pads add a lot of heat to the rotor so the rotor in our testing has demonstrated that it would stress crack Those stress cracks would propagate to the point where it would exceed what CSA allows so you could potentially be taken out of service and or it would rupture the rotor to the point where it would fail And linings and pads are usually formulated to suit specific applications In longhaul over the road operations braking demands and heat dissipation requirements are lower than those of a concrete mixer or a logging truck You need the correct friction formula for your application says John Thompson OE sales manager for TMD Friction Each formula is specifically designed for different purposes such as carrying heavier loads on off highway driving temperature ranges or frequent stops etc How do you evaluate what youre buying Lining and pad material are marked with letters and numbers called edge codes but they really dont tell you much beyond who made it what its made of and its coefficient of friction According to Abex they are in no way an indication of lining quality The letters EE FF GG etc describe a range of normal and hot friction values measured when a 1 inch square piece of material is subjected to varying conditions of temperature pressure and rubbing speed on a test machine Its important to know who youre buying from who is actually making the product says Dennis Griffin product manager for Abex friction There are certain recognized names at the top of the aftermarket friction supplier list and we have come to know and trust them But with the whitebox and private label products you have no idea what youre getting how it was made or how it was tested Some supplier test results can be misleading if you dont know what youre looking at APRIL 2019 HDT 55 WWW TRUCKINGINFO COM Edge markings on brake lining material are not indicators of lining quality or performance The markings indicate who made it what its made of and its coefficient of friction LININGS closure mitigation system says Keith Mc Comsey director of marketing and customer solutions for wheel ends at Bendix Spicer Foundation Brake To save a few dollars on friction material youre effectively hindering all those investments you made in making the vehicle much safer Those systems are designed to reduce the closing speed as much as possible to hopefully prevent a collision or at worst slow the truck sufficiently to minimize the impact of a collision By changing the stopping characteristics of the foundation brakes the collision mitigation system cannot perform as it was intended That shouldnt come as a surprise and its a fact widely understood by plaintiffs attorneys Imagine yourself in the witness chair defending your choice of