Monday, 01 July 2019 17:19

ASA Webinar Wednesday Addresses Belt Slip

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The belt must always point to the root cause of the failure. When a customer comes in, you need to gauge belt wear.


Addressing the problem of belt whip where the belt whips as it rotates over the back of the system, Bassett explained that this creates torsional vibration and the solution is to create an aramid cord belt. He provided detailed information on the wear-and-tear parts of the serpentine belt drive components, emphasizing, “The belt has one job—to transfer the power from the crank, but the ABDS is not just a belt; it’s a system that includes the belt, the tensioner, system pulleys and related accessories, and the repairer needs to verify that everything in the system is operating correctly.”


Belts can only tolerate a misalignment variance of one degree, and excess variances often lead to belt noise. Bassett explored belt noises related to tension and alignment, reiterating “The belt is doing its job which is to grip the pulley and create friction, but it is being forced to slip.”


After sharing some trouble-shooting tips for Micro-V belt noise problems, Bassett covered some common perceived belt failures and he described the tensioner’s two job functions: maintaining the correct belt tension throughout the tensioner’s duty cycle and dampening the impulses from the engine as each cylinder fires. Bassett then identified the four failure modes of a tensioner.


Like a tire that requires four things to ensure proper performance (proper tread, alignment, balance and air pressure), the belt’s proper performance relies on proper rib depth, alignment, dampening and belt tension. Bassett added, “Belts and tensioners were designed as a system. Correct alignment and tension are critical to the system. For best results, replace both together.”


Next, Bassett covered modes of belt failure and understanding those failures. He wrapped up his webinar by describing the Gates Solution to the problem. “Without proper tension, even the best new belt can’t efficiently transfer power. Kits get to the root of the problem. A worn or noisy belt is only part of the issue. Tensioners wear at the same rate as the belt and should be replaced together.

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