Truckers News

November 2011

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BIG RIG BASICS Inspect, adjust and replace Proper attention to belts will save you from the wasted time and expense of a road call -belts need two forms of main- tenance: They need to be kept at the correct tension, and they need to be inspected and replaced before they fail. Adjusting tension will extend belt life. V Belts are tensioned two differ- ent ways. The standard system is designed so the position of one of the driven accessories can be shifted with a rotatable bolt, to increase or decrease tension. Newer systems use an automatic ten- sioner and roller that bears on the back side of the belt. It rotates on a pivot that has an internal spring and dampener. TO MANUALLY CHECK THE TENSION OF BELTS WITHOUT AN AUTOMATIC TENSIONER For standard, rigid mounting sys- tems, the best way to check belt tension is with a tension gauge. However, with experience, you can effectively check with your thumb. Depress the belt with the maximum FIGURE 1 force you can comfortably exert (see figure 1 above). You should not be able to depress the belt more than its thickness in a short span like 1 foot or less, or more than twice its thickness in a span of 2 feet or more. BELT MAINTENANCE USING A TENSION GAUGE: Look at the gauge dial and make sure it is cali- brated in pounds (figure 2, next page). Then look up the required tension in pounds in a guide that comes 1 2 Job difficulty on a scale of 1-10: 5 Tools required: Note: with the gauge, or in your owner's manual. Position the gauge with the face toward you. Depress the knob on the gauge and then assemble it around one strand of the belt, with the two stationary prongs on the inside of the V and the movable one on the outside surface. Release the knob to obtain the reading (figure 3). TO ADJUST THE TENSION alternator, air-condi- tioning compressor or fan hub. Typically, there is a hinge bolt on one side of the accessory that has a nut on one end, and a simple bolt in a slotted mount on the other side. You'll have to use a wrench on either end of the hinge bolt. 1 increase tension or counter-clock- wise to reduce it. Once tension is to specification, tighten the mounts and recheck. 2 3 RANDY ROBERTS RUNS SIX CATTLE HAULING RIGS OUT OF WINCHESTER, OHIO. He maintains his belts in several ways. When his trucks come to their home base, he opens the hood and looks underneath. He eyeballs belts for fraying or cracks. For standard mounting systems, he checks tension by feel in the standard way. For automatic tensioners, he puts a wrench on the tensioner and rotates it in the direction that loosens the belt. This will tell him right away if the 28 TRUCKERS NEWS NOVEMBER 2011 change. BIG RIG BASICS TIP DIY TO SAVE tensioner is getting weak. Several of his drivers carry extra belts and use standard tools to replace them on the road. This can save a lot of money on road calls and is probably the best tip of all. He also has the trucks inspected regularly at East Earl Truck Repair in East Earl, Pa. Their mechanics inspect belts and make repairs and adjustments to the belts, mounts and tensioning mechanisms as necessary. If necessary, repeat steps 1 and 2 to compensate for any Turn the adjusting bolt clockwise to Loosen the mount- ing bolts for the JOHN BAXTER

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