How to Adjust Tandems on a Semitrailer
Designed to distribute the weight of a loaded semitrailer evenly between the axles of the truck and trailer, many semitrailers are equipped with adjustable tandem axles. Improperly loaded semitrailers result in an unbalanced load, posing a safety risk by affecting turning and braking, as wells as fuel economy. Knowing how to adjust the tandems on a semitrailer to establish proper load balance is necessary to comply with safety regulations mandated by the Department of Transportation.
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Instructions
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Park the tractor and trailer on a level spot. With the tractor properly coupled to the trailer, set the parking brake on the tractor.
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Locate the tandem locking lever on the driver’s side of the trailer, forward of the front wheels of the trailer. Lift the lever up and pull the lever out, toward you.
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3
Confirm the tandem locking pins, located on each side of the undercarriage of the trailer, are disengaged. Grasp the locking lever and slide the guide bar along the tandem rail so the openings in the bar are lined up with the holes on the rail where you want to set the new locking points.
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Start the truck engine and open the driver-side window. Set the trailer brakes and release the tractor brakes.
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Move the tractor forward to increase the length of the trailer, shifting the weight of the load to the rear of the trailer. Conversely, back up the tractor to shift the weight of the load closer to the front of the trailer, onto the axles of the tractor. Listen for the loud and distinctive “click” of the locking pins snapping into place as you are moving the tractor.
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Walk around the trailer and confirm all four pins are properly seated into the locking holes on the rail. Wiggle the handle of the locking lever to confirm the lever has snapped securely in place.
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References
- How to Prepare for the CDL; Mike Byrnes and Associates
Resources
- Photo Credit Jupiterimages/Comstock/Getty Images
