Axle-weight violations are no joke. They’re aggravating and expensive, in more ways than one: an hour wasted looking for a certified scale, or worse, shifting an illegal load at an official scale, is an hour lost from the workday.

Having a scale on board can strip away the guesswork and even add a few dollars to your payload if you’re billing by weight. Generally, all your profit is in the last few thousand pounds, so why rob yourself just because you’re not sure whether you can legally top ‘er up?

Today the popularity of pressure-sensing air-suspension-based scales has soared, mostly because of the dramatic reduction in complexity and cost, along with the wide acceptance of air suspensions in highway and other applications.

And of course there are segments of the industry where access to a scale may be a moot point anyway. In the livestock business, correcting an overload is no easy matter. “We haul cattle and hogs. Once they’re on the truck, you can’t take them off until you get them to their destination”, says Pat Hoffman of Hoffman Trucking in Sherwood Park, Alta. “With scales on our tractors and livestock trailers, drivers can weigh as they load.”

The real benefit comes with the elimination of scale fees, overweight fines, off-route miles, and wasted time and fuel in finding a scale. Many operators would find that their actual cost to check-weigh probably runs from $20 to $30 per trip to the scale when they factor in miles, fuel, and time. The cost of air suspension scales makes them attractive options in today’s every-dollar-and-every-second counts world. Some aftermarket kits sell for a little more than $1,000 US, while the trailer kits can be had for about $600.

Does it make sense to buy a scale for only the tractor if the trailer isn’t equipped with a scale? Peter Powell, vice-president of marketing at Air-Weigh, a maker of on-board scales, says it does.

“Many owner-operators who pull company trailers find that having a scale on just their tractor enables them to legalize their axle weights as long as they know that the load is legal for the GVW of the entire vehicle,” Powell says. For example, say the driver knows the freight must weigh less than 46,000 pounds to keep the entire GVW under 80,000 pounds. By either sliding the van suspension forward or backward until the scale shows the drive-axle weight is a little less than the legal maximum tandem weight of 34,000 pounds, the other end takes care of itself. If you’re legal on one end of the trailer–as long as the payload and the tractor-trailer tare weight combined weigh less than 80,000 pounds–you’ll be legal at the other.

Scale Configurations
On the basic highway rig, scales can be installed on the tractor and trailer air suspension systems, under the fifth wheel, or on steel springs or spring hangers. In-cab displays can show individual and combined weights, or the systems can be kept separate, with dash-mounted displays for the tractor suspension and nose- or bogey-mounted displays for the trailer.

Steer-axle scales are available, too, using electronic load cells, and now that air suspension is gaining acceptance on steers, air-pressure scales for them are now coming onto the market.
For dump haulers, Vulcan and Air-Weigh both offer hydraulic pressure sensors for lift rams. And Vulcan also offers a full range of specialty load cells for fifth wheels, center hangers, end-dump shear pins, and most other types of spring and air suspensions. On-board scales can be installed on virtually any truck or trailer with air, spring or mixed suspensions.

Today’s on-board scales require little maintenance. If weights are consistently different than a certified scale by more than 300 pounds, recalibration is simple and generally requires the operator to enter the loaded axle weights into the scale when the vehicle is loaded. The in-cab display needs no more cleaning or care than a CB or other electronic device.

For years, drivers have relied on simple air gauges to estimate weight. They remain reasonably accurate, but the best they can do is warn you that you’re close enough to legal that maybe you’d better hit a truckstop scale just to be sure.

On-board scales remove the doubt, and if your profit depends on squeezing every possible pound onto the truck, like in a game of horseshoes, close sometimes isn’t good enough.

MORE INFORMATION:
Air-Weigh Scales: www.air-weigh.com or call 541/343-7884. Vulcan On-Board Scales: www.vulcanscales.com, or call 1-800/663-0854