Logging truck drivers in Saskatchewan have the tricky task of eyeballing the weight of every load, since they have no access to commercial scales. When they overestimate, they miss out on revenue, as they are paid by weight. If they underestimate and their load exceeds the weight limit, a new law that came into effect this year requires mills, which weigh every load, to levy fines.

“We’ve had a lot of weight problems, up and down,” says Mark Heppner, the owner of A. Heppner & Sons Pulp Ltd. in Meadow Lake, Sask. “We have no way of knowing till we hit the mills what we weigh. When we reach the mill and are overweight, the mill will fine us.”

Heppner has seven tri-axle trailers on tandem trucks, and has installed on-board scales, manufactured by the Oregon company Air-Weigh Scales, on six of them. He has been using them since 2000 and says, “We had an extremely difficult time in the past. We put on on-board scales so we can maintain a consistent weight. It’s almost to the point where we have no choice but to have some sort of scale system,” Heppner explains.

No carrier can afford to deny itself revenue, or have it eaten up by fines. Heppner’s weight limit is 62,500 pounds, and in one typical week when one of his drivers hauled 11 loads, nine of them, thanks to the on-board scales, were between 62,000 and 62,500 pounds. The other two weighed in at 61,930 and 61,860 pounds. One September morning the same driver called him to say that the difference between the on-board and mill scales was only 80 pounds.

“We are not getting any fines. We are running so close to maximum weight and not going over. I can say that we are in the best situation we can be in under the circumstances. These scales are phenomenal,” Heppner says.

On-board scales have been used in niche markets for a long time, but lower purchase costs – as little as US$600-$700 – and the appearance of air suspensions has fueled more widespread use by mainstream fleets.

The main components of an on-board scale are the load sensors and a meter. Load sensors can be mounted over spring suspensions, in hydraulic systems to measure fluid flow, or spliced into air suspension lines to measure an increase in compensating air pressure as a trailer is loaded. They can be mounted in tractors or trailers and, depending on how many are installed, can measure the total tractor and trailer weight, or the weight on individual axles. On-board scale systems can be purchased as an option from an OEM or as an aftermarket product.

The meter is the brain of the system. It collects and interprets the data from the sensors and displays it to the driver. Some are installed externally on trailers, some are dash-mounted, with liquid crystal displays (LCD). Others are hand-held, battery-operated units.

Which manufacturer’s scale to buy depends on variables such as the truck type, data collection requirements and whether the tractors are fleet-owned or run by owner/operators. Model selection also depends on the number of tractor and trailer axles from which the driver needs to obtain weight information.

Vulcan On-Board Scales, manufactured by Stress-Tek, Inc, in Seattle, Wash., which designs and manufactures solutions for spring, air and mixed spring/air suspensions, lays claim to being able to fit scales on anything with wheels. For over-the-road work, where weights need only be displayed to check weight limits, the Vulcan V300 is sufficient. The high-end model, the V600, has additional display capabilities and can communicate with other smart devices, such as computers – useful if load information is to be incorporated into a billing system. It can capture over 1700 events, including date, time, and weight for later downloading.

Buyers may prefer to choose a brand that is available from their regular OEM. This August, for example, Freightliner announced the availability of the Air-Weigh AW5800 model as an in-dash, production option. “It is a repackaging of the 5750 model. It takes it out of an aftermarket installation into a production installation,” says Peter Powell, Air-Weigh’s vice president marketing.

The AW5800 is a digital scale with a keypad and a three-line LCD display. When the AW5800-equipped tractor is connected to an Air-Weigh-equipped trailer, the driver can see trailer weight data, including six axle weights, GVW and net payload displayed in the cab. The scale can be connected to the 1708 data bus, enabling the on-board computer to pull off data and send it to any on-board communications system.

Air-Weigh sells 60% of scale systems as a standard production option on trailers from 84 trailer manufacturers. The AW5802 Self-Weighing Trailer Scale is mounted independently on the trailer, with its own display, keypad and axle weight sensors. It is accurate to within 135 kilograms, (300 pounds) of a DoT scale. The AW5802 is a stand-alone unit, but it can communicate with any Air-Weigh equipped tractor.

Weigh-Right on-board scales can measure the weight on all axles, including air suspension, steel spring, rubber spring, and hydraulic suspension axles. Its clients are typically in the 18-wheel motor freight, construction, logging, waste, aggregate hauling, and agricultural markets. The Easy Air II, designed for air suspension systems, consists of a sensor system in trailers, and a hand-held meter that drivers connect to a quick connect port to get weight readings.

Prime Inc. of Springfield, Missouri, decided that the Weigh-Right system was ideal, and installed it in over 4000 trailers. The drivers – mostly owner/operators with their own tractors – own hand-held meters which they use to check the trailer weight after they have hooked their tractors up to the trailers.

Prime has become so confident of its on-board scales that if its clients insist on having loads weighed at commercial scales, Prime bills them. “Prime is telling their customers that if they make them go out of route to find scales they will be billed for it. In a case where [a load] is overweight they will tell the customer, [but] they sometimes say, ‘”That is not a certified scale. I am not going to believe that.”‘ Prime is taking advantage of their scales and investment and are using it as a productivity tool. Their drivers make more money,” says Weigh-Right president Dave Dohrmann.

Schaffer Trucking, in New Kings Town, Pennsylvania, is using Weigh-Right scales to save time by not having to drive to commercial scales. “We utilize them in a metropolitan atmosphere where scales are difficult to get at. They help us make two deliveries a day instead of one. It is positive for us and our shippers. The shipper saves costs in multiple ways, including having to use fewer of their own trucks. It enhances our product and saves the shipper money,” explains the company’s Ray Dunn.

“Productivity is becoming something that is on everyone’s mind. As the industry is becoming managed to a higher level, they start looking for fruit higher in the tree. It is the reason people want to talk to us. They realize there is a variable there they can affect,” says Dohrmann.