Proper maintenance of truck scales ensures accurate tracking of material sales.

by Bill Murphy

Truck scales are a vital tool for aggregate operations, and the performance of the scale can have an enormous impact on profitability. The truck scale is the cash register through which materials are bought and sold and where profit and loss is measured.

A challenge facing many truck scale owners today is determining how long they should continue spending money on repairing an aging truck scale. When is it time to replace it? Today, the average cost of a truck scale service call can run anywhere from a few hundred dollars to several thousand dollars depending on the age, condition, type of problem, and design of the equipment being used. Chances are if maintenance costs are already significant, they will increase in the future.

Choosing the right truck scale for the application is the best long-term plan. Heavily concentrated and high-traffic volumes make rock and gravel applications some of the most demanding in the weighing industry. With that in mind, a well-designed truck scale and proper maintenance plan are the two most important elements in ensuring the sustained profitability of your aggregate facility.

Choosing the right truck scale

Truck scales are traditionally long-term investments that should provide decades of reliable and dependable service with minimum maintenance. Saving a few hundred dollars on the front end may cost thousands in unexpected maintenance costs later. In recent years, many truck scale owners have experienced higher maintenance costs and in some cases, even structural failures after just seven to nine years of reasonable usage.

Generally, the life expectancy of a truck scale is dependent on three primary factors, including the following:

1. The daily truck volume,
2. The axle loading and axle configurations, and
3. The scale weighbridge design.

Most truck scale products on the market have been designed for legal highway loading, which in most states means a gross vehicle weight in the range of 80,000 pounds. For a typical 18 wheeler, that means 12,000 pounds on the steering axle, 34,000 pounds on the drive axle, and 34,000 pounds on the trailer axle. The higher the axle load, the higher the stress concentrated on the weighbridge and load cell mounts.

It is important to ensure that trucks such as tri- or quad-axles are weighed with the tag or pup axles in the down position to ensure the load is spread over a wider area of the scale platform. Signs should be posted at the entrance of the scale to be sure drivers adhere to these regulations.

The design and type of steel used in the weighbridge is the most important factor in determining the eventual lifespan of the scale. The main support structure should be composed of structural I-beams, not channel, tubing, or bent-steel shapes. Because the steel weighbridge accounts for nearly 70 percent of a scale’s cost, some designers have taken shortcuts by using lighter and fewer steel components. These products are less expensive and may offer a lower capital price, but the result may be a shortened scale life and increased maintenance expenses.