The Importance of Proper Truck Scale Calibration

american scale truck scale calibration test truck

Truck scales are used to weigh trucks for compliance and can often be seen along interstates. Many businesses also use them to measure inbound or outbound materials for inventory purposes.

If you’re responsible for managing a truck, then you know that truck scale calibration is a vital part of keeping the scale accurate—especially for applications that require legal for trade use. Even the smallest error can result in fines, tickets, safety issues and revenue loss.

Truck scales need to be tested and calibrated by certified scale technicians using the proper equipment and traceable calibration weights. But what exactly is involved in the calibration process? How often should it be calibrated? And how can you ensure that your truck scale is well maintained going forward?

In this blog post, we’ll answer these questions by providing insights on the truck scale calibration process, why it’s important, and how to sustain your scale for the long haul.

Why You Need to Calibrate Your Truck Scale

Truck scales are an important part of many businesses, from those in the shipping and receiving industry to waste management and recycling companies. Truck scales are often used to weigh shipments so that the proper amount is paid for the load. 

If you own a business that requires large trucking, then you know how important it is to have accurate weight readings. An inaccurate truck scale could not only cause you to over-or under-pay for your shipments, but can become a major safety issue if the truck is overloaded. 

It’s essential to calibrate your truck scale on a regular basis to ensure accuracy and avoid any potential problems. This keeps your business running smoothly while also keeping yourself, your equipment, and others out of any potential danger.

The Initial Truck Scale Calibration

Once you have selected a truck scale that is right for your business, it will need to be installed and properly calibrated. This initial calibration and certification is a critical step to ensuring that your truck scale is working properly right out of the gate. 

Each section of the scale has to be tested with the proper amount of time and precision. The scales model, location and gravity tolerance are all in play for determining if the scale is working properly in the initial testing.

Regularly Calibrate the Truck Scale with A Certified Company 

Certified truck scale calibration technicians working on a job site to test a truck scale.

After the initial testing, you will need to calibrate your truck scale regularly. How often this calibration should be done is determined by several factors. Important considerations include how often the scale is used, what it is used for, the environment it is in, and the application requirements.

There are many different methods for scale calibration but truck scale calibration is best performed on a weighbridge. If a weighbridge isn’t an option, it must be performed on a flat, horizontal and level surface with any dirt or obstructions removed before the testing.

In some cases, it may be necessary to trim the load cell outputs in the junction box to equalize the weight reading from all load cells in the truck scale system before performing any tests. This, of course, is something that would need to be determined and performed by a certified scale technician.

Performing the Test

When a certified scale calibration company conducts a standard truck scale calibration or test, they will typically use certified test truck, test weights and a test cart.

The test truck and test cart are driven onto the scale and kept running to provide air to the suspension system. Weights are placed onto the testing equipment and the readings are reviewed on the digital reader. 

There are usually three types of tests that can be performed as a part of the truck scale calibration process in order to confirm that the scale is in proper working order. 

3 Truck Scale Calibration Tests Desktop

  • Linearity Test – Grouping different weights together to see if there are any errors showing.
    • At American Scale we apply 3K of weights at a time until we reach 21K. We record the readings on each 3K drop. If we have any errors + or – during these drops, it’s a linearity error which tells us the scale needs to be serviced.
  • Repeatability Test – Adding and removing a set amount of weight onto the scale over and over, usually with a test cart, and sometimes moving around to different locations on the scale. 
    • At American Scale we load our test cart with 20K of weights. The test cart we use weights 5K. We drive the cart in many different locations on the scale platform and look for repeatability. The reading on the scale should be within .1 of 1% on a new scale and .2 of 1% on a used scale. If the repeatability is not within tolerance, we adjust the scale.
  • Eccentricity Test – Placing the weight onto different spots on the scale.
    • At American Scale, we repeat the same steps that we did in the repeatability test but we are checking to see if eccentricity is within tolerance.
    • There is typically an acceptable margin of error allowed which varies based on the manufacturer. If these readings match what is showing on the weighbridge, within the acceptable range, then the scale is working properly. If there is a discrepancy, the scale may need some adjustment. 

At American Scale, we have one enclosed test truck and three open style test trucks, and a set process for standard calibration by placing weights in the test cart and driving it across the truck scale.

First we load 20,000 lb of certified test weight into the 5,000 lb certified test cart and then use the test cart to perform the scale section and load cell tests. Once all the sections are weighing the same, we load 20,000 lbs of weights on one end of the scale. We also perform load/strain tests where we place our empty test truck off the scale and pick up 20,000 lbs of test weights while the test truck is on the scale.

American Scale truck scale calibration test trucks parked outside of American Scale Louisville, KY location.

Making Adjustments

If the truck scale reading is showing as inaccurate, then adjustments need to be made to the load cells, the platform, or even recalibration to the entire scale system. 

Making regular adjustments to your truck scale will help ensure that it remains accurate and in good working condition.

Cleaning & Maintaining Your Truck Scale

Treating your truck scale with the proper maintenance and care is vital to successful readings. 

Check the scale and the I-beams for debris like mud, dust and dirt. The gravity drain should also be free from any obstructions, allowing free flow through the drain openings. This may not seem like a high priority, but this muck can build up over time resulting in inaccurate measurements. 

The best way to clean the scale is with a power washer. If you don’t have a power washer, you can use a hose and a brush to clean the scale. 

You also need to make sure there is no standing water around the scale, this moisture around the sale can lead to corrosion. If there is any rust on the surface, cleaning it with a steel brush and repainting the area is the best way to extend the life of your scale and keep it looking its best. However, if you find areas where the rust has caused holes, it is best to have that looked at by a professional. Holes can be a safety hazard depending on where the scale has been compromised. 

Check for regular wear and tear, such as corrosion on the connecting cables, or cracks in the foundation. These things may seem small, but they could be a very expensive fix later. For example, if your cables are not in place or are covered in corrosion, a strike of lightning can result in major damage to the scale which will require expensive repairs to fix.  

Consider winterizing your scale for accurate readings in colder temperatures. Conducting a Spring cleaning ritual is a great way to ensure that you are regularly having your scale serviced and calibrated. 

Calibrate Today with American Scale

Truck scale with rails

Truck scales are important to the trucking industry and the accuracy of the weighing has a direct impact on the products being shipped and received. No matter what your truck scale is being used for, or whether it is above ground or in ground, calibration is a vital step in making sure the measurements are correct.

It is important to regularly check and make adjustments as needed in order to keep it accurate and ensure a safe and efficient operation.

If you’re interested in a truck scale product or if you’re ready to have your truck scale serviced and calibrated by a professional scale calibration company, contact American Scale today at 800-928-5005, or fill out a form on our website to book an appointment.