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Semi Trucks: How To Read Air Suspension Load Gauge? (Solved)

Have you ever wondered how semi-truck drivers can keep track of how heavy their truck is? How do they know how much cargo can be loaded onto their semi-truck?

The majority of drivers use a handy tool called an air suspension load gauge. If you want to find out what it is and how it works, read on!

Here’s a short summary on How to Read Air Suspension Load Gauge:

To read a semi-truck air suspension load gauge, the system’s PSI must be correlated to the weight on the truck. You must ensure that your load gauge is calibrated properly. When reading the load gauge, make sure your truck is on a flat surface, with the parking brakes off and the HCV fully engaged.

What is an Air Suspension Load Gauge?

An air suspension load gauge is a beneficial tool that can be installed on a semi-truck. There are tons of semi-truck drivers out there who use this tool to make their lives easier.

Many modern semi-trucks have them installed as standard. However, they can be installed on older semi-trucks if they are not standard with a specific model.

An air suspension load gauge helps the driver by indicating how much weight is in the trailer. It’s not 100% accurate, especially if the gauge is not calibrated correctly.

However, the air suspension gauge can get a close estimate of how much weight is on the suspension. This will save the driver time from weighing the semi-truck to ensure that it’s within the required weight limits.

It helps the driver manage the load that is put on their semi-truck, and they can check the gauge to see how much more cargo can be loaded on the truck.

How does the Air Suspension Load Gauge work?

The air suspension load gauge has a clever system to determine the cargo’s weight in a semi-truck.

Air suspensions found on semi-trucks have an element known as an airbag. The airbags inflate based on the weight that is out on them. They act like the springs you would find in a standard suspension.

An air suspension load gauge uses sensors to determine the flex or pressure in the airbags. The sensors send out readings to the gauge in the cabin which gives the driver an indication of how much weight is on the suspension.

How to Read the Air Suspension Load Gauge?

Air suspension load gauges do not give out a ‘weight’ reading. This can make it a little bit more complicated to understand what the gauge is telling you entirely.

Instead of indicating the weight on the air suspension, it gives you a reading in PSI. This is because the sensors measure the PSI in the airbags instead of the weight put on them.

Reading the PSI as opposed to the weight makes them more accurate as the weight can be split into different sections of the semi-truck, which will affect the weight reading.

There are a few steps you need to follow if you want to get an accurate reading out of your air suspension load gauge.

  1. Park the semi-truck on a level surface. This will ensure that the weight is evenly distributed across the axles. Shift the semi-truck into neutral and set the parking brakes.
  2. Check the wheels to ensure that the semi-truck does not roll or move unexpectedly.
  3. Release the parking brake as it can put extra pressure on the suspension’s airbags, influencing your load gauge readings.
  4. Make sure that your Height Control Valve (HCV) has fully inflated the airbags. If they are not fully inflated, you will need to dump the air out of them and refill them again. This could take a couple of minutes.
  5. Check the load gauge to get an idea of the weight over the axles.

How to correlate the pressure reading to weight?

It’s difficult to accurately correlate the pressure from the airbags to the weight of the load on the semi-truck.

Most drivers state that it entirely depends on the combinations of tractors and trailers that you have and that each one is unique in the readings that it gives.

Some drivers also say that the right height, size of the fifth wheel, and airbags on your air suspension can influence the reading you get from the gauge.

What should the reading be when not loaded?

Many people think that because there is no cargo in their semi-truck that the reading on their air suspension load gauge should be 0.

However, this is not the case. There is still some weight on the airbags in the suspension, which causes them to flex, and in most cases, the gauge will read around 20 PSI.

What should the reading be on each of the axles when loaded?

Most semi-truck drivers say that the air suspension load gauges should read no more than 60 PSI.

In most cases, 60 PSI is the maximum allowed weight of 80,000 lbs. However, this does vary according to your truck and trailer combination.

It’s also important to remember that the gauges are not always 100% accurate, especially if they have not been appropriately calibrated.

It also depends on the calibration of your load gauge. It can be calibrated to show a different figure for the weight that is loaded on the semi-truck.

It isn’t easy to correlate 60 PSI on the gauge with 80,000 lbs in weight. However, these figures have been established through trial and error and experience.

Can it read the weight on combination of axles when loaded?

There are different types of air suspension load gauges. The first can measure the load on one axle of the semi-truck.

The other can measure the pressure on multiple axle groups. For example, the trailer’s axles combined, and the tractor’s axles combined.

Is the Air Suspension Load Gauge Accurate?

The answer is that it depends. In the majority of cases, the gauge needs to be calibrated correctly for it to be accurate.

Even then, there have been cases where the load gauge is not 100% accurate. One driver has reported that they loaded their truck to where they usually do when measuring with the load gauge.

However, when their semi-truck was weighed it was 3 tonnes overweight. This could be down to poor calibration or a faulty load gauge.

How to know if the reading is true?

The only way to know if your load gauge reading is accurate is to load cargo on the semi-truck and weigh it on a scale.

While doing so, it’s also good to find which PSI is shown on the gauge based on the weight put on the semi-truck.

How to Calibrate the Air Suspension Load Gauge?

There is a specific process you need to follow to calibrate your semi-trucks air suspension load gauge properly. If you follow these steps, your gauge should be accurate.

  1. The first step is that you need to load the semi-truck. It would help if you never calibrate the gauge while the truck is empty, affecting the readings. You’ll want to load the semi-truck just under the legal weight limit. Usually, within 1500 lbs is a good weight to aim for.
  2. The next step is to find a certified ground scale to measure the weight on the specific axle or axle group that your air suspension load gauge is measuring.
  3. When measuring the weight of the semi-truck on the scales you want to prevent any kind of movement as this can shift the weight or the pressure on the air bags. Thus, it is important to put the transmission into neutral and set the parking brakes.
  4. You’ll also want to check the wheels to keep the semi-truck as steady as possible.
  5. The next step is often overlooked but very important. You need to release your parking brakes as they can put pressure and load on the airbags.
  6. The next step is to ensure that your Height Control Valve (HCV) has fully inflated the airbags. If they aren’t fully inflated, you’ll need to dumb the air and refill them, which could take some time.
  7. Next, you need to use a flat screwdriver to turn the calibration screw on the load gauge. You must ensure that it matches the certified scale weight.

How often should the air suspension load gauge be calibrated?

In most cases, the calibration will last a long time. However, it can be a good idea to occasionally check it to ensure that you are within the legal weight limits.

The checks can be done every month or so and the actual calibration should be done approximately every 12 months. This will vary with how frequently you use your truck to carry loads.

The last thing you want is to get an inaccurate reading and have to pay a fine for your semi-truck being overweight.