What Is Axle Ratio on a Semi Truck?

Axle ratio is the ratio of the number of revolutions of a driving wheel to one revolution of the driven wheel.

The axle ratio of a semi truck determines how much torque is delivered from the engine to the wheels, and is an important factor in determining fuel economy.

The axle ratio is typically expressed as a number such as 3.73 or 4.10. How this number is determined is by counting the number of teeth on the ring gear on one side and then multiplying it by two, then counting the number of teeth on the pinion gear and dividing it by two. This will give you your axle ratio.

Choosing an axle ratio for a semi truck can be tricky because there are so many factors to consider, such as fuel economy, performance, and payload capacity. Generally speaking, a lower axle ratio – such as 3.73 – will provide better fuel economy but less power and performance than a higher axle ratio like 4.10 or 4.56.

For most semi trucks, a 4:10 axle ratio offers good balance between fuel efficiency and performance because it provides more low-end torque than other ratios without sacrificing too much in terms of gas mileage or top speed.

Conclusion:

Axle ratio on a semi truck is an important factor that affects its overall performance and fuel efficiency. A lower axle ratio generally provides better fuel economy but less power than higher ratios like 4:10 or 4:56 which offer good balance between fuel efficiency and performance.

Photo of author

Karen Watkins