A standard semi truck is a large vehicle used to transport goods across the country. It is also commonly referred to as a big rig, eighteen-wheeler, or tractor-trailer. The exact number of axles can vary based on the size and weight of the load being hauled, but the most common configuration has three axles.
The front axle of a semi truck is known as the steer axle and provides directional control of the vehicle. The wheels on this axle are connected to a steering system and are capable of turning in either direction. On most trucks, this axle also carries some weight in order to maintain balance as the truck turns.
The two remaining axles are known as drive axles. These are connected to the engine and provide power to move the vehicle forward or backward. Most standard semi trucks have two drive axles with four wheels each for a total of eight wheels that provide power to move the truck down the highway.
The rear axle on a semi truck is usually much heavier than either of its two counterparts up front, due to its job of carrying most of the load’s weight. This axle is often referred to as a “pusher” axle since it pushes most of the trailer’s weight when driving uphill or against strong winds. On some larger trucks, you may find an additional fourth axle located between these two rear axles; this helps spread out even more of the load’s weight so that it can be safely carried without exceeding legal limits imposed by state laws or federal regulations.
In conclusion, a standard semi truck typically has three axles: one steer axle up front for directional control; two drive axles in back for powering the vehicle forward; and sometimes an additional fourth “pusher” axle between them for carrying extra weight from large loads. Altogether, these three (or four) axles provide enough strength and stability for safely transporting goods across long distances with minimal wear and tear on both drivers and vehicles alike.