The axle is one of the key components on the vehicle chassis, especially the rear axle of the trailer, which bears the main weight of the loaded goods, and is directly related to the strength of the vehicle's load-bearing performance.

Generally speaking, the axle is connected to the frame through suspension. However, in actual vehicle applications, we can often hear the saying "reverse axle mounting". What kind of installation method is "reverse axle installation"?

The so-called reverse mounting of the axle refers to the installation of the leaf spring originally installed above the axle on the lower side of the axle, which is reinforced by the riding screws, the lower card plate and the invisible bow bracket, commonly known as the hoisting axle. As shown in the figure below:

Reverse installation of axle

Front mounted axle

Why should the axle be reversed? The main reason is to reduce the height of the body. After the leaf spring is installed under the axle, the working surface of the whole vehicle can be reduced, which can not only improve the passing ability of the vehicle on the road section with height limit, but also load more goods and pull more squares.

In addition, after the axle is installed reversely, the chassis of the vehicle is lower, the center of gravity is also lowered, and the vehicle runs more stably.

Of course, the disadvantages of reverse axle mounting also exist. The most obvious is that the requirements for road conditions are improved. If the road conditions are relatively poor, the vehicle chassis trafficability will also be affected.

More worrying for car owners is whether the load-bearing performance of the vehicle will be affected after the axle is reversed.

Theoretically, if the leaf spring is installed above the axle, that is, when it is installed formally, the leaf spring directly bears the weight of the vehicle body; When the leaf spring is installed at the lower side, the axle directly bears the load, and then transmits the force to the leaf spring through the riding screw, which is almost equivalent to directly bearing the force with the riding screw. The risk of the screw breaking is great. The leaf spring is still the largest force bearing side even if it is installed reversely. Once the screw is broken, the leaf spring is easy to fall off.

Although this is the case in theory, the reputation of reverse loading axle seems not very bad in practical use:

So, which is better, the front axle or the reverse axle? The operating conditions of the vehicle shall be comprehensively considered.

It is better to install the leaf spring of the minivan under the axle. The chassis is low, the center of gravity is low, and it is not easy to float when running, and it is not easy to roll when turning. This is also the reason why minivans, micro trucks, and light trucks use reverse loading axles.

However, the stress area of the reverse loading axle is much smaller than that of the normal loading axle, which tests the quality of the riding screws. Therefore, too heavy goods cannot be loaded.

The leaf spring of medium and large freight cars is better and more firm when installed above the axle, which can maximize the load bearing performance of the leaf spring, with strong load bearing capacity, and is more suitable for heavy loads.