The adjusting arm, also known as the brake clearance adjusting arm, is mainly used to adjust the brake clearance of the brake.

During the braking process of the vehicle, the brake elements will be constantly worn, and the gap between the brake drum and the brake shoes will increase in varying degrees, resulting in too long pedal formation, reduced thrust of the brake air chamber, brake lag, reduced braking force, wheel deviation, vehicle tail spin and even brake failure.

In order to ensure driving safety, maintain the stability of the brake pedal stroke and the working balance between the brakes, the brake clearance needs to be constantly adjusted.

The automatic adjustment arm refers to the vehicle adjustment arm that can automatically adjust according to the wear of the brake shoe and the brake drum to ensure that the brake drum and the brake shoe are always at the set optimal clearance.

In simple terms, its working principle is to set the brake clearance value in the design. If the clearance is exceeded during use, the self-adjusting arm will drive the internal one-way clutch to turn down the clearance value when the brake returns, so that the brake clearance is always kept within the preset range.

Compared with the manual adjustment arm, the automatic adjustment arm has the advantages of good brake gap adjustment consistency, short brake stroke, large torque, stable effect, low air consumption, and no manual intervention. It has become the standard configuration of heavy-duty vehicles in Europe and America as early as more than ten years ago.

Then, can the brake clearance be adjusted manually for vehicles with automatic adjustment arms? In other words, can the automatic adjustment arm be used as a manual adjustment arm?

If the worm bolt on the self-adjusting arm is turned with a wrench, the brake clearance can be adjusted. However, in general, it is not recommended for vehicle owners to do this, because manual adjustment will cause great damage to the mechanical structure inside the self-adjusting arm, and several manual adjustments may cause damage to the transmission mechanism.

In addition, some vehicle owners asked whether the control arm of the self-adjusting arm could be removed and then used as a self-adjusting arm, which is also not allowed, because the most common damage reason of the adjusting arm is locking failure and can not play the role of fixing the gap. If the control arm is removed, the internal mechanism of the automatic adjustment arm will not meet the self-locking condition. When the vehicle is braked, the internal mechanism of the automatic adjustment arm will rotate. Over time, the brake gap will become larger and larger, which will easily lead to brake failure.

It is worth noting that the matching self-adjusting arms on different models of axles are different, especially the preset brake clearance. It is best for the owner not to modify them without authorization, otherwise the brake clearance may be too large or too small. If it needs to be replaced, it is recommended to confirm the model of the self-adjusting arm and use the original accessories.

In terms of maintenance and repair, the self-adjusting arm is relatively simple. Generally, it is checked every three months and greased every 20000 km or every six months.