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What are the advantages and disadvantages of manual and automatic control arms?
To ensure sufficient braking power, most modern trucks use air brakes. Air brakes can provide stronger braking force compared to hydraulic brakes. However, like hydraulic brakes, air brakes also require an appropriate gap between the brake pads and the brake drum to function properly.
In an air brake system, the gap between the brake drum and brake shoes is not fixed. Since brake shoes are consumables, they gradually wear down over time, becoming thinner and increasing the gap between them and the brake drum. As the gap increases, the braking force of the truck decreases, so it is essential to maintain the gap between the brake shoes and the drum within an appropriate range. If the gap is too small, it can cause braking drag; if too large, the braking force will be insufficient.
The device responsible for adjusting this gap is the adjuster arm, which mainly comes in two types. The most common is the manual adjuster arm, but many trucks now also use automatic adjuster arms.
● Manual Adjuster Arm: Large margin of error, adjustment is inconvenient
Trailer axle with manually adjustable arms
As the name suggests, a manual adjustment arm is an arm used to manually adjust the brake clearance. It is currently the most widely used and common type of adjustment arm. It has the advantages of being inexpensive and easy to maintain, but it also has some drawbacks. Since the brake clearance is controlled by manually operating the arm based entirely on the operator's experience, significant errors can easily occur, which can seriously affect driving safety. Additionally, the operator has to go under the vehicle to make adjustments, which is very cumbersome.
● Automatic adjustment arm: Convenient and safer
As truck technology continues to advance, and electronic brake assistance systems like ABS become more common, manually adjustable arms are gradually failing to meet the increasing performance requirements. On the other hand, automatic adjustment arms are appearing more and more frequently. So what are the advantages of automatic adjustment arms?
Automatic Adjusting Arm
First, Stable Braking Force
The automatic adjusting arm does not have the problem that manually adjusted arms do, where the braking force is strong right after adjustment but decreases with use. It is very stable because it can constantly maintain the brake clearance within the optimal range, making it safer compared to manual arms.
Second, Easy Maintenance
The automatic adjusting arm eliminates the need to frequently crawl under the vehicle to adjust the brake clearance, allowing you to say goodbye to days of getting covered in dust and grease while adjusting brakes.
Third, Suitable for ABS
Automatic adjusting arms are more suitable for modern trucks equipped with ABS systems and can maximize the advantages of the ABS system.
● Regulatory Support: Automatic adjustment is a mandatory standard
The national standard GB 12676-2014 "Technical Requirements and Test Methods for Brake Systems of Commercial Vehicles and Trailers," released on October 10, 2014, clearly requires that road transport vehicles with a curb weight greater than 3.5 tons must be equipped with automatic brake adjustment arms. This standard has been in effect since July 1, 2015. With regulatory restrictions in place, manual adjustment arms have become gradually obsolete.
● Epilogue
With technological progress, some outdated products will inevitably be replaced by high-tech products. Just like adjustment arms, automatic ones will inevitably replace manual ones, bringing us not only convenience but, more importantly, safety.
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