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2025
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Driving is safer with automatically adjusted braking gaps - a guide for awareness.
At the 2014 Hannover Motor Show, many domestic component manufacturers showcased their advanced products, among which the automatic brake gap adjustment arm from Longzhong Holdings left a deep impression on us. The automatic brake gap adjustment arm has long been used in vehicles with drum brakes in Europe and the United States, but it has not become widespread in China. From the Truck Home forum, we learned that many users still have no clear concept of the automatic brake gap adjustment arm, so today I will briefly introduce this device.
● What is a brake gap automatic adjustment arm?The brake gap automatic adjustment arm, abbreviated as "automatic adjustment arm," is a device that can automatically and in real-time adjust the brake gap, ensuring that the brake gap is maintained at an appropriate value. This allows for timely and reliable braking, which is very beneficial for driving safety. It should be noted that the use of the automatic adjustment arm is limited to drum brake systems.Additionally, vehicles equipped with ABS that do not have an automatic adjustment arm cannot ensure optimal performance, as manual adjustments may lead to differences in the lever arm and braking force of individual brake cylinders.
The automatic adjustment arm products displayed by Longzhong Holdings at the Hannover Motor Show in 2014However, the manually adjustable brake gap arms that are currently widely used in the domestic market have certain drawbacks.Firstly, manual adjustment has a certain cycle, and during the later part of this cycle, which is the period before the next adjustment of the brake gap, the brake gap may already have a relatively large value. This can lead to a longer braking distance, insufficient braking response, and in severe cases, it could cause brake power fatigue, posing a safety hazard while driving.Secondly, manual adjustments make it difficult to ensure high consistency of gap adjustments across different wheels, which may lead to issues such as wheel misalignment and vehicle tail swinging.
● European and American automatic brake gap adjusting arms are standard, with few applications in domestic trucksAbroad, manufacturers of heavy-duty trucks, buses, and trailers in regions such as Europe and America have made automatic brake gap adjusting arms a standard component for drum brakes. In contrast, these are more commonly used in buses domestically, while the matching rate in trucks is very low, less than ten percent.The brands used abroad are primarily Hande, which occupies a large portion of the overseas market; whereas in the domestic market, there are many brands, with Longzhong having a significant market share. Other brands we have learned about include Hengxin, Shenyu, Anjie, and Tie Ge Men.
Longzhong's Second Generation Automatic Adjustment ArmRegarding the issue of the automatic adjustment arm for brake clearance, we also interviewed Yang Liying, the general manager of Longzhong Holding Group's Sales Center. According to Mr. Yang, by the end of last year, Longzhong Holding's automatic adjustment arms had captured 55% of the domestic bus market and 42% of the truck market. This year, Longzhong's production of automatic adjustment arms reached 580,000 units, and it is expected that by the end of this year, the market share in the truck sector will exceed 50%.Additionally, an industry insider mentioned that currently, most clients for automatic adjustment arms come from bus manufacturers, with truck users being a minority, along with a small number from logistics fleets.● Why hasn't the automatic adjustment arm become widespread in the domestic market?First, manual adjustment arms are cheaper; switching to automatic adjustment arms would increase the cost per axle of drum brakes by 200-300 yuan.
Isuzu with automatic adjusting armsCurrently, the prices of manually adjusting arms on the market are around 50 yuan, while domestically produced automatic adjusting arms are about 150 yuan, with more expensive ones possibly reaching 200 yuan, and imported Hand brand automatic adjusting arms priced at around 260 yuan. It’s evident that there is a significant price gap between automatic and manual adjusting arms. Additionally, a single vehicle may require multiple adjusting arms, which amplifies the price disparity, making it hard for users to accept.Second, there are no mandatory requirements for trucks to install automatic adjusting arms according to national policies. Under the current national standards, only passenger vehicles are required to have automatic adjusting arms for drum brakes, and there are no compulsory measures for trucks yet.Third, people's awareness of safety is not deep enough. Driving safety is the greatest benefit, and the losses caused by accidents cannot be weighed against the increased costs brought by automatic adjusting arms.
Automatic adjustment arm installed on the 457 axleFourth, users lack an adequate understanding of the automatic adjustment arm. Some users have experienced poor matching after using the automatic adjustment arm, and coupled with the high cost, it is easy to revert to choosing the manual adjustment arm.I also learned from the forum that some maintenance personnel are not well acquainted with the automatic adjustment arm and have caused damage to it. The consequence is that many maintenance personnel are hesitant to handle automatic adjustment arms, significantly hindering their widespread adoption.
● The new national standard for automatic adjustment arms will become standard equipment.According to the national standard GB 12676-2014 "Technical Requirements and Testing Methods for Braking Systems of Commercial Vehicles and Trailers" published on October 10 of this year, road transport vehicles with a gross vehicle weight greater than 3.5 tons must be equipped with automatic adjustment arms for brake clearance. This standard will take effect on July 1, 2015, at which time automatic adjustment arms will be standard equipment installed on road freight vehicles over 3.5 tons.The promulgation of this national standard will greatly promote the popularization and development of automatic adjustment arms in our country, making a significant contribution to improving the safety of transportation in China.
● Postscript: The mandatory implementation of national standards serves merely as a powerful driving force; the crucial issue is that the public's awareness of safety needs to be enhanced for automatic adjustment arms to be more widely understood and accepted by users. With the promulgation of national mandatory standards, automatic adjustment arms are bound to experience explosive growth in the Chinese truck sector, and the foreseeable market potential is very vast. For more information about automatic adjustment arms, please stay tuned for follow-up articles from the Truck Home.
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