HOWO and Shacman Brake System: Parts, Maintenance and Common Problems
For a heavy-duty truck, the braking system is one of the components that should never be treated as an afterthought.
HOWO and Shacman trucks are commonly used for heavy loads, long-distance transportation, construction work and mining operations. These working conditions put continuous stress on brake chambers, valves, drums, shoes and other pneumatic brake components.
A small problem in the air brake system can gradually become a serious braking problem. Regular inspection and timely replacement of worn parts are therefore essential for both truck safety and operating costs.
How the HOWO and Shacman Air Brake System Works
Most heavy-duty HOWO and Shacman trucks use a pneumatic braking system.
The basic system consists of an air compressor, air dryer, air reservoirs, brake valves, brake chambers, slack adjusters, brake drums, brake shoes and, on applicable models, ABS and electronic brake control components.
The compressor produces compressed air, which is stored in the reservoirs. When the driver applies the brake, air pressure is directed through the relevant valves to the brake chambers.
The brake chamber converts air pressure into mechanical movement. The pushrod then operates the braking mechanism, pressing the brake shoes against the drum.
Because so many components work together, a braking problem is not always caused by the brake shoe or drum itself. A leaking valve, damaged diaphragm or contaminated air system can also reduce braking performance.
Brake Chambers and Diaphragms
The brake chamber is one of the most important working components in a pneumatic braking system.
Inside the chamber, a rubber diaphragm moves repeatedly whenever the brakes are applied. Over time, the diaphragm can become hard, cracked or damaged, particularly when the truck operates frequently under heavy loads or in harsh environments.
A damaged diaphragm may result in air leakage, reduced braking response, uneven braking or excessive compressor operation. In some cases, the driver may notice that the braking response has gradually changed before the component completely fails.
A leaking diaphragm should not be ignored. Continuing to operate the truck with a damaged chamber can place additional stress on the rest of the braking system.
When ordering a replacement brake chamber or diaphragm, the exact truck model, axle configuration and original part number should be confirmed first. HOWO and Shacman use many different brake components depending on the vehicle configuration, so checking the part number is always safer than relying only on the truck brand.
Brake Valves
Brake valves control the distribution and release of compressed air throughout the braking system.
Depending on the truck configuration, the system may include a foot brake valve, relay valve, trailer brake valve, quick-release valve and other pneumatic control components.
A valve with damaged seals or internal contamination may cause slow brake response, delayed release or abnormal air pressure loss.
For example, if the brakes do not release smoothly after the driver releases the pedal, the problem may not be the brake chamber itself. The relevant valve and air lines should also be inspected.
For fleet operators, replacing a worn valve or seal before it causes a major pneumatic problem can help reduce unexpected downtime and repair costs.
Slack Adjusters
The slack adjuster transfers the movement of the brake chamber pushrod to the brake mechanism.
Manual slack adjusters require regular adjustment as the brake lining wears. Automatic slack adjusters reduce the need for manual adjustment, but they are not maintenance-free.
Corrosion, dirt, lack of lubrication or mechanical wear can affect the operation of an automatic slack adjuster. Excessive pushrod travel is another condition that deserves attention.
If the brake chamber has to move too far before the brake shoes properly contact the drum, braking efficiency can be reduced. The system may also require more air pressure and chamber movement to achieve the desired braking effect.
Brake Drums and Brake Shoes
Brake drums and brake shoes work together to generate friction and slow the vehicle.
Heavy-duty trucks carrying large loads generate considerable heat during braking. This becomes particularly important for vehicles operating in mountainous areas, construction sites or conditions involving frequent braking.
Brake drums should be inspected for excessive wear, cracks, heat damage and abnormal scoring. The internal diameter should also remain within the applicable manufacturer's specification.
Brake shoes should be checked for lining thickness, uneven wear and contamination. If the lining has been contaminated with oil or grease, simply continuing to use it can affect braking performance.
When replacing brake linings, choosing the correct friction material is important. Different trucks, loads and operating conditions can require different friction characteristics. The correct replacement should be selected according to the original specification and the truck's actual working environment rather than simply choosing the lowest-priced option.
Air Dryer and Air System Contamination
The air dryer is easy to overlook because it does not directly produce braking force. However, it plays an important role in protecting the entire pneumatic system.
Compressed air can contain moisture and traces of oil from the compressor. The air dryer removes moisture before the air enters the reservoirs and brake system.
If the dryer cartridge becomes saturated or the dryer stops working correctly, moisture can accumulate inside the reservoirs and air lines. Over time, this can contribute to corrosion, contamination of valves and damage to pneumatic seals.
In cold environments, accumulated moisture can also freeze and interfere with the operation of pneumatic components.
Checking the air reservoirs regularly is a simple way to monitor the condition of the air system. If excessive water or oil is found during draining, the air dryer and compressor should also be inspected instead of treating the problem as normal.
ABS and Electronic Brake Components
Newer HOWO and Shacman trucks may also use electronic systems to monitor wheel speed and control braking performance.
Depending on the vehicle configuration, these systems can include ABS sensors, electronic control units and other brake control components.
An ABS warning light does not necessarily mean that the mechanical brake components have failed. The problem may be related to a sensor, wiring, control module or another electronic component.
When diagnosing electronic brake problems, it is important to use diagnostic equipment compatible with the specific truck system rather than relying only on a generic vehicle scanner.
Before ordering an electronic control unit or ABS component, the vehicle model, system configuration and original part number should be confirmed. This is particularly important because similar-looking electronic components may not be interchangeable.
Common Signs of Brake System Problems
Drivers and fleet managers should pay attention to changes in braking behavior. A brake system problem often develops gradually rather than appearing as a complete failure without warning.
A change in pedal response can indicate an air pressure, valve or mechanical problem. If the air pressure drops unusually quickly while the truck is parked or operating, there may be a leak somewhere in the pneumatic system.
A compressor that runs more frequently than usual can also be a sign of an air leak or another pneumatic problem.
If the brakes release slowly after the pedal is released, the relay valve, quick-release valve, brake chamber and air lines should all be considered during inspection.
Uneven braking can have several possible causes, including brake chambers, slack adjusters, brake shoes, drums or other mechanical components. Similarly, an ABS warning light should be properly diagnosed before replacing expensive electronic parts.
The important point is that a change in braking performance should be investigated rather than temporarily ignored.
A Practical Brake Maintenance Routine
Brake maintenance should always follow the truck manufacturer's recommendations and should be adjusted according to the vehicle's workload, mileage and operating environment.
Daily inspection can include checking the air pressure, listening for obvious air leaks and paying attention to any unusual change in braking behavior or warning lights.
During regular maintenance, the air reservoirs should be drained and the brake chambers, pushrods, slack adjusters, hoses and air lines should be inspected. Any signs of leakage, excessive movement or mechanical damage deserve further investigation.
During scheduled service, the brake drums and linings should be inspected for wear and heat damage. Pneumatic valves, the air dryer and compressor should also be checked when necessary.
There is no single replacement interval that applies to every HOWO or Shacman truck. A dump truck working on construction sites can experience very different brake wear from a highway tractor operating mainly on flat roads. Maintenance decisions should therefore take actual operating conditions into account.
Choosing Replacement Brake Parts
For HOWO and Shacman trucks, similar-looking components can have different specifications depending on the truck model, axle, production year and brake configuration.
When requesting a quotation, providing the truck model and original part number is the most straightforward way to identify the correct component. If the part number is unavailable, the VIN or chassis number can usually provide additional information for identification.
The required quantity and destination are also important when purchasing from an overseas supplier, especially when the order contains multiple types of brake components.
For fleet customers and distributors, purchasing commonly used brake components together can also make transportation more efficient and reduce the risk of unexpected parts shortages.
Final Thoughts
The braking system of a heavy-duty truck is made up of many components, and a problem in one part can affect the performance of the entire system.
For HOWO and Shacman trucks, brake chambers, diaphragms, valves, slack adjusters, drums, shoes, air dryers and electronic brake components all deserve regular attention.
Good maintenance is not simply about replacing parts after they fail. It is about identifying wear early, using the correct replacement components and keeping the pneumatic system clean and properly maintained.
If you are looking for HOWO or Shacman brake parts, you can send us the part number, truck model or VIN together with the quantity you need. We can check the available specification and provide suitable replacement options according to your truck and application.
Please contact us if you have any requirement.