Air Brake Components – Wholesale & Export from Thailand

Air brake systems use compressed air to apply brakes on medium- and heavy-duty trucks, buses and trailers. They are robust but depend on clean, dry air and regular maintenance, and failed valves or chambers directly affect braking safety.

Air supply and treatment

Air compressor and governor or unloader – see air compressors.
Air dryer and desiccant cartridge – removes moisture and oil before air enters the tanks.
Reservoirs and drain valves – store air and collect condensation.
Protection valves – multi-circuit protection valves separate brake circuits.

Control valves

Foot brake valve (dual brake valve) – controls service brake air pressure to front and rear circuits.
Relay valves – speed up application and release at the rear axles.
Quick release valves – exhaust air quickly from front chambers.
Hand control and parking valves – operate spring brakes and trailer brakes.

Foundation brake actuation

Service brake chambers – identified by type numbers such as 16, 20, 24 or 30, which relate to the effective diaphragm area in square inches.
Spring brake chambers – combine a service chamber with a powerful spring for parking and emergency braking, identified by combinations such as 24/24 or 30/30.
Slack adjusters – manual or automatic, specified by spline count, arm length and cam shaft diameter.
Wedge brake actuators on some truck axles.

Air-over-hydraulic systems

Some Japanese medium trucks use an air master (air-hydraulic booster) that converts air pressure into hydraulic pressure for wheel cylinders. These boosters and their repair kits are a distinct part group.

Maintenance and failure drivers

Moisture in the system causes valve corrosion and freezing in cold climates; oil carryover from worn compressors damages diaphragms and seals. Neglected air dryer cartridges are a frequent root cause. Trucks such as the Hino 500 should be checked for system type before ordering. See truck brake parts for linings and drums.

Buying & specification guide

Chassis model, brake system type and axle position.
OEM number or manufacturer reference stamped on valves and chambers.
Chambers: type size, stroke length, pushrod length and clevis, mounting stud spacing, port positions.
Slack adjusters: manual or automatic, spline count, arm length, shaft diameter and left or right orientation.
Valves: port count, thread sizes and function; confirm whether repair kits are available.
Repair kits: diaphragms, seals and springs by valve reference.
Air dryer cartridges: thread size, seal diameter and whether oil-coalescing.
Packaging: cap all ports and protect threads; chambers are heavy and should be boxed individually.
Quality: rubber compounds for heat and oil resistance; valve body casting quality.
Safety: spring brake chambers contain high spring force and must never be disassembled without proper tools and procedures. Include warnings with the product.
Maintenance kits: air dryer cartridges and valve repair kits are recurring items; stock them in proportion to the trucks in your customers' fleets.

Frequently asked questions

What does a 30/30 spring brake chamber mean?

It indicates a chamber with a type 30 service section and a type 30 spring brake section, referring to their effective diaphragm areas. Chamber size must match the axle specification.

Why should air dryer cartridges be replaced regularly?

A saturated desiccant cartridge lets moisture and oil into the system, corroding valves and damaging diaphragms. Regular replacement protects the entire brake system.

Are automatic and manual slack adjusters interchangeable?

An automatic slack adjuster can often replace a manual one if spline, arm length and geometry match, but installation and setup procedures differ. Follow the axle manufacturer's guidance.