Is a brake chamber the same thing as a brake cylinder?

In a heavy commercial air brake system, yes — both terms describe the same part. Brake chamber, brake cylinder, brake piston, and brake actuator are all field names for the same air brake actuator. The terminology varies by region and technician; the selection criteria is not the name but Type, axle position, and OE number.

What's the difference between a Type 20 and a Type 24 chamber — are they interchangeable?

The Type number denotes the diaphragm's effective area in square inches; a Type 24 has a larger area than a Type 20, and therefore higher brake force at the same pressure. These two types are not interchangeable at will. Fitting a chamber of a different Type than the manufacturer specified for an axle upsets brake force balance and can cause the vehicle to pull under braking. The correct Type is determined by the vehicle's OE brake calculation and should always be replaced with the same one.

The parking brake won't release — is the chamber to blame?

It could be, but park line pressure should be checked first. In a spring chamber, the parking brake releases when the spring compresses as system pressure arrives. If the brake stays applied despite pressure being present, there is likely corrosion or piston seizure in the spring chamber, and the chamber must be replaced. If pressure isn't arriving at all, the problem lies upstream of the chamber, in the valve or air line.

Why does removing a spring brake chamber require so much caution?

Because the spring in the chamber's parking section stores very large amounts of energy while caged. If the housing is opened before this spring is compressed and locked with a caging bolt, the released spring can fly out with great force, causing serious or even fatal injury. That's why every spring chamber removal procedure starts by draining the system of air, then caging the spring, and only then working on the part.

Can a vehicle be driven with a brake chamber air leak?

It should not be. A leak from the chamber both reduces brake force and continuously drains system pressure, leaving the brakes inadequate in an emergency. The air brake system is directly a life-safety system; once a leak is noticed, the vehicle should be stopped safely and taken to service. This is also an inspection/safety violation.

Why is push rod stroke increasing — should I replace the chamber?

Increasing stroke is usually caused not by the chamber itself but by a worn lining or a malfunctioning automatic slack adjuster. When stroke approaches the limit, lining thickness and the adjuster should be checked first. If the diaphragm or return spring has weakened, the chamber can also be the cause; the correct order is to check the adjustment first, then question the chamber.

Should I replace the brake chamber on one side or both?

Since the two chambers on the same axle are the same age and have the same operating history, if one has fatigued the other is likely close behind. To preserve brake balance, it's correct to evaluate at least the opposite chamber's stroke and leak status together; many shops renew both at once.

What is the service life of a brake chamber?

A brake chamber has no fixed lifespan schedule; its life depends on air quality, ambient conditions, and maintenance discipline. A chamber supplied with dry air and an open drain hole lasts a long time; one that draws in moist air or is exposed to corrosion fatigues early. That's why replacement is planned around periodic stroke and leak checks rather than a fixed mileage.

Does a vehicle with disc brakes also have a brake chamber?

Yes. Heavy commercial vehicles with disc brake systems also use an air brake chamber; the difference is that the chamber actuates a disc caliper mechanism instead of an S-cam. Because disc system actuators have different stroke and connection characteristics than S-cam systems, the chamber must still be selected by axle and OE compatibility.

How do I choose the correct brake chamber?

Vehicle model alone is not enough for selection. Chamber type (Type), axle position (front/rear/mid), whether it's a service or spring/combination unit, production year, and, whenever possible, the OE reference number on the old chamber should all be used together. In the VADEN catalog, search can be performed using this data: entering the OE number or Type printed on the old chamber shows the matching VADEN part number, which you can verify against axle position and application information before ordering. As an application example, Mercedes-Benz Actros/Axor, Volvo FH/FM, DAF XF/CF, MAN TGX/TGS, and Scania series use Wabco, Knorr-Bremse, and Bendix-origin OE chambers on the air brake side; the correct part, however, is always determined by Type and OE number, not brand name.

Technical Guides

Brake Chamber: Fault Diagnosis, Replacement and Maintenance Guide

Learn what a brake chamber does, how to diagnose air leaks and stroke faults, replace it safely, and maintain it for reliable heavy-duty air brakes.

01 Aug 2026 22 min read

The force that stops a wheel on a heavy commercial vehicle when the driver hits the pedal doesn't actually come from air itself — it comes from the point where that air is converted into mechanical push: the brake chamber. Known on the shop floor as a "brake cylinder" or "brake piston," this component takes the compressed air produced by the diesel engine's compressor and turns it into the thrust that presses the brake lining against the drum or disc. Every truck technician knows two familiar scenes: a continuous hiss of air heard from under a parked vehicle, and a parking brake that simply won't release in the morning. Both usually trace back to the same part. This guide explains, from a workshop foreman's and service technician's point of view, what the brake chamber does, how it fails, the correct diagnostic sequence, and — most importantly — the life-critical discipline required when removing and installing it.

This document was prepared by the VADEN technical team based on heavy commercial vehicle air brake system service practice and OE manufacturer documentation. The values given here are general reference figures; for exact data such as chamber type, stroke limit, working pressure and tightening torque, the current OE service manual matching the vehicle's chassis/axle code is authoritative. Last updated: July 2026.

What Is a Brake Chamber? Function and Working Principle

A brake chamber (air brake actuator) is the air brake component that converts compressed air into mechanical thrust through a diaphragm or piston, moving the brake adjuster arm (S-cam) or disc caliper via a push rod to press the lining against the friction surface. The service chamber brakes with air; the spring chamber provides parking and emergency braking through spring energy.

The brake chamber goes by many names on the shop floor and in catalogs: air brake chamber, brake cylinder, brake piston, brake actuator, and for the spring-loaded version, parking chamber or spring brake chamber. All of them perform the same job: converting air pressure into the linear thrust the brake mechanism needs. Regardless of which name is used, the selection criteria stay the same: chamber type, axle position, and OE reference number.

The working principle follows a force-conversion logic. When the driver presses the brake pedal, the foot brake valve sends compressed air from the air tank to the service chamber. The air pushes against the flexible diaphragm inside the chamber; the diaphragm pushes the pressure plate, which in turn drives the push rod outward. The fork at the end of the push rod rotates the brake adjuster arm. In S-cam systems, this rotation turns the S-shaped cam, spreading the linings against the drum; in disc systems, it compresses the caliper mechanism, pressing the lining against the disc. When the pedal is released, the air escapes, the return spring inside the chamber pulls the diaphragm and push rod back to their starting position, and the lining separates from the friction surface.

In spring (combination) chambers, a second chamber is added behind this service chamber. Inside it sits a very powerful parking spring. While the engine runs and pressure is present in the system, this powerful spring is held compressed — "caged" — by air pressure, and the brake stays released. When the parking brake is applied or the system loses air, the pressure holding the spring back drops, the spring extends and pushes the push rod, braking the vehicle mechanically and without any air at all. This design is a lifesaver: if the air system loses pressure due to a fault, the vehicle doesn't end up with no brakes — quite the opposite, the spring engages and stops it. That same feature, however, is also the greatest hazard during service, because that spring stores enormous energy.

What Do Brake Chamber Types (Type) Mean?

The brake chamber type is expressed as a number describing the diaphragm's effective area in square inches. Type 16, Type 20, Type 24 and Type 30 are the most common on the shop floor; the larger the number, the greater the thrust produced at the same pressure. A Type 30 chamber, for example, has a larger diaphragm area than a Type 20, so it produces higher brake force at the same air pressure. Type selection is not arbitrary; it is determined by the vehicle's axle load, the brake mechanism's lever ratio, and the design brake force. In spring combination chambers, two numbers are often written together (for example 20/24 or 24/30): the first denotes the service chamber's type, the second the parking spring chamber's type. Fitting the wrong type upsets brake balance, which is why a chamber is always selected by Type and OE number, never by brand name alone.

Service, Spring, and Combination Chamber Differences

Brake chambers fall into three main groups based on function and internal structure. A service (single-diaphragm) chamber performs only the foot-brake function; it is typically used on the front axle of tractors and trucks. A spring / combination (dual-chamber) chamber combines both the service brake and the parking/emergency brake in a single housing; it is standard on rear and mid axles. In a combination chamber, the service section has a diaphragm while the parking section has a strong spring and piston. This distinction is critical for service work: a single-diaphragm chamber has no parking spring, while a combination chamber always contains an energy source that must be secured before disassembly.

Components and Auxiliary Elements

Diaphragm (membrane): the flexible rubber element that converts air pressure into mechanical motion; the most frequently fatigued part of the chamber.
Push rod and clevis: the steel rod and connecting fork that transfer the diaphragm's motion to the brake adjuster arm.
Pressure plate and return spring: the plate that pushes the diaphragm and the spring that pulls the rod back when the brake is released.
Clamp ring: the banded connection that holds the two halves of the housing and the diaphragm together.
Parking spring (in the spring chamber): the high-energy heavy-duty spring that provides parking and emergency braking — the component at the center of service safety.
Pressurized and non-pressurized housing halves: the two-piece aluminum or steel housing with the air inlet.
Air inlets and drain plug: the service and park port connections plus the moisture drain hole.
Dust boot and seal elements: sealing components that protect the push rod exit from dirt and moisture.

Chamber Type	Chamber Structure	Function	Characteristic Service Note
Service (single-diaphragm) chamber	Single diaphragm chamber	Foot (service) brake only	No parking spring; disassembly less risky, but the system must be depressurized
Spring / combination chamber	Service diaphragm + parking spring chamber	Service + parking/emergency brake	The parking spring must always be locked with a caging bolt before disassembly
Type 16 / 20 (small)	Small diaphragm area	Front axle and light-axle applications	Type is selected per axle load; must not be substituted
Type 24 / 30 (large)	Large diaphragm area	Heavily loaded rear/mid axles	High thrust; spring energy is also greater
Disc brake actuator	Diaphragm type, caliper-mounted	Actuates disc brake mechanism	Stroke and connection differ from S-cam systems

The parking spring chamber of spring and combination brake chambers stores a large amount of energy while caged. This energy must never be underestimated: a damaged or improperly disassembled spring chamber can launch the parking spring like a projectile, causing serious or even fatal injury. Select a chamber not just by "vehicle model" but by Type, axle position, and the OE number on the old chamber; never touch the spring section unless it has been locked with a caging bolt.

How Is a Brake Chamber Fault Diagnosed?

Brake chamber faults typically show up in three behaviors: leaking air, weakening brake force, and holding or failing to release the parking brake. The first is heard as a hiss and pressure drop, the second as a slow and weak brake bite, and the third as the vehicle refusing to move. The table below matches brake chamber field symptoms with likely causes and verification methods.

Symptom	Likely Cause	Check / Verification
Continuous air leak, hissing sound from chamber housing	Diaphragm torn or punctured; clamp ring loose	Soap-bubble leak test at the chamber drain hole and around the clamp ring while the brake is applied
Brake bites late, pedal response soft and weak	Internal diaphragm leak, push rod stroke lengthening, air supply restriction	Push rod stroke measurement; air tank pressure and brake response time check
Parking brake won't release, vehicle won't move	Parking spring seized, piston corroded, or park line not receiving pressure	Park line pressure check; mechanical wind-off (caging) of the spring if necessary
Excessive push rod stroke, increased stopping distance	Lining wear or automatic slack adjuster fault	Measurement with a stroke gauge; check whether the adjustment limit has been exceeded
Intermittent air leak from clamp ring area	Clamp ring loose, diaphragm not seated correctly, corroded band	Band bolt torque check; visual inspection of the diaphragm seating surface
Corrosion, blistering, or holes on housing surface	Road-salt and moisture corrosion; blocked drain hole	Visual check of housing and drain hole; look for signs of moisture buildup
Brakes don't fully release, chamber heats up, lining drags	Weak return spring, push rod not returning, parking spring not fully caging	Check that the rod fully returns and the lining opens when the brake is released
Brake imbalance on one axle, vehicle pulls under braking	Chamber on one side holding weaker, or stroke difference	Right-left stroke comparison; force measurement on a brake test roller stand

Air Leak or Mechanical Fault?

The distinction in a brake chamber is usually clear: a diaphragm-related problem shows up as an air leak, while a spring- or push rod-related problem shows up as a motion fault. If air comes out of the chamber's drain hole only when the brake is applied, the service diaphragm is suspect; if it comes out continuously whenever the system has pressure, the spring chamber diaphragm is suspect. The drain hole also serves as a diagnostic window; if it is clogged with mud, internal leakage accumulates and rots the diaphragm, which is why keeping the hole open matters.

Verification by Stroke Measurement

Measuring push rod stroke is the most concrete step in brake chamber diagnosis. With the brake released, a mark is made on the rod; when the brake is fully applied, the distance the rod travels is measured with a ruler. Stroke must stay within the adjustment limit tied to the Type. Exceeding that limit is often caused not by the chamber itself but by a worn lining or a malfunctioning automatic slack adjuster; still, since a long stroke reduces brake force, the cause must always be identified. Right- and left-side stroke should be close to each other; a noticeable difference is a warning sign of brake pull.

If the Parking Brake Won't Release

A parking brake that won't release has two possible roots: the parking line isn't receiving pressure, or the spring itself is mechanically seized. First check park line pressure; if pressure is present but the brake won't open, there may be corrosion or piston seizure in the spring chamber. Such a chamber can be temporarily released with its mechanical wind-off (caging) bolt to move the vehicle — but this does not mean the fault is fixed; a seized or corroded spring chamber must be replaced.

How Is a Brake Chamber Replaced? Step by Step

The parking spring in a spring or combination brake chamber stores very high energy while caged. Before starting disassembly, this spring MUST be compressed and locked with a caging bolt; otherwise, once the housing is opened, the spring can fly out and cause serious or fatal injury. Personal protective equipment is mandatory: impact-resistant goggles or a face shield, gloves, and work clothing. On older/single-piece clamp-ring chambers, the band must never be opened under pressure or with the spring loaded. If in doubt, do not open a spring chamber — replace it as a complete unit.

Secure the vehicle: Park on level ground, stop the engine, and chock the wheels. Make sure the wheels on axles other than the one being serviced are held fixed; the parking brake may be disabled during this procedure.
Fully drain the air system: Drain the brake air tanks completely via the drain valves until the gauge reads zero. Never work on a chamber under pressure.
Cage the parking spring: On a spring/combination chamber, install the caging bolt supplied with the unit into the parking section and tighten it to lock the spring. Do not proceed with any disassembly step until the spring is fully compressed and locked. This is a life-critical safety step.
Disconnect the air lines: Remove the service and park air lines from the chamber. Cap the open line ends and chamber ports with clean plugs to prevent dirt from entering; a single particle can damage a valve surface in an air brake system.
Disconnect the push rod: Remove the pin/clip connecting the push rod's clevis to the brake adjuster arm. Note the adjustment position of the clevis-arm connection; this reference will help set the same stroke adjustment on the new chamber.
Unbolt the chamber: Remove the mounting nuts (usually two) that secure the chamber to the axle bracket. Don't let go of the chamber unsupported; combination chambers are considerably heavy, so support it while lowering if needed.
Remove and inspect the old chamber: Examine the removed chamber's diaphragm, push rod, clamp ring, and housing for corrosion. Check the chamber on the opposite side of the same axle as well, since it is the same age; evaluating both together is the right approach for brake balance.
Verify the new chamber: Place the new chamber next to the old one and compare Type, push rod length, mounting pattern, air inlet position, and clevis shape. On a spring chamber, confirm the new unit's caging bolt is also installed and locked.
Fit the new chamber: Seat the new chamber on the bracket and tighten the mounting nuts to the manufacturer's specified torque in a crosswise sequence. Don't force it into place; if it doesn't seat properly, the Type or mounting pattern is wrong.
Connect the air lines and rod, adjust the stroke: Connect the service and park air lines to the correct ports (don't mix them up). Connect the push rod clevis to the brake adjuster arm and set the stroke/free-play adjustment based on the reference you noted. On systems with automatic slack adjusters, make sure the adjuster resets correctly.
Remove the caging bolt: Once the air lines are connected and the stroke is adjusted, remove the spring chamber's caging bolt to release the parking spring. Remember that park line pressure must be present in the system before this step; otherwise the spring releases and the brake stays locked.
Pressurize and test: Start the engine and build the air system to full pressure. With the brake applied and released, check around the chamber with soap solution to confirm there is no air leak. Apply and release the parking brake several times to confirm the spring cages and releases smoothly, the stroke is within limits, and the vehicle doesn't pull under braking. Perform a cold check after the first short drive as well.

Things to Watch Out For (Common Mistakes)

Trying to open the housing of a spring/combination chamber with a caged parking spring, without a caging bolt, is the most dangerous mistake in heavy commercial vehicle brake service. The energy released when the spring lets go can be directly fatal. On single-piece clamp-ring chambers, the band must never be loosened under a caged spring or system pressure. The rule is clear: first drain the system, then cage the spring, and only then touch it.

Replacing a brake chamber with an "approximately similar" Type upsets brake force balance. Fitting the wrong Type chamber to an axle causes that axle to brake either too little or too much, makes the vehicle pull under braking, and disrupts ABS/EBS behavior. A chamber is always replaced with the same Type and OE compatibility.

Removing without caging the spring: the number-one fatal mistake in brake service; a caging bolt is mandatory on every spring chamber.
Leaving the drain hole blocked: a blocked hole traps moisture and internal leakage inside the housing, rotting the diaphragm from within.
Mixing up the service and park lines: incorrectly connected lines can leave the brake unable to release, or leave the parking brake nonfunctional.
Skipping the stroke adjustment: if stroke isn't adjusted after fitting a new chamber, the brake bites late and the lining wears prematurely.
Replacing only one side's chamber: the chamber on the opposite side of the same axle is the same age, so balance is upset; both should be evaluated together.
Tightening the clamp ring to the wrong torque: under-tightening causes leaks, over-tightening crushes the diaphragm; both leak.
Mistaking long stroke for a chamber fault: excessive stroke is usually a worn lining or faulty adjuster; check adjustment before replacing the chamber.
Ignoring a corroded housing: as rust blistering progresses, the housing perforates; a chamber that looks sound outside may be fatigued inside.
Sending the vehicle out without testing: a vehicle should never leave service without leak, stroke, and parking function checks.

Technical Values and Check Points

The values below are general reference ranges commonly encountered in heavy commercial vehicle air brake systems. Chamber type, axle load, brake mechanism, and production year all affect these ranges. Braking is a system that directly concerns life safety; always check the current OE service manual matching the vehicle's chassis/axle code for exact values. Brake performance and actuator design are defined within the framework of ECE R13 (heavy commercial vehicle braking regulation) and ISO 611 (road vehicle braking terminology); these standards provide the general requirement framework, while vehicle-specific values must be verified from the OE catalog.

Brake chamber technical values (general reference)
Parameter	Typical Range (General Reference)	Note
System working pressure	7–8.5 bar (approx. 100–125 psi)	Brake force is the product of this pressure and diaphragm area
Common chamber types (Type)	Type 16 · 20 · 24 · 30	The number denotes the diaphragm's effective area in square inches
Push rod stroke adjustment limit	Varies by Type (general: intervention required if limit exceeded)	Exceeding the limit requires lining/adjuster check; exact value is OE
Combination chamber type notation	e.g. 20/24 · 24/30	First number is service, second is parking spring chamber
Parking brake release pressure	Typically above 5–6 bar	Below this pressure the parking spring engages; value is OE-specific
Right-left stroke difference	As equal as possible, limited difference	A noticeable difference signals brake pull and imbalance
Diaphragm / chamber service life	Depends on usage and environment, periodic check	Assessed by stroke and leak checks rather than a fixed calendar

The values above are guidance only. The same vehicle may use different chamber Types on the front and rear axle, while the stroke adjustment limit and parking release pressure are direct OE values. Before ordering, read the Type and OE number on the old chamber, verify the axle position, and check brake values against the vehicle manufacturer's service manual.

Is the chamber housing and drain hole dry; is there any sign of moisture or oil?
Is the push rod stroke within the Type limit; is the right-left difference acceptable?
Is there an air leak around the diaphragm area and clamp ring (soap-bubble test)?
Does the spring cage and release properly when the parking brake is applied and released?
Does the push rod fully return and the lining open when the brake is released?
Is there corrosion, blistering, or impact damage on the housing?
Are the air lines and mounting nuts at the correct torque and sound?

Maintenance and Service Life

A brake chamber has no fixed "replacement mileage"; its life is determined by air quality (moisture and oil), ambient conditions (road salt, mud), and the discipline of regular inspection. A chamber supplied with dry air, with an open drain hole and stroke within limits, is one of a vehicle's long-lived components. In contrast, a chamber that draws in moist air, has a blocked drain hole, or is left running with a long stroke has its diaphragm fatigue prematurely and start leaking.

Air dryer discipline: The air dryer cartridge should be replaced per the manufacturer's schedule. Moisture entering the system corrodes the brake chamber's diaphragm and spring section from within.
Keeping the drain hole open: The chamber's lower drain hole must not become clogged with mud and salt; this hole both drains moisture and gives early warning of internal leakage.
Periodic stroke check: Push rod stroke should be measured at every brake service; when stroke approaches the limit, the lining and automatic slack adjuster should be inspected.
Leak scanning: During regular maintenance, the chamber housing and clamp ring area should be scanned for leaks with soap solution.
Corrosion and external damage check: In areas exposed to road salt, housing corrosion should be monitored regularly, and replacement planned before rust blistering progresses.
Respect the parking spring: Every spring chamber entering service must have the caging bolt and correct release procedure applied; the spring must never be touched without caging it first.
Think per axle: If one chamber has fatigued, the opposite chamber on the same axle is the same age; evaluating both together preserves brake balance.

For fleet operations, the most efficient approach is to think about the brake chamber not in isolation but as part of the axle and brake maintenance set. Checking chamber stroke and leak status during the same service visit as lining, drum/disc, or slack adjuster work is far more economical than having to lift the vehicle again a few months later. VADEN's air brake actuator and brake chamber product family is built exactly around this logic: service chambers, spring and combination chambers, and different Type options can be matched by axle position and OE number, so a vehicle entering brake service leaves with a complete chamber set in a single visit. And a stroke, leak, and parking brake test before sending the vehicle back out is the cheapest insurance against a roadside failure and a braking safety violation.

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Frequently Asked Questions

Is a brake chamber the same thing as a brake cylinder?: In a heavy commercial air brake system, yes — both terms describe the same part. Brake chamber, brake cylinder, brake piston, and brake actuator are all field names for the same air brake actuator. The terminology varies by region and technician; the selection criteria is not the name but Type, axle position, and OE number.
What's the difference between a Type 20 and a Type 24 chamber — are they interchangeable?: The Type number denotes the diaphragm's effective area in square inches; a Type 24 has a larger area than a Type 20, and therefore higher brake force at the same pressure. These two types are not interchangeable at will. Fitting a chamber of a different Type than the manufacturer specified for an axle upsets brake force balance and can cause the vehicle to pull under braking. The correct Type is determined by the vehicle's OE brake calculation and should always be replaced with the same one.
The parking brake won't release — is the chamber to blame?: It could be, but park line pressure should be checked first. In a spring chamber, the parking brake releases when the spring compresses as system pressure arrives. If the brake stays applied despite pressure being present, there is likely corrosion or piston seizure in the spring chamber, and the chamber must be replaced. If pressure isn't arriving at all, the problem lies upstream of the chamber, in the valve or air line.
Why does removing a spring brake chamber require so much caution?: Because the spring in the chamber's parking section stores very large amounts of energy while caged. If the housing is opened before this spring is compressed and locked with a caging bolt, the released spring can fly out with great force, causing serious or even fatal injury. That's why every spring chamber removal procedure starts by draining the system of air, then caging the spring, and only then working on the part.
Can a vehicle be driven with a brake chamber air leak?: It should not be. A leak from the chamber both reduces brake force and continuously drains system pressure, leaving the brakes inadequate in an emergency. The air brake system is directly a life-safety system; once a leak is noticed, the vehicle should be stopped safely and taken to service. This is also an inspection/safety violation.
Why is push rod stroke increasing — should I replace the chamber?: Increasing stroke is usually caused not by the chamber itself but by a worn lining or a malfunctioning automatic slack adjuster. When stroke approaches the limit, lining thickness and the adjuster should be checked first. If the diaphragm or return spring has weakened, the chamber can also be the cause; the correct order is to check the adjustment first, then question the chamber.
Should I replace the brake chamber on one side or both?: Since the two chambers on the same axle are the same age and have the same operating history, if one has fatigued the other is likely close behind. To preserve brake balance, it's correct to evaluate at least the opposite chamber's stroke and leak status together; many shops renew both at once.
What is the service life of a brake chamber?: A brake chamber has no fixed lifespan schedule; its life depends on air quality, ambient conditions, and maintenance discipline. A chamber supplied with dry air and an open drain hole lasts a long time; one that draws in moist air or is exposed to corrosion fatigues early. That's why replacement is planned around periodic stroke and leak checks rather than a fixed mileage.
Does a vehicle with disc brakes also have a brake chamber?: Yes. Heavy commercial vehicles with disc brake systems also use an air brake chamber; the difference is that the chamber actuates a disc caliper mechanism instead of an S-cam. Because disc system actuators have different stroke and connection characteristics than S-cam systems, the chamber must still be selected by axle and OE compatibility.
How do I choose the correct brake chamber?: Vehicle model alone is not enough for selection. Chamber type (Type), axle position (front/rear/mid), whether it's a service or spring/combination unit, production year, and, whenever possible, the OE reference number on the old chamber should all be used together. In the VADEN catalog, search can be performed using this data: entering the OE number or Type printed on the old chamber shows the matching VADEN part number, which you can verify against axle position and application information before ordering. As an application example, Mercedes-Benz Actros/Axor, Volvo FH/FM, DAF XF/CF, MAN TGX/TGS, and Scania series use Wabco, Knorr-Bremse, and Bendix-origin OE chambers on the air brake side; the correct part, however, is always determined by Type and OE number, not brand name.

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