Wholesale European Trailer Emergency Release Valves Factory, Manufacturers

Product Overview

What Is a European Trailer Emergency Release Valve?

Definition

A European trailer emergency release valve is the trailer-mounted valve that applies the trailer brakes automatically from its own reservoir whenever the supply line loses pressure, and that also gives the operator a manual means of releasing those brakes when the trailer is parked and disconnected from a tractor. It combines an emergency function and a release function, and it is the key safety valve on any European trailer with a two-line air brake system.

A trailer that breaks away from its tractor must stop itself. There is no driver aboard, no engine and no compressor, so the only energy available is the compressed air already stored in the trailer's own reservoir. The emergency release valve holds that air in reserve while the supply line is charged, and the moment the line is cut, torn or uncoupled, the valve uses the stored air to apply the trailer brakes at once. When the trailer is later parked in a yard or depot and must be moved without a tractor, the release function lets an operator free the brakes temporarily.

Automatic Application When the Supply Line Fails

The trailer is connected to the tractor through two main air lines. The red supply line keeps the trailer reservoir charged. The yellow control line carries the brake signal during normal braking. While the supply line is at working pressure, the emergency valve holds an internal piston in the released position and does not apply the brakes. If supply pressure falls to a low level, typically in the region of two bar, the piston moves, the reservoir is connected to the trailer brake chambers, and the brakes are applied. This is the behaviour that vehicle regulations require for trailers with air brakes.

The Release Function for Shunting and Recovery

A parked trailer that has been uncoupled will have its brakes applied because its supply line is empty. To move it by hand, by a yard tractor with no air connection or onto a transporter, the operator operates a release button or lever on the valve. This connects reservoir air to the brakes, or reverses the piston position, and frees them. The release is temporary. It is designed so that the brakes re-apply when the button returns, when the reservoir bleeds down, or when the supply is reconnected and released properly.

Why Release Is Not a Parking Function

Release is a convenience, not a substitute for the parking brake. The trailer's own air reservoir will slowly leak, and when it does the brakes re-apply, sometimes without warning. The trailer must never be left released on a slope, and wheels must be chocked whenever a trailer is moved with its brakes released. Good workshops and yards train their staff on this point as much as on the valve itself.

Combined Valves and Separate Release Valves

Some designs integrate the emergency function and the release function into a single body, often described as a trailer brake valve with release. Others use a separate relay emergency valve plus a manually operated release valve fitted elsewhere in the system. The two arrangements deliver the same result but have different port layouts and different fitting requirements.

Signs of Failure

A failing valve may apply the trailer brakes when they should be released, fail to apply them when the supply line is cut, or leak air continuously from the exhaust. Because the valve is exposed to road spray and the supply line often carries oil and moisture from the tractor, contamination and freezing are common causes. A release button that sticks, or that applies no effect, is also a frequent complaint in depots and yards.

Matching the Valve to the Trailer Air System

Match the valve type, the supply and control port threads, the delivery ports, the release button or lever design, the reservoir port and the mounting pattern. A valve with the correct emergency function but a different release arrangement will not fit the yard procedures or the trailer layout.

Fit point: trailer chassis near the reservoir
Emergency function: automatic brake application on supply loss
Release function: manual button or lever
Line connections: supply, control, reservoir, delivery
Trailer types: semi-trailers, draw-bar and rigid trailers
Service parts: piston kit, release button, filter, seals

Technical Data

Emergency Release Valve Model Range

Standard configurations below. Custom port threads, release button styles and mounting patterns can be produced to your drawing.

Table 1 — Genuine gzbrake.com Ref NO. and OE cross-reference data for representative European Release Valve products.

Ref NO.	Product Name	Application	Technical Specification	OE / Cross-Reference (Sample)	Cross-Ref. Count	Product Line
9630010010	Precision Release Valve for DAF Series	DAF	Port 1-1 = M22x1.5,Port 1-2 = DIA 7,Port 2 = DIA 21.5	DAF:0736144，719991，736144，	1	European Release Valve
9630060010	Universal Release Valve with Black Knob for European Series	RVI, DAF, IVECO, MAN	Port 1-1 = M16x1.5,Port 1-2 = M16x1.5,Port 2 = M16x1.5,Knob: Black	RVI:5021170428 / DAF:1325331 +2 more	4	European Release Valve
9630060030	High-Efficiency Pneumatic Quick-Release Valve	DAF	Port 1-2 = M16x1.5,Port 2 = M16x1.5,Knob: Red	DAF:867882	1	European Release Valve
9630060050	Precision Release Valve with Green Knob for KRONE Series	KRONE	Port 1-2 = M16x1.5,Port 2 = M16x1.5,Knob: Green	KRONE:5811329	1	European Release Valve
9630060060	Precision Release Valve with Yellow Knob	—	Port 1-2 = M16x1.5,Port 2 = M16x1.5,Knob: Yellow	—	—	European Release Valve
9710029000	All-Weather Pneumatically Controlled Release Valve	MAN, SCANIA, DAF	Port 1-1 = M16x1.5,Port 1-2 = M16x1.5,Port 21,22 = 2xM16x1.5,Port 4 = M16x1.5,Dataplate...	MAN:ZG046540002 / SCANIA:1738468 +1 more	3	European Release Valve
K015849	Emergency Release Valve for SCANIA/SCHMITZ Series	SCHMITZ	Port 1,1-2 = 2x M16x1.5,Port 2 = M22x1.5,Charging Valve: without，Emergency pressure: 2....	SCHMITZ:055016	1	European Release Valve
K015380	Enhanced Emergency Release Valve for SCANIA Series (with Charging Valve)	SCANIA	Port 1,1-2 = 2x M16x1.5,Port 21,22 = 2x M16x1.5,Port 2 = M22x1.5,Charging Valve Opening...	SCANIA:2121603	1	European Release Valve

Ref NO. and cross-reference numbers above are drawn directly from our European Release Valve product range on gzbrake.com. Cross-reference lists are sampled for space; contact us with your vehicle's OE number or chassis details for the complete, current cross-reference list and stock availability.

Trailer Manufacturer Reference List

Schmitz CargobullKrone TrailerKögel TrailerKässbohrerFlieglWieltonFaymonvilleMeillerLangendorfBenaluLamberetFruehaufKaiserFeldbinderMagyarSpitzerVan HoolLawrence David

Working Principle

How an Emergency Release Valve Works

The valve responds to supply line pressure. Five stages describe how it behaves in normal use, in an emergency and during release.

Coupled and Charged

When the tractor is coupled, the red supply line delivers air to the trailer reservoir and the valve inlet. Supply pressure holds the internal piston in the released position.

Normal Braking

The yellow control line carries the brake signal. The valve acts as a relay and sends reservoir air to the brake chambers in proportion to the signal.

Supply Line Fails

If the line is cut or uncoupled, supply pressure falls. When it reaches the threshold, the piston moves and connects the reservoir directly to the brake chambers.

Automatic Application

The trailer brakes apply with reservoir air and hold the trailer stationary or bring it to a stop. No driver action is needed.

Manual Release

With the trailer parked, the operator operates the release button or lever. Air is directed to free the brakes for a short period, and the brakes re-apply when the release is cancelled.

What Happens When the Emergency Release Valve Stops Working

A valve that does not apply on supply loss leaves a disconnected trailer with no brakes, which is a serious safety hazard.
A valve that applies when it should not causes trailer brakes to drag and overheat in service.
A leaking exhaust drains the trailer reservoir, so the trailer cannot be released or braked reliably.
A release button that fails to operate makes shunting and recovery difficult and can lead to unsafe workarounds.
Freezing or contamination at the piston can hold the valve in the wrong position in winter.

Product Features

Built to Stop a Trailer Without a Driver

The valve may sit idle for months and then be needed instantly. Each unit is designed for dependable, repeatable operation.

Automatic Emergency Application

A calibrated piston moves as soon as supply pressure falls, applying the brakes without driver action.

Integrated Release Function

A button, lever or knob allows brakes to be freed safely for yard shunting and recovery.

Reservoir Protection

A non-return valve protects the reservoir air so that stored energy is not lost during a supply failure.

Inlet Filter Options

Fine filters at the supply and control inlets keep oil, water and particles away from the piston seals.

Wide Port Options

Combined and separate valve designs with M16 × 1.5 and M22 × 1.5 ports suit most European trailer layouts.

Winter-Ready Materials

Seals and springs are selected to stay flexible in cold weather and to resist sticking.

Selection Guide

How to Choose the Right Emergency Release Valve

Five checks decide whether the valve fits the trailer's air system and works correctly with yard procedures.

01
Identify the valve concept
Determine whether the trailer uses a combined trailer brake valve with release, or a relay emergency valve with a separate release valve. The port layouts and fittings are different.
02
Match the ports
Supply and control ports are commonly M16 × 1.5, while delivery ports are often M22 × 1.5. Confirm which port carries the reservoir connection as well.
03
Check the release design
Push button, pull knob and lever versions operate differently. Staff in yards and depots are trained on the design they know, so use the same type.
04
Consider the parking function
Some trailers use a parking valve that works together with the emergency valve. Confirm that the replacement has the correct parking function.
05
Verify the mounting
Bolt pattern, orientation and port position vary between trailer builders. A photo of the valve in place, with its lines attached, helps us confirm the correct variant.

Table 2 — Trailer type and typical emergency release valve setup.

Trailer Type	Typical Setup	Note
Semi-trailer, standard	Relay emergency valve with release	Most common European layout
Semi-trailer with spring brakes	Trailer brake valve with parking control	Check spring brake circuit
Draw-bar trailer	Relay emergency valve, dual release	Two circuits, separate release
Yard-use trailer	Push button release	Simple operation for shunt drivers
Special transport trailer	Lever release, lockable	Prevents accidental release

These setups are indicative. Always check them against the trailer's air brake diagram.

Applications

Where These Emergency Release Valves Are Fitted

Every European trailer with air brakes needs an emergency function, and most also have a release function. The trailer types below account for most of our orders.

Curtainsider and Box Semi-Trailers

Standard two-line trailers use a relay emergency valve with a release button so drivers can move trailers in the yard.

Tanker and Silo Trailers

Heavy loads and hazardous cargo make automatic emergency braking on separation particularly important.

Tipper Trailers

Dirty, wet working conditions call for filters, robust seals and a sealed release button.

Container Chassis

Frequent uncoupling in ports and terminals make the release function a daily requirement.

Refrigerated Trailers

Long-distance transport and depot handling require reliable emergency and release operation.

Car Transporters

Long combinations use multiple axles and two circuits, and need a valve that works with both.

Draw-Bar Trailers

Full trailers coupled behind rigid trucks need emergency braking on the trailer alone.

Fleet Retrofits

Older trailers can be upgraded with a modern emergency valve with release for safer yard handling.

Installation

Installation Notes for Workshops

An emergency valve is a critical safety part. The steps below prevent the mistakes that leave a trailer without its emergency function.

Chock the Wheels

Chock the trailer wheels before disconnecting any line. The brakes may apply or release unexpectedly when the valve is removed.

Drain the Reservoir

Release the trailer reservoir pressure and confirm zero pressure. Reservoir air can remain even when the supply line is drained.

Label Every Line

Mark supply, control, reservoir and delivery lines before removal. Crossing the supply and control lines will disable the emergency function.

Clean and Fit New Seals

Clean the connections and fit new sealing washers. Dirt in the ports will foul the piston and the filter.

Check Filters

Clean or renew the inlet filters or coupling-head filters. Dirty filters are a common cause of sluggish piston movement.

Test Emergency and Release

Charge the system, then disconnect the supply line and confirm that the trailer brakes apply. Reconnect, charge and check that the brakes release. Test the release button while the trailer is uncoupled.

Maintenance

Emergency Function Tests and Service Parts

The valve waits for a rare event and then must work perfectly. A simple schedule prevents most problems.

Table 3 — Recommended inspection and replacement schedule for trailer emergency release valves.

Item	Interval	What to Check
Emergency function test	Every 6 months	Disconnect the supply line and confirm that the trailer brakes apply automatically.
Release function test	Every 6 months	Operate the release button on an uncoupled trailer and check that it frees the brakes and re-applies.
Coupling-head filters	Every 6 months	Clean or replace filters; dirt and oil restrict flow and slow piston movement.
Reservoir drain	Every service	Drain the reservoir and check for water or oil, which points to a supply air quality problem.
Exhaust port	Every service	Check for continuous leakage, ice or blockage.
Piston and seals	Every 4 years or 400,000 km	Replace with a repair kit before the valve begins to stick or leak.
Mounting and lines	Annual inspection	Check bolts, brackets and fittings for looseness, chafing and corrosion.

We supply repair kits, release buttons, filters, seal sets and complete replacement valves for every model listed on this page.

Diagnostics

Emergency Release Valve Troubleshooting Guide

Check the symptom against the likely cause before replacing the valve. Some complaints trace back to a leaking coupling head or a dirty supply line.

Table 4 — Common emergency release valve symptoms, causes and corrective actions.

Symptom	Likely Cause	Recommended Action
Trailer brakes do not apply when the supply line is disconnected	Piston stuck in the released position or reservoir empty.	Check the reservoir pressure and replace the valve or repair kit.
Trailer brakes stay applied after coupling	Supply pressure too low, blocked line or valve stuck in the emergency position.	Check supply pressure and coupling; replace the valve if the piston is jammed.
Trailer brakes drag in service	Leaking inlet seat or sticking piston.	Replace the seals or valve and check for contamination.
Air leaks steadily from the exhaust port	Worn seat or torn diaphragm.	Renew the seat and diaphragm, or replace the valve if the leak persists.
Release button does not free the brakes	Empty reservoir, worn seal or blocked release passage.	Check the reservoir pressure; replace the release seals or valve.
Brakes re-apply immediately after release	Reservoir leaking or release seal leaking.	Test the reservoir for leaks and replace the valve if necessary.
Valve freezes in winter	Moisture in the supply air and cold-hardened seals.	Service the tractor air dryer and fit correct cold-grade seals.
Emergency application is very slow	Restricted delivery line, dirty filter or weak piston spring.	Clean the filters and check the lines; replace the piston kit.

If the symptom continues after valve replacement, the fault is usually in the coupling head, the supply line or the tractor air system. Tell us how the trailer brakes behave when coupled, uncoupled and released, and our technicians will help you trace the fault.

Terminology

Emergency Release Valve Glossary

Plain-language definitions of the terms you will see on trailer brake diagrams, workshop manuals and part listings.

Emergency Valve: A valve that applies the trailer brakes automatically using reservoir air when the supply line loses pressure.
Release Valve: A valve or function that lets an operator temporarily free the trailer brakes when parked.
Supply Line (Red): The coupling line that charges the trailer reservoir from the tractor.
Control Line (Yellow): The coupling line that carries the brake signal from the tractor to the trailer.
Two-Line System: The European braking system that uses separate supply and control lines between tractor and trailer.
Coupling Head: The connector at the end of each air line that joins tractor and trailer, often with a filter.
Trailer Reservoir: The trailer's own air tank that holds the energy for emergency and normal braking.
Automatic Application: The brake application that happens without driver action when supply pressure falls.
Shunting: Moving a trailer in a yard or depot, often with no air supply.
Parking Valve: A valve that controls spring brakes for parking, sometimes combined with the emergency function.
Spring Brake: A brake chamber with a spring that applies the brake automatically when air pressure is removed.
Non-Return Valve: A one-way valve that traps reservoir air and stops it flowing back into the supply line.

Questions

Frequently Asked Questions

Twelve questions our distributors, workshops and fleet buyers ask most often about European trailer emergency release valves.

It applies the trailer brakes automatically from the trailer's own reservoir if the supply line loses pressure, and it gives the operator a way to free the brakes temporarily when the trailer is parked and disconnected.

The supply line pressure holds the emergency valve open. When the line is cut, pressure falls, the valve moves and connects the reservoir directly to the brake chambers, so the brakes apply without driver action.

It is used in yards and depots to move a trailer without a tractor connected, for example on a shunting truck or a transporter. The operator presses a button or moves a lever to free the brakes for a short time.

No. The release is temporary, and brakes will re-apply when the reservoir bleeds down. Never leave a trailer released on a slope and always chock the wheels.

A relay emergency valve provides relay and emergency function only. A trailer brake valve with release combines relay, emergency and release in one body. The port layouts differ, so the two are not directly interchangeable.

Signs include trailer brakes that do not apply when the supply line is disconnected, brakes that stay on after coupling, continuous air leakage, a release button that does not work and a valve that freezes in winter.

Yes. Send the diagram or a photo of the valve with the reservoir and coupling lines visible, together with the trailer make and model. We will confirm the valve type, ports and release style within two working days.

Yes, in many cases. A separate release valve can be fitted to a trailer with a relay emergency valve, provided the reservoir and delivery lines are accessible. Send us the trailer air diagram for advice.

Yes. Filters, release buttons, piston kits and seal sets are available for the models listed on this page. Tell us the valve type and the release style, and we will list the matching part numbers for you.

At least every six months and at every inspection. The test is simple: charge the system, disconnect the supply line and check that the trailer brakes apply.

Yes. Trailer builders and repairers can order a few pieces of stocked models, or a full set for a batch of trailers. Stock items ship within 3 to 7 working days after payment, and any special release style is scheduled on the proforma invoice.

Yes. We can produce valves with alternative release button styles, port threads and mounting patterns to your drawing, and supply them in neutral cartons or under your own brand.

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