System overwiev

System overview Brake System 002

Complies with directives

• 71/320/EEG
• 74/132/EEG
• 79/489/EEG

Test report from Swedish National Road and Transport Institute (VTI)

Towing vehicle

The towing vehicle can include various types of lorries, cars, lift trucks, etc. The only requirement is that they have an hydraulic brake fluid system.

Tow coupling

• Standard trailer and semi-trailer couplings
• Fifth wheel
• Ball hitch
• VBG coupling 
• DIN tow hitch

Special types of trailers

Some examples:

• Large horse boxes
• Exhibition trailers
• Various specially built trailers

Other possible applications

Instead of supplying a wheel cylinder for use with brake fluid, the system can be connected to a slave cylinder (receiver cylinder) that applies force to an S-cam brake or cam shaft brake.

Axle weights

Commonly used wheel pair axle weights are a KNOTT 6,000 kg sprung wheel pair, but we can also supply KNOTT axles for lighter and considerably heavier applications.

The towing vehicle sets the limit, together with the relevant laws, directives and regulations.

High level of safety

There is a high level of safety in the event of hose rupture or coupling failure when the brakes are applied at full force and maximum braking torque is applied to the wheels.

It just requires failure of a single hose to trigger the safety system.

Principle function of control unit

The control unit consists of two main sections, A and B, mounted in a black box with a built-in tank for mineral oil.

Section A, pump unit

Consists of:

• Hydraulic gear pump
• 12V electric motor (also available in 24V version)

Section B, pressure converter unit

Consists of:

• Control valve, available in four different versions to suit the application. 
• Pressure monitors for electric motor. 
• Pressure monitor that gives a warning signal if the charge pressure drops below 75 bar. 
• Accumulator (power store). 
• Relay with fuse. 
• Connection for towing vehicle’s master cylinder, circuits 1 and 2, signal outputs. 
• Connection for supply pressure to trailer assembly (relay valve). 
• Connection to signal output for retardation.

Coupling housing

A non-drip (non-spill) coupling intended for both control line and power line, allowing connection and disconnection while pressurised.

Consists of:

* Hydraulic non-drip coupling housing for medium-grade mineral oil.

* Two connections.

* A male coupling fitted to the towing vehicle.

* A female coupling fitted to the semi-trailer or trailer.

Trailer assembly

Trailer assembly (relay valve) consists of:

• Two accumulators (power stores), the capacity of which is matched to the application. 
• Emergency brake valve (relay valve). 
• Connection for feed pressure to trailer assembly (relay valve) from pressure converter unit, section B. 
• Connection for retardation signal output from pressure converter, section B. 
• Connection from brake pressure output to transmission cylinder (converter cylinder/amplifier).

Transmission cylinder

Transmission cylinder (converter cylinder/amplifier) consists of:

• One cylinder with two pistons with different areas that convert the pressure ratio between the fluids.

Load-sensing ALB valve

The load-sensing ALB valve adapts the pressure supplied to the brake cylinders to suit the load on the trailer axles.

The ALB valve consists of:

• A reducer valve.

Brakes

The brakes are matched to the axle weight, retardation requirements and type of application.

Examples of brakes:

• Drum brakes  with wheel cylinder
• Disc brakes   
• S-cam brake
• Cam shaft brake

Read more about the advantages of ALB >>