History

History and background to the creation of Brake System 002.

Brake System 002 is an hydraulic operating system for unique specially built vehicles, large semi-trailers and other trailers.

Problems with American semi-trailers!

American semi-trailers arrived on the Swedish market in the 1980s with electro-pneumatic brakes that could not be coupled to the hydraulic brake systems that are most widely used on light commercial vehicles and cars in Sweden and the rest of Europe.

American electro-pneumatic brake systems should not be confused with our technical approach, which uses an hydraulic load-sensing system.

Large lorries generally use a pneumatic system that is fed by a compressor. These are not normally fitted to smaller towing vehicles.

How did the problem arise?

A horse trailer that was imported to Sweden from the USA was only fitted with electric brakes that could not be used in the Swedish or European markets.

Who solved the problem?

The trailer owner got in touch with the Swedish National Road and Transport Institute (VTI), who were unable to help solve the technical problem but were able to recommend a company that specialized in brake systems. That company is now fully integrated in Rydahls’ BRAKE SYSTEMS department.

How was the problem solved?

This group of people saw the problem as an interesting technical challenge and over the next year developed a prototype solution for an hydraulic operating system for semi-trailers and trailers that incorporated an hydraulic load-sensing system as part of the overall solution.

Power from the towing vehicle has to be transferred in some way to the trailer, but unfortunately there is no way of connecting two separate brake fluid systems with direct couplings without getting air in the system.

The only solution is to divide the system into two separate parts.

Technical solution

The towing vehicle’s system consists of a system box with its own electric pump and tank that supply pressure to an accumulator and a control valve with a variable ratio. The control valve ratio must always be chosen so that a retardation of 5m/s2 delivers a pressure of around 50 bar to the trailer coupling.

The system box

Alternative names: Control unit or "Black Box"

• The coupling point has a non-drip coupling hub that connects the vehicle and trailer using a dual hose system.
• The first unit that is connected to the coupling hub is a trailer assembly (relay valve) that consists of two accumulators (power storage units) plus an emergency valve in case of coupling failure or hose rupture.
• Then there is the transmission cylinder (sometimes also known as a converter cylinder or amplifier), which is supplied with mineral oil and delivers brake fluid.
• Mounted after the transmission cylinder is a load-sensing ALB valve.
• The ALB valve adapts the pressure supplied to the brake cylinders to suit the load on the trailer axles.

What did the customer have to do?

The solution was to switch to KNOTT hydraulic brakes and the newly developed Brake System 002.