Hydraulic-powered brake system
New dual-circuit hydraulic brake system
The effectiveness of hydraulic brake systems in agricultural trailers has been proven on countless occasions. This is also true for the breakaway safety function, which for years has been servicing trailers that travel at speeds of up to 40 km/h. These positive experiences are being carried over into the next stage of development.
The new dual-circuit hydraulic brake system, with its additional line, provides users with an element of security that surpasses any of its regular functions. For the driver, the system is also a reassuring visual feature, both on the towing vehicle and on the trailer.
A new trailer brake valve secures the oil pressure supply of both standardised brake connectors:
During operation, the brake line, with its already-recognised male connector (standardised as per ISO 5676:1983), increases the brake pressure from 0 to 150 bar, pressure which continues to be used by the customary single-circuit brake to operate the service brake on the trailer.
The new, additional line, with its male connector coupling (as per ISO 16028:2006 /DIN 10), maintains a continuous, constant pressure of 15–35 bar. A drop in the pressure in this line will cause the trailer to brake automatically.
An electrical connector (as per ISO 7638-2, 5/7 pole ABS plug) should be installed on the towing vehicle, in order both to monitor the trailer electronically and to be able to tow trailers with electronic braking systems.
Intelligent trailer brake valves on the towing vehicle are downward compatible and can accommodate both older single-circuit or new dual-circuit brake systems.
On the trailer:
The central element on the trailer in the figure below is the new dual-circuit emergency brake valve (NBV16). All the necessary functions are performed from this single unit, which includes the brake line, the additional line, the breakaway function, and the auxiliary brake with pressure reservoir, as well as the automatic load-dependent braking system (ALB) and reservoir emptier.
The system displayed below ensures that trailers can also be towed by those towing vehicles which only have one hydraulic brake connector. The parking brake is activated mechanically from the trailer’s brake linkage.
The electrical connection is used for the system monitor, the immobiliser and the power supply for the automatic braking system. It is possible to route the brake line and the additional line to the second trailer.
Example on a R3a tandem vehicle
|1. Hydraulic dual-circuit emergency brake valve with ALB and reservoir||4. Electrical system monitoring with ABS plug 7638-2|
|2. Load sensor for ALB (automatic load-dependent braking system)||5. Mechanical emergency brake|
|3. Brake line and an additional line for the 2nd trailer|
Other features and advantages:
The deadlines for registering new vehicles with single or dual-circuit hydraulic trailer brake systems are specified in the EU regulation. It should be noted that vehicles already equipped with brake systems that meet EU standards can be put into circulation in Switzerland and EU-countries. For tractors, the grace period expires in 2020. The deadlines for trailers are yet to be fixed.