3.9.3 Double-line pneumatic drive of trailer brakes

tor; 9 – emergency air pressure lamp; 10 – pressure sensor; 11 – emergency pressure sensor; 12 – tank; 13 – condensate drain valve. Figure 3.9.1 – Single-line pneumatic drive of trailer brakes Air is fed to the compressor 1 (figure 3.9.1) from the engine intake manifold through the line 2. The air is compressed in the compressor 1 and delivered through the pressure regulator 3 to the tank 12, from which the compressed air is fed to the brake valve 5. With the brake pedals not pressed air goes to the connecting head 7 through the brake valve 5 and the control line 6 and further to the trailer brake pneumatic drive. The pressure regulator 3 has an air bleed valve 4, which is used for tire inflation. Air pressure in the tanks 12 is controlled by the air pressure indicator 8 with an emergency air pressure lamp 9 (red color) in the instrument cluster as well as by pressure sensors 10 and emergency pressure sensors 11. To remove the condensate from the tank 12 there is a valve 13. The connecting head 7 is valve-type. The valve prevents compressed air from going out when using the pneumatic drive without a trailer attached (when inflating tires). The trailer brakes are controlled in two modes: direct and automatic. The direct control of the brakes is performed by means of pressure drop in the connecting line 6 when the tractor decelerates. In such case, delivery of compressed air to the trailer pneumatic system stops. The automatic control of the trailer brakes is performed in case of emergency disconnection of the trailer and the tractor due to pressure drop to zero in the trailer connecting line. Note – Rules on checking and adjustment of the brake valve of the single-line pneumatic drive are given in clause 3.9.4.2.2.

3.9.3 Double-line pneumatic drive of trailer brakes

The double-line pneumatic drive provides controlling brakes of trailers and agricultural machines, equipped with double-line pneumatic brake drives, as well as tire inflation. A diagram for the double-line pneumatic drive is shown in figure 3.9.2.

1- compressor; 2 – line from engine intake manifold; 3 – condensate drain valve; 4 – brake valve; 5 – feed line; 6, 7 – connecting heads; 8 – control line; 9 – tank; 10 – pressure regulator; 11 – air bleed valve; 12 – air pressure sensor; 13 – emergency air pressure sensor.

Figure 3.9.2 – Double-line pneumatic drive of trailer brakes