It ensures that the optimum temperature in the cab is maintained when the ambient temperature drops

Electric motors 1 (Fig. 1) pump air through the cabin heating radiator

When installing electric motors, pay attention to the direction of rotation of their shafts.

Reversible electric motors ME250 are used in the heating system.

When the positive pole of the source is connected to the red wire, the motor shaft rotates to the right, and the negative pole to the left.

Electric motors can operate in two modes, connected in parallel or in series. The modes are controlled using the key switch 2 located in the cab.

Audio alarm system

It includes pneumatic and electrosound signals 13 of the external alarm and an audible signal 12 (buzzer) of the internal alarm, indicating an emergency pressure drop in the pneumatic circuits of the vehicle's brakes.

Audible pneumatic signal is activated by pressing the button located on the right side of the combination // light switch.

In this case, voltage is applied to the electro-pneumatic valve 10, which opens the air from the brake pneumatic drive to the signal.

When the air pressure in the pneumatic system is 400...70 kPa, the sound should be clear.

Electro-acoustic signals are located under the cab on the front cross member and are activated by moving the combination switch handle up; the signals are powered through an intermediate relay 14 installed on the lower instrument panel.

A buzzer installed under the instrument panel is included in the circuit for signaling a pressure drop in the brake pneumatic circuits.

Signal 12 is connected to the vehicle ground through a block of control lamps and switches for control lamps of air pressure drop in the receivers; it sounds simultaneously with the ignition of any of the control lamps, signaling a decrease in air pressure in one of the circuits.