The system includes direction indicators, brake signals, identification mark of the road train and equipment for their activation
Schemes for switching on light signaling products are shown in fig. 1 and 2
The cars are equipped with an electronic switch 7 (see Fig.1) of direction indicators.
A feature of this interrupter is the presence of separate circuits for controlling the flashing and controlling the operation of the direction indicators of the tractor and semi-trailer.
Power to the turn signal interrupter is supplied from the fuse via the red wire to the plug-in block of the alarm switch 3 and through its permanently closed contacts returns to the plug-in block and is fed through the gray wire to the plug-in block of the interrupter 7, to the "+" terminal.
Next, the operating current enters the "+" of the electronic element and exits it to "-" through the plug and black wire.
The electronic element sets a certain frequency and duration of the flashing signal and sends it to the winding of the main relay Pr, which is connected to the electronic element.
The permanently open contacts of the relay Rg begin to turn on at a given frequency, and this signal comes from the contacts of the relay Rg to the terminal P of the plug block, from it through the brown wire to the alarm switch, through the other brown wire to the plug block of the combined steering column switch 11.
When the left turn is turned on, power is supplied to the plug block, from it through the green wire to the “LB” terminal (left side) of the breaker 7, From the “LB” terminal, the working current passes in two ways:
- - to the winding of the Rt relay (tractor relay),
- - to the winding of the RP relay (semi-trailer relay).
Both windings are wound with a thick wire and are power. From the windings of these relays, the operating current is supplied to the terminals "LT" (left turn of the tractor) and "LP (left turn of the semi-trailer).
From the “LT” terminal, the current flows through the yellow wire to the plug connector XV and from it through the yellow wire to the left side repeater of the tractor and simultaneously from the “LT” terminal through the yellow wires to the plug connectors II and XIII and through them to the front and rear left direction indicators of the tractor.
From the “LP” terminal, the operating current flows through the red wire to the plug connectors II and XI and through them to the terminal II of the power cable plug of the main consumers of the semi-trailer.
Thus, the circuits of the tractor and the semi-trailer are made separately, and the operating current of their lamps passes through the windings RT and Rp, respectively, which makes the permanently open relay contacts Pt and Rp operate at the same frequency as the main relay Rg.
Simultaneously with the described power supply, it is supplied from the terminal of the plug-in block of the breaker 7 to the relay contacts Рт and Рп and through them it goes to the terminals "CT" (tractor control lamp) and "KP" (semi-trailer control lamp).
From the “KT” terminal via a blue wire and from the “KP” terminal via a pink wire, an intermittent signal from the relay Rt to Rp is supplied to the control lamps installed in the block of 6 control and signal lamps.
The operating current passes through the indicator lamps of the tractor and semi-trailer, and they begin to flash, indicating that the main lamps installed in the lamps are working.
If the lamps in the lamps of the semi-trailer burn out, then there will be no operating current through the relay winding Rp, and the relay contacts will remain open. The semi-trailer's turn signal lamp will not light up.
If any of the tractor's three lamps (front, rear, or side) burn out, the tractor's turn indicator lamp also goes out. Thus, with the help of control lamps, the serviceability of the lamps installed on the tractor and semi-trailer is monitored.
According to the principle of operation of the direction indicators of the left side of the tractor and semi-trailer described above, according to the scheme of fig. 1 you can trace the similar operation of the starboard turn signals.
In case of an emergency on the road or a malfunction of the road train, the driver has the opportunity to simultaneously turn on all the direction indicators of the tractor and semi-trailer using switch 3 (see Fig.1) of the alarm.
At the same time, all direction indicators work in a flashing mode.
Enable is done as follows.
The switch handle 3 is pulled out.
In this case, the operating current flows from fuse No. 5 through a white wire to the contacts of the alarm switch, which, when turned on, close and the operating current passes to the plug and to the gray power wire of the direction indicator breaker.
The breaker operates in the mode described above and generates an intermittent signal through the contacts of the main relay Rg to the breaker’s “Sh” terminal.
From it, the operating current is supplied through the brown wire to the alarm switch, through the closed contacts of which it enters the control lamp; the lamp is flashing.
At the same time, the current is supplied to the pink and green wires of the plug-in block of the alarm switch 3, which go respectively to the plugs PB and LB of the plug-in block of the breaker 7.
From these terminals, the operating current is output not to two windings Pt and Rp, as when turning on the direction indicators, but to all four.
From these windings, current is supplied to the working lamps of the direction indicators of the left and right sides of the tractor and semi-trailer, as described above.
When switch 3 is turned off, the entire system is turned off.
The vehicles have four switches used in the brake system to turn on the brake lights.
This is due to the fact that cars have a number of brake systems: working, parking, auxiliary, spare.
Each of the switches is installed in a specific line of the brake systems and works on the same brake signal lamps of the tractor and semi-trailer.
Switches 2, 3 and 5 (see Fig. 2) turn on when air is supplied to them.
Switches 1 and 4 are pressure drop sensors (MM124B), they work in the brake system under air pressure, as a result of which their contacts are open.
When air is released from the sensors, their contacts turn on.
When you press the brake pedal of the main brakes, switch 5 is turned on, made with permanently open contacts (MM125), when braking, compressed air is supplied to it and switches its contacts on.
When the tractor's auxiliary brake is applied, compressed air is supplied to the brake signal switch 2, also made with permanently open contacts (MM 125).
When air is supplied, the contacts are switched on.
When the air pressure in the semi-trailer supply line decreases, which may be due to a violation of the tightness of the system, if its elements break or the semi-trailer breaks, the contacts of switch 4 also turn on.
This switch-sensor (MM124B) closes the contacts when the pressure in the system decreases.
All three switches 2, 4 and 5 are interlocked on plug-in connectors I and III in one circuit and connected with a red wire to the plug on the block of control and signal lamps.
These three switches turn on the brake lights as follows. Voltage is supplied from fuse No. 9 to terminal 30 of relay P2 for turning on brake signals, as well as to terminal 85 of the same relay.
After passing the relay winding, the operating current from terminal 86 flows to the terminal of the control signal lamp unit 13 and from it through plug connectors I and II to switches 2, 4 and 5.
When any of these three switches is activated, contacts 30 and 87 of relay P2 are closed and current is supplied through gray wires to plug connectors III, XI, XIII and XIII and from them to brake lamps, as well as to terminal 1 of plug 15 connecting electric power cable for the main consumers of the semi-trailer.
When the auxiliary brake is applied, switch 3 is activated together with switch 2.
When compressed air is supplied, the contacts of the switches close and turn on the winding of relay P7 to ground.
The operating current from fuse no. 11 is supplied to terminals 30 and 5 of relay B7, through the relay coil to terminal 86, to plug connector III and via the black wire to switch 3.
Relay P7 closes the contacts of plugs Z0 and 87 and the working current is supplied through the purple wire to plug connectors III and XI and to terminal III of the power plug of the electric power cable for the main consumers of the semi-trailer, and to the electro-pneumatic valve that controls the braking system of the semi-trailer.
Thus, when the auxiliary brake of the tractor is turned on, the semi-trailer is simultaneously braked and the brake lights are turned on both on the tractor and on the semi-trailer.
The brake light switch 1 (MM124B) turns on the latter when the car is set to the parking brake. It is under pressure and its contacts are open.
When the brake is applied, air is released from the brake chambers and the switch and its contacts are closed.
The operating current passes from fuse 12 through the gray wire to the “+” terminal of the breaker (see Fig. 2) of the parking brake control lamp, through the closed contacts of the breaker, the winding for heating the thermobimetallic element and goes to the “-” terminal, from which the brown wire is fed to the plug-in connector of the unit 13 of control and signal lamps, then the current flows through the brown wire through connector I to switch 1.
When switch 1 is turned on, the indicator lamp comes on. The operating current passing through this circuit heats the thermobimetallic element of the interrupter.vatel 7, and its contacts open.
After the element cools down, the breaker contacts close and the cycle repeats, the control lamp flashes.
At the same time, when the parking brake is turned on, the operating current flows from fuse No. 9 to terminals 85 and Z0 of relay P2, through the relay winding to plug 86 and then to block terminal 3 of control and warning lamps, from which it enters the plug block of the block through a separating diode and through the brown wire to connector I and switch 1.
The relay will close the contacts of plugs 30 and 87. The operating current through the gray wire enters connectors III, XI, XIII and XIV, and through terminal I of the plug of the electric cable for supplying the main consumers of the semi-trailer, the braking signals of the tractor and semi-trailer are switched on.
Maintenance
Possible malfunctions of the light signaling system and how to fix them
- Cause of malfunction
Remedy
Turn indicators not working
- Fuse No. 7 blown
Replace fuse
- The PC951A turn signal breaker has failed
Replace breaker
Alarms do not turn on
- Fuse No. 5 blown
Replace fuse
- The alarm switch is out of order
Replace switch
Brake lights not turning on
- Fuse No. 9 blown
Replace fuse
- Faulty switches 2, 4 and 5
Check switches and replace
- Faulty relay P2
Check relay and replace
When operating vehicles, it is necessary to monitor the cleanliness of the lenses of direction indicators and brake signals by wiping them with a rag.
Rubber protective covers on switches and sensors should fit snugly, preventing moisture from getting inside.
The products of the electrical equipment of the light signaling system are not repaired, as they are non-separable. When they fail, they must be replaced with new ones.