The system includes direction indicators, brake signals, a road train identification sign and equipment for switching them on
The wiring diagrams for the light signaling products are shown in Fig. 1 and 2
The vehicles are equipped with an electronic interrupter 7 (see Fig. 1) for the direction indicators.
A special feature of this interrupter is the presence of separate circuits for controlling the flashing and monitoring the operation of the direction indicators of the tractor and semi-trailer.
Fig. 1. Light signaling system: 1, 5 - side direction indicators; 2, 4 front direction indicators; 3 hazard warning light switch; 6 - control and signal lamp unit; 7 direction indicator flasher; 8, 10 - rear direction indicators; 9 trailer fork; 11 steering column switch
Power is supplied to the turn signal flasher from the fuse via the red wire to the plug-in block of switch 3 of the hazard warning lights and through its permanently closed contacts returns again to the plug-in block and via the gray wire goes to the plug-in block of breaker 7, to the terminal "+".
Then the working current goes to the "+" of the electronic element and leaves it to the "-" through the plug-in block and the 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 Rg, which is connected to the electronic element.
The permanently open contacts of the relay Rg begin to turn on with a given frequency, and this signal comes from the contacts of the relay Rg to terminal P of the plug-in block, from it via the brown wire to the hazard warning light switch, through another brown wire to the plug-in connector of the combined steering column switch 11.
When the left turn signal is turned on, power is supplied to the plug-in connector, from there via the green wire to the terminal "LB" (left side) of the breaker 7. From the terminal "LB" the working current passes in two ways:
- - to the winding of the relay RT (tractor relay),
- - to the winding of the relay RP (semi-trailer relay).
Both windings are wound with thick wire and are power ones. From the windings of these relays, the operating current goes to the terminals "LT" (left turn of the tractor) and "LP (left turn of the semitrailer).
From the "LT" terminal, the current goes via the yellow wire to the plug-in connector XV and from it via the yellow wire to the left side repeater of the tractor and simultaneously from the "LT" terminal via the yellow wires to the plug-in connectors II and XIII and through them to the front and rear left turn signals of the tractor.
From the "LP" terminal, the operating current goes via the red wire to the plug-in connectors II and XI and through them to the terminal II of the plug of the power cable of the main consumers of the semitrailer.
Thus, the circuits of the tractor and semitrailer are made separately, and the operating current of their lamps passes through the windings PT and Rp, respectively, which makes the constantly open contacts of relays Rt and Rp with 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 contacts of the relay Rt and Rp and through them goes to the terminals "KT" (pilot indicator lamp) and "KP" (semi-trailer indicator lamp).
From the "KT" terminal via the blue wire and from the "KP" terminal via the pink wire, an intermittent signal from the relay Rt in Rp is supplied to the indicator lamps installed in block 6 of indicator and signal lamps.
The working current passes through the indicator lamps of the tractor and semi-trailer, and they begin to flash, signaling the serviceability of the main lamps installed in the lights.
If the lamps in the semi-trailer lights burn out, then there will be no working current through the winding of the relay Rp, and the contacts the relays will remain open. The semitrailer turn signal indicator lamp will not light.
If any of the three tractor lamps (front, rear or side) burns out, the tractor turn signal indicator lamp also goes out. Thus, the indicator lamps are used to check the serviceability of the lamps installed on the tractor and semitrailer.
According to the above-described principle of operation of the left-hand side turn signal indicators of the tractor and semitrailer according to the diagram in Fig. 1, you can follow the similar operation of the right-hand turn signals.
In the event of an emergency on the road or a malfunction of the road train, the driver has the ability to simultaneously turn on all the turn signals of the tractor and semi-trailer using switch 3 (see Fig. 1) of the emergency signaling.
In this case, all the turn signals operate in flashing mode.
To turn on, do the following.
Pull the handle of switch 3 towards you.
In this case, the working current comes from fuse No. 5 via the white wire to the contacts of the emergency signaling switch, which close when turned on and the working current goes to the plug block and to the gray power wire of the turn signal interrupter.
Interrupter operates in the mode described above and produces an intermittent signal through the contacts of the main relay Rg to the "Ш" terminal of the breaker.
From there, the operating current is supplied via the brown wire to the emergency signal switch, through the closed contacts of which it reaches the control lamp; the lamp flashes.
At the same time, current is supplied to the pink and green wires of the plug-in block of switch 3 of the emergency signaling system, which go to plugs PB and LB of the plug-in block of interrupter 7, respectively.
From these terminals, the working current is output not to two windings Rt and Rp, as when turning on the direction indicators, but to all four.
From these windings, the current goes to the working lamps of the direction indicators on 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 are equipped with four switches used in the braking system to turn on the brake lights.
This is due to the fact that the vehicles have a number of braking systems: service, 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.
Fig. 2. Brake signal connection diagram: brake signal switches: 1 - parking brake; 2 - auxiliary brake; 3 - semi-trailer braking; 4 - in case of depressurization of the semi-trailer brake system; 5 - main; 6 instrument and starter switch lock; 7 - interrupter 8 - starter relay; 9 relay P1 of the mass switch lock; 10 - relay P2 for turning off the brake lights; 11 - relay P4 for turning on the reversing lights; 12 relay P7 for turning on the electronic brake control system of semi-trailers; 13 - block of control and signal lamps; 14, 16 - rear lights 15 semi-trailer power plug; I, III, XI, XIII, XIV plug connectors
Switches 2, 3 and 5 (see Fig. 2) are switched on when air is supplied to them.
Switches 1 and 4 are pressure drop sensors (MM124B), they operate 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 are switched on.
When the brake pedal of the main brakes is pressed, switch 5, made with constantly open contacts (MM125), is switched on; during braking, compressed air is supplied to it and switches its contacts on.
When the auxiliary brake of the tractor is switched on, compressed air is supplied to switch 2 of the brake signals, also made with constantly open contacts (MM 125).
When the air supply, the contacts are switched on.
When the air pressure in the semitrailer supply line decreases, which may happen if the system is not hermetically sealed, if its elements break, or if the semitrailer breaks, the contacts of switch 4 are also switched 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 connectors I and III in one circuit and are connected with a red wire to the plug on the control and signal lamp unit.
These three switches switch on the brake signals as follows. Voltage is supplied from fuse No. 9 to terminal 30 of relay P2 for switching on the brake lights, as well as to terminal 85 of the same relay.
After passing the relay winding, the operating current from terminal 86 goes to the terminal of block 13 of the control signal lamps and from it through plug connectors I and II to switches 2, 4 and 5.
When any of these three switches is triggered, contacts 30 and 87 of relay P2 close and current is supplied through the gray wires to plug connectors III, XI, XIII and XIII and from them to the brake light lamps, as well as to terminal 1 of plug 15 of the connecting electric cable for powering the main consumers of the semitrailer.
When the auxiliary brake is engaged, switch 3 is triggered together with switch 2.
When when compressed air is supplied, the contacts of the switches close and ground the winding of relay P7.
The operating current from fuse #11 is supplied to terminals 30 and 5 of relay B7, through the relay winding to terminal 86, to plug connector III and through the black wire to switch 3.
Relay P7 closes the contacts of plugs 30 and 87 and through the violet wire the operating current is supplied to plug connectors III and XI and to terminal III of the plug of the power cable of the main consumers of the semitrailer, and to the electro-pneumatic valve controlling the semitrailer braking system.
Thus, when the auxiliary brake of the tractor is engaged, the semitrailer is simultaneously braked and the brake signals are turned on both on the tractor and on the semitrailer.
Switch 1 of the brake lights (MM124B) turns on the latter when installing the car 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 close.
The operating current passes from fuse 12 along the gray wire to the "+" terminal of the breaker (see Fig. 2) of the parking brake indicator lamp, through the closed contacts of the breaker, the winding for heating the thermobimetallic element and goes to the "-" terminal, from which it is fed via the brown wire to the plug connector of the block 13 of the indicator and signal lamps, then the current goes along the brown wire through connector I to switch 1.
When switch 1 is on, the indicator lamp lights up. The operating current passing through this circuit heats the thermo-bimetallic element of breaker 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 applied, the operating current flows from fuse No. 9 to terminals 85 and 30 of relay P2, through the relay winding to plug 86 and then to the terminal of block 3 of control and signal lamps, from which through a separating diode it goes to the block plug and along the brown wire to connector I and switch 1.
The relay closes the contacts of plugs 30 and 87. The operating current goes through the gray wire to connectors III, XI, XIII and XIV and through terminal I of the plug of the power cable of the main consumers of the semitrailer, the brake signals are switched on tractor and semi-trailer.
Maintenance
Possible malfunctions of the light signaling system and how to eliminate them
- Cause of malfunction - Method of elimination
Direction indicators do not work:
- - Fuse No. 7 has blown - Replace the fuse
- - The PC951A turn signal interrupter has failed - Replace the interrupter
The hazard warning lights do not turn on:
- - Fuse No. 5 has blown - Replace the fuse
- - The hazard warning switch has failed - Replace the switch
The brake lights do not turn on:
- - Fuse No. 9 has blown - Replace fuse
- - Switches 2, 4 and 5 are faulty - Check switches and replace
- - Relay P2 is faulty - Check relay and replace
When operating vehicles, it is necessary to monitor the cleanliness of the direction indicator and brake light lenses by wiping them with a rag.
The rubber protective covers on the switches and sensors must fit tightly, preventing moisture from getting inside.
The electrical equipment of the light signaling system cannot be repaired, since they are made non-disassemblable. If they fail, they must be replaced with new ones.