Additional electrical equipment and sound signal

Sound signal

Technical specifications:

• Rated voltage, V - 12
• The strength of the current consumed by the signal, A - 4
• Basic sound frequency, Hz:
• signal S-304 - 420... 455
• signal S-305 - 470... 495

On cars, one sound signal is installed: C-304 low tone or C-305 high tone. The sound signal is located in the engine compartment and is mounted on a bracket to the front front panel.

Interchangeable non-separable sound signals of type 20.3721-01, 201.3721-01 or C3-3 can also be used.

The low-pitched C-304 and high-pitched C-305 signals are noise-type electromagnetic signals that produce a sound of a relatively wide frequency range. They differ only in the thickness of membrane 11: signal C-304 has a thicker membrane than C-305.

The signals have a steel case 2, to which a core 4 and a yoke 1 are welded by resistance welding, forming the magnetic system of an electromagnet. Winding 3 is located under the yoke, insulated from the body with cork gaskets and a nylon bushing. Between the body and the ring 13, a membrane 11 made of alloyed hardened steel is clamped. An anchor 5 and a steel diffuser 12 are fixed in the center of the membrane. The diffuser serves to create the sound of the required frequency and timbre. For normal operation of the signal, there must be a gap of 0.4±0.05 mm between armature 5 and core 4. This gap is ensured by selecting a gasket between membrane 11 and body 2.

Inside the signal housing there is a bridge 7 with a breaker having tungsten contacts. One end of the bridge is attached to the body, and the other can be moved with a screw 6. A holder 9 with a fixed breaker contact and a spring plate 10 with a movable contact, isolated with getinaks gaskets, are fixed on the bridge. A textolite or getinax plate 8 is installed between them. Plate 10 presses the movable contact to the fixed one, and therefore the breaker contacts are closed at the off signal.


When the signal is turned on, the current passes through the closed contacts of the breaker and through the winding 3, creating a magnetic force that attracts the armature 5 to the core. The armature is attracted, presses the plate 8 with a shoulder of a larger diameter and opens the breaker contacts, turning off the power to the winding. The core 4 is demagnetized, and the armature 5 is pulled back by the elastic forces of the membrane. The breaker contacts close again and the cycle repeats. With a frequency of 420... 495 Hz, the vibrations of the membrane and diffuser create air vibrations and provide sound. The strength and timbre of the sound can be adjusted by moving the edge of the bridge 7 with the screw 6 together with the contact plates. This changes the period of opening and closing of the breaker contacts.
Signals S-304 and S-305 are designed to be switched on in a two-wire circuit. Winding output 3 and plate wire 10 are soldered to plugs that are in a plastic block. attached to the body. One of the plugs is connected to power sources through a fuse (generator and battery), and the other through the horn switch with ground.

Heater motor

Technical specifications:

• Shaft rotation frequency when the electric motor is loaded with an impeller at a voltage of 12 V and a temperature of 25±10°C, rpm - 3000±150
• Current consumption at the specified load and speed, A - 4.5

To drive a fan in a car heater «Oka» the ME-255 electric motor is used. It is a two-pole, two-brush DC motor with permanent magnet excitation. The electric motor has two rotation speeds: 3000 and 2200 rpm. A lower speed is provided by the inclusion of an additional resistor type 123729 in its power circuit.


The electric motor has a stamped steel housing 16, in which two permanent magnets 20 are fixed with spring holders 14. The armature shaft rotates in two ceramic-metal bushings 18 and 23. The bushings are held by washers. The washer of the upper bushing is embossed in the body, and the washer of the lower bushing is riveted to the cover 26. The outer spherical surface of the bushings is surrounded by felt rings 19. The bushings and felt are impregnated with oil, and therefore it is not required to additionally lubricate the motor bushings.

The armature has a core made of electrical steel plates. Along the edges of the core, plastic insulating plates are pressed onto the shaft. A wave winding is laid in the grooves of the core, insulated with cardboard, the leads of which are soldered to the copper plates of the collector 24. The collector is pressed onto the lower end of the shaft, and on the upper (day off) a plastic impeller is installed at the end. It has a steel collet hub that compresses the shaft after screwing a special nut onto it. The axial free play of the armature shaft is regulated by the selection of fiberglass washers located on both sides of the sleeve 18. The armature shaft is fixed in the housing with the help of a spring washer 17.

From below, the motor housing is closed with a cover 26. It is attached to the housing with two screws that are screwed into steel plates 27 inserted from the outside into the grooves of the cover and housing. A textolite traverse 25 with brush holders is attached to the cover.

Additional resistor of the electric motor of a heater

To reduce the frequency of rotation of the armature shaft of the heater electric motor on cars «Oka» an additional resistor of type 12.3729 is used. Its resistance value is 1.5 ohms at 20°C. It is a nichrome wire spiral 43 placed in a tubular ceramic insulator 42. The insulator with the spiral is fixed on a heat-resistant plastic base 41. On the underside of the base there are cylindrical protrusions with which the resistor is attached to the heater fan housing. The protrusions enter the openings of the casing and are fixed with spring washers.

Engine cooling fan motor

Technical specifications:

• Frequency of rotation of the armature shaft with an impeller at rated power, rpm - 2600⁺²⁰⁰_-100
• Current consumption at rated power, A - 14

To drive the engine cooling fan, an electric motor of domestic production of the ME-272 type or an electric motor of the same type manufactured in Slovenia is used. The electric motor is installed in a special casing, which is attached to the radiator of the engine cooling system.

The ME-272 electric motor is eight-pole, four-brush, with excitation from permanent magnets. Body 28 and cover 32 are cast from light alloy. Four steel holders 30 are installed around the perimeter of the body, each of which has two magnets 39 glued to it. The body, cover and magnet holders are tightened with four bolts.

Bearing 40 is fixed in the housing with a retaining ring, into which the front end of the armature shaft is pressed. The rear end of the shaft rotates in a ceramic-metal bushing 35 impregnated with oil and surrounded by a felt ring 34 also impregnated with oil. A core made of electrical steel plates is pressed onto the armature shaft. The armature winding is laid in the grooves of the core, insulated with paint. The winding leads are soldered to the collector plates 36. The plastic brush holder 33 is fixed to the cover 32 with two screws.

The electric motor is turned on when the ignition is on using a sensor 65 type TM-108 and an auxiliary relay 67 type 113.3747-10 located near the fuse box.

Fan motor activation sensor

To turn on and off the electric motor of the fan of the engine cooling system, depending on the temperature of the coolant, a sensor of the TM-108 type is used, which is wrapped in the right radiator tank. A sensor of the 9030330 type made in Slovenia can also be used.

In the brass case 44 sensors are rolled plastic plug holder and pusher guide. A spring plate 47 with a moving contact is riveted to one of the plugs. A bimetallic washer 45 is installed at the bottom of the housing, at a temperature below 94°C it is curved towards the bottom of the housing. A plastic pusher 46 rests against the center of the washer. At a temperature of 99°C and above, the washer bends towards the pusher, which, in turn, presses on the plate 47, and the sensor contacts close.

Cigarette lighter

The cigarette lighter 11 3725 is mounted on the instrument panel with two spring latches made in one piece with the diffuser 48. On the rear side of the housing 51, a ceramic insulator 50 with a bimetallic spring clip 52 is fixed with a nut. From the front side, a cartridge with a heating element is inserted into the housing, which is a spiral from a special alloy and is mounted on a ceramic insulator 54, which is connected through a glass 55 to a plastic handle. The outer end of the spiral is connected to the cup, and the inner end is connected to the pin, which is used to riveted glass 55 to the insulator.

Outside, a plastic orange diffuser 46 is put on the body. The cap of the cigarette lighter socket lighting pump, which is used as an A12-4 lamp, is inserted into the grooves of the diffuser. The light from the lamp spreads through the diffuser, and the cigarette lighter cartridge is surrounded by an orange luminous rim.
The cigarette lighter works as follows. When the handle is pressed, the cup 53 with the heating element is pinched between the tabs of the bimetallic bracket 52 and held in this position. The current from the current source is supplied to the bimetallic bracket and closed to ground through the cup, the heating element, the glass 55 and the housing. The heating element heats up, the bimetallic bracket also heats up, and its paws diverge, freeing the cup. Under the action of the spring, the cup with the heating element, along with it, the handle returns to its original position, signaling that the cigarette lighter is ready for use.

On the insulator on the rear side of the cigarette lighter, a light alloy safety washer is put on. This washer will melt if the cigarette lighter cartridge is depressed for more than 30 seconds. The molten metal of the washer flows and closes the rod of the bimetallic clip with the mass. As a result, the N9 10 fuse in the fuse box blows and the cigarette lighter is switched off. In this way, the car is protected from fire if the cigarette lighter cartridge jams in the bimetallic bracket or if the cigarette lighter handle is accidentally pressed for a long time.

Rear window cleaner

The rear window wiper is mounted on a bracket to the tailgate. It consists of a geared motor type 47 3730, one lever and a brush. The shaft of the gearmotor makes approximately 50 double strokes per minute.

The electric motor of the motor-reducer is DC, two-pole, with excitation from permanent magnets. Magnets 63 are made in the form of half rings and are fixed inside the steel case with spring holders riveted to the case. The armature shaft rotates in a ceramic-metal bushing impregnated with oil. Traverse 64 with two brush holders is riveted to the gearbox housing 62. A single-threaded worm is cut at the end of the shaft. The axial free play of the armature shaft is adjusted by screw 58.

In the case 62, cast from a light alloy, there is a worm gear and a crank gear mechanism for converting the rotational movement of the gear of the gearbox into the reverse rotation of the output shaft 59 of the gear motor. The plastic driven gear of the gearbox rotates on an axle pressed into the housing. A connecting rod 57 is put on the steel pin of the gear, connected by an axis to the planet carrier 61, which can freely rotate on the rear end of the shaft 59. The end of the connecting rod is made in the form of a gear sector meshing with the gear sector 60 fixed on the shaft 59.

When the gear 56 rotates, the connecting rod rotates the carrier and at the same time rotates the shaft 59 for the gear sector 60. Such a mechanism allows, with a relatively small angle of rotation of the carrier, to obtain a rotation of the gearbox output shaft by 120°.

On the other hand, gear 56 has a cam, and a plastic panel with limit switch contacts is installed in the gearbox housing 62. It works in the same way as the windshield wiper limit switch. Outside on housing 62 there is a thermal bimetallic fuse for overload protection.