Additional electrical equipment and sound signal

Sound signal

Technical specifications:

• Nominal voltage, V — 12
• Current consumed by the signal, A - 4
• Fundamental sound frequency, Hz:
• signal C-304 - 420...455
• signal C-305 - 470...495

The cars are equipped with one sound signal: low-tone C-304 or high-tone C-305. The sound signal is located in the engine compartment and is attached to a bracket on the front panel.

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

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

The signals have a steel body 2, to which the core 4 and yoke 1 are welded by contact electric welding, forming the magnetic system of the electromagnet. Under the yoke is a winding 3, insulated from the body by cork gaskets and a nylon bushing. Between the body and ring 13, a membrane 11 made of alloyed hardened steel is clamped. Anchor 5 and steel diffuser 12 are fixed in the center of the membrane. The diffuser is used to create a 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 anchor 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 housing, and the other can be moved by screw 6. On the bridge there are fixed a holder 9 with a fixed breaker contact and a spring plate 10 with a movable contact, both insulated with getinax gaskets. A textolite or getinax plate 8 is installed between them. The plate 10 presses the movable contact to the fixed one, and therefore the breaker contacts are closed when the signal is switched off.


When the signal is switched on, the current passes through the closed contacts of the interrupter and through the winding 3, creating a magnetic force that attracts the anchor 5 to the core. The anchor is attracted, with a flange of a larger diameter it presses on the plate 8 and opens the contacts of the interrupter, disconnecting the power supply to the winding. The core 4 is demagnetized, and the anchor 5 is pulled back by the elastic forces of the membrane. The contacts of the interrupter are closed again, and the cycle is repeated. With a frequency of 420... 495 Hz, the vibrations of the membrane and the 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 together with the contact plates with screw 6. This changes the period of opening and closing the contacts of the interrupter.
Signals C-304 and C-305 are intended for switching on via a two-wire circuit. The output of winding 3 and the wire of plate 10 are soldered to the plugs, which are located in a plastic block attached to the body. One of the plugs is connected to the current sources via a fuse (generator and battery), and the other through the sound signal switch with ground.

Heater electric 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 rotation speed, A - 4.5

The ME-255 electric motor is used to drive the fan in the Oka car heater. It is a two-pole, two-brush DC electric motor with excitation from permanent magnets. The electric motor has two rotation speeds: 3000 and 2200 rpm. A lower speed is ensured by including an additional resistor of type 123729 in its power supply circuit.


The electric motor has a stamped steel housing 16, in which two permanent magnets 20 are secured with spring holders 14. The armature shaft rotates in two metal-ceramic bushings 18 and 23. The bushings are held by washers. The washer of the upper bushing is hammered into the housing, 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 additional lubrication of the electric motor bushings is not required.

The anchor has a core made of electrical steel plates. Plastic insulating plates are pressed onto the shaft along the edges of the core. The wave winding is placed in the grooves of the core, insulated with cardboard, the terminals of which are soldered to the copper plates of the collector 24. The collector is pressed onto the lower end of the shaft, and a plastic impeller is installed on the upper (output) end. It has a steel collet hub that compresses the shaft after a special nut is screwed onto it. The axial free play of the anchor shaft is adjusted by selecting fiberglass washers located on both sides of the bushing 18. The anchor shaft is fixed in the housing using a spring washer 17.

The electric motor housing is closed from below by a cover 26. It is fastened to the housing with two screws, which are screwed into steel plates 27, inserted from the outside into the grooves of the cover and housing. A textolite crossbar 25 with brush holders is attached to the cover.

Additional resistor of the heater electric motor

To reduce the rotation frequency of the heater electric motor armature shaft, an additional resistor of type 12.3729 is used on Oka cars. Its resistance value is 1.5 Ohm at 20°C. It is a spiral 43 made of nichrome wire, placed in a tubular ceramic insulator 42. The insulator with the spiral is fixed on a base 41 made of heat-resistant plastic. On the lower side of the base there are cylindrical projections, with the help of which the resistor is fixed to the heater fan casing. The projections enter the holes in the casing and are fixed with spring washers.

Engine cooling system fan electric motor

Technical specifications:

• Rotation speed of the anchor shaft with impeller at rated power, rpm - 2600⁺²⁰⁰_-100
• Current consumption at rated power, A - 14

To drive the engine cooling fan, a domestically produced electric motor of the ME-272 type or a similar electric motor made in Slovenia is used. The electric motor is installed in a special casing, which is attached to the radiator of the engine cooling system.

Electric motor ME-272 — eight-pole, four-brush with excitation from permanent magnets. Housing 28 and cover 32 are cast from light alloy. Four steel holders 30 are installed along the perimeter of the housing, to each of which two magnets 39 are glued. The housing, cover and magnet holders are tightened with four bolts.

The bearing 40 is secured 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 metal-ceramic 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 placed in the grooves of the core, insulated with paint. The winding terminals are soldered to the plates of the collector 36. The plastic brush holder 33 is secured to the cover 32 with two screws.

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

Fan motor switch sensor

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

In the brass body 44 of the sensor, the plastic plug holder and the pusher guide are rolled. A spring plate 47 with a movable contact is riveted to one of the plugs. A bimetallic washer 45 is installed on the bottom of the body, at a temperature below 94°C it is bent towards the bottom of the body. 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

Cigarette lighter 11 3725 is secured to the instrument panel with two spring latches made in one piece with diffuser 48. Ceramic insulator 50 with bimetallic spring clamp 52 is secured to the rear side of housing 51 with nut. A cartridge with a heating element is inserted into the housing from the front side, which is a spiral made of a special alloy and is secured to ceramic insulator 54, which is connected to plastic handle via cup 55. The outer end of the spiral is connected to the cup, and the inner end to the finger, with which cup 55 is riveted to the insulator.

On the outside of the housing there is a plastic orange diffuser 46. The cap of the cigarette lighter socket illumination lamp is inserted into the grooves of the diffuser, for which the A12-4 lamp is used. The light from the lamp spreads along the diffuser, and the cigarette lighter socket 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 clamped between the tabs of the bimetallic bracket 52 and held in this position. Current from the power source is supplied to the bimetallic bracket and is shorted 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 tabs move apart, releasing the cup. Under the action of the spring, the cup with the heating element, together with the handle, returns to its original position, signaling that the cigarette lighter is ready for use.

A safety washer made of light alloy is placed on the insulator at the back of the cigarette lighter. This washer will melt if the cigarette lighter socket is pressed for more than 30 seconds. The molten metal of the washer flows and short-circuits the rod of the bimetallic clamp with the ground. As a result, fuse N9 10 in the fuse box burns out, and the cigarette lighter is switched off. In this way, the car is protected from fire if the cigarette lighter socket gets stuck in the bimetallic clamp or if the handle of the cigarette lighter 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 47 3730 type gear motor, one lever and a brush. The gear motor shaft makes approximately 50 double strokes per minute.

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

In the housing 62, cast from a light alloy, there is a worm gear reducer and a crank-and-tooth mechanism for converting the rotary motion of the gear reducer gear into the reverse rotation of the output shaft 59 of the geared motor. The plastic driven gear of the reducer rotates on an axis 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 rotate freely on the rear end of the shaft 59. The end of the connecting rod is made in the form of a toothed sector, which is in engagement with the toothed sector 60, fixed on the shaft 59.

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

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