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BUYING, DO NOT MISTAKE

SPEEDOMETERS. TACHOMETERS. AMPMETERS

Anton Utkin

About kilometers and miles on the dials of speedometers and other useful things - in the next review of electrical equipment.

Automotive instrumentation (hereinafter instrumentation) are divided into two groups - indicating and signaling. The first, usually arrow type, inform the driver about the value of the measured value. The second - give a signal about the emergency mode in the operation of any vehicle system.

All instrumentation in the normal OH 025215–69 belong to the group of parts "38". You will always see these two numbers in the marking on the device immediately after the point. They are collected at factories both in buildings and without them. Cabinet-mounted units are placed on car panels or individually, or on special shields *, such as, for example, in an UAZ vehicle. But on most modern cars, instrumentation is frameless. Mount them in instrument combinations. Shields and combinations for most domestic cars, as well as all instrumentation in their composition, are made by the Vladimir plant of Avtopribor AP. For Moscow ZIL and AZLK, as well as ZAZ and RAF, the devices are supplied by the Riga AEP (now RAR). Izhmash, as a defense enterprise, receives them from its former colleagues - the Tochmash plant (Vladimir). The latter is now throwing something to the Muscovite.

The most important instrument of the car, of course, is a speedometer (subgroup 3802). Most often it has a mechanical drive with a flexible shaft from the gearbox. But on large trucks and buses, electric speedometers. In such machines, the motor and gearbox are located far from each other and a cable that is too long between them will not work for long.

The most important parameter of a speedometer (mileage counter) is the gear ratio of its internal gearbox. As a rule, it is 1000. According to the international standard, for each linear unit of the path traveled by a car (for example, a kilometer), the speedometer drive shaft must make 1000 revolutions. However, in the speedometers of automobiles of the construction of the 60s (Volga, UAZ, IZH, trucks) this number is less than 624. In them, the speedometer cable makes 1000 revolutions not per 1 kilometer, but per 1 land mile (1609 m). At one time, copying American cars, our designers left the "American" gearbox (drive) in the gearbox and only altered the speedometer itself - it was easier. If you put a speedometer on the Volga, for example, from the Zhiguli, it will underestimate the speed by 1.6 times, but the mileage counter (sometimes called the odometer) will begin to accurately count miles.

This should be remembered to the owners of foreign cars and re-export cars of VAZ, received from America, England, Canada and other countries where inch calculation is accepted. Such “Zhiguli” and “Samar” have their own mile reducer with a gear ratio of 1600 in the odometer, and a standard one in the gearbox. These unusual instrument combinations are also found in spare parts in the markets. So be careful.

Speedometers of the latest car models (VAZ 2110, GAZ 3110) will no longer be confused with gear ratios - they are electronic. Receiving signals from the Hall sensor installed on the gearbox, such a device converts them into a constant voltage. The frequency of the pulses determines the speed and mileage readings. According to the international standard, for each kilometer of the way, the sensor must send 6000 pulses.

The next parameter of the speedometer is its landing diameter. Of course, this applies only to case instruments (85, 98, 100, 125, 130, 140, 165 mm). Focusing on the diameter, gear ratio and maximum speed on the scale, you can easily pick up a speedometer instead of a faulty standard one.

Unpacked speedometers, as a rule, are non-interchangeable, and are rarely found on sale, so they are usually changed together with a combination of instruments. Speedometers range from 20 for unpacked for Izhevsk Moskvich to 160 rubles for a box from GAZ 3102 9 / "> GAZ 31029. The applicability of speedometers is in Table 1.

Flexible speedometer drive shafts (subgroup 3819) for most domestic cars are made by the LETZ plant in Lyskovo, Nizhny Novgorod Region, and partly by the AED in Riga. All shafts are identical in design and differ only in length. If the regular purchase failed, then a little longer in length will do. The connecting dimensions of the shells of most shafts are the same: the thread of the nipple nut on the drive side is M22x1.5, and on the speedometer side is M18x1.5. An exception is the cables of VAZ cars: threads M18x1.5 and M16x1.5, respectively. However, the shell rarely breaks, much more often the shaft itself. Repair it like that. Take the ragged shaft from the shell and determine the length by combining the pieces. And they are preparing a new one from a longer one, possibly also worthless. I note that the diameters of the shafts are the same - 3.3 mm, and their ends are crimped onto a square with a side of 2.7 mm. With a chisel on the anvil we chop off the measured part of the cable. Degrease the round end in a solvent and dip in a solution of hydrochloric acid for a couple of minutes for etching. Then - into the molten rosin and tin solder. The tin-impregnated part of the cable is sawn up to a square section. The speedometer cable prices are usually from 15 to 40 rubles. Their length - for domestic cars - in the table. 2.

Tachometers, as a rule, are dial gauges (subgroup 3813). They are induction or electronic. The first are driven by a cable (on motorcycles and tractors) or by an electric motor (on trucks). The second ones register the frequency of voltage ripples either in the ignition system (on those engines where it is) or on the output of the generator phase (on diesel engines) and, in accordance with these data, indicate the speed of the engine crankshaft. Devices operating from the "phase" are not interchangeable. A tachometer that “reads” information from the ignition coil can be adapted to any car, unless, of course, it is designed for a motor with the same number of cylinders. Tachometers do the same factories that produce speedometers, and their retail price can range from 45 rubles for an open box to 130 for a box. True, open boxes are quite rare on sale and mainly from Tochmash. Tachometers of domestic cars operating from the ignition system are presented in table. 3.

Ammeters, voltmeters - devices for monitoring the operation of the generator are, respectively, in subgroups 3811 - "Current indicators" and 3812 - "Voltage indicators." An ammeter is perhaps the most informative of them. Unfortunately, it disappears from the panels of modern cars. PCB tracks in combination are not designed for high current passing through the ammeter. Its place is taken by a voltmeter consuming a meager current. Alas, the voltage gauge does not react so sensitively to “illnesses” in electrical equipment as an ammeter, or even completely silent about a malfunction. For example, a voltmeter with the ignition off, will not show the battery discharge through any device (wiper motor reducer, glass heater, headlights, etc.). And the arrow of the ammeter will definitely indicate this. If at times the generator brush freezes, the arrow will jump sharply from zero to plus and vice versa.

The last car with an ammeter was GAZ 3102 9 / "> GAZ 31029, and now this useful device is not even put on an UAZ. For the retrofitting of any car, the universal ammeter AP110 is most suitable - perhaps the most massive on our trucks. It costs from 20 to 30 Of course, its archaic dial is unlikely to fit into the design of the instrument panel of a modern car, especially foreign cars, so that it can be seen only by the driver, for example, it can be installed to the left of the steering column. We carefully cut out a round file in the wall " orpedo "hole diameter 60 + 1 mm, insert the device and presses its nominal strip. The additional wire from generator 6 mm2 pave to the ammeter along the main harness, so convenient.

* The instrument panel (subgroup 3805) is a metal structure on which pointer devices and indicator lamps in individual housings are fixed with clamping bars. The instrument cluster (subgroup 3801) is a compact plastic block of indicators and indicator lamps, closed by common glass.

Instrument panel 17.3805.

A combination of devices 151.3801.

SP135 speedometer in the housing.

The TX200 tachometer is unpacked.

Flexible shaft GV124-E.