Compression in internal combustion engine cylinders is measured using special device, called a compression gauge. It is a pressure gauge main feature which can be called the presence of a free valve. Such a pressure gauge does not release the pressure it receives until the maximum value is recorded at the top dead center of the cylinder. Let's try to figure out how to do it and how to make a compression gauge with our own hands?

A new high-quality compression meter is quite expensive, and cheap analogues have serious errors that are unacceptable when carrying out precise measurements. That is why many motorists either go to the station Maintenance and take measurements for just a little money, or make a compression meter yourself.

This device can be made using several parts that can be found in the garages of experienced drivers or at any auto parts store.

List of what you will need:

• High pressure hose.
• Nipple (or, as it is also called, spool).
• Pressure gauge.
• Adapters are made of brass, on which the required thread is already cut.
• A valve used on a truck wheel tube.

The last element must be in in good condition and not bent. The diameter is usually 8 millimeters and the end is slightly curved. To use it in the manufacture of a compression gauge, it is necessary to level it, leave the threaded part as is, and the end that was intended for welding into the chamber must be sawed off.

Take a soldering iron and solder a nut onto the cut end of the valve, which you need to screw into the pressure gauge. You need to screw the valve into the resulting tube and insert the hose there. The other end of the hose can be bored into a cone, which will be inserted into the spark plug hole, or a threaded tip can be attached.

Use this homemade device very simple: the free end of the hose is inserted or twisted into the spark plug hole, measurements are taken and recorded on paper. To relieve pressure from the pressure gauge, it is necessary to clamp the spool.

The thread diameters at the end of the hose must exactly match the spark plug hole. This requirement is associated with increased sealing, which should be present at the moment the piston approaches top dead center. The accuracy of measurements will depend on this requirement, which also does not exclude the occurrence of small errors. It is still not recommended to rely completely on such a device.

To avoid confusion, try to use the units of measurement on the pressure gauge that are indicated by the manufacturer in the technical literature.

Video - How to make a homemade compression gauge

This is how you make a compression meter yourself. This device will help you save a lot on professional tools and achieve approximately the same result at minimal cost.

If just recently the car’s engine was working properly - fuel and oil consumption, as well as power were within normal limits, but then everything became completely the opposite, then it’s time to check the pressure in the engine cylinders. As you know, the compression drop is not the most best sign for any engine, since the fuel supplied there does not burn completely and remains in the form of sediment, which can cause defects on both the cylinders and pistons.

How to find out compression?

As you already understood, in order to measure compression, you need to purchase a compression meter. After this, it is necessary to perform a number of special actions so that the readings are as accurate as possible and have minimal deviations.

1. The engine must be warmed up to operating temperature. This is the time when it can work at full capacity. Then turn it off.
2. While the engine is warm, you need to turn off the fuel pump. If you have an injection engine, then you just need to disconnect the special plug designed to power the fuel pump. In the case of a carburetor, disconnect the hose going from the gas line to the fuel pump and the hose on the carburetor float chamber. To prevent it from burning out, disconnect the terminal from it.
3. Remove all spark plugs. Many drivers make the common mistake of removing only one spark plug. Doing this is strictly prohibited!
4. Now screw the compression gauge into one of the spark plug holes. It is recommended to immediately purchase attachments that are designed for mounting on different engines.
5. Ask your partner to get into the car and press the gas pedal all the way. This is done to ensure that the throttle valve is open. Then, he must turn on the starter for 2 seconds.
6. Readings are taken from the compression gauge, and this procedure is applied to the remaining cylinders. Operating standards can be found in the technical literature for your vehicle.
7. Based on the deviations from the norm obtained during measurements, one can judge the type and scale of the malfunction that affected the engine of your car.

No circuits, no programs, no pressure gauge, yes

Having smoked a little on these topics: Digital pressure gauge

I realized that many car enthusiasts are not programmers or radio enthusiasts and not everyone will be able to assemble this digital pressure gauge. I propose a simpler digital pressure gauge that almost every car enthusiast can replicate

Since all of the above devices are based on voltage measurement. I decided to pair up a 24 V voltmeter I have, implemented on a MEGA48PA microcontroller, and a MM370 0-10 kg/cm2 pressure sensor with a resistance of 195 Ohms. Since we have an upper limit of the sensor of 10 kg/cm2, I applied a voltage of 10V to a voltmeter and measured the voltage at the input of MEGA48PA 28 leg; it was 0.5 Volt; therefore, the measurement limit of 0-10 kg/cm2 will correspond to 0-0 at the input of the ADC (28 leg), 5V.

Since the resistance of the sensor decreases with increasing pressure from 195 Ohm to 0 Ohm, it is necessary to alter it slightly so that the resistance increases with increasing pressure from 0 Ohm to 195 Ohm.

Conversion of the MM370 sensor for a digital pressure gauge.

Before remaking the sensor, its diagram can be drawn as follows (resistance decreases with increasing pressure)

we need to redo it so that the circuit looks like this (increasing resistance with increasing pressure)

To do this, you need to flare the sensor; I used side cutters.

Before doing this, you need to put marks on the cover and body of the sensor (later it will be useful during assembly). After disassembly, we see what is inside, namely the measuring element itself and the moving contact. Using a screwdriver, unscrew and remove the measuring element,

it needs to be turned 180 degrees, before doing this, trimming the contact a little (so that it doesn’t reach the body for me)

Test measurements were made, and a graph was drawn up of the dependence of the MM370 resistance on the pressure gauge readings

and built a graph (almost linear)

My MM370(BU) also had a damaged wire,

connecting the moving contact to the body, I replaced it with wiring from a telephone headset.

We assemble and carefully roll (without using a hammer), you can fix it a little by welding (semi-automatic)

DEVELOPMENT OF THE VOLTMETER

To do this, you need to replace the 28 volt divider (in my case) in the input circuits of the voltmeter

Since we need a voltage limit from 0 to 0.5V, we use a 5V reference voltage source which is located in the voltmeter itself (power supply for the MEGA48PA microcontroller 4 pins). Using simple calculations, we need a divider by 10, since the resistance of the MM370 pressure sensor is 195 Ohms, then the resistance for the divider you need 1.95 kOhm, it’s better to put two, one of which is variable, I put two at 1 Kohm

Now we have three wires on the voltmeter plus + minus - power supply and pressure measurement.

We connect the pressure gauge to the compressor and do the calibration variable resistor(for more accurate readings, calibration must be carried out at the pressure at which we expect to use)

Hello! Many people know firsthand about this measuring device like a pressure gauge. But many people find it difficult to imagine the device and the principle of its operation.

A pressure gauge is designed to measure the pressure of a liquid or gas. Moreover, the pressure gauge for measuring gas and liquid pressure is not structurally different from each other. So if you have a pressure gauge lying around somewhere to measure liquid pressure, then you can safely use it to measure gas pressure and vice versa.

To better understand how the pressure gauge works and works, look at the figure below.

The pressure gauge consists of a body with a measurement scale, a copper flat tube 1 folded in the shape of a circle, a fitting 2, a transmission mechanism 3 from the tube to the pointer 4. Using the fitting, the pressure gauge is wrapped in a vessel where the pressure of the medium (gas or liquid) is to be measured.

How does a pressure gauge work?

When gas and liquid under pressure are supplied through fitting 2, the folded tube 1 will tend to straighten, and through the transmission mechanism the movement of the tube will be transmitted to the arrow 4. It, in turn, will indicate the amount of pressure, which can be read using a scale. When the pressure decreases, the tube will collapse again and the arrow will indicate a decrease in pressure.

Electric contact pressure gauge device

I think you can guess how an electric contact pressure gauge works. Its design is no different from a conventional pressure gauge, except that it has built-in contacts. There are usually two of them and their position on the pressure gauge scale can be changed.

What if you don’t have an electrical contact pressure gauge, but you really need one? What to do then? Then you need to make a homemade electric contact pressure gauge.

I'll tell you how to make a homemade electric contact pressure gauge. To do this you will need a simple pressure gauge, two small strips of tin from tin can, double-sided tape and two thin wires.

Using a sharp awl, pry up and remove the large retaining ring. Then remove the glass and then the rubber washer. Drill two holes in the pressure gauge housing to allow two wires to pass through them.

Cut two strips from tin and bend them in the shape of the letter L. Solder a thin insulated wire to the base. From double-sided tape, cut two strips equal in size to the strips and stick it on the strips. Next, glue the resulting contacts to the pressure gauge scale within the specified pressure limits.

Pass the wires through the holes and bring them out.

Reinstall rubber gasket and then glass. Secure everything with a locking ring. That's it, the homemade electric contact pressure gauge is ready. For example, I used this one in a homemade automatic system water supply of a private house.

Connection diagram for electrical contact pressure gauge

In order for this pressure gauge to influence any actuator, a special circuit is needed. You can see an example of this scheme in the figure below.

At a minimum pressure of the medium (gas or liquid) in the electric contact pressure gauge, contacts 1 and 2 will be closed. In this case, the electromagnetic relay K1 will operate. It, in turn, with its contacts K1.1 will supply power to the winding of the magnetic starter K3. Using contacts K3.1, it will bypass contacts K1.1, and when the contacts in pressure gauge 1 and 2 open, relay K1 will release its contacts K1.1. But at the same time, the starter winding K3 will continue to flow around with current. With its contacts K3.2, the magnetic starter will supply power to the motor M of the pump or compressor.

With a further increase in pressure in the pressure gauge, contacts 1 and 3 close. At the same time, the electromagnetic relay K2 will operate and with its contacts will open the power circuit of the coil K3 of the magnetic starter. Contacts K3.2 will open and the power supply to motor M will disappear. With a further decrease in pressure and the closure of pressure gauge contacts 1 and 2, the cycle will repeat.

Pressure gauges– instruments for measuring the pressure of liquids or gases – there are different designs. You can do a simple measurement of air pressure, for example in a car or bicycle inner tube, with your own hands. Depending on the power of the spring and the strength of the housing, it can also be used to measure oil pressure. It is suitable for school experiments in physics lessons. Plus, you can do it with your children.

You will need

• - Disposable syringe
• - A metal spring, the diameter of which is equal to the diameter of the syringe container
• - Needle
• - Alcohol or gas burner
• - Glue “Moment”
• - Pliers
• - Wire cutters

Instructions

Take a disposable syringe and push the plunger out of it to the limit. Cut the piston rod so that a piece about 1 cm long remains. Heat the remaining piece of the rod using gas burner and melt one of the ends of the coil spring into it.

Insert the plunger back into the syringe barrel so that a small piece of the spring remains outside and the larger part is inside the balloon.

Warm up the needle and pierce the syringe barrel with it from the side opposite the tip, not far from the edge. Using pliers, attach the end of the spring to the needle. Bite off the excess part of the spring. The result is a spring pressure gauge.

If you place a rubber tube instead of a needle at the tip of the syringe and connect it to the container or pipeline in which the pressure is measured, the piston in the container will move relative to the graduation scale on the syringe body, thus indicating the pressure in the line or container being tested.

It is recommended to first calibrate the scale against a known pressure source. Link the scale to pressure units based on the reference source. To do this, pick up the phone from transparent material and fill it with water to a certain height. On the other side, connect a rubber tube with a pressure gauge. Mark the scale according to the height of the water column using Torricelli's law. At the place where the piston moved, make a mark of the resulting pressure. After changing the amount of water in the tube, make the following marks.

They withstood the blow of the elements at the Sayano-Shushenskaya hydroelectric power station. They work on submarines and in mines. They are not affected by tropical humidity and arctic cold. They are real Tomsk pressure gauges.

The former Tomsk Pressure Gauge Plant, and now the Manotom company, managed to provide almost half the world with its instruments. 70 years of experience, combined with a modernized material base and a retained team at the enterprise, allows us to practically work miracles.

The plant produces 500 thousand devices per year. Together with all modifications, the production range includes 10 thousand items. All this is supplied to almost 10 thousand consumers from different areas– from shipbuilding to nuclear power plants.

What is the production of pressure gauges like today?

The first step is development

It all starts when the company receives an order. The first to get involved are the design department employees. They determine what the device should be. If necessary, additional design equipment is ordered, which is produced here in the tool shop. As soon as the designers create an image of the future device, production workshops get involved. It is not so rare to develop new modifications of devices - consumers ask for something new all the time.

Parallel production: from body to spring

From the designers, the development goes into the main production cycle, where 700 people work and the equipment fleet is 527 units. The technologies used here, by the way, were developed within the factory walls.

Once the design enters the main production cycle, case manufacturers come into play. Each type of pressure gauges and pressure sensors requires its own housing. If the device will be used in not too harsh conditions, the housing can be made of plastic or aluminum. If the pressure gauge is made for the military, or will be used in a “harsh” environment, then the case will be steel. IN different cases, the device body enters the mechanical or galvanic processing workshop. There is also a cold stamping workshop.

In parallel with this, the “insides” of the device are being assembled in other workshops.

The next step is painting the body. Here, too, there was some know-how. “We have introduced the most advanced powder coating technology to date,” says the deputy general director produced by Andrey Metalnikov. — The bottom line is that conventional painting from a spray bottle with paint using the spray method is too expensive. Too much of it simply dissolves in the air without getting onto the product. With powder coating, 100% of the paint is used, because what does not end up on the product is returned to the drum and is not lost. In addition, the coating is more durable and durable.”

A special place in the list of divisions of the plant is the flexible springs section. This is where the heart of any pressure gauge is made. The reliability and accuracy of the pressure gauge depends on the quality of the flexible spring, its specifications. For Manotomi, Ural metallurgists developed a special alloy from which the springs are made.

The soldering section is the next step. Depending on the need, either soft or hard soldering of the device is performed, and if necessary, welding, including argon-arc.

A separate direction is the plastic products workshop. Thanks to modern thermoplastic equipment, parts from polypropylene, polystyrene and any other plastics can be produced here.

Naturally, Manotom cannot make the production cycle completely autonomous. For example, the plant receives glass parts and rolled metal from trusted suppliers. But, whenever possible, the plant tries to produce everything necessary in its own own workshops. By the way, here they work only with Russian materials, imported parts are not used.

Those pressure gauges that require case strengthening, being almost ready, are sent to the galvanizing shop. Its presence is a feature of the Tomsk plant, because few enterprises can afford to maintain a galvanic shop. This is a very expensive production - and necessary equipment, and by its very essence. After all, electroplating involves various chemicals and acids that need to be disposed of after technological processes. And here they not only maintain such a workshop, but also constantly improve technological process in him.

The most important element of pressure gauge production is the workshop in which the transmission mechanism is created. The transmission mechanism is the central element of the pressure gauge, no less important than the spring. The more accurately and finely the transmission mechanism works, the more accurate the readings of the device. Therefore, the most experienced workers work in the production of transmission mechanisms, and technological equipment The workshop meets the most stringent modern requirements.

“We installed the latest equipment in mid-2010. This gave several tangible advantages at once. Firstly, the processing accuracy of transmission mechanism parts has increased. We managed to eliminate roughness and increase the accuracy of readings of our products. Secondly, thanks to this we were able to raise guarantee period the work of our pressure gauges has doubled from one and a half years to three,” explained Andrey Metalnikov. Other suppliers Russian market The pressure gauges still come with a year and a half warranty.

The final stage of production is the assembly line. There are four main conveyors. Each serves its own direction: technical devices, thermometers, special instruments and electrical contact devices. Here the devices are assembled and undergo final quality control.

Before handing over products, each workshop must check it for compliance with the requirements. The plant's technical control department puts a stamp on the product and this completes the process of creating a pressure gauge.

IN last years"Manotom" is developing the direction service their products. Thus, customers from nearby regions can send a broken product to the factory, where specialists will take care of it. In more remote areas and outside Russia, the plant enters into contracts for the maintenance of its pressure gauges with contractors.

Another new direction in work is the production of so-called “smart” electronic pressure gauges. They not only provide data, but also participate in the process of managing production facilities, replacing the human operator. So far, their share is not so large - only 15-20%. But the production volume of such pressure gauges is growing all the time.

“Today our devices float not only on all civilian, but also on all military ships, fly in missiles, and serve artillery. Supplies go to the CIS countries, Europe, Asia and Africa,” notes Andrey Metalnikov.

Traditionally short video about how pressure gauges are made: