Compressor piston ring replacement. The compressor is warming up too much

Piston compressor repair?

The main compressor components perform rotary or relative translational motion, so they are subject to intensive wear and tear.

The main types of wear on reciprocating compressor parts are related to the nature of the motion and the loads acting, and can be as follows:

1) Crankshaft. Change of shape and dimensions of crank and main shaft journals, cracks in the journals to jaw transition, deflection;

2) Main bearings. wear of babbitt casting, warping of bearing shells;

3) connecting rod. bending of connecting rod, wear of bearing shells, pulling of connecting rod bolts;

4) Crosshead. guides and pin wear;

5) Rod. rod wear at the point of passage through the gland, bending, thread breakage;

6) piston. wear of piston ring mounting holes, ring wear;

7) Cylinder. change of shape of cylinder (ovality, conicity, barrel-shape);

8) Valves. wear of springs and working surfaces of valve seat and pallet.

The service life of the parts can be divided into three groups:

1) Wearable replaceable. piston rings, packing packing, valve plates and springs;

2) with medium service life. main bearing shells and connecting rod, connecting rod pins and crosshead;

3) with a long service life. crankshaft, connecting rod, crosshead, cylinders, pistons.

Preparation for repair consists of stopping the compressor, unplugging it, releasing it from the product, cleaning, blowing out, and selecting tools, devices and spare parts.

At the beginning of disassembly remove the external piping, valves, gauge board, oil filters, compressor water line and flywheel half coupling.

The compressor has many similar parts: valves, bearing shells, fasteners, etc. д., valves, which either were adjusted during initial assembly or were lapped during operation with mating parts; therefore, they must be reinstalled after repairs. At disassembly it is necessary to check presence of marks at identical details and at its absence to put chisel marks on nonworking places of joining details or to beat out identical figures.

During any subsequent compressor disassembly, the cylinder heads, discharge valves and buffer springs are removed, valve plates are removed, crankcase side covers are opened, and the crankshaft is turned until the pistons are in the upper position practical for removal of the intake valves. Then disassemble and remove the connecting rod bearing, use eyebolts to drive the piston and connecting rod out, use a handwheel puller to remove the flywheel, and then open the gland cap. Next, the oil seal, and intake and discharge valves are disassembled. Dismantling involves inspection of parts.

Crankshafts and main bearings. Inspection of the crankshaft and main bearings is conducted at least once a year. The checks are performed to:

1) condition of the shaft, its jaws, necks, flanges for the purpose of detecting scoring and dents;

3) The presence of surface and internal cracks of the shaft;

4) Shaft axis rotation as judged by the divergence of jaws.

Checking the condition of the crankshaft starts with checking the clearances in the connection of the shaft with the main bearings with a feeler gauge in the connection of crank journals with rods and checking the axis of the shaft by divergence of jaws. These types of control can indicate the mutual wear of the mating surfaces of the crankshaft, main bearings, connecting rod.

If the shape deviation exceeds the allowable limits, the journals are ground. Allow for 3% reduction in diameter from original diameter. If wear is severe the shaft is turned over and a jacket consisting of two halves is welded on. Welded seams connect the shell halves to each other and to the shaft journal. The torque on the crankshaft journal is negligible and the welds are sufficiently strong to produce a solid joint.

Scoring and dents found on crankshaft journals and flanges can be corrected by grinding or boring followed by grinding. Main and connecting rod journals are subject to sharpening, if ovality and taper exceeds the maximum tolerance of 0.15 mm. Deviations of diameter of repaired journals shall not exceed the normal tolerances for ovality and conicity: for main journals. 0.03 mm, con rod journals. 0.01 mm; to runout. 0.05 mm. jaw deflection should be no greater than 0.14 mm or 0.00025s (where s is piston stroke). Restoration of the nominal diameter of journals is possible by surfacing and subsequent grinding. Cracks can be repaired by welding, and the shaft deflection can be straightened mechanically, thermally, or thermo-mechanically.

The following work is done when inspecting the main bearings:

2) check the clearance at the top liner for vertical compressors and at the side liners for horizontal compressors;

The babbitt casting of the bearings is inspected;

4) check the fit of the liners’ surfaces to the shaft journals and bearing housings.

check the side clearances with a feeler gauge, and the top clearances with an impression of a lead wire, 1. 1,5 mm in diameter, which is placed under the top bearing shell. The upper bearing cap is then installed and tightened, then the bearing is disassembled and the lead wire is measured with a caliper or micrometer.

The main type of wear in plain bearings is the change in size and shape of the sliding layer. If there is a slight increase in the clearance between the liner and the shaft, it is possible to reduce the clearance by removing the gaskets between the liner halves. The basic method of bearing repair is refilling of the sliding alloy, followed by boring, scraping, and fitting onto the crankshaft journal.

Cast by hand or by centrifugal force. The quality of casting should be such that the bearing shell should give a clean knocking sound. A rattling or thudding noise indicates that the primer bulb is not adhering to the bearing shell in places.

Connecting rod. Connecting rod and connecting rod bolts checked for cracks in kerosene. If cracked, the connecting rod must be replaced.

Connecting rod rod rod deflection can be corrected by straightening when cold or by heating. Parallelism of connecting rod crank and crosshead bore axis is checked after installation of mandrels in the holes and verification of parallelism of mandrels on a special device. If not parallel, this indicates the connecting rod is twisted. Twisted connecting rods must be replaced.

How Rings Should Stand on a Compressor

Air compressor (automotive). Installing piston rings.

Fit the piston rings on the piston only after the piston is connected directly to the connecting rod.

If removed pistons are reinstalled, they must be thoroughly cleaned, especially the piston ring grooves and oil drain holes, which are located in the groove of the piston ring.

Cleaning of piston groove from all sorts of carbon deposits can be done with a special tool or with a piece of old piston ring. When cleaning the piston ring grooves, care must be taken not to remove any metal from the piston.

Before the process of installing the rings into the piston grooves, check the piston lock end clearance in the cylinder and the side clearance between the ring and the piston groove wall.

Piston ring should be inserted into cylinder. To set the ring perpendicular to the cylinder axis, the ring must be aligned in the cylinder with the piston inverted. If installing a new piston ring in a cylinder that has not been bored, the ring must be pushed through to the depth of the piston stroke, since the top of the cylinder may be enlarged in diameter due to wear.

Use a set of flat feelers to measure the clearance in the piston ring lock, which must comply with the manufacturer’s specifications. The gap is within 0.5 ÷ 0.15 mm, depending on the piston diameter. If the gap is less than the specified value, it should be adjusted by filing the ends of the ring lock.

Vertical (axial) clearance between the end face of the ring and the piston groove:

Use a set of flat feeler gauges to check the clearance between the groove surface and the end face of the ring. There is no need to install the ring on the piston to perform this check. The clearance should be checked all around the piston. Compare the clearance with that given by the manufacturer. Usually the gap is 0.04 ÷ 0.08 mm. If this clearance is greater than the specified piston clearance, the piston must be replaced or a thicker ring must be added

Carefully examine the compression rings and determine which is the upper ring and which is the second. Determine which side of the ring goes to the bottom of the piston (up).

Labels may be of the form: “”, “○”, “TOR”, “T”. Generally, information on the mark and how to identify the top ring can be found on the piston ring kit packaging.

Install the liner ring first. When installing a boxed wiper ring with an expander in the form of a coil spring, the spring lock must be shifted 180 ° with respect to the lock of the ring.

If installing a composite liner, first install the spacers (reamer). After checking that the expander is correctly positioned, the lower lamellar ring and then the upper lamellar ring must be installed. The lugs of the laminar rings should be positioned at an angle of 180º in relation to each other.

Parts of composite piston rings are installed by hand, without any special tool.

Determine which one of the compression rings is the lower ring and which side of the ring should be installed towards the bottom of the piston.

Very carefully using a special tool when installing the ring.

Do not install compression piston rings by hand. Use the special tool for this. If the ring is installed by hand, it can be irreparably damaged, and there is no way to verify that the ring is in good condition.

Do not unclamp the ends of the rings more than necessary to install the rings on the piston.

Install the upper compression ring in the same manner.

You need to make sure that all the rings without jams and easily rotate in their grooves around the circumference and when compressed, the rings can be fully recessed into the grooves, without protruding beyond the surface of the piston.

Once again it is worth checking the clearance between the side surface of the compression rings and the wall of the piston groove (vertically).

Before installing the piston and rings directly into the cylinder, set the locks of all piston rings at 120º.

Do not put the piston ring locks in the center of the piston bearing surfaces, especially the base surface. You should not place the locks of piston rings on the side of the end surfaces of the piston pin.

Before installing the assembled connecting rod and piston group make sure once again that you have positioned the piston ring locks correctly.

Transferring this article to the onboard magazine, at first I wrote in the wrong place, just because I do not understand in the early days, being on a drive there is a blog and there is a board magazine)) The old place was here.

P.s.By popular demand the sequel and a more detailed description will be in the second part which will be ready in a day, I apologize that I was delayed with it so long)

Everyone who has ever rebuilt an engine or tried to do it with their own hands, probably changed the piston rings or “wipers” caps and t.д. For the most inquisitive testers, and perhaps the naturalists, the question arose about the “one-piece” piston rings) Why do manufacturers ignore this issue, why do they not care about us, the common people, how we will suffer with such “technique” ill-conceived?!In the car repair book there are minimum and maximum allowable calculations about the gap in the joint of piston rings, so that when expanding from temperature these joints do not meet, and our rings do not start “tear” cylinder, until it simply jams or at best leaves risks, which again will de-energize the compression. For example ours, for the tenth family of cars VAZ, these gaps are: 0.25-0.45 maximum allowable 1mm. Honestly these are huge sizes, especially 1mm.))) We have many amateurs and even professional mechanics who are guilty of this, that they simply forget about the clearance. Just for example, the block, let’s say, was turned at the factory to 84.0, that is under zero repair, and put the same rings of the second repair and put them there, well if they check at least the gap in tolerance?! But! Backlash can be in tolerance, but the cylinders are not honed in a perfect equally in each, because many met in their cylinders pistons of different groups, piston rings in the production process you also do not do the same, so that the gap in each cylinder can easily stray! That is, in one cylinder let’s say 0.25, in the other 0.35 etc.д. As a result, different compression in all cylinders, one cylinder kicks in, the other half working, and the engine is not stable, so the wear and tear of the piston is different, why when we check compression in two cylinders can be 12 kPa, and in two others 10 kPa for example! And sometimes the difference is much larger! My father used to tell me, when I started to learn the technique, that you should always buy more rings per repair, to fit them perfectly for each cylinder in the same way. I experimented with this when I was still riding motorcycles, and “Ural”, the first one to get it in these tests, but to this day it still runs on these rings, it has gone 170,000 miles on them., compression shows 12 kPa, and in fact in the passport should be 8.5 kPa, and starts like new, with a half turn in any weather!=) Other bike would have died, and the rings will not let him so easily go to rest)))) Naturally, the test touched my four-wheeled friend 2111, when I changed the pistons with deeper scrapes to prevent bending the valves when the timing belt is broken, refinements were a lot of engine, but we will touch on this topic is the piston rings, because they play a huge role in the “health” and the length of time the engine has been running! This is so to speak the source of all work in the whole internal combustion engine!I changed the piston rings on my 2111 with my own technology and checked the compression at 200 km. After running out of gas, the compression in each cylinder showed 14 kPa, I decided to check next time after a full run-in, when I drove 1.500 km., and an increase of 0.5 kPa, so it should be 14.5 kPa) That is, with such rings, compression only increases, and runs the engine many times more, if not to say that all will fall apart, the liners will no longer hold oil pressure, and the rings will faithfully work to overhaul!

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How Rings Should Be Fitted on a Compressor

Air compressor (automotive). Installing Piston Rings.

Piston rings should be installed on the piston only after connecting the piston directly to the connecting rod.

If removed pistons are reinstalled, they must be thoroughly cleaned, especially the grooves for installing piston rings and the holes for removing oil, which are located in the groove of the piston ring.

Cleaning of piston groove from all sorts of carbon deposits can be made with a special device or with a piece of old piston ring. In the process of cleaning the piston ring grooves, you must be careful not to remove metal from the piston.

Before the process of installing the rings in the piston grooves to check the piston lock end play in the cylinder and lateral clearance between the ring and the wall of the piston groove.

It is necessary to insert the piston ring into the cylinder. In order to install the ring in a position perpendicular to the axis of the cylinder, it is necessary to align the ring in the cylinder with the inverted piston. When installing a new piston ring in a cylinder that has not been bored, you must push the ring to the depth of the piston stroke, because in its upper part of the cylinder may have an increased diameter due to wear.

Using a set of flat feelers to measure the gap in the piston ring lock, which should comply with the manufacturer’s technical standards. This gap is between 0.5 ÷ 0.15 mm depending on the diameter of the piston. If the gap turns out to be less than the set standard, you should adjust by filing the ends of the ring lock.

Vertical (axial) clearance between the end face of the ring and the piston groove:

compressor, piston, ring, much

Use a set of flat feelers to check the clearance between the groove surface and the end face of the ring. It is not necessary to install the ring on the piston for this check. The clearance should be checked all around the circumference of the piston. Compare the clearance value with that given by the manufacturer. Usually the clearance is 0.04 ÷ 0.08 mm. If the gap is greater than the prescribed amount, the piston should be replaced or the ring thickness should be increased

Examine the compression rings closely to determine which is the top ring and which is the other. Locate the mark on the rings, which indicates which side of the ring, set towards the bottom of the piston (up).

Tags may look like: “”, “○”, “TOR”, “T”. Typically, information about the label and how to identify the top ring can be found on the packaging of a set of piston rings.

The first ring to install is the liner ring. When installing a box liner with expander in the form of a coil spring, the spring lock must be displaced 180º relative to the lock of the ring itself.

When installing a composite liner, first install the spacers (expander). After ensuring that the expander is positioned correctly, the lower laminar ring and then the upper laminar ring should be installed. The lugs of the laminated rings should be positioned at a 180º angle with respect to one another.

Parts of the composite liner are installed by hand, without special tools.

Determine which compression ring is the lower compression ring and which side it should face toward the bottom of the piston.

Very carefully, using a special tool, install the ring.

Do not install compression piston rings by hand. Use the special tool for this. If the ring is installed by hand, it can be irreparably damaged, and there is no way to verify that the ring is in good condition.

Do not squeeze the ends of the compression rings more than necessary to install the rings on the piston.

Install the upper compression ring in the same manner.

It is necessary to make sure that all the rings without jams and easily rotate in their grooves around the circumference and when compressed the ring can be completely sunk into the grooves, without protruding beyond the surface of the piston.

Once again it is worth checking the clearance between the side surface of the compression rings and the wall of the piston groove (vertically).

Install the collar locks on all piston rings at a 120º angle before placing the piston and rings directly into the cylinder.

Piston ring locks should not be placed in the middle of the piston bearing surfaces, especially the main surface. You should not place the piston ring locks on the side of the piston pin end faces.

Before installing the assembled connecting rod and piston group make sure you put the piston ring locks in the correct position again.

Transposing this article in the logbook, at first I wrote in the wrong place, just because I do not understand in the early days while on the drive is a blog and is a logbook)) The old place was here.

P.s.By popular demand, continuation and a more detailed description will be in the second part, which will be a day, I apologize for its delay)

Everyone who has ever rebuilt an engine or tried to do it themselves has probably changed piston rings or “linchpins” caps and t.д. For the most inquisitive testers, and perhaps even naturalists, there was a question about “whole” piston rings) Why did the manufacturers missed this issue, why do they not care about us, the ordinary people, how we will suffer with such “equipment” ill-conceived?!In the car repair book there are minimum and maximum allowable calculations about the gap in the joint of the piston rings, so that when expanding from temperature these joints do not meet, and our rings did not start “tear” cylinder, until they simply jam or at best leave the risks, which again will deform the compression. For example our, for the tenth family of cars VAZ, these gaps are: 0,25-0,45 allowable 1mm. Honestly it is huge sizes, especially 1mm.))) We have many amateurs and even professional mechanics who are guilty of it. they just ignore the clearance. Just for example turned the block let’s say the factory at 84.0, that is, under zero repair, and insert the same rings second repair and put them there, well if checked, at least the gap in tolerance?! But! Backlash can be in tolerance, BUT the cylinders are not honed straight in the ideal is the same in each, because many met in their cylinders pistons of different groups, piston rings in the production process you also do not do the same, so that the gap in each cylinder can easily stray! So in one cylinder let’s say 0.25, in the other 0.35 and t.д. This causes different compression in all cylinders, one cylinder kicks in, the other half working, and the engine is not stable, so the wear of the piston is different, why when we check compression, in two cylinders may be 12 kPa, and the other two 10 kPa for example! And sometimes there’s a lot more difference! My father told me when I first started learning about technology, that the rings should always buy more for the repair, to fit them perfectly for each cylinder equally. I’ve been experimenting with them since I was riding motorcycles “Ural”, who was the first to get it in these tests, but to this day it still works on these rings, it has been on them for 170,000., Why is it that when we check the compression in two cylinders it may be 12 kPa and in two other cylinders it may be 10 kPa, e.g!=) Another bike would have died, and these rings will not let him so easily go to rest)))) Naturally, the test touched and my four-wheeled friend 2111, when I changed the pistons with deeper scallops, so as not to bend the valves at timing belt breakage, modifications were a lot of engine, but we will touch on this topic is the piston rings, because they play a huge role in the “health” and the length of time the engine has been running! This is so to say the source of all work in the whole internal combustion engine!I changed the piston rings on my 2111 with my technology and checked the compression at 200 km. I decided to check the compression in each cylinder 14 kPa, next time after a full run-in, when I drive 1.500 km., and expect a boost of 0.5 kPa, so it should be 14.5 kPa) That is, with such rings the compression only increases, and runs the engine many times more, if not to say that all will fall apart, the liners will no longer hold oil pressure, and the rings will faithfully work up to overhaul!

How to change the rings on the compressor

The main compressor parts perform rotational or relative translational motion, so they are subject to intense wear and tear.

The main types of wear in piston compressor parts are related to the nature of motion and the loads involved and can be as follows:

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1) crankshaft. change in shape and size of connecting rod and main shaft journals, cracks in the place of journals to jaws transition, deflection;

2) main bearings. wear of babbitt casting, warping of liners;

3) connecting rod. bending of connecting rod, wear of bearing shells, pulling of connecting rod bolts;

4) crosshead. wear of guides and pin;

5) connecting rod. rod wear at the point of passage through the packing, bending, thread breakage;

6) Piston. wear of piston ring bores, ring wear;

7) Cylinder. change in the shape of the cylinder (ovality, conicity, barrel-shape);

8) Valves. wear of springs and valve seat and valve disk working surfaces.

The service life of the parts can be divided into three groups:

1) Replaceable wear parts. piston rings, gland packing, valve plates and springs;

2) medium life. main bearing shells and connecting rod, connecting rod and crosshead pins;

3) long life. crankshaft, connecting rod, crosshead, cylinders, pistons.

Preparation for repair consists of a stop of the compressor, switching-off from a power supply, release from a product, cleaning, blowing out, selection of tools, adaptations and spare parts.

At the beginning of disassembly, external piping, valves, pressure gauge, oil filters, compressor water piping and flywheel half coupling are dismantled.

The compressor has several similar parts: valves, bearing shells, fasteners, etc. д., which were either adjusted during initial assembly or were run-in during work with the mating parts; therefore, after repair, they must be installed in their former places. At disassembly it is necessary to check availability of marks at identical details and in its absence to put with a core on nonworking places of connecting details the conventional signs or to beat out identical figures.

At the subsequent disassembly of the compressor covers of cylinders, pressure valves with buffer springs are removed, valve boards are dismantled, side covers of the crankcase are opened and the crankshaft is turned so that the pistons were in the upper position, convenient for removing the suction valves. Then the connecting rod bearing is disassembled and removed and the piston and connecting rod are removed with eyebolts, the flywheel is removed with a puller, and then the oil seal cover is opened. Then the stuffing box, suction and discharge valves are disassembled. When disassembling, parts are examined for defects.

Crankshafts and main bearings. Crankshaft and main bearings are inspected at least once a year. This is checked:

1) condition of the shaft, its jaws, necks, flanges in order to detect burrs and dents;

3) presence of surface and internal cracks of the shaft;

4) the axis of the shaft by the divergence of the jaws.

Crankshaft condition inspection begins with a crankshaft bearing clearance inspection using a feeler gauge, crank pin to crank pin connection, and a shaft axis misalignment check. These types of control can indicate mutual wear of mating surfaces of crankshaft, main bearings, connecting rod.

If the shape deviation exceeds the allowable limits, the journals are ground. Allowable diameter reduction is 3% of the original diameter. If wear is severe, the shaft is turned over and the jackets that comprise the two halves are welded together. Welded seams connect the shell halves with each other and with the shaft journal. The torque on the crankshaft journal is negligible and there are enough welds to ensure the strength of the joint.

Scoring and dents detected on journals and flanges on a crankshaft can be corrected by grinding or reaming followed by grinding. Main and connecting rod pins are turned if ovality and conicity exceed the maximum allowable tolerance of 0.15 mm. Deviations of the diameter of the repaired journals shall not exceed the normal tolerances for ovality and taper: for main journals. 0.03 mm, connecting rod journals. 0.01 mm; for runout. 0.05 mm. The gap between the jaws should be no greater than 0.14 mm or 0.00025s (where s is the piston stroke). Restoring the nominal value of the diameter of the journals is possible by surfacing and subsequent grinding. Cracks are eliminated by welding, and shaft deflection is corrected by mechanical, thermal and thermo-mechanical methods.

The following work is done when main bearings are inspected:

1) Check the divergence of the crankshaft jaws in two positions;

2) Check the clearance of the top liner for vertical compressors and the side liners for horizontal compressors;

3) inspect the babbitt casting of the bearings;

4) check the fit of bearing shells to shaft journals and bearing housings.

side gaps are checked with a feeler gauge, and the upper. with an impression of a lead wire diameter 1. 1.5 mm, which is placed under the upper liner. Then the bearing top cover is installed and tightened, then the bearing is disassembled and the lead wire is measured with a caliper or micrometer.

The main type of plain bearing wear is the change in dimension and shape of the sliding layer. If there is a small increase in the clearance between the casting and the shaft, it is possible to reduce the clearance by removing the gaskets between the bearing halves. The main method of bearing repair is refilling of the antifriction alloy, followed by boring, scraping, and fitting to the shaft journal.

Casting by hand or by centrifugal force. The quality of the casting should be such that the shell should give a clear sound when tapped with a hammer. A rattling or thudding noise indicates the primer is not adhering in places to the bearing.

connecting rod. Connecting rod rod and connecting rod bolts checked for cracks with kerosene. If cracked, the connecting rod must be replaced.

Buckling of the connecting rod rod is corrected by straightening in a cold condition or with heating. Parallelism of rod crank and crosshead bore axes is checked after installation in the holes of mandrels and reconciliation on a special device parallelism mandrels. 3. connecting rod. bending in the crank arm, bearing wear, bearing pin pulls, and connecting rod bolts. Torsionally twisted connecting rods need to be replaced.

How to change the rings on a compressor

The main parts of the compressor perform rotary or relative translational motion, so they are subject to intensive wear and tear.

The main types of wear in piston compressor parts are related to the nature of movement and the loads involved and can be as follows:

1) crankshaft. change in shape and dimensions of crank and main journals of the shaft, cracks in the journals to jaw transition, deflection;

2) Main bearings. wear of babbitt casting, warping of bearing shells;

3) connecting rod. bending of the connecting rod, wear of the shells, pulling of the connecting rod bolts;

4) crosshead. wear of guides and pin;

5) rod. wear of the rod at the point of passage through the gland, bending, thread breakage;

6) Piston. wear of piston ring bores, ring wear;

7) Cylinder. change in the shape of the cylinder (ovality, conicity, barrel-shaped);

8) Valves. wear of springs and valve seat and disc surfaces.

According to their service life, parts can be divided into three groups:

1) Wear parts that are replaceable. piston rings, packing, valve plates and springs;

2) medium-life main bearing shells and connecting rod, connecting rod pins and crosshead;

3) long service life. crankshaft, connecting rod, crosshead, cylinders, pistons.

Preparation for repair consists of stopping a compressor, unplugging it, releasing it from the product, cleaning, blowing out, and selecting tools, devices and spare parts.

At the beginning of disassembly, external piping, valves, pressure gauge, oil filters, compressor water piping and flywheel half coupling should be disassembled.

The compressor has a number of similar parts: valves, bearing shells, fasteners, etc. д., which either were adjusted during initial assembly or were lapped during operation on the mating parts; therefore, they must be reinstalled after the repair. During disassembly, it is necessary to check the presence of the markings on the identical parts and in its absence make a core marking on the non-working places of the connecting parts or punch out the same numbers.

A further disassembly of the compressor involves removing the cylinder head, discharge valves and buffer springs, removing the valve plates, opening the crankcase side covers and turning the crankshaft so the pistons are in their highest position for removal of the intake valves. Then disassemble and remove connecting rod bearing and piston and connecting rod with eyebolts, pull flywheel with puller, and open gland cap. Next the stuffing box, suction and discharge valves are disassembled. During disassembly the parts are examined for defects.

Crankshafts and main bearings. Check crankshaft and main bearings at least once a year. This checks:

1) condition of the shaft, its jaws, necks, flanges in order to detect scoring and dents;

3) the presence of surface and internal cracks of the shaft;

4) axis of the shaft by divergence of jaws.

Crankshaft condition inspection begins with checking the clearances at the connection of the shaft with the main bearings with a feeler gauge, the connection of the crank pins with the connecting rod, and checking the axis of the shaft by divergence of jaws. These inspections can indicate wear between the mating surfaces of the crankshaft, main bearings, and connecting rod.

If the shape deviation exceeds the allowable limits, the journals are ground. Allowable diameter reduction is 3% of the original diameter. If the wear is too severe the shaft is ground and a sheath that consists of two halves is welded on. The welds connect the jacket halves to each other and to the shaft neck. The torque on the crankshaft journal is low, and there are enough welds to ensure the strength of the joint.

Scoring and dents found on the journals and flanges of the crankshaft are corrected by grinding or boring with subsequent grinding. Main and connecting rod journals should be reground if ovality and conicity exceed a maximum allowance of 0.15 mm. Deviations of diameter of repaired journals shall not exceed normal tolerances for ovality and conicity: for main journals. 0,03 mm, con rod journals. 0,01 mm; for run-out. 0,05 mm. Jam divergence should be no greater than 0.14 mm or 0.00025s (where s is piston stroke). Restoration of the nominal diameter of pins is possible by surfacing and subsequent grinding. Cracks are eliminated by welding, and shaft deflection. by straightening the mechanical, thermal and thermomechanical methods.

The following work is done while inspecting main bearings:

1) check the divergence of crankshaft jaws in two positions;

2) Checks the clearance at the top liner for vertical compressors and at the side liners for horizontal compressors;

3) The babbitt casting of the bearings is inspected;

4) checking the fit of liner surfaces to shaft journals and bearing housings.

check the side clearances with a feeler gauge, and the top clearances with an impression of a lead wire, 1. 1,5 mm in diameter, which is placed under the top shell. Then the upper bearing cap is installed and tightened, then the bearing is disassembled and the lead wire is measured with a caliper or micrometer.

The main type of plain bearing wear is the change in size and shape of the sliding layer. If there is a slight increase in the gap between the filling and the shaft, it is possible to reduce this gap by removing the gaskets between the halves of the liners. The main method of bearing repair is refilling of antifriction alloy followed by boring, scraping and fitting on a shaft journal.

Pouring is carried out manually or by centrifugal method. The quality of the casting should be such that the liner should give a clean sound when tapped with a hammer. Rattling and thudding noises indicate that the primer is not adhering in places to the liner.

Connecting rod. Connecting rod rod and connecting rod bolts are checked for cracks in kerosene. Cracked connecting rod must be replaced.

The rod deflection can be corrected by cold straightening or by heating. Check the parallelism of the crankpin and crosshead bore axis holes by installing mandrels in the holes and realigning the mandrels on a crosshead fixture. Unparallelism indicates crank rod twist. Bent connecting rods need to be replaced.

Compression Rings, Wiper Rings, Installation

Piston rings provide the seal between the cylinder wall and piston. Must provide good sealing across the entire cylinder surface over a wide temperature range. Three rings are used more frequently in four-stroke engines, including two compression rings and a bottom liner.

  • The first compression ring ensures a tight seal between the cylinder and piston to seal the combustion chamber.
  • Divert heat from the piston to the cylinder walls.
  • The lube oil rings remove excess oil from the cylinder walls, preventing it from penetrating into the combustion chamber. However, it is not completely removed, but regulated, leaving just the right amount of oil for the compression rings.
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First compression ring

Designed exclusively to prevent bursting of expanding gases in the combustion chamber. During the stroke cycle, the increasing pressure in the combustion chamber presses the first compression ring against the bottom of the piston groove and presses it harder against the cylinder walls, thus ensuring adequate insulation of the combustion chamber. The pressure in the ring groove is maintained during subsequent cycles without having sufficient time to decrease. The clearance between the ring and the groove is 0.04-0.08 mm

Protects the second ring from high combustion temperatures and reduces the load. Has the greatest heat transfer from piston to cylinder, with approximately 50-60% of the heat transfer from piston to cylinder occurring on the compression rings. Some of the gases escape and the second ring begins to perform its function, more on that later.

The first compression ring is made of high grade cast iron or steel that can withstand high temperatures and loads while having a low coefficient of thermal expansion. During engine operation the temperature of the ring reaches 180-210°C, at the upper dead centre where there is little or no lubrication due to friction, an even higher temperature is reached. There is often a special coating on the outer running surface of the ring to reduce friction. This can be plasma cladding of molybdenum, ceramic metal, ceramic. common is a chrome plating which has a matte gray color (electroplated) and a peculiar porous structure that allows oil retention for greater friction reduction. Black color on remaining surfaces due to phosphating. The coating provides anti-friction and anti-corrosion properties.

Compression rings are not completely round, but have a complex arc shape in the free state and a rather large end gap. Once in place in the piston and inside the cylinder, it provides an even clamping force all around the circumference.

Second compression ring

works under more favorable conditions and performs the function of an additional seal. Also, because of its special shape, it helps the wiper to remove excess oil, leaving only an oil film on the surface of the cylinder. Average Ring Temperature at 150-170 Celsius in operation. The clearance between the ring and the piston groove is slightly less than that of the first 0.03-0.06 mm. Made of cast iron and very brittle. The variety of ring shapes results in certain functions. Such as load distribution in the groove, reduction of piston skirt friction by aquaplaning on oil, removal of excess oil.

The bevel on the inside of the ring determines in which direction the ring will bend. If the chamfer is at the bottom, then after heating the ring will be everted by the outer surface downwards, as shown in the picture. Correspondingly, if the bevel is at the top, the outside surface of the ring will unscrew upwards.

The liner ring

Underneath the compression rings is an oil release ring, which has the function of removing excess oil from the cylinder walls.

Large amounts of oil that penetrate through the compression rings into the combustion chamber can be very harmful to the engine. During operation, the combustion oil is deposited on the valve walls, combustion chamber, spark plugs, piston bottom. Heavy soot build-up heats up the ring, increasing the chance of detonation. Exhaust valves are subjected to increased temperature load.

The thin film of oil left on the rings reduces the frictional force of the compression rings, increasing their durability. Compared to compression rings, linchpins are not pressed by operational gas pressure to the groove surface in the piston and cylinder walls, so they have special axial and radial expander rings.

Two types of rings can be distinguished by their design: boxed and dialed rings, both of which can have different extensions.

As the piston moves down, the wiper rings scrape excess oil from the cylinder walls, guiding it through drainage holes in the piston back into the crankcase. An oil wedge in front of the ring helps effectively lubricate the sliding skirt of the piston. The walls of the cylinder have a roughness, the so-called honing, which helps trap the thinnest layer of oil, for the compression rings.

Design of a single-cylinder KAMAZ compressor

1 Crankcase complete 2 53205-3509039 Cylinder head with cover complete 3 53205-3509088 Rear cover complete 4 53205-3509154 Piston complete 7 53205- 3509030 Cylinder 8 53205-3509045-10 Cylinder head gasket 9 53205-3509045-11 Head gasket 10 53205-3509056-10 Intake valve Cylinder 8 53205-3509045-10 Head gasket 9 53205-3509045-11 Head gasket 10 53205-3509056-10 Suction valve 12 53205-3509110 Crankshaft shaft 13 53205- 3509130 Pinion assembly 3509130 Gear 14 53205-3509131 Nut 15 53205-3509137 Transport flange cover 16 53205-3509170 Piston pin 18 53205-3509172 Piston pin retainer 19 53205- 3509180 Rod 3509180 Connecting rod 20 53205-3509203 Bolt M8-6gx80 21 53205-3509204 Pin M8x27 22 53205-3509239 Plate branded 23 53205-3509283 M26x1 plug 5-6g 23 53205-3509283 M26x1,5-6g 24 53205-3509206 8×18 washer 24 53205-3509206 8×18 washer 25 53205-3509301 M22x1,5 transport plug 26 53205-3509302 M26x1,5 28 53205-3509304 O-ring 29 53205-3509305 O-ring 30 53205-3509306 Gasket 26×32 31 1/60434/21 Bolt M8-6gx20 32 53205-3509316 Nut 33 1/21647/11 Nut M10x1,25-6H 34 1/05304/50 Rivet 2×6,37 35 2.6,37 Rivet GOST 10299-80 36 1/02646/60 Gasket 26×32 38 1/05168/77 Washer 10 spring 39 10.65Г.019 Spring washer 10.65Г.019 40 M8-6gx20.88.35.019 Bolt M8-6gx20.88.35.019 41 С8.04.019 41 C8 washer.04.019 Washer Link to this page: http://www.kspecmash.ru/catalog.php?typeauto=2mark=8model=755group=621

Repair of single-cylinder compressor

Repair of piston compressor

Maximum piston rod runout in the vertical and horizontal planes for G series normalized base compressors and M series opposed base compressors during operation must not exceed:

  • – at working pressures up to 15 at at at piston stroke up to 450 mm. 0,3 mm within the stroke limits;
  • – at cylinder working pressures in excess of 15 atmospheres. 0.2 mm within the stroke.

The maximum piston rod run-out in the horizontal and vertical planes for all other horizontal reciprocating compressors shall not exceed 0.3 mm per linear meter.

If the measured wear on the rod exceeds the limits given in the table, the rod should be turned.

When reaming and grinding, the rod should be taken out of service if reductions in rod diameter exceed the limits (4M Compressor size 16) 3mm).

When fabricating a new piston rod, be sure to refer to the compressor manufacturer’s drawings and specifications. Particular attention shall be given to the quality of the thread corners. The cleanliness of the machining of the cylindrical rubbing part should not be less than 10 %.

During compressor operation, the following piston group faults may occur

  • – triggering of the bearing surface at the sliding pistons, resulting in misalignment of the row movement, a significant increase in the gap between the piston and the mirror of the cylinder and the slope of the rod with respect to the cylinder axis;
  • – loose fit of the piston on the piston rod;
  • – appearance of scoring, deep grooves on the piston working surface, which may occur as a result of foreign objects getting into a cylinder (broken valve plates, wires from springs, caps);
  • – Disassembly of piston ring grooves as a result of operating with increased piston-cylinder clearance, increased piston ring end gap, large barrel-shaped cylinder or insufficient lubrication;
  • – increased wear of piston rings due to insufficient lubrication or contaminated gas.

Piston rings with piston ring radial wear greater than 30 percent of their original thickness must be replaced.

Valve defects

The main valve defects can be:

  • – Wear of the valve seat sealing belts (uneven wear of the sealing belts, dents and risks);
  • – Wear on or damage to the valve plate;
  • – Breakage of its plate and its deformation;
  • – contamination of the valve;
  • – Wear of valve springs, which leads to loss of elasticity, formation of cracks in coils;
  • – Wear of the valve fasteners, gaskets of the valve plate squeezing mechanism parts;
  • – the springs of the seats in the stop (socket) of the valve are worn out.

Depending on degree of pollution or aggressiveness of compressed gas as well as operating conditions, i.e. determined on the basis of practical data of operation in specific conditions, periodicity of checking technical condition of valves is determined.

compressor, piston, ring, much

The compressor valve must be repaired or replaced:

  • – If there are cracks or breaks in the plates and other parts of the valve;
  • – the values of leakage exceed the standards specified in the table;
  • – If the cross sectional area has been reduced as a result of contamination by more than 30% of the nominal cross sectional area;
  • – in case of jamming of the plates when moving them;

with an increase in the lifting height of the plates

  • – if there is more than 25% of the nominal wire diameter and if the residual deformation of the springs is more than 0.1 of the nominal height;
  • – if cotter pin securing valve parts is broken;
  • – when the thread of the tie rod (stud) or nut is worn
  • – in case of violation of kernel preventing the stud from turning;
  • – When the valve guide plates wear out, causing the plate to have a large radial displacement and not overlap the seat bore;. When the valve guide plates wear out, causing the plate to have a large radial displacement and not overlap the seat bore.

Straight-line valves if pressure drop time from 4 to 2 Kg/sm 2 in a specially adapted container

The valve plates are considered suitable for operation if, within 5 min. dripping of individual drops of kerosene poured on the plate to a height of 5-10 mm not exceeding

for single leaf valves. 5 drops per min.;

for two-plate valves. 12 drops per min.;

for three-plate valves. 20 drops per minute.;

for four-plate valves. 30 drops per min.

After repair, the plates are checked on a test plate.

The clearance is measured under the plate clamped by a weight approximately equal to the force of the valve spring in the operating position.

Valve plates are mostly made of 30 KHSA steel, high chromium ZC 13 or austenitic IX18H9T steel. Billet plates of alloyed steel, regardless of the mechanical properties of their metal in the delivery condition, are heat-treated.

The hardness of heat-treated plates should not be lower than 40 NKC. After heat treatment the plates are ground in 2-3 passes alternately on each side, grinding should be concentric.

The height of the plates of each valve is set according to the manufacturer’s drawings. Material of valve plates can be changed, i.e. plates are made of sheet textolite. In our case the valve plates are made of textolite.

Running-in of compressor after middle and complete overhauls

Running-in of the compressor is carried out in the following modes:

At running-in of the compressor without valves it is necessary to reach the following results

  • – operation of the compressor without sharp bumps, knocks and extraneous noises;
  • – Temperature of bearings regardless of duration of work must not exceed 60°C;
  • – normal oil pressure in the circulating lubrication system in the range of 1.94 kgf/cmL;
  • – uninterrupted flow of oil to all lubrication points and lack of its leakage;
  • – Adjusting the valves is important for the engine’s long life and trouble-free operation of the water cooling system;
  • – Temperature of rubbing parts shall not exceed: rod temperature not exceed 650C; temperature of crosshead guide parallels not exceed 400C. Measure temperature with contact thermometer or pyrometer.

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