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LESSON

2LECTURE

REPLACE COMPRESSOR INTERNALCOMPONENTS

SUB-OBJECTIVE

At the end of the Lesson the Trainees wi !e a!e to"Re#a$e $o%#ressor interna $o%#onents

&'( INTRO)UCTION

The compressor is the heart of the refrigeration system. It receives refrigerant vapor at lowpressure and low temperature from the evaporator, and delivers it at high pressure and hightemperature to the condenser. Almost all kinds of system malfunctions, if not corrected in time,

will eventually cause compressor failure. A defective hermetic compressor cannot be servicedand has to be replaced. Semi hermetic and open-type compressors are serviceable and theirdefective parts can be replaced.The service will be limited to frequently failing parts.Semi-hermetic compressors are also called bolted or serviceable hermetic. They have fromtwo to eight cylinders and range in sie from five to one hundred tons. The function of thecompressor is to compress refrigerant. The following components and actions providecompression!". An electric-powered motor turns a crankshaft.#. The crankshaft moves pistons up and down in cylinders.$. The pistons compress refrigerant in the cylinder head.%. The cylinder head directs the compressed vapor into the discharge manifold and to the

condenser. This module e&plains how to replace these basic components.

2'( REPLACE COMPRESSOR

There are many reasons for compressor failures. 'ost of these reasons cause compressorburnout. The main reason for compressor replacement is a burnout motor (shorted orgrounded motor). *verheating causes a motor burnout. *verheating causes the refrigerant tobreak down, and the oil becomes acidic. Acidic oil separates the insulation from the motorwindings, causing a short circuit or ground. Acids and overheating also introducecontaminants into the system. +ou must clean the refrigeration system to remove all acids andcontaminants before replacing the compressor. *therwise, a repeat burnout will occur.'any compressors fail because of these causes! Slugging looding looded starts oss of lubrication /ontamination *verheating

2'& SLU**IN*

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Slugging is defined as a short term returns of liquid refrigerant, oil, or both .to the compressorcylinders instead of a superheated gas. If slugging occurs, it will occur at start-up or during arapid change in system operating conditions. It is indicated by a periodic :knocking: noise atthe compressor. This is due to the compressor trying to compress a liquid. Slugging couldresult in damaged pistons, valves, and blown cylinder head or gasket. (See I6. #.".)Slugging is caused by! a. iquid refrigerant in the evaporator during the off cycle b. T;1

hunting c. *il trapping

+I*' 2'& )AMA*E )UE TO SLU**IN*

a. iquid in the 3vaporator 5efrigerant can condense in any cold part of the system during theoff cycle. This could be the evaporator coil or water cooler. *n the ne&t start-up, this liquidcould return to the compressor as a slug. To minimie this condition, a :pump-down: controlsystem can be used. (See I6.#.#). In this system, a solenoid valve is installed in the liquidline. It stops the refrigerant flow to the evaporator when the thermostat is satisfied. Thecompressor pumps down the system. A low-pressure switch stops the compressor. The

compressor restarts when the thermostat energies the solenoid. *nly vapor returns to thecompressor at start-up.b .T;1 hunting an oversied e&pansion valve can hunt badly under a light load. (See I6.#.$.) It causes a slug of liquid to return to the compressor. In general, it is better to undersierather than *ver sie the e&pansion valve.

2'2 +LOO)IN*

is the continuous return of liquid refrigerant or liquid droplets to the compressor. It is normallyassociated with improper refrigerant flow control. looding causes oil dilution. If flooding issevere, it can damage the pistons, rings, and valves due to liquid pumping. Also, liquid

refrigerant washes the oil off the bearing surfaces.

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+I*' 2', TV .UNTIN* +I*' 2'2 PUMP-)O/N CONTROL PREVENTS SLU**IN*

2'2'& Oi tra##in0

oil trapping occurs when the suction, gas does not have-enough velocity to return the oil tothe compressor. This can occur in the suction riser at " on I6. #.%. The oil settles in theevaporator or in suction traps. This condition of low velocity occurs at low loads and


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+I*' 2'1 SUCTION PRESSURE AN) LINE )ESI*N A++ECT OIL RETURN

An oversied metering device or too low a superheat setting would allow more refrigerant toflow to the low side of the system. The refrigerant may flow back to the compressor in asaturated state with liquid droplets. This would gradually wash the oil off the lubricatedsurfaces.

2', +LOO)E) STARTS

looded starts are a- result of the oil in thecrankcase absorbing refrigerant. *il will absorbrefrigerant under most circumstances. The amount absorbed depends on the temperature ofthe oil and the pressure in the crankcase. The lower the temperature and the higher thepressure, the more refrigerant absorbed. This condition usually occurs during shutdown. *nstart-up, the lubrication received by the bearing will at best be minimum. In addition to that, asthe crankcase pressure drops, the refrigerant will flash from a liquid to a gas causing foaming.This can cause restriction in the oil passages. It can also cause enough oil and liquid mi&tureto enter the cylinder, causing a hydraulic slug as previously described under slugging.0amage from a flooded start may be immediate broken. 1alves or blown gaskets. The failure

may come on gradually if! There is a partial loss of lubrication for-some period of time after start-up. A ma>or portion of the oil is pumped out of the crankcase during a flooded start. In thesecases, compressor failure is due to the lack of lubrication.looded starts can be reduced by using crankcase heaters. The heater should be energiedfor #% hours before starting a unit that has been off for a long time.

2'1 LOSS O+ LUBRICATION

ack of lubrication can result from >ust the absence of oil in ?the crankcase.0uring normal operation, some oil will leave the crankcase of a reciprocating compressor. The

successful operation of the system requires that this oil returns at the same rate at which itleaves the compressor./auses of oil leaving at an e&cessive rate are those usually associated with oil foaming.These are! looding overcharge of oil 4se of non-approved oil

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5easons for oil not returning at a satisfactory rate are! ow refrigerant velocity ow load ow suction pressure Short cycling Traps 8oor piping design

The results of lack of lubrication are overheating and scored bearing surfaces, usually uniformthroughout the compressor.

2' CONTAMINATION

/ontamination is the presence of foreign. substances in the refrigeration system. Thesesubstances (contaminants) may cause a chemical reaction or change the chemicalcomposition of materials within-the ,system. /ontaminants include moisture,air,non-condensables metal chips, braing flu&, product of a previous burnout, and othersubstances? that might enter a system accidentally during installation or servicing./ontaminants must be eliminated at the time of installation or at the time of service. This is

what to do! Air @ evacuate, moisture @ dehydrate, /hips and dirt - work carefully and usestrainers and filters, Acid - replace oil and the filter drier.

2'3 OVER.EATIN*

The reasons for overheating are mechanical (refrigeration) and electrical.

2'3'& Me$hani$a 4Refri0eration5 Ca6ses of O7erheatin0

The first cause of overheating is the improper setting of controls.These controls could be a T;1, A;1, evaporator pressure regulator, hot gas bypass, orpressure control switches. 9igh superheat is not only caused by improper control settings. Itcould be caused by a piping problem or the suction line not having proper insulation. 9ermeticcompressors are cooled by suction gas. The ability of the suction gas to cool the windingsdepends on the gas flow and the temperature of the gas entering the compressor. 9ighcompression ratios are also cause for overheating. /ompression ratio is the ratio of thedischarge absolute pressure to the suction absolute pressure. 9igh compression ratio is dueto low suction pressure, high head pressure, or a combination of both. 9igh head is the morelikely cause of high compression ratios. ook for the following causes!

*= S4/TI*2853SS453

9I69 93A0853SS453

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". ow oad#. 3vaporator8roblems$. *perating Below0esign /onditions

". 0irty /ondenser#. Too 9igh Ambient$. /ondenser an%. 2on/ondensables

9igh discharge temperature affects valves, pistons, and cylinder walls. Some contaminants

are formed within the system because of e&cessive heat. This causes a reaction between theoil and the refrigerant. In some cases heat will break down the oil. This forms sludg and coatsinternal surfaces with carbon. /opper plating is a result of a combination of contaminants, thetype of oil used, and high temperature. The gradual buildup of copper plating on bearingsurfaces reduces the clearances and results in increased friction. This, in turn, causes highertemperatures and decreases the life of the compressor.

2'3'2 Ee$tri$a Ca6ses of O7erheatin0

In a three-phase compressor, motor failure can happen because of voltage and currentunbalance. 1oltage 4nbalance! The ma&imum allowable voltage unbalance for winding to

winding is #C. If the voltage unbalance is more than #C, the temperature rise, in percent,generated at the windings would be equal to double the square of the voltage unbalance. (SeeI6. #..)or e&ample, a voltage unbalance of #C would cause an DE increase in winding temperatureFa $C voltage unbalance would cause an "DC increaseF and at only C voltage unbalance, thewinding temperature would soar to EE over normal. /urrent 4nbalance! 1oltage unbalancecauses a current unbalance, but a current unbalance does not mean that a voltage unbalancenecessarily e&ists. Take a three-phase situation where there is a loose terminal connection onone leg or where there is a buildup of carbon on one set of contacts. This increases theresistance (and reduces the current) on that leg. The result is current increase in the other leg.9igher current causes more heat to be generated in the windings. 8ercent of currentunbalance allowed is "EE. Single-phasing is a condition where one leg of a three-phasesystem is not energied.

+I*' 2' VOLTA*E UNBALANCE AN) TEMPERATURE INCREASE

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This reacts much the same as the condition >ust described, but the end results of motor failuremay be more rapid. Another cause of overheating is from too high or too low an incomingvoltage condition. This is where the voltage is outside of the ma&imum-minimum limits set bythe manufacturer of the equipment. or a compressor with a single rating of #$E volts, theoperating limits are within H "EC of #$E volts (#E to #$1). on a dual-rated voltage unit, suchas a #ED


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+I*' 2'9 SEVERE BURNOUT( CONTAMINANTS

+I*' 2': NITRO*EN C8LIN)ER SETUP +OR +LUS.IN* S8STEMS

2ote! or severe burnouts, both filter-driers should be the acid-core type. Triple evacuate andrecharge the system. *perate the unit, then remove an oil sample. Test the oil for acidity. Ifacidic, change the oil and operate the unit again.*perating the system and checking oil acidity is the most thorough method of cleanup. Itallows the refrigerant and oil to circulate and pick up contaminants, if any are still in thesystem.

1'( PARTS O+ A SEMI- .ERMETIC COMPRESSOR

1'& Piston and Conne$tin0 Rod Asse%!;

I6. #.K identifies the internal parts of a semi-hermetic-reciprocating compressor I6. #."E

shows details of a piston and connecting rod assembly. The assembly consists of the! 8iston,8iston rings, /onnecting rod ,8iston pin

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+I*' 2'< INTERNAL PARTS O+ A SEMI-.ERMETIC COMPRESSO

1'&'& Piston

The piston compresses vapor refrigerant, drawn from the low side, in a smaller area anddelivers it through the discharge valves, at a high pressure, to the high side. 8istons for smallsie compressors are usually made of diecast aluminum, while the medium and large sie areusually,made of cast iron. I6. #."E shows

+I*' 2'&( PISTONS AN) CONNECTIN* RO) ASSEMBL8

1'&'2 Piston Rin0s

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Two types of piston rings are used. The upper rings are known as compression rings and thelower ring is known as the oil ring. The function of the compression rings is to seal thecompression chamber and prevent downward gas leaks. The function of the oil ring is to limitthe flow of oil into the compression chamber Small sie pistons are not equipped with pistonrings, only oil groves are cut in them. I6. #."" shows these groves cut in a small piston.8iston rings are usually made of cast iron.

+I*' 2'&& OIL *ROVES CUT IN A SMALL PISTON

1'&', Conne$tin0 Rod

The connecting rod attaches the piston to the crankshaft. The lowerr end of the connectingrod could be one unit or split, defending on the type of crankshaft used. The connecting rodbearing must be fitted to a clearance of E.EE" inch. Therefore, tightening the cap screws ofthis bearing to.The recommended torque is very critical./onnecting rods are usually made of drop forged steel.

1'&'1 Piston Pin

The piston pin is used to connect the connecting rod to the piston. 8iston pins are made ofhardened high carbon steel ground to sie. They are hollow to reduce weight. 8ins are free toturn in both the connecting rod bushing and the piston bushing.

1'2 Va7e Pate Asse%!;

I6. #."# shows the valve plate with valves and gasket.

1'2'& Va7e Pate

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There are a number of different valve plate and gasket arrangements used, even on the samecompressor. =hen replacing valve plates and gaskets, make sure to pick the correctreplacement. The valve plate supports valves and directs gas in and out of the cylinders.I6.s #."$ shows the flow of gas through the valve plate. valve plates are usually made ofcast iron or hardened steel.

1'2'2 Va7es

/ompressor valves are usually carbon alloy steel. 9eat treating gives the valves theproperties of spring steel. This allows grinding them to a perfectly flat surface. The intakevalve is kept in place by one of two ways. *ne way is by using small pins. The other way is bythe clamping action between the compressor head and valve plate. The e&haust valve can beclamped the same way. *f the two valves, the intake valve gives the least amount of trouble.This is because it is constantly lubricated by oil circulating with the cool refrigerant vapor.

Also, it operates at a relatively low temperature. The e&haust valve must be fitted with specialcare. It operates at high temperatures. It must be leak proof against a relatively high-pressuredifference. The valves open about .E"E inches. If the movement is more, a valve noisedevelops. If the movement is too little, not enough vapors can move past the valve.

+I*' 2'&2 +I*' 2'&,VALVE PLATE AN) *AS=ET *AS +LO/ T.ROU*. VALVE PLATE

I6. #."% shows two types of compressor valves in common use. These are! (") 5eed ordisc valves (#) 5ing valves

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+I*' 2'&1 T8PES O+ COMPRESSOR VALVES

I6. #." shows another type of valve plate. A is the inlet port with an e&tension to prevent oilfrom entering the intake. B is the e&haust port with a wire lock between the two e&haustscrews. / is the oil return to the crankcase. The valve disks or reeds are perfectly flat. A defectof only .EEE" inch will cause the valve to leak.

+I*' 2'& VALVE PLATE

'( Cran>shaft

The crankshaft changes the rotary motion of the motor to a reciprocating motion in thecompressor. Two types of crankshafts are in use! crank-type crankshaft eccentric-type crankshaft/rankshafts are usually made of forged steel.

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I6. #."G shows a crank throw-type crankshaft. As the crankshaft revolves, the pistonreciprocates (moves up and down). The piston pin oscillates (swings back and forth) as itreciprocates with the piston. The lower end of the connecting rod rotates with thecrankshaft.Some compressors use the eccentric-type crankshaft. The eccentric type shown inI6. #." uses a straight shaft, with the eccentrics clamped onto the shaft. Sometimes theeccentrics are part of the shaft.The crankshaft?s main bearings support the crank. They also carry any end load. The

crankshaft and connecting rod fit with great accuracy.

+I*' 2'&3 CRAN=-T8PE CRAN=S.A+T

+I*' 2'&9 ECCENTRIC-T8PE CRAN=S.A+T

3'( L6!ri$ation S;ste%

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ubrication is vital to the operation of reciprocating compressors. I6. #."D shows two ways areciprocating compressor can be lubricated. I6. A shows the splash lubrication system andI6. B shows the pressure lubrication system. A B

3'& S#ash S;ste%

In the splash system, the crankcase is filled with the correct oil up to the middle of thecrankshaft. The crank, equipped with dips, splashes the oil around the inside of thecompressor to the points that need lubricrion. The splash system is suitable for small siecompressors.

+I*' 2'&: COMPRESSOR LUBRICATION S8STEMS

3'2 Press6re S;ste%

The pressure system uses a small oil pump to force oil through drilled passages in thecrankshaft and connecting rods to reach various bearings at high pressure. The pump islocated under the pump end cover and is driven by the crankshaft. I6. #."K shows the oilpump assembly, including the pump end bearing head.

". 84'8 320 B3A5I26 93A0#. 05I13 S36'32T$. *I 330 64I03 1A23%. *I 330 64I03 1A23 S85I26. /*135 8AT3

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+I*' 2'&< OIL PUMPASSEMBL8

9'( MEC.ANICAL SEI?URE

A compressor is considered mechanically seied when it passes all electrical tests, but cannotstart when supplied with the correct voltage.ubrication failure is the ma>or cause of compressor seiure. This could happen by!

A. *il being trapped in the systemB. looded start due to the accumulation of refrigerant in the crankcaseIf a seied hermetic compressor has no lubrication problems, then the cause of the seiurecan be a factory defect. Seiure can be the result of a burn-out.

:'( NOISE

3&cessive noise in a compressor generally indicates wear due to lack of lubrication. 2oise can

be caused by the same conditions that lead to seiure. 5attling of the compressor on start-up,sometimes called slugging, is caused by the accumulation of liquid refrigerant in thecompressor crankcase during the off cycle. The sudden reduction in crankcase pressure asthe compressor starts, causes the refrigerant oil mi&ture to foam. This foam, passing throughthe valves, causes the rattle which continues until the refrigerant is distilled. /rankcaseheaters eliminate initial slugging. Bad or broken valves are also a source of compressor noise



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$. 5emove the bolts which hold the bearing head to the crankcase. Tap lightly on thebearing head to break the gasket seal. 5emove the bearing head as shown in I6. #.##%. 4sing a putty knife, clean the gasket material from the seating surface of the crankcaseas shown in I6. #.#$ 5emove any gasket material that may fall into the oil sump.. 'oisten the new gasket surface with oil. 0o not soak the gasket with oil. 'ake surethenew gasket is the correct one. 5einstall the new gasket and bearing head as shown in

I6. #.#%

+I*' 2'22 +I*' 2'2,

+I*' 2'21 +I*' 2'2

G. 5eplace the bearing head bolts and torque to manufacturer?s specifications as shown inI6. #.# (*n /arrier EG0 compressors, torque to #-$E foot pounds).. Install the replacement oil pump drive segment as shown in I6. #.#GD. 5eplace the guide vane and spring. The guide vane is put in before the spring asshown in I6. #.#



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=A52I26I2 S*'3 T+83S * /*'853SS*5S. /+I2035 93A0S A53 S85I26 *A030./+I2035 93A0 B*TS S9*40 2*T B3 53'*130 /*'83T3+ 42TI T93S85I26 T32SI*2 IS 533AS30.". To remove the cylinder head, loosen and remove the cylinder head bolts. Insert a studinto one of the bolt holes. This is done to prevent the head from falling off the compressoras shown in I6. #.#K

#. Insert a putty knife to break the gasket seal holding the cylinder head. If the head mustbe tapped, as shown in I6. #.#K, e&treme care should be taken to prevent breaking thedowel pins that position the suction valves and valve plate.

+I*' 2'2ect to higher heat and pressure thanthe rest of the compressor. The high heat and pressure can warp or crack cylinder heads,valve plates, and the cylinder deck. Stresses caused by slugging can also crack headsand valve plates or damage valves and gaskets. 9igh heat and pressure also causecarbon and sludge buildup on the discharge valves, guides, and cylinder heads. Thiscauses leaking valves.

&1'2 PISTON ASSEMBL8

As seen in I6. #.$D the piston assembly is comprised of the!(") piston,(#) compression and oil rings,

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($) piston pin and piston pin locks,(%) connecting rod and cap with the rod bolts and nuts, and() connecting rod bearing.The piston assembly translates the rotary motion of the crankshaft into the reciprocal (upand-down) movement of the piston in the cylinder. The piston compresses the refrigerantvapor, which has been directed into the compression chamber by the cylinder head andvalve plate assembly.

+I*' 2',: PISTON SSEMBL8

8istons are sub>ect to damage from slugging, and to scoring, burning, and scuffing from oilcontamination and inadequate lubrication. *ther common problems are cracked orcollapsed piston skirts, broken lands, and worn ring grooves. These problems areillustrated in I6.s #.$K through #.%E 5ings are usually replaced during maintenance.9owever, if low hour rings are to be used again, they should be checked for scoring andscuffing, and for clogging of the oil control ring slots.

+I*' 2',< SLU*-)AMA*E) PISTON

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+I*' 2'1( BURNE) PISTON +I*' 2'1& CRAC=E) AN) SCORE) PISTONS

The piston pin and connecting rod small end are sub>ect to wear from improper clearanceand inadequate lubrication. The worn wrist pin hole in the connecting rod in I6. #.%# isthe result of a failed discharge valve and inadequate lubrication. /onnecting rods must bechecked for cracking, twisting, and bending, as shown in I6.s #.%$ and #.%% /onnectingrod large end bearings are sub>ect to e&cessive and uneven wear.

+I*' 2'12 )AMA*E) CONNECTIN* RO)

+I*' 2'1, T/ISTE) AN) CANTE) RO)S +I*' 2'11 BEN) RO)

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&1', OIL PUMP ASSEMBL8

The oil pump assembly consists of the oil pump, oil regulator, oil pressure failure control,oil strainers and suctions, oil screens, and oil passage (both drilled holes and piping).These components are shown in I6. #.% The oil pump assemblylubricates the compressor by both splash and pressure lubrication. The oil pump in most

compressors, as shown in I6. #.%G is a simple vane and rotor mechanismlocated in the pump-end main bearing housing. *il is pumped through the drilled holes inthe crankshaft to bearings and >ournals. It is also splashed onto cylinder walls, pistons,and connecting rods by the spinning movement of the crankshaft. This splashing creates afine oil mist which clings to the compressor?s internal components.

+I*' 2'1 OIL PUMP ASSEMPLA8

". 8 320 B3A5I26 93A0#. 13 S36'32T$. 330 64I03 1A23%. 64I03 1A23 S85I26. /*135 8AT3

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+I*' 2'13 OIL PUMP ASSEMPLA8

The oil pump assembly and lubrication system components are sub>ect to many problems.Among these are oil contamination, flooding, slugging, oil migration, oil passage plugging,foaming, wa& formation, copper plating, and carbon deposits. *ther compressor problemscaused by inadequate lubrication include piston scuffing and burning, cylinder wallscoring, bearing failure, and compressor overheating.

&1'1 MOTOR ASSEMBL8

The motor assembly is composed of the stator, rotor, and terminal plate, as shown inI6. #.%

The compressor motor converts electric power into the rotary or circular motion of therotor. The spinning rotor turns the crankshaft assembly.The motor assembly is sub>ect to overheating, burned windings, nicks, and burrs on therotor that can hang up on the stator, peeling lamination, electrical shorts, and faulty wiring.

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+I*' 2'19 REMOVIN* ROTOR

&1' CRAN=S.A+T ASSEMBL8

The crankshaft assembly is made up of the crankshaft, pump-end, and motor-end mainbearings. See I6. #.%D

+I*' 2'1: CRAN=S.A+T ASSEMBL8

The crankshaft, together with the connecting rods, changes the rotary motion of theelectric motor into the reciprocating motion of the pistons. The crankshaft is sub>ect tocracking, warping, scoring, plugging of its drilled oil holes, copper plating, and uneven

>ournal and main bearing wear. An e&ample of a badly scored connecting rod >ournalcaused by oil hole plugging is shown in I6. #.%K

+I*' 2'1< )AMA*E) CRAN=S.A+T

&'( MEASURIN* INTERNAL MEC.ANICAL COMPONENTS

In this section we will look at the internal components which must be checked andmeasured to insure they are within the manufacturer?s wear limits.

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&'& VALVES

Suction and discharge valves are measured with an outside micrometer, as shown in I6.#.E To measure the diameter of a suction valve, place the valve between the end of thespindle and the anvil, as shown in I6.#.E Turn the thimble gently tomove the end of thespindle toward the valve. The valve should be touched lightly on one side by the anvil andon the other side by the end of the spindle. 2ever turn the spindle tight against anything.

This will ruin the micrometer. Turn the thimble until thespindle almost touches the valve. Then use the ratchet stop.

+I*' 2'( MEASURIN* A SUCTION VALVE

To read the micrometer add the numbered lines and intermediate lines e&posed by thethimble. To this sum add !he value of the thimble line that is even with (or slightly below)the reading line. Their total is the micrometer reading. 4se the micrometer reading shownin I6. #." as an e&ample!2umbered lines (on hub) # & E."EE M E.#EE inch

Intermediate lines (between numbers) # & E.E# M E.EE inchThimble lines (around thimble) " & E.EE" M E.E" inch'icrometer reading M E.#G inch

+I*' 2'& MICROMETER REA)IN*

&'2 C8LIN)ER .EA) VALVE PLATE AN) C8LIN)ER )EC= STRAI*.TNESS

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The cylinder heads, valve plates, and cylinder decks are sub>ect to warping from hightemperature and pressure. They must be checked for straightness, as shown in I6. #.#To check this lay a precision steel ruler across the face of each component. See if a bladefrom the thickness gauge fits between the ruler and the face of the cylinder head, valveplate, and cylinder deck.

+I*' 2'2 C.EC=IN* C8LIN)ER )EC= STRAI*.TNESS

&', PISTONS

8istons are sub>ect to scoring, scuffing, and cracked and collapsed skirts. They must bemeasured for wear and ovality. These measurements are made with an outside

micrometer, as shown in I6. #.$'easurements at right angles are made above the ring grooves and below, on the pistonskirt. The measurements are recorded, then compared with cylinder bore measurementsto calculate piston clearance and wear.

+I*' 2', MEASURIN* A PISTON

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&'3 CONNECTIN* RO) AN) CRAN=S.A+T JOURNAL

The collecting rod big end bore and its crankshaft >ournal must be measured forclearance, ovality, and taper. These measurements are made with an inside and outsidemicrometer, and 8lastigage. /rankshaft >ournals should be measured with an outside

micrometer for both vertical and horiontal taper and ovality at locations.AT 3A/9 320 * N*452A

A vs B - 135TI/A TA835/ vs / - 9*5IO*2TA TA835

A vs / and B vs 0 - *4T-*-5*420/93/L *5 *4T-*-5*420

+I*' 2'3( MEASURIN* CRAN=S.A+T JOURNAL

The big end connecting rod bore should be measured for ovality with an inside micrometer

at three different positions, GE degrees apart, as shown in I6. #.G" *vality can also bemeasured with the ederal 'ogul gauge shown in I6. #.G#

+I*' 2'3& +I*' 2'32

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MEASURIN* CONNECTIN* RO) C.EC=IN* CONNECTIN* RO)BI* EN) BORE BI* EN) OVALIT8

The clearance between the connecting rod big end bore and its >ournal is measured with8lastigage. A strip of 8lastigage is placed across the width of the bearing on theconnecting rod cap, about "ected to considerable torsional stress, particularly during cold startsand slugging. These stresses can cause the crankshaft to bow out of alignment./rankshaft alignment is measured with a dial indicator, as shown in I6. #.GTo check crankshaft alignment, place the crankshaft in 1 blocks on a surface plate ortable. 'ount a dial indicator ad>acent to the main >ournals, as shown in I6. #.GG 8lace

the contact point of the dial indicator against the crankshaft >ournal. Ad>ust the stand of theindicator until you see the indicator?s needle move around the dial. 5otate the beelserrations until the needle is aligned with the ero (E) mark on the dial. 5otate thecrankshaft slowly in the 1 blocks. =atch the dial indicator. 1ariations in the readings willindicate whether the crankshaft is out of alignment. 3very mark on the dial equals E.EE"inch.

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+I*' 2'3 C.EC=IN* CRAN=S.A+T ALI*NMENT

&'< T.RUST /AS.ER

The thrust washer?s thickness is measured with an outside micrometer, as shown in I6.#.GG

&'&( CRAN=S.A+T EN) CLEARANCE

/rankshaft end clearance is measured with a thickness gauge when the crankshaft isreinstalled in the compressor housing.

+I*' 2'33 MEASURIN* T.RUST /AS.ER

&3'( SPECIAL PRECAUTIONS

". =ear gloves to remove the stator if you heat the motor case.#. Take e&tra care when removing safety heads. There may be a large spring underneath.

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&9'( TOOLS AN) MATERIALS

Air-acetylene station 'ultimeter/lean A/5 oil 8lastigage/rack detection fluid Semi-hermetic, multi-cylinder compressoreeler gauges Standard set A/ hand tools

Nackscrew Surface plate or table'egohmmeter Torque wrench.'icrometer

&:'( EERCISE A" )ISASSEMBLE COMPRESSOR

". 8ump down compressor.#. 0isconnect and lock out electric power.$. 0rain oil.%. 5emove cylinder head


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+I*' 2'3: )O/EL PINS IN C8LIN)ER )EC=

"". To remove the valve plate, remove one of the valve stop cap screws. Swivel thevalve stop to allow access to the hole from which the cap screw was removed.5einsert the cap screw and tighten to break the seal. Tightening the valve stopcap screw lifts the valve plate from the compressor (I6.#.GK) .

"#. 5emove suction valves and backers from the dowel pins."$. 5epeat the procedure on the other cylinder heads and valve plate assemblies.

+I*' 2'3< BREA=IN* VALVE PLATE SEAL

&:'& REMOVE CRAN=CASE BOTTOM COVER PLATE

". 5emove the crankcase bottom cover plate (I6. #.E) .#. 5emove the oil filter screen.

$. /heck the screen for breaks or tears and for foreign matter such as pieces ofmetal, grit, etc.

&:'2 REMOVE PISTONS AN) CONNECTIN* RO)S

". /heck cylinders for are worn enough to ridges. If ridges catch your fingernail underthem, the cylinder must be rebored before removing the piston assembly (I6.#.")

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+I*' 2'9( REMOVIN* COVER PLATE AN) OIL SCREEN

+I*' 2'9& C.EC=IN* +OR C8LIN)ER RI)*E

#. 'atch mark the connecting rods and connecting rod caps.$. oosen and remove the connecting rod cap bolts.%. 5emove the connecting rod cap. 'ake sure the rod cap bearing liner stays with the

rod cap.. 8ush the piston connecting rod assembly up through the top of the cylinder bore.

'ake sure the connecting rod bearing liner stays with the connecting rod.G. 8lace the piston and connecting rod assembly on the bench with the rod cap. Leep

all of the same cylinder parts together (I6.#.#) .. 5epeat the procedure for all the pistons.D. 'atch mark the connecting rod to the piston.

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#. Bend rotor lock washer tab backward and remove rotor lock bolt (I6. #.% ).$. If the crankshaft turns, preventing the bolt?s removal, place a rubber plug on top of one

of the pistons. 5eplace the valve plate and cylinder head. 4se two bolts to hold thehead in place. 8roceed to remove the lock bolt, lock washer, and plate (I6. #. ).

+I*' 2'91 Re%o7e rotor

+I*' 2'9 r6!!er #60 in $;inder

&:' REMOVE CRAN=S.A+T

". 5emove si& of the eight bolts which hold the pump end bearing head to thecrankcase. oosen the remaining two bolts two or three turns. The two remainingbolts should be opposite each other.

#. Tap lightly on the bearing head with a mallet to break the gasket seal. 5emove thebearing head.

$. 5emove the thrust bearing from the crankshaft end.%. 8ull the crankshaft out through the pump end opening.

&:'3 REMOVE STATOR

". 5emove the acorn nut and washer (I6. #.G) .#. Back out the locking pin and bushing.

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$. 5emove the >unction bo& from the terminal plate.%. 5emove the cap screws holding the terminal plate to the compressor.. 'ark all motor leads for correct reassembly.

+I*' 2'93 REMOVE STATOR

G. oosen the screws holding the motor leads to the terminal plate.. 5emove the terminal plate.D. Slid the stator out. If necessary, heat the crankcase motor housing with an

air-acetylene torch to between #E and $E degrees ahrenheit above the stator?stemperature. This will e&pand the housing enough to allow you to remove thestator.

&


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/lean parts with a solvent recommended by the manufacturer. 0o not use solvents orcleaners that attack aluminum or the metals used in the bearings.8ut the cleaned components on a clean workbench and cover them with clean workcloths. 0o not mi& parts from one valve or cylinder group with another. =hilecleaning the parts, inspect them visually for scuffing, scoring or other unusual wear.

2('& CLEAN AN) INSPECT STATOR

". /heck the stator for damage to windings and wires.#. 4se a megohmmeter to check for grounds.$. 4se a multimeter to check winding resistance.

2('2 CLEAN AN) INSPECT T.E ROTOR

". /lean the rotor thoroughly with solvent.#. /heck the rotor for loose laminations and signs of rubbing, scuffing,or overheating.$. /heck for knicks, burrs, or other rough spots that might hang up on the stator.

2(', CLEAN AN) INSPECT T.E CRAN=S.A+T

". 8ut the crankshaft on a 1-block stand. /lean the crankshaft.$. /heck oil passages for clogging. 5emove the oil plugs and clean the oil passages

thoroughly. Blow them out with compressed air.%. Inspect the main and connecting rod >ournals for damage, copper plating, scoring,

or burrs.. 4se a dye-penetrant to check for cracks.

2('1 CLEAN AN) INSPECT T.E CONNECTIN* RO)S

". /lean the connecting rods, connecting rod caps, and bolts, leaving the bearings inplace.

#. /heck bearings for wear, pitting, scoring, corrosion, or signs of fatigue.$. /heck each connecting rod for twisting, bending, or other damage.%. 4se a dye-penetrant to check for cracks.

2(' CLEAN AN) INSPECT PISTONS

". Soak the piston in solvent to loosen carbon deposits. /lean the entire piston,including inside the skirt.

#. /lean the piston ring grooves. A stiff brush or an old piston ring can be used to

scrape out the carbon in the grooves.$. /heck the piston grooves and lands for cracks, nicks, and burrs.%. /lean the oil return holes in the oil control wiper ring groove.. /heck the piston skirt for scoring, grooves, cracks, discoloration, and abnormalwear.G. /heck the wrist pin hole for elongation and other signs of wear.

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2('3 CLEAN AN) INSPECT OIL PUMP ASSEMBL8

". /lean the pump end bearing head, oil pump assembly, pressure regulator, oilscreen, and sump straining in solvent.

#. /lean the oil lines with a small, round, stiff-bristled brush and solvent. Blow out thetubes with compressed air.

$. /heck all parts for wear and damage.

%. /heck the oil feed guide vane spring and the pressure regulator spring for tension.

2('9 CLEAN AN) INSPECT VALVES AN) VALVE PLATES

". /lean the cylinder heads, valve plates, and valves in solvent. 4se a stiff-bristledbrush on carbon deposits. Be sure to keep the component parts for each cylinderseparate.

#. As you clean, check for broken or bent valves.$. /heck cylinder heads, valve plates, and valves for abnormal carbon and sludge

buildup.%./heck the cylinder heads and valve plates for cracks using the dye-penetrant

method.

2(': MEASURE VALVE T.IC=NESS

". 'easure suction and discharge valve thickness with an outside micrometer. 5ecordthe measurements. /ompare them with the manufacturer?s limits for ma&imumallowable wear.

2('< C.EC= C8LIN)ER .EA) STRAI*.TNESS

". 'easure straightness across the face of the cylinder head and cylinder deck with aprecision steel ruler and thickness gauge.

2('&( MEASURE PISTON /I)T.' OVALIT8 AN) TAPER

". /heck pistons for ovality and taper with an outside micrometer.#. 5ecord piston outside diameter. /ompare with the manufacturer?s limits for

ma&imum allowable wear. Save piston diameter measurements for use incalculating piston-cylinder clearance.

2&'( EERCISE )" MEASURE COMPRESSOR COMPONENTS

/*'853SS*5 8A5TA/T*5+T*. (in.) 'A;I'4'

A*=AB3=3A5? (in.)

'a& 'in

'*T*5 320'ain Bearing 0iameterNournal 0iameter

".DGE-

-".D#

E.EE"P

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84'8 320'ain Bearing 0iameterNournal 0iameter

".G#GE-

-".G#$$

E.EE"P

/*223/TI26 5*0Bearing 0iameter(After Assembly)

/rank pin 0iameter

","

-

-

".%D$

E.EE#P

T954ST =AS935(Thickness) - E." -

/+I2035SBore8iston 0iameter=rist 8in 0iameter/on. 5od =rist 8in I08iston 5ing 3nd 6ap8iston 5ing Side

/learance

#.GDD--

E.DE.EEE.EE$

-#.GD"E.D%D

-E.EE#E.EE"

E.EE#E.EE#E.EE"E.EE"E.E"E.EE#

1A13T9I/L23SS

Suction0ischarge

E.E$" E.E$EE.EE#E.EE#

E.E# E.E#%E.E## E.E#"

320 /3A5A2/3 E.E$" - E.E"E

P'a&imum allowable wear above ,ma&imum or below minimum

factory tolerances shown. or e&ample! difference between mainbearing diameter and >ournal diameter is .EE$ in. (".DGE -".D#) per factorytolerances. 'a&imum allowable difference is .EE% in. (.EE$ Q .EE").TAB3 *23 /A55I35 /*'853SS*5 =3A5 I'ITS

22'( MEASURE C8LIN)ER )IAMETER OVALIT8 AN) TAPER

". 'easure cylinder diameter with inside micrometer. 5ecord the measurements.#. 4sing piston diameter and cylinder bore width measurements, calculate

piston-cylinder clearance. Subtract piston diameter from cylinder bore width./ompare the results with the manufacturer?s allowable wear limits.

$. /heck cylinder for wear, ovality, and taper with inside micrometer and dial indicator.

22'& MEASURE RIN* /I)T.' *ROOVE CLEARANCE' RIN* *AP

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". 'easure ring width with an outside micrometer.#. 'easure ring side clearance with a ring and thickness gauge. 5ecord the results

and compare them with the manufacturer?s allowable wear limits.$. 'easure ring gap at the bottom of ring travel in the cylinder with a thickness gauge.

5ecord the results and compare them with the manufacturer?s ma&imum andminimum clearances.

22'2 MEASURE PISTON PIN AN) CONNECTIN* RO) CLEARANCE

". 'easure piston pin outside diameter and connecting rod small end bore insidediameter with a vernier caliper, or outside micrometer and telescoping gauge.5ecord the results.

#. /alculate the clearance. /heck to see if the measurements are within themanufacturer?s allowable wear limits.

$. /heck the wrist pin for unusual wear and ovality.%. /heck the connecting rod small end bore for ovality.

22', MEASURE CONNECTIN* RO) AN) CRAN=S.A+T JOURNAL CLEARANCE

". 'easure the crankshaft >ournal outside diameter with an outside micrometer. Alsomeasure the connecting rod large bore inside diameter (with bearing) with aninside micrometer. 5ecord the results.

#. 4se 8lastigage to measure the clearance between the >ournal and the connectingrod bearing. 5ecord the results.

$. /ompare the results of the micrometer measurements with that of 8lastigage. 9owwell do they agreeR Are they within the manufacturer?s allowable wear limitsR

%. /heck the >ournals for taper and ovality.

22'1 MEASURE CRAN=S.A+T AN) MAIN BEARIN* CLEARANCE

". 'easure the outside diameters of the crankshaft >ournals and the inside diametersof the main bearings with an outside micrometer and telescoping gauge. 5ecordthe results. /alculate the clearance. Is it within the manufacturer?s allowable wearlimitsR

#. /onfirm your micrometer measurements with 8lastigage. 0o the results of the twomeasurement techniques agreeR

$. 'easure crankshaft >ournal for taper and ovality with the outside micrometer.

22' C.EC= CRAN=S.A+T ALI*NMENT

". 'easure crankshaft alignment or straightness with a dial indicator.

22'3 MEASURE T.RUST /AS.ER

". 'easure thrust washer thickness with an outside micrometer. 5ecord the results. Isthe washer measurement within the manufacturer?s allowable wear limits.

#. /heck results with a dial indicator.

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21'( INSTALL MOTOR AN) CRAN=S.A+T

". Install stator halfway into housing.#. Insert the terminal leads first.$. 0o not push the stator in completely until the rotor is in place.%. Be sure the compressor end bearing washer is in place on the dowel pin.

. Install the crankshaft through the pump end opening. 6uide it carefully through themain bearings.

G. 3ase the rotor onto the shaft about "unction bo&.

". Install the suction strainer."G. Install the motor end bell gasket.". Install the motor end bell and torque to specifications.

21'& INSTALL PUMP EN) BEARIN* AN) OIL PUMP ASSEMBL8E"

". Install the lightly oiled pump end bearing head gasket.#. 5eplace the pump end bearing head and torque bolts to specifications.$. Install the oil pump drive segment. Torque the large and small set screws to

specifications.%. 5eplace the guide vane and spring. The vane goes in before the spring.. Install the lightly oiled cover plate gasket.G. 5eplace the cover plate and torque bolts to specifications.

21'2 INSTALL PISTON ASSEMBL8

". Install the compression rings in the top piston grooves.#. Install the oil rings below the compression rings, with the ring notch facing the

bottom of the piston.$. Space the ring gaps "DE degrees apart.%. /heck the rings for free action.. /onnect the rod to piston by inserting the piston pin.

G. ock the piston pin in place with retaining rings.. 'ake sure all position identifying marks are in the correct location.D. 0ip the piston head in lubricating oil.K. Insert the connecting rod and piston into the cylinders with each piston positioned

correctly."E. Install the caps to each matching connecting rod. Torque to specifications."". Turn the crankshaft to be sure there is no binding between the bearing surfacesand >ournals.

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21'2 INSTALL BOTTOM COVER PLATE

". Install the oil screen and bottom cover plate.2'

21', INSTALL C8LIN)ER .EA) ASSEMBL8

". Install the lightly oiled valve plate gasket.#. Install the valves and valve plates.$. Install the valve plates.%. Install the cylinder head gasket.

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