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10
SERVICE INSTRUCTIONS, YORK
COMPRESSORS
 
A. GENERAL INSTRUCTIONS
 
10A1. Precautions. The York Balanseal compressors, 2 5/8- and 4-inch bore, are so designed that any competent mechanic can service them in the field. Good judgment should always be used in the analysis of service troubles and specific instructions should be followed as directed.

It is important that the following precautions be observed:

1. Before dismantling the compressor, be sure that the faulty operation of the installation is not caused by trouble in some other part of the system.

2. Dismantle only the part of the compressor necessary to correct the fault.

3. Never open any part of the compressor while it is under vacuum; be sure that there is some pressure inside as indicated by a reading above zero on the gage. Be sure that the gage is accurate. If any part of the system is opened while under vacuum, that is, when the pressure inside is lower than the pressure

  outside, air will enter the system. This air nearly always contains some moisture, which freezes and interferes with the operation, or even causes damage. It is also important that air or moisture be prevented from coming in contact with machined parts after they have been exposed to Freon 12.

4. Internal machined parts of the compressor, such as the valves, pistons, shaft seal, and crankshaft, must be protected from the atmosphere immediately upon being removed from the compressor. Corrosion occurs quickly if this precaution is neglected. As soon as removed, each part must be wrapped in paper.

5. IMPORTANT. To disassemble or reassemble the compressor, use only the tools specified for the particular operation involved.

10A2. Direction of rotation. The shaft seal on submarine installations is designed for counterclockwise rotation of the compressor as viewed from the flywheel end. The compressor must not be operated in the opposite direction.

 
B. OPENING COMPRESSOR FOR REPAIRS
 
10B1. Pumping down for repairs. Before opening a compressor for examination or repair, it is necessary to pump down the system.

a. Pumping Freon 12 out of the compressor. To pump Freon 12 out of the compressor, proceed in the following manner:

1. Close the suction stop valve.

2. If the compressor is operated normally under suction pressure control, block the suction pressure switch in its running position. This can be done without disturbing the adjustment. Open the compressor discharge valve about two turns of the stem.

4. Start the compressor and let it run until the greatest vacuum possible is obtained.

5. Stop the compressor and immediately close the discharge stop valve. The procedure

  outlined in Step 4 and the first part of Step 5 should be repeated if the pressure indicated by the suction gage rises rapidly to 15 psi or more above zero pressure, for such a rise indicates that considerable Freon 12 remains in the crankcase oil. Do not expect to retain zero pounds' pressure on the suction gage, because Freon 12 vapor is continually released from the oil in the crankcase.

6. After the vacuum is pumped, wait until the pressure builds up to 2 or 3 pounds above zero pressure before opening any part of the compressor or its connections.

7. Before proceeding with any work on the compressor, see that the main disconnect switch is open. After examination or repair, remember to unblock the suction pressure switch before resuming operation.

 
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b. Evacuating air from the compressor. To evacuate air from the compressor after completing its reassembly, proceed as follows:

NOTE. During examination or repair, the compressor suction and discharge stop valves have been closed to trap the Freon 12 charge in the system.

1. Break the discharge gage valve line to the atmosphere.

  2. Start the compressor and let it run until the greatest vacuum possible is obtained.

3. Stop the compressor and immediately crack the suction stop valve to blow Freon 12 gas through the compressor valves and purge the air above the discharge valve through the open gage line. Then close the discharge gage line and the suction stop valve.

 
C. COMPRESSOR VALVES
 
10C1. Indications of faulty valves. Faulty compressor valves in the air-conditioning compressors may be indicated either by a gradual or sudden decrease in the expected compressor capacity. Either the compressor fails to pump at all, or the suction pressure cannot be pumped down to the proper pressure. This causes the compressor to run for prolonged periods, or even continuously. Short shutdown periods may indicate leaky compressor valves, if the faulty operation is not caused by any of the conditions listed above.

10C2. Analysis of faulty valves. Before opening a compressor for valve inspection or replacement, the auxiliary man should be definitely sure that the faulty operation of the system is caused- by the valves. Therefore, before assuming that the compressor valves must be serviced, carefully check each of the following possible causes of trouble:

1. Be certain that the Freon 12 system is fully charged.

2. Be certain that the expansion valve is in a normal operating condition.

3. The suction pressure cutout switch should be adjusted to stop the compressor when the suction pressure drops to 2 psi; the compressor should not start until the pressure setting at which it should start the compressor, 20 psi, is reached.

4. The temperature control switch (room type thermostat), provided for the purpose of cutting off refrigeration in the rooms when the desired temperature has been reached, closes the solenoid valve and stops the admission of liquid to the evaporator.

5. The compressor motor should be run at its rated speed. A low speed reduces the capacity of the compressor.

  The compressor should not be opened for inspection until each of the above possible sources of faulty operation has been eliminated. The correct method of disassembling and reassembling each part of the compressor is outlined below under the respective headings.

10C3. Compressor discharge valves. There is no satisfactory field method of analyzing the efficiency of the compressor discharge valves. except by the process of elimination. The serviceman must analyze and eliminate all possible sources of trouble in other parts of the system before opening the compressor for valve inspection or replacement.

10C4. Removing the discharge valve assembly. To remove the discharge valve assembly, proceed as follows (see Figures 7-3 and 7-4):

1. Pump out the compressor.

2. Remove the cylinder head (7), using care not to damage the thin metal gasket (41). Do not use a screwdriver or similar tool to pry off the cylinder head. Tapping the head lightly around the edge helps to loosen the joint. As the cylinder head is lifted, the gasket may adhere to both the head and the discharge valve plate (8). Use a knife blade or other flat instrument to help release the gasket.

3. Remove the capscrews (48) that hold the discharge valve plate and lift off the valve assembly, using the same precaution with the gasket (40) as explained in Step 3 above.

4. Handle the gaskets with care, placing them aside where they will not be damaged. The same gasket (40), or one of exactly equal thickness, must be used in replacing the discharge valve assembly. This is important because the thickness of this gasket determines the clearance between the valve plate and the

 
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piston when at the top of its stroke. This clearance is only a few thousandths of an inch.

10C5. Disassembling the discharge valve assembly. Whenever the discharge valves are found to be defective, replace the entire discharge valve assembly with a new one and return the defective assembly to a tender or base for repair. Generally, if the valve operation is faulty, the valve plate as well as the valve diaphragm is defective; if the valve diaphragm is broken, the valve plate will be scratched or marred. In either case, the valve seats on the discharge valve plate must be relapped. This lapping process requires highly specialized machinery and cannot be done in the field.

If disassembling the discharge valve assembly cannot be avoided, proceed as follows (see Figures 7-3 and 7-4):

1. Remove the cotter pin (12) from the valve bolt (9).

2. While loosening the castellated nut (11), hold the valve bolt with a wrench on the fiat projection above the nut. Take care that the wrench does not slip and damage the valve or valve plate.

3. Note that the valve diaphragm (13) seats on two narrow concentric surfaces machined on the valve plate. These surfaces are very finely lapped and must not be scratched.

4. Note that the gasket (9A) seals the joint between the valve bolt and the under side of the discharge valve plate.

10C6. Reassembling the discharge valve. In reassembling the discharge valve, proceed in the following manner (see Figures 7-3 and 7-4):

1. Thoroughly wash each individual part in approved cleaning solvent, giving a final rinse in approved cleaning solvent, and dry in air without wiping.

2. Place the first valve diaphragm (13) in position on top of the discharge valve plate, with the concave side down.

3. Place the diaphragm spacer (14) on top of the first valve diaphragm.

4. Place the second valve diaphragm on top of the spacer with concave side up.

5. Place the third valve diaphragm on top of the second valve diaphragm with concave side down.

  6. Place the valve bolt washer (10) in position with the rounded edge of the washer against the valve.

7. See that the holes in the discharge valve diaphragms are in alignment while the assembly is being tightened.

8. Draw the castellated nut firm with a 6 inch wrench, holding the flat projection above the nut with another wrench. If the cotter pin hole through the nut does not match the hole in the valve bolt, try another nut if available; otherwise dress the face of the nut with fine emery cloth. Care must be exercised not to put too much strain on the valve bolt.

10C7. Installing the discharge valve assembly. In installing the discharge valve assembly, proceed in the following manner (see Figures 7-3 and 7-4):

1. Thoroughly wash the valve assembly in approved cleaning solvent. Give the valve assembly a final rinse in approved cleaning solvent, and dry in air without wiping.

2. Clean the gaskets, the surface on top of the cylinder, and the cylinder head. 3. Place the proper thin metal gasket (40) in position on top of the cylinder.

CAUTION. The thickness of this gasket determines the clearance between the top of the piston at the top of its stroke and the bottom surface of the discharge valve plate. For this reason it is important to use either the original gasket or a new gasket whose thickness is the same as the original. These gaskets are available in three thicknesses: 0.010 inch, 0.015 inch, and 0.020 inch. When the discharge plate gasket (40) is in position on top of the cylinder block, check the clearance between the surface of the gasket and the suction valve when the pistons are at the top of their stroke. The clearance between the top surface of the gasket and each suction valve should be 0.015 to 0.025 inch for the 2 5/8-inch compressor, and 0.015 to 0.030 inch for the 4-inch compressor.

4. Place the discharge valve assembly in position, making sure that the port through the plate coincides with the cylinder discharge port.

5. Fasten the valve plate with the two capscrews (48), using a wrench with a leverage that does not exceed 9 inches.

 
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6. Place the cylinder head gasket (41) and cylinder head (7) in position, making sure that no dirt has fallen on the discharge valves. Tighten all cylinder head capscrews evenly, to insure a tight joint and to prevent distorting the cylinder head or twisting off the capscrew heads.

IMPORTANT. To insure a tight gasket joint between the cylinder head and the discharge valve plate without an excessive strain on the cylinder head capscrews, see that the gasket surface on the cylinder head is flat. To determine whether the cylinder head gasket surface is flat, place the cylinder head on a surface plate and test the flatness with a 0.0015-inch thick feeler gage. If the gasket surface of the cylinder head is uneven, use a new cylinder head. If no new cylinder head is available, resurface the gasket surface by hand scraping.

7. Break the discharge gage valve line to the atmosphere. Crack the suction stop valve to blow Freon 12 through the compressor valves, and purge the air out through the open gage valve. Close the discharge gage valve line and the suction stop valve. Then close the discharge gage valve line and the suction stop valve.

8. Open the discharge stop valve and test for leaks.

9. If there are no leaks, open the suction stop valve, and the compressor is ready for normal operation.

10C8. Compressor suction valves. The compressor suction valves may be checked for leakage in the following manner:

1. Close the suction stop valve.

2. Start the compressor.

3. Continue to run the compressor by blocking the suction pressure control switch in the running position. This may be done by means of a screwdriver placed under the main operation lever. If a vacuum of approximately 20 inches can be readily pumped, as indicated by the suction gage, the compressor suction valves are satisfactory.

NOTE. A vacuum cannot be maintained after the compressor stops, because of the Freon 12 being released from the oil in the crankcase.

Do not attempt to check the compressor

  suction valve efficiency until after the compressor has been in operation for a minimum of three days, as it may be necessary for the valve to wear in.

10C9. Removing the suction valve assembly. To remove a compressor suction valve, proceed in the following manner (see Figures 7-3 and 7-4):

1. Pump out the compressor.

2. Remove the cylinder head (7).

3. Remove the discharge valve plate assembly (8).

4. Rotate the flywheel until the piston-from which the suction valve is to be removed is about 1 inch below the top of the cylinder, so that the screwdriver bushing may be inserted in the cylinder bore.

5. Use the T-handled screwdriver with its guide bushing, and remove the valve screw (25).

6. Rotate the flywheel until the piston is at top dead center and remove the valve diaphragms (13A) and the diaphragm spacer (14).

7. Tag each part as it is removed, so that the parts can be replaced in their original position.

10C10. Inspection of the suction valve assembly. In inspecting the-suction valve assembly, proceed in the following manner:

1. Examine the valve seats on the piston and the valve diaphragm. If either of the narrow concentric valve seats on top of the piston is marred, the piston must be replaced.

2. Examine the suction valve screw. If the head is not perfectly round and free from burrs on the underside and edges, it must be renewed. A flat side on the screw head is apt to cause the valve to break.

NOTE. If a suction valve has been broken, a new suction valve screw should be used with the new valve.

3. Before replacing a broken suction valve; be certain that all the small pieces of the broken valve are accounted for; if necessary, remove the cylinder. Small pieces of the broken valve may drop through the suction valve port in the top of the piston and lodge in the cylinder, in the trunk of the piston, or in the suction connection between the strainer and the cylinder. If these pieces are not removed, the piston and cylinder surfaces will be damaged, and the new suction valves may be cut or broken when

 
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the pieces are drawn through the compressor valves. To protect the compressor against such damage, the cylinder and suction strainer should be removed, and the internal parts thoroughly cleaned. Particular care should be taken to clean the suction connection between the suction strainer body and the compressor cylinders.

NOTE. If a suction valve is only cracked, or all the parts of a broken valve can be found, it is not necessary to remove the cylinder.

10C11. Installing the suction valve assembly. In installing the suction valve assembly, proceed as follows (see Figures 7-3 and 7-4):

1. Thoroughly wash each individual part in approved cleaning solvent, giving a final rinse in approved cleaning solvent, and dry in air without wiping.

2. Place the first valve diaphragm (13A) in position on top of the piston with the concave side down.

3. Place the diaphragm spacer (14) on top of the first valve diaphragm.

4. Place the second valve diaphragm on top of the spacer with concave side up.

5. Place the third valve diaphragm on top of the second valve diaphragm with the concave side down.

6. Install the suction valve screw (25) through the center hole of the valve diaphragms, and screw into the head of the piston by hand. The suction valve screw may fit tightly the full length of its threads. With screwdriver bushing in place, firmly seat the valve screw with the T-handled screwdriver. Use careful judgment in tightening this screw.

7. Closely examine the head of the suction valve screw and remove all traces of burrs from it. Do not file, scrape, or grind off the burrs because of the danger that emery dust or metal filings may get into the cylinder. Peen the

  burrs down with a light hammer or small steel rod. This insures a clean job and does not impair the strength of the screw as would filing or grinding.

8. Install the discharge valve plate assembly (8).

9. Replace the cylinder head (7) and prepare the compressor for operation.

10C12. Discharge valve plate gasket data. The table below indicates the thickness of the discharge valve plate gaskets required when the pistons are flush with or below the top of the cylinders. This table is to be used only when installing lead-coated copper gaskets. Take indicator readings as close as possible to the suction valve screw.

2 5/8-INCH COMPRESSOR

Piston flush with top of cylinder, use one 0.015 gasket.

Piston flush to 0.005 below top of cylinder, use one 0.015 gasket.

Piston 0.005 to 0.010 below top of cylinder, use one 0.010 or one 0.015 gasket.

Piston Clearance with Gaskets in Place

Distance between top of suction valve and a line horizontal with top of discharge valve plate gasket: minimum 0.015; preferred 0.020; maximum 0.025.

4-INCH COMPRESSOR

Piston flush with top of cylinder, use one 0.015 gasket.

Piston flush to 0.010 below top of cylinder, use one 0.015 gasket.

Piston 0.010 to 0.015 below top of cylinder, use one 0.010 or one 0.0.15 gasket.

Piston Clearance with Gaskets in Place

Distance between top of suction valve and a line horizontal with top of discharge valve plate: minimum 0.015; preferred 0.025; maxi mum 0.030.

 
D. COMPRESSOR CYLINDERS
 
10D1. Removing the cylinders. In removing the cylinders, proceed in the following manner (see Figures 7-3 and 7-4):

1. Pump out the compressor.

2. Disconnect the discharge piping at the compressor.

3. Disconnect the suction piping at the compressor.

  4. As soon as each connection referred to in Steps 2 and 3 is disconnected, close all openings to prevent air and dirt from entering.

5. Carefully wipe all dirt from the cylinders and around the capscrew heads so that none is apt to fall into the crankcase when the cylinder is removed.

6. Remove the discharge valve assembly.

 
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7. Rotate the flywheel until one of the pistons is at the bottom of its stroke.

8. Unbolt the cylinder from the crankcase and blow off all dirt or paint that may have been loosened in removing the capscrews.

9. Raise the cylinder enough to insert a knife blade or other fiat instrument to help release the gasket (38) from the cylinder. If the cylinder is removed without this precaution, the gasket may be torn. A new gasket of equal thickness must be used when the cylinder is again installed, because the thickness of this gasket assists in determining the clearance between the top of the piston, when at the top of its stroke, and the bottom of the discharge valve plate.

10. Slowly lift the cylinder straight up, and at the same time support each piston as, it leaves the cylinder bore. If an auxiliary man must do this without assistance, he should pull the cylinder toward him as it is raised, so that each connecting rod rests against the crankcase as it leaves the cylinder. This is important, as the pistons are liable to be damaged if permitted to fall against the edge of the crankcase,

CAUTION. When lifting the cylinder off the pistons, be careful not to twist it, as this is liable to bend the connecting rods; a slight twisting motion exerts considerable bending force because of the leverage on the rods,

11. Place the cylinder on a clean sheet of paper or on a clean bench.

10D2. Installing the cylinders. In installing the cylinders, proceed in the following manner (see Figures 7-3 and 7-4):

1. Thoroughly wash all parts in approved cleaning fluid, rinse clean with approved cleaning fluid, and permit to dry without wiping.

2. Make sure that all internal parts are properly tightened, that the piston rings are free in their grooves, and that the oil in the crankcase is clean and covers 1/2 to 3/4 of the bull's-eye sight glass.

3. See that the gasket surface on the crankcase is clean, dry, and free of oil.

4. Clean the gasket and place it in position on the crankcase.

CAUTION. The thickness of this gasket assists in determining the clearance between

  pistons and the discharge valve plate. Hence it is important to use a gasket with a thickness, equal to the original. These gaskets are available in two thicknesses, 0.010 inch and 0.015 inch. It is necessary to determine whether the original gasket was 0.010- or 0.015-inch thick. The correctness of the choice of the gasket is further checked when Step 9 is reached.

5. Lubricate the pistons and cylinder bores with new Freon 12 compressor oil, Navy Symbol No. 2135, or its equivalent.

6. Make sure that the suction and discharge connections on the cylinder face in the proper direction to match the adjacent piping; then with the cylinder held directly above the crankcase, lower it to enter the pistons one at a time. No difficulty should be encountered if the piston rings are centered and the highest piston is entered first.

CAUTION. Do not twist the cylinder as it is lowered, because of the danger of bending the connecting rods.

7. After all the piston rings are entered, the cylinder may be pushed steadily down until the locating pins on the crankcase properly center it.

8. Bolt the cylinder to the crankcase, carefully drawing all the capscrews evenly.

9. Place the discharge plate gasket (40) in position on top of the cylinder and check the clearance between the gasket and each suction valve when the pistons are at the top of their stroke. The clearance between the top of the gasket and each suction valve should be 0.015 inch to 0.025 inch for the 2 5/8-inch compressor; and 0.015 to 0.030 inch for the 4-inch compressor.

10. Clean and install the discharge valve plate assembly.

11. Reconnect all the piping connections in the proper manner.

12. Pump the air out of the compressor.

13. Open the discharge stop valve and test all joints that were disconnected.

14. If there are no leaks, open the suction stop valve, and the compressor is ready for normal operation.

15. Wipe the oil from the outside of the compressor. The compressor gaskets may then be examined for oil, as an indication of leakage, the next time the installation is inspected.

 
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E. COMPRESSOR PISTONS
 
10E1. Removing the pistons. For access to the pistons, remove the cylinder. (See Figures 7-3 and 7-4.) There is no locking device on the piston pins. The piston pins are placed centrally in the holes at assembly, so that the two ends are clear. Soft metal plugs are provided in each end of the piston pin, so that if the piston pin works to one side or the other, the soft plugs prevent scoring of the cylinder wails.

1. Remove the cylinder (6).

2. Rotate the crankshaft (26) so that the piston to be removed is at the top of its stroke.

3. Use a wood or soft metal rod to drive out the piston pin (24). It is best to have a rod with a countersunk end to fit the rounded end of the piston pin.

CAUTION. Support the piston centrally and back it up with a wood block while driving out the piston pin, in order to cause no strain on the connecting rod. If this precaution is neglected, the rod may be bent, due to the enormous leverage on the rod which is supported only by the crank pin. Even an imperceptible bend in the rod may be sufficient to cause binding of the piston in the cylinder and subsequent trouble. Also, unless the piston is properly supported, it is apt to bump against the rod and raise burrs on the end of the piston pin bushing.

  4. Place the piston on a sheet of clean paper.

10E2. Installing the pistons. To install the pistons, proceed in the following manner (see Figures 7-3 and 7-4):

1. Rotate the crankshaft (26) until the connecting rod to which the piston is to be attached is at the top of its stroke.

2. Clean the parts thoroughly with approved cleaning fluid, rinse in clean approved cleaning fluid, and permit to dry without wiping.

3. The piston pins (24) are ground to such close tolerance that extreme care must be exercised in lining up the hole in the rod with the hole in the piston, to prevent raising a burr on either the piston pin or the hole in the piston, or the bushing in the rod.

CAUTION. Be sure to support the piston at its middle narrow section and back it up with a wood block while driving the piston pin in to prevent bending the rod, or burring the bushing, as discussed in Section 10E1. The piston pin is shorter than the diameter of the piston; be sure to center the piston pin in the piston so that it clears the cylinder wall on both sides.

4. See that the rings and ring grooves are clean, and that the rings are free and snug fitting in the grooves; then install the cylinder.

 
F. COMPRESSOR CRANKSHAFT
 
10F1. Removing the crankshaft. When it is necessary to remove the crankshaft, the piston, connecting rods, and crankshaft may be removed as a complete assembly. To remove the crankshaft proceed in the following manner (see Figures 7-3 and 7-4):

1. Pump out the compressor.

2. Remove the flywheel (34).

3. Remove the cylinder (6).

4. Remove the shaft seal (31).

5. Unbolt and remove the bearing head (2), using the two jacking screws in the tapped holes provided in the bearing head. While removing the bearing head, keep an even tension on the jacking screws to prevent binding the head in the crankcase. As the bearing head comes loose, support the flywheel end of the

  shaft to prevent damage to the shaft when the weight of the bearing head is supported only by the shaft.

6. While holding the pistons so that none falls against the crankcase and is damaged, slide the shaft forward out of the rear main bearing. Work the flywheel end of the shaft through the opening left by the bearing head, and at the same time raise the rear end of the shaft until it clears the back edge of the crankcase. The assembly may then be lifted out and placed on a sheet of clean paper.

10F2. Installing the crankshaft. To install the crankshaft assembly, proceed in the following manner (see Figures 7-3 and 7-4):

1. See that the inside of the crankcase (1) is clean. Clean all parts with approved cleaning

 
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fluid, rinse in clean approved cleaning fluid, and dry without wiping.

2. Slip the shaft in place in the same way as in removing it.

3. Use the same gasket (39), or one of the same thickness, when installing the bearing head. This gasket determines endwise clearance in the shaft. The gasket for the 2 5/8-inch compressor is minimum 0.007, preferred 0.009, maximum 0.012. The gasket for the 4-inch compressor is minimum 0.009, preferred 0.011, maximum 0.014.

4. Slide the bearing head over the shaft and use particular care to enter it squarely. This bearing head fits with small clearance in the crankcase opening, and time is saved if it is carefully started. While forcing the bearing head into place, tap lightly all around the edge of the head flange. Use two cylinder head capscrews

  to pull the bearing in until the bearing head capscrews engage the thread.

5. As soon as the capscrews engage the thread, use them to draw the head in place, being careful to draw evenly on all screws.

6. While pushing against the flywheel end of the crankshaft, check with a thickness gage the clearance between the face of bearing head (2) and the shoulder on the crank throw. This clearance must not be less than 0.007 inch nor more than 0.012 inch for the 2 5/8-inch compressor; and not less than 0.009 nor more than 0.014 inch for the 4-inch compressor. To adjust this clearance, change the thickness of gasket (39) between bearing head and crankcase.

7. Install the cylinder (6).

8. Install the shaft seal. Do not neglect to adjust the shaft seal if new bearings, shaft, or seal have been installed.

 
G. CONNECTING RODS
 
10G1. Removing the connecting rods. If a connecting rod becomes defective in any way, the complete connecting rod should be replaced with a new one. The piston pin bushing cannot be properly applied to the rod in the field, and no field repair of the crank end bearing should be attempted. These bearings are not adjustable, and any attempt made in the field to fit by filing is apt to result in excessive clearance of incorrect rod lengths, which might cause damage to the compressor valve assembly. To remove the connecting rods, it is advisable to remove the crankshaft assembly. To remove a connecting rod, proceed in the following manner (see Figures 7-3 and 7-4):

1. Remove the crankshaft assembly (26).

2. Remove the piston (21).

3. Remove the connecting rod bolts (16), wire keepers (18), and castellated nuts (11).

4. To loosen the connecting rod bearing cap, insert a drift pin in the dowel pin holes that extend through the rod side of the bearing. Then tap the drift pin.

10G2. Installing the connecting rods. To install the connecting rods, note that the parts of each rod are correspondingly lettered or

  numbered, and proceed in the following manner (see Figures 7-3 and 7-4):

1. Clean all parts with approved cleaning fluid, rinse with approved cleaning fluid, and let dry without wiping.

2. Assemble the rod on the crank pin with the dowel pins properly entered.

3. Draw the connecting rod bolts (16) finger tight only. Then insert drift pin through the holes which extend through the bearing cap and tap lightly on the dowel pins. This locates the cap accurately while the bolts are still loose enough to permit the cap to shift.

4. Tighten the bolts evenly and tap again on the dowel pins. Peen the holes as they were originally, to lock the dowels.

5. If the pin hole in the nut does not align with the hole in the bolt, dress the face of the nut with emery cloth. Do not back off on the nut to align the holes.

6. Attach the piston (21) to the rod (15). NOTE. It may be more convenient to install the crankshaft assembly before attaching the pistons to the rods.

7. Install the crankshaft assembly and complete the assembly of the compressor.

 
H. CRANKSHAFT BEARINGS
 
10H1. Front main bearing. The crankshaft main bearings cannot be repaired. The only   reason for removing either crankshaft main bearing is to replace it with a new one when
 
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it has become worn to such an extent that it no longer gives satisfactory operation.

a. Removing the front main bearing. To remove the front main bearing, proceed in the following manner:

1. Remove the bearing head.

2. With a wood or soft metal rod, drive the defective bearing out of the bearing head.

b. Installing a new front main bearing. To install a new front main bearing, proceed in the following manner:

1. Clean the bearing and head with approved cleaning fluid, rinse with clean approved cleaning fluid, and let dry without wiping.

2. Oil the bearing and hole in the head with new Freon 12 compressor oil, Navy Symbol No. 2135, or equivalent.

3. Carefully enter the bearing squarely in the hole, and be sure that the bearing key, cast on the bearing, lines up exactly with the key way in the bearing head. To do this, lay a steel scale or similar straightedge along the key on the bearing, and scribe a line the full length of the bearing. Enter the bearing with this line placed on the corner of the keyway.

4. Drive the bearing into the bearing head, tapping lightly all around the bore to keep it from binding. While driving the bearing in, use a block of wood to protect the end of the bearing to prevent raising burrs or distorting it. When the bearing is in place, the flange of the bearing must be tight against the bearing head.

  5. Install the bearing head and complete the assembly of the compressor.

10H2. Rear main bearing. To remove the rear main bearing, proceed in the following manner:

1. Remove the crankshaft assembly.

2. Use a blunt chisel to crush the bearing flange near one of the oil grooves. After the bearing is crushed, it may be withdrawn. Use care not to damage the bearing bore in the exchange.

3. Place the new bearing in position, following the instructions given for the front main bearing.

4. Install the crankshaft, and complete the assembly of the compressor.

NOTE. Another method of removing the rear bearing is by using a puller. The puller can be constructed as follows: Use a tap that can be threaded into the bearing and weld a round piece of 1-inch steel stock to it. Thread the other end of the steel rod. The rod should be long enough to extend about 3 inches through the front opening of the crankcase. A cross-bar drilled to fit the 1-inch rod is placed across the front of the crankcase in a horizontal position. Screw the tap into the bearing and take a strain on the rod by screwing a 1-inch nut on the free end of the shaft, taking up very slowly. Care should be taken that the tap is screwed into the bearing far enough so that it does not pull out when tension is applied to the puller.

 
I. OIL SIGHT GLASS
 
10I1. Removing the oil sight glass. The only reasons for which the glass is removed are a broken glass or defective gaskets. If the glass is broken so that pieces may have dropped inside the crankcase, it is necessary to remove the cylinder and clean the inside thoroughly. To remove the oil sight glass, proceed in the following manner (see Figures 7-3 and 7-4):

1. Pump out the compressor.

2. Attach a piece of tubing to the oil drain valve and drain the oil into a bucket. Avoid spilling oil on the deck.

3. Remove the oil sight nut (42), taking

  care not to destroy the spanner wrench slots in the nut.

4. Insert the tip of a knife blade under the washer (43) and gaskets (45) to loosen them.

10I2. Installing the oil sight glass. To install the sight glass, proceed in the following manner:

1. Clean all the parts with approved cleaning fluid, rinse with clean approved cleaning fluid, and let dry without wiping.

2. Arrange the parts as originally assembled and tighten the lock nut.

3. Pump clean oil into the crankcase.

4. Pump the air out of the crankcase.

 
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J. FLYWHEEL
 
10J1. Removing the flywheel. To remove the flywheel, proceed in the following manner (see Figures 7-3 and 7-4):

1. Open the compressor disconnect switch. Remove the V-belts.

2. Unscrew the flywheel lock nut and mount the flywheel puller. Tapped holes are provided in the flywheel hub (34) for the pulley screws.

3. Apply even tension on the screws until the flywheel is free on the tapered shaft. Remove the flywheel and save the Woodruff key.

10J2. Installing the flywheel. To install the flywheel, proceed in the following manner (see Figures 7-3 and 7-4):

  1. Mount the flywheel (34) on the shaft with the Woodruff key (28) in place.

2. Draw the flywheel tight on the tapered shaft by means of the lock nut (27); do not drive the flywheel into place because of danger of damage to the rear main bearing and to the shaft seal adjustment.

3. Be sure that the lock nut is tight. On some compressors, the lock nut is locked by means of a cotter pin (140). If the cotter pin cannot be inserted, remove the nut and dress the face of the nut with emery cloth. Do not back off on the nut to align the cotter-pin holes.

4. Put on the V-belts, and the compressor is ready for operation.

 
K. COMPRESSOR CRANKSHAFT SEAL
 
10K1. The shaft seal. The lubricating oil in the compressor fills the crankcase to a level just above the top of the crankshaft bearings. Therefore, a seal is necessary to prevent the oil from leaking out between the shaft and its bearing.

The rear end of the shaft, that is, the end opposite the flywheel or power end, is completely enclosed by the one-piece crankcase. No oil can leak from this end, so only one seal is needed. (See Figures 7-3 and 7-4.)

The seal mechanism is composed of two parts, a collar (30) rotating with the shaft, and a diaphragm assembly (31). The diaphragm is stationary, being rigidly fixed to the crankcase, and carries a ring similar to the shaft collar. There are really two individual parts to this seal, a rubbing seal part and a non rubbing seal part. They are described separately.

a. Rubbing seal. The contact face between collar and ring, at right angles to shaft axis, is the rubbing seal, the two parts having been accurately lapped together at the factory. Since the ring is stationary, while the collar rotates, the two parts are in contact under pressure. The rubbing contact thus set up between them must be lubricated. Lubrication is facilitated by a spiral line of small pockets or holes bored in the ring face, which insures that oil flowing into the seal is carried properly across the whole contacting face.

  This spiral line of holes will, of course, differ in direction of winding, according to whether the rotation is clockwise or counterclockwise. Submarine installations use counterclockwise rotation. The outermost hole of the spiral must be in the five o'clock position, as observed by the operator facing the flywheel, when the diaphragm is installed. The small amount of oil required to lubricate the rubbing surfaces, after passing the seal, is carried to the compressor base from the seal cover plate by an oil drain pipe (5).

The success of this seal depends upon the accuracy of the machining and lapping together of the two contact surfaces and upon the pressure of the ring against the collar maintained by the diaphragm. The action of the diaphragm in producing this pressure is described in Sections 10K5 and 10K6.

b. Nonrubbing seal. The shaft collar (30) is pressed against a shoulder of the shaft by the spring diaphragm, acting through the seal ring (31). The collar is keyed stationary to the shaft by a small steel ball which projects half way into each. The face between collar and shaft shoulder, that is, opposite the rubbing face, is also a seal, called the nonrubbing seal. This must be an absolute seal, and the collar must therefore be lapped to the crankshaft collar with the greatest care.

10K2. Shaft seal leakage. For the reason explained previously, a small amount of oil

 
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may be expected to seep from the seal. Before compressor is replaced because of apparent oil leakage from the shaft seal, consider the following (see Figures 7-3 and 7-4):

1. Do not use a halide torch to test the shaft seal for Freon 12 leaks. Oil from the seal contains some Freon 12, the release of which causes a false indication if the seal is tested with a halide torch.

2. The oil leakage from the shaft seal may be considered excessive if the compressor requires an additional charge of oil within a period of six months. Before it is assumed that the oil has leaked past the seal, be certain that the design of the cooling system has not caused the oil to be trapped in the evaporator coils. in general, series feed evaporators, or parallel feed evaporators with thermal expansion valves, permit oil to return to the compressor with the Freon 12 gas after the initial oil requirement of the evaporators has been satisfied.

3. If oil occasionally spurts from the shaft seal, the fault is probably due either to the system's hook-up or to the operating conditions rather than to the seal. If this condition occurs, be certain that the arrangement of the system does not permit an excessive accumulation of oil or liquid Freon 12 in the compressor crankcase. Liquid Freon 12 may tend to accumulate in the compressor crankcase when the temperature around the compressor is lower than the temperature in the evaporator coils. This condition may exist during the winter months if the compressor is in an unheated room.

4. IMPORTANT. Do not assume that an apparent accumulation of oil on the compressor base indicates an excessive leakage of oil from the shaft seal. What may appear to be a large quantity of oil from the shaft seal may in reality be some of the condensate from the compressor suction line with a film of oil over it, oil from the compressor motor, or a mixture of both. Rather than judge the shaft seal leakage by the mixture of oil and water on the compressor base, check the compressor crankcase oil level to determine the amount of oil actually remaining in the crankcase. If the oil has not dropped appreciably below the normal

  level, it is safe to assume that the shaft seal is not leaking.

When excessive leakage at the shaft does exist and replacement is necessary, both shaft seal collar (30) and shaft seal assembly (31) must be replaced. Do not attempt to replace one part without also replacing the other. These parts are lapped together and are not interchangeable.

10K3. Removing the shaft seal. To remove the shaft seal, proceed in the following manner (see Figures 7-3 and 7-4):

1. If the shaft seal is broken or permits an excessive leakage of oil, do not attempt to pump out the Freon 12 contained in the compressor, because air containing moisture may be drawn into the system through the damaged seal. When this condition exists, close the compressor suction and the discharge stop valves, and bleed the pressure to the atmosphere through the pressure gage valves.

2. Attach a piece of tubing to the oil drain valve and drain the oil from the crankcase into a bucket. As the oil is saturated with Freon 12, it foams considerably while being drained. Avoid spilling oil on the deck. Leave the oil drain valve open while working on the seal so that Freon 12 escaping from the oil remaining in the crankcase cannot build up a pressure sufficient to blow out the seal unexpectedly while removing it.

3. Remove the V-belts and flywheel (34). NOTE. After removing the flywheel lock nut (140), rotate the shaft until the keyway is on top. This brings the shaft seal collar locating ball (29) on top so that the ball does not drop out and get lost when the seal collar is removed.

4. Unbolt and remove the shaft seal cover plate (4).

5. Carefully remove the shaft seal assembly (31) by grasping it with the fingers. If this assembly is not easily dislodged, work the shaft in and out while tapping lightly all around the edge of the assembly. If this fails to loosen the shaft seal assembly, create a slight pressure in the compressor crankcase by opening the suction or discharge stop valve; press against the seal to prevent it from being blown from the compressor.

CAUTION. When the shaft seal assembly

 
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is removed, the shaft seal collar (30) usually follows it. As the shaft seal assembly is with drawn with one hand, support the shaft seal collar with the other, holding the collar with the thumb and one finger on its edges. Be careful not to drop either part and do not touch the sealing surface of the seal collar or seal ring of the shaft seal assembly. Lay the parts on a sheet of clean paper.

6. Do not disturb the shaft seal diaphragm gaskets (37), except to remove any thin edges that may have been squeezed out.

7. Save the shaft seal collar locating ball (29). If necessary, this ball may be lifted from its socket with a toothpick or any small sharpened piece of wood.

10K4. Repairing the shaft seal. Both the shaft seal collar (30) (see Figures 7-3 and 7-4), and the shaft seal assembly (31) must always be renewed when either is renewed. These parts are furnished in sets and should not be separated.

a. Faulty shaft seal. A faulty shaft seal may be attributed to any one or a combination of the following causes:

1. Ruptured seal diaphragm. This causes the complete failure of the shaft seal, and necessitates replacement of the shaft seal assembly.

2. Dirt between the seal surfaces. Small particles of dirt between the seal surfaces can be readily removed by lapping.

3. Seal surfaces cut or scored. Unless the defect can be completely removed by lapping, the seal assembly (31) and the seal collar (30) must be replaced. The shaft shoulder is hardened; if the ground surface is damaged beyond field repair, the crankshaft (26) must be replaced.

4. Seal surfaces not parallel. To determine whether or not the seal surfaces are parallel, wash the surfaces with approved cleaning fluid, permit them to dry without wiping, apply a small amount of Prussian blue, and then rub the surfaces together. Unless the surfaces can be lapped to form a full contact of color over the whole surface of the seal, the seal assembly (31) and the seal collar (30) should be replaced.

5. Incorrect shaft seal tension. A definite initial deflection of the shaft seal diaphragm is essential to maintain the correct pressure between the seal surfaces.

  b. Lapping the shaft seal collar to the shaft shoulder. To lap the shaft seal collar to the shaft shoulder, proceed in the following manner (see Figures 7-3 and 7-4):

1. Clean the surface of the shaft shoulder with a chamois or hard cloth, saturated with approved cleaning fluid. Wash the shaft seal collar in approved cleaning fluid.

2. Lap the back of the shaft seal collar (30) to the crankshaft shoulder. It is important that this lapping be done carefully and thoroughly because this joint must be an absolute seal.

IMPORTANT. Use levigated alumina, jeweler's rouge, or powdered Bon Ami, mixed with Freon 12 compressor oil, Navy Symbol No. 2135, or equivalent, to form a smooth paste. Use the paste sparingly to avoid getting it into the shaft bearing. As the lapping operation proceeds, use progressively thinner paste until only oil is used. When the lapping is completed, the shaft seal collar should be in position on the shaft, so that the recess for the shaft seal collar locating ball (29) is opposite the corresponding recess in the shaft shoulder.

3. After lapping, thoroughly clean the shaft shoulder with a piece of chamois or clean hard cloth saturated with approved cleaning fluid, and let it dry without wiping. With the shaft shoulder and the shaft seal collar perfectly clean and dry, rub the two surfaces against each other as a final lapping operation. End the final lapping with the shaft collar in position on the shaft so that the recess for the shaft seal collar locating ball (29) is opposite the corresponding recess in the shaft shoulder.

4. The surfaces are properly lapped when the surface of both the shaft shoulder and the shaft seal collar form a perfect contact and are free from scratches or other imperfections. It is preferable to make this examination with the aid of a good magnifying glass.

IMPORTANT. Do not lap a new shaft collar to a new shaft seal ring. This is done at the factory. However, if required, a used shaft seal assembly may be lapped to a shaft seal collar in the same manner as explained earlier.

10K5. Installing the shaft seal. IMPORTANT. The performance and life of the shaft seal depend upon the care with which the following instructions are observed. The importance of the proper diaphragm tension and

 
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the limitations as stated in these instructions should not under any circumstances be over looked.

When assembled, the shaft seal diaphragm must be under a definite tension. This tension depends upon the deflection secured by bolting the shaft seal cover plate (4, Figures 7-3 and 7-4) over the diaphragm with the proper thickness of gaskets (37) in the gasket recess. The thinner the gaskets used, the greater the deflection, and vice versa. The gaskets are available in three normal thicknesses: 0.005 inch, 0.010 inch, and 0.015 inch. However, these gaskets vary from 0.014 inch to 0.016 inch, so that different thicknesses can be secured by combining gaskets of varying thicknesses.

1. If a new shaft seal assembly is used, lap the shaft seal collar (30) to the crankshaft shoulder.

2. Clean the sealing surface of the shaft shoulder with a chamois or hard cloth, saturated with approved cleaning fluid, and let it dry without wiping.

3. Thoroughly wash each part, taking particular care to clean with a matchstick the small holes in the sealing face of the shaft seal assembly (31). Rinse the parts in approved cleaning fluid, and let them dry in air without wiping. Any discoloration on the sealing surfaces of either shaft seal assembly or shaft seal collar should be removed with a soft pencil eraser. These parts must then be washed again in approved cleaning fluid.

CAUTION. After the final rinse, do not touch the sealing surfaces.

10K6. Determining the shaft seal pressure. The action of the diaphragm in producing the required pressure between the seal ring and the seal collar is illustrated in Figure 10-1.

When bolted on, the shaft seal diaphragm must cause the diaphragm ring to press against the shaft collar. This pressure depends upon the deflection given to the diaphragm when the shaft seal cover plate (4, Figures 7-3 and 7-4) is bolted over the diaphragm. The required deflection is the result of having gaskets of the proper thickness in the gasket recess. The thinner the gaskets, the greater the deflection, and vice versa. In Figure 10-1, Sketch A, this deflection (X) is shown exaggerated.

  When the seal cover plate is removed, the diaphragm, being of spring metal, recovers from the deflection, standing flat and perpendicular to the shaft axis. If the diaphragm ring is held in contact against the shaft collar, there is a space (Y) between the gasket and the top of diaphragm, exactly equal to the deflection (X), as shown in Sketch B.

A steel ring gage (of the shape of such a gasket) can now be placed between the gasket and the diaphragm. If the ring gage has exactly the thickness (Y), the whole seal can be bolted together. The diaphragm ring will touch the shaft collar but will not press against it because the diaphragm will have no deflection. This assembly with steel ring gage is shown in Sketch C.

If the operator knew that the conditions shown in the assembly of Sketch C were a result of a chosen gasket and the same ring gage, he would know that when he removed the ring gage and reassembled the seal, he would get the desired deflection (X). Unfortunately, it is impossible to tell from the outside whether or not there is any deflection of the diaphragm. The diaphragm ring might just be touching the shaft collar, or it might be pressing hard against it, but it would be impossible to tell which. However, by using two different ring gages instead of one, the operator can find out by the following method:

First, it is obviously impossible always to select a gasket combination of absolutely the correct thickness. A certain tolerance must be permitted. This tolerance, however, is limited, and in order to keep within its limits two steel ring gages are used, one a maximum thickness ring gage (slightly thicker than Y), and the other a minimum thickness ring gage (slightly thinner than Y). A comparison of these two gages shows the limited tolerance permitted and the extreme care with which the gaskets must be selected.

Moreover, by the use of these two ring gages, the operator determines whether or not the diaphragm has the proper deflection. The method of using them is based upon the following considerations:

If the seal is assembled with the maximum ring gage on the proper thickness of gaskets, that is, with the same gaskets referred to in

 
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Figure 10-1. Enlarged view of crankshaft seal.
Figure 10-1. Enlarged view of crankshaft seal.
 
78

Sketches A, B, and C, the shaft seal ring is held away from the shaft seal collar (30), as shown in Sketch D. This condition is easy to observe, because the shaft seal ring can be moved perceptibly inward toward the seal collar; a few thousandths of an inch can be perceived.

If the seal is assembled with the minimum thickness ring gage on the same thickness of gaskets, the shaft seal ring is held firmly against the shaft seal collar (3) with a slight deflection of the diaphragm, as shown in Sketch E. This condition can also be easily observed because the shaft seal ring cannot be moved, and when tapped lightly with the point of a screwdriver, or similar small steel rod, it rings with a solid metallic sound, being held firmly against the seal collar.

Hence, since the thickness of the maximum thickness ring gage is equal to the maximum permissible deflection, any gasket combination that provides a definite perceptible movement of the shaft seal ring when assembled with the maximum thickness ring gage, and that responds with a solid metallic sound on tapping when assembled with the minimum thickness ring gage, is within the allowable limits.

10K7. Adjusting the shaft seal. The correct maintenance of a perfect seal depends upon the care with which the adjustment is made to produce the proper pressure. First, be sure that Section 10K6 is thoroughly understood. Then follow the routine given below, omitting no steps (see Figure 10-1):

1. After the shaft seal collar (30) has been lapped to the shaft shoulder (this lapping operation is, of course, unnecessary if the original shaft and shaft seal are installed, wash all parts with approved cleaning fluid. Use care to clean with a matchstick the small holes in the sealing face of the shaft seal ring. Rinse the parts in approved cleaning fluid and let them dry in air without wiping. Any discoloration on the sealing surfaces of either shaft seal ring (31) or shaft seal collar (30) should be removed with a soft pencil eraser. These parts must then be washed again in approved cleaning fluid.

CAUTION. After the final rinse, do not touch the sealing surfaces.

2. Place a trial thickness of gaskets (37) in

  the gasket recess. The original gaskets, or some of the same total thickness, should be used for the first trial, as they are nearly correct for the new parts.

3. Place the maximum thickness ring gage in the recess on the gaskets.

4. Place in position the locating ball (29), the seal collar (30), and the seal assembly (31), taking care not to touch or mar the sealing surfaces.

5. Bolt the seal cover plate (4) in position, taking care to pull the capscrews evenly all the way around and as tight as if assembling the seal for normal operation.

6. With a screwdriver, or other small steel rod, push in on the seal ring. If the seal ring can be moved in perceptibly, the thickness of the gasket combination chosen is greater than the minimum permissible. That is, the gasket is not too thin, but it may be too thick; this is determined when checked with the minimum thickness ring gage. If the seal ring cannot be moved in perceptibly, tap it lightly with the screwdriver. If this tapping produces a solid metallic sound, the gasket is too thin, and further trial is necessary with thicker gaskets. However, if the tapping produces a hollow, loose sound, the sealing may be just touching or separated from the seal collar by only a fraction of a thousandth of an inch. This indicates that the thickness of the gaskets is close to the minimum permissible, and a gasket combination of 0.001 inch or 0:002 inch thicker would be better.

7. When a combination of gaskets is found that, when assembled with the maximum thickness ring gage, permits the seal ring to be moved perceptibly, remove the maximum thickness ring gage and reassemble the seal with the minimum thickness ring gage in place taking care to draw the capscrews evenly all around and as tight as if assembling the seal for normal operation.

8. With a screwdriver, or other small steel rod, tap on the seal ring. If this tapping produces a solid metallic sound, the gaskets chosen are correct and no further trial is necessary However, if the tapping produces a hollow loose sound, the gasket thickness is too great and further trial is necessary with thinner gaskets.

 
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9. If further trial with thinner gaskets is necessary when checking with the minimum thickness ring gage, a recheck must be made with the maximum thickness ring gage.

10. This alternate checking with maximum thickness ring gage must be repeated until such combination of gaskets is found that, when checked with the maximum thickness ring gage, permits the seal ring to be moved

  perceptibly; or causes it to produce a hollow, loose sound when tapped; or when checked with the minimum thickness ring gage, causes it to produce a solid metallic sound when tapped.

11. When the proper thickness of gaskets has been determined, proceed with the installation of the shaft seal. Refer to Section 10K1.

 
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