1. Select one of the following:
HD942 Compressor
This presentation is a simplified description of the disassembly of a Blackmer HD942A.
With some minor differences, this presentation is also appropriate for the HDL942A and the LB942A.
Select one of the following:
Hilites Only
Detailed Text

2. HD942 Industrial Compressor
These slides give a simplified description of the disassembly of a Blackmer HD372A.
The current production model is HD372C. Significant changes are needle bearings at the wrist pin, a larger wrist pin [ 1” instead of 7/8”] and a full-flow, spin-on, oil filter as standard equipment.
With some unimportant differences, this presentation is also appropriate for the other Blackmer 1 and 2 stage models, with the exception of the HD942, double-acting compressor.

3. Literature Have the literature for your machine at hand Parts lists
Installation, Operation and Maintenance manual
Call your Blackmer distributor for literature or go to our website:
Be sure that you have the literature you require before starting to work on the compressor. Locate the parts list and Installation, Operation and Maintenance instructions. In addition, you may have received additional instruction sheets with your machine that further describe such items as valves and packing.
If you do not have all of the necessary information, call your Blackmer distributor

4. Literature
Be sure that you have the appropriate literature before starting work on the compressor. Locate the parts list and Installation, Operation and Maintenance instructions. In addition, you may have received additional instruction sheets with your machine that further describe such items as valves and packing.
If you do not have all of the necessary information, call your Blackmer distributor.
Literature is also available on our website:

5. Tools Use standard tools for small machines
Blackmer adjustable spanner with 1/4” pins (p/n )
Blackmer spanner (p/n ) for valve hold down screws
Packing installation Cone (p/n )
Inside snap ring pliers
Blackmer offers a complete tool kit which has all of the hand tools necessary to dismantle the machine.
The tools normally required for small machine service will be adequate for the work on an HD compressor. A small strap wrench is useful and a good spanner. The Blackmer p/n spanner is used for valve hold down screws. The Blackmer spanner p/n has 1/4” pins and is used for piston removal. A flat scraper and inside snap ring pliers are also needed.
On larger machines a small hoist might be needed for one man to do the job, depending on the environment. Generally, two men can handle the disassembly of any Blackmer machine.

6. Tools
Blackmer offers a complete tool kit which has all of the hand tools necessary to dismantle the machine.
The tools normally required for small machine service will be adequate for the work on an HD compressor. A small strap wrench is useful and a good spanner. The adjustable spanner (p/n ) has 1/4” pins and is used for piston removal. The Blackmer spanner (p/n ) is used for valve hold down screws. An Installation Cone p/n should be used to protect the packing during assembly. A flat scraper and inside snap ring pliers are also needed.
On the HD942 a small hoist will be needed.

7. Nameplate Model number Serial number I.D. number Oil capacity
Defines construction
Oil capacity
Rod inspection access
Nameplate
On the side of every Blackmer compressor is a nameplate which doubles as an access opening for inspecting the piston rod.
The nameplate will show the compressor’s model number, serial number, ID number, and oil capacity.
The compressor ID is a coded number that fully describes the compressor’s construction.
Make certain that you have these identifying numbers when you call your Blackmer distributor for parts or service assistance.

8. On the side of every Blackmer compressor is a nameplate which doubles as an access opening for inspecting the piston rods.
The nameplate will show the compressor’s model number, serial number, ID number, and oil capacity.
The compressor ID is a coded number that describes the compressor’s construction.
Make certain that you have these identifying numbers when you call your Blackmer distributor for parts or service assistance.
Nameplate

9. HD942 Single-stage 50 bhp (37 kw ) Non-lubricated 400-825 rpm
Reciprocating air-cooled
Double-acting
Various gases
The HD372A is a two-stage, non-lubricated, reciprocating compressor designed to handle many different gasses. It is rated for up to 20 bhp (15kw) and operates generally between rpm.
The HD372A is an air-cooled machine and is normally fitted with an air-cooled intercooler for the compressed gas. The intercooler shroud was removed for these photos.
Some process application will require engineered intercooling systems with heat exchanger and liquid separation equipment. These are provided by the equipment packager as part of an integrated system.

10. HD942
The HD942A is a single-stage, non-lubricated, reciprocating, double-acting compressor designed to handle many different gasses. It is rated for up to 50 bhp (37kw) and operates generally between rpm.
The HD942A has an air-cooled head and cylinder.

11. HDL942 Water-cooled Head & Cylinder
Blackmer offers a variety of two-stage compressors.
The HDL372 is similar to the HD372 shown in this presentation but is liquid cooled. It has a water cooled head and cylinder for lower metal temperatures and longer life of wearing parts. It is also fitted with a water cooled intercooler to keep gas temperatures at acceptable levels for continuous duty.
The smaller HD172 air-cooled model is rated for 10 bhp (7.5 kw).
The larger HD612 (air-cooled) and HDL612 (liquid cooled) models are rated for 40 bhp (30 kw).

12. HDL942
Blackmer also offers the water-cooled model HDL942A. Note the water jacket covers on each side of the cylinder and on top of the cylinder heads.
Smaller models are available.
Blackmer offers a variety of two-stage compressors.
The HDL372 is similar to the HD372 shown in this presentation but is liquid cooled. It has a water cooled head and cylinder for lower metal temperatures and longer life of wearing parts. It is also fitted with a water cooled intercooler to keep gas temperatures at acceptable levels for continuous duty.
The smaller HD172 air-cooled model is rated for 10 bhp (7.5 kw).
The larger HD612 (air-cooled) and HDL612 (liquid cooled) models are rated for 40 bhp (30 kw).

13. Cylinder Drain & Distance Piece Drain
Inlet / Discharge pressure taps
Cylinder drain
Seal connections
Distance piece openings
The HD372 is a two cylinder compressor. Each cylinder has a suction and discharge valve. These operate automatically and independently for each cylinder.

14. Cylinder Drain & Distance Piece Drain
The port on each side of the cylinder may be used as a cylinder drain. A pressure port is provided at both the suction and discharge flanges.
Each side of the distance piece has two openings. The lower opening may be used as a drain, while the upper may be used as a vent or purge connection.
Not shown: Beneath the lower valve on each side of the cylinder may be vent or purge connections for the rod seals.
The HD372 is a two cylinder compressor. Each cylinder has a suction and discharge valve. These operate automatically and independently for each cylinder.

15. Head with Standard Suction Valves
The HD942A is a 2 cylinder double-acting compressor. Each cylinder end is fitted with both a suction valve and a discharge valve for a total of 4 each. All 4 suction valves are on one side of the compressor; the 4 discharge valves are on the other side.
The HD372 is a two cylinder compressor. Each cylinder has a suction and discharge valve. These operate automatically and independently for each cylinder.

16. Removing Standard Valves
Remove hold down screw from valve cap
Reinstall cover plates first, then the hold down screws.
O-rings are not normally reusable
The HD372 is a two cylinder compressor. Each cylinder has a suction and discharge valve. These operate automatically and independently for each cylinder.

17. Removing Standard Valves (part 1)
Remove the valve caps to access the valves. After the valve caps have been removed, the valve hold down screws can be removed with a spanner wrench (Blackmer PN ). To prevent possible damage to the valves during reassembly, the hold down screws must be completely removed from the valve cover plates.
The HD372 is a two cylinder compressor. Each cylinder has a suction and discharge valve. These operate automatically and independently for each cylinder.

18. Removing Standard Valves (part 2)
Once the valve caps and hold down screws have been removed, the cover plates may be removed. During reassembly the valve cover plates must be installed first, then the hold down screws.
Note the O-ring under each valve cap and cover plate. The compressor I.D. number on the nameplate contains a code for the O-ring material used. Typically, O-Rings are not reusable and should be replaced any time the cover plates are removed.
The HD372 is a two cylinder compressor. Each cylinder has a suction and discharge valve. These operate automatically and independently for each cylinder.

19. Valves Valve cages Valves Gaskets - usually iron
Always replace gaskets
Reinstall valves in correct ports
Optional suction valve unloaders allow the compressor to be deactivated in service. That is, gas that is drawn into the cylinder during the suction stroke is expelled through the suction valve on the discharge stroke and does not pas through the machine into the discharge line. This is accomplished by holding the compressor suction valve plates open throughout the full cycle. The unloader mechanism does this mechanically and can be powered by compressed gas from the discharge storage or an independent source, as required.
The suction valves can be unloaded to produce no-load starts or reduced capacity operation on demand.

20. Valves
With the cover plates removed, the valve cage, valve and gasket may be taken out. Make sure the valve gaskets are removed with each valve. When they are left in the head, they may be very difficult to see. The valve gaskets are normally iron although other materials are occasionally used. Valve gaskets should be replaced anytime the valves are removed.
Suction and discharge valves must be reinstalled in the correct ports.
Optional suction valve unloaders allow the compressor to be deactivated in service. That is, gas that is drawn into the cylinder during the suction stroke is expelled through the suction valve on the discharge stroke and does not pas through the machine into the discharge line. This is accomplished by holding the compressor suction valve plates open throughout the full cycle. The unloader mechanism does this mechanically and can be powered by compressed gas from the discharge storage or an independent source, as required.
The suction valves can be unloaded to produce no-load starts or reduced capacity operation on demand.

21. Head with Suction Valve Unloaders
Loadless starting
Constant speed operation
Optional suction valve unloaders allow the compressor to be deactivated in service. That is, gas that is drawn into the cylinder during the suction stroke is expelled through the suction valve on the discharge stroke and does not pas through the machine into the discharge line. This is accomplished by holding the compressor suction valve plates open throughout the full cycle. The unloader mechanism does this mechanically and can be powered by compressed gas from the discharge storage or an independent source, as required.
The suction valves can be unloaded to produce no-load starts or reduced capacity operation on demand.

22. Head with Suction Valve Unloaders
Optional suction valve unloaders allow the compressor to be deactivated in service. That is, gas that is drawn into the cylinder during the suction stroke is expelled through the suction valve on the discharge stroke and does not pass through the machine into the discharge line. This is accomplished by holding the compressor suction valve plates open throughout the full cycle. The unloader mechanism does this mechanically and can be powered by compressed gas from the discharge storage or an independent source, as required.
The suction valves can be unloaded to produce no-load starts or reduced capacity operation on demand.
See bulletin CB-039 for more information.

23. Removing Suction Valves with Unloaders
Unloader Assembly
O-ring
Unloader Plunger
Remove hold down screw from valve cap
Use a strap wrench to remove the unloader assembly and its O-ring. Alternately, a bar can be levered against a pair of unloader cap screws.
Once the unloader assembly is removed, the valve hold down screw can be removed.
When assembling, make sure the cover plate is firmly secured before reinstalling the hold down screw.

24. Removing Suction Valves with Unloaders
Use a strap wrench to remove the unloader assembly and its O-ring. Alternately, a bar can be levered against a pair of unloader cap screws.
Once the unloader assembly is removed, the unloader plunger and valve hold down screw can be removed.
When assembling, make sure the cover plate is firmly secured before reinstalling the hold down screw.

25. Suction Valve Removal Valve cage Valve with actuator
Always replace gasket
Once the hold down screw is removed, the cover plate and its O-ring can be removed. Under the cover plate is the valve cage, unloader plunger, suction valve with unloader actuator, and a valve gasket.

26. Suction Valve Removal
Once the hold down screw is removed, the cover plate and its O-ring can be removed. Under the cover plate is the valve cage, suction valve with unloader actuator, and a valve gasket.

27. Suction Valve Unloaders
PTFE Unloader piston seals
All Stainless Steel Parts
The unloader assembly consists of a cap, body with O-ring, and a piston with two spring loaded PTFE seals. The open side of the seals should face outward. The unloader actuator and spring are held to the valve with a snap ring.
The unloader cap, body piston, actuator and spring are all stainless steel.

28. Suction Valve Unloaders
The unloader assembly consists of a cap, body with O-ring, and a piston with two spring loaded PTFE seals. The open side of the seals should face outward. The unloader actuator and spring are held to the valve with a snap ring.
The unloader cap, body piston, actuator and spring are all stainless steel.

29. Disassembled Valves Valve components: seat bumper springs plate post
nut
lock washers
A disassembled suction valve is shown on the left, a discharge valve on the right.
Each valve consists of a seat, stop ( bumper ), springs, plate, threaded post, nut and locking washers.

30. Disassembled Valves
A disassembled suction valve is shown above and a discharge valve is below. Each valve consists of a seat, bumper, springs, plate, threaded post, nut and lockwashers.

31. Cylinder Head O-ring head - to - cylinder seals
To remove the cylinder head, unbolt the two center head bolts from the top of the head and the eight head bolts from the bottom of the head. After the cylinder head bolts have been removed, the head may be lifted from the cylinder. Note that the head is sealed to the cylinder by an O-ring at each cylinder bore.

32. Cylinder Head
Unbolt the four head bolts from the top of each head and lift the heads out. Note the O-rings under each head.

33. Piston Removal Remove piston cap with 1/4” pin spanner
Upper shims are under the piston cap
Lower shims are under the piston
Shims adjust deck height
4 rings & expanders on each piston
The piston nut is removed with an adjustable spanner. This spanner has two 1/4” pins which fit into holes in the top of the piston nut. Note the nylon locking device on the piston nut.
Once the piston nut has been removed, the same spanner can be used to unscrew the piston from the rod. There is a thick washer under each piston and one, or more, shims. These shims adjust the height of the piston in the cylinder. This is referred to as the “deck height”. Unless a major part has been changed, the deck height should not need adjustment. Change of the piston, crosshead assembly, cylinder body, main bearings or crankshaft may require adjustment of the deck height.
Rotate the crankshaft to bring the other piston to top-dead-center for removal. Each piston is fitted with three piston rings. Each ring has a stainless steel expander between it and the piston.

34. Piston Removal
Bring the piston to top-dead-center and remove the piston nut. Remove the piston cap using the two ¼” puller holes (the oil pump cover bolts may be used). Note the O-ring and a number of shims under the piston cap. Lift out the piston assembly. Under the piston there are one or more shims. The upper and lower shims are used to adjust the height of the piston in the cylinder. Keep the shim sets together to simplify reassembly. Bring the other piston to top-dead-center for removal.
Each piston is fitted with four piston rings. Each ring has a stainless steel expander behind it.

35. Piston Installation Ring gap is 180o from expander gap
Stagger ring gaps around piston
When installing he piston rings and expanders make sure that each piston ring is installed with its gap 1800 from the expander gap. Also, the piston ring gaps should be staggered around the piston.
With the pistons removed, the cylinder can be unbolted and removed to gain access to the packing boxes. Two O-rings seal the bottom of the cylinder.
Notice the passage in the bottom of the cylinder between the bores. This allows gas to move from one cylinder to the other as the pistons move up and down.

36. Piston Installation
When installing the piston rings and expanders make sure that each piston ring is installed with its gap 1800 from the expander gap. Also, the piston ring gaps should be staggered around the piston.

37. Piston Clearance
Set both upper and lower clearance.
Use shims

38. Piston Clearance
Since the HD942 is a double-acting compressor, both the upper and lower piston clearance must be set. This is done via shims under the piston and between the piston body and piston head. The piston clearance is measured with the valves removed.

39. Cylinder Removal Use a hoist
Do not remove the packing boxes with the cylinder

40. Cylinder Removal
With the pistons removed, the cylinder can be unbolted and lifted off with the use of a hoist. Do not allow the upper packing boxes to be lifted off with the cylinder as the packing will be damaged.

41. Upper Packing Box Removal
Note packing box orientation
Use packing installation cone
Some boxes have vent rings
The packing boxes are secured by a hold down screw which is removed with the same adjustable spanner that was used on the piston nut and piston. Note that the hold down screw also has a nylon insert that keeps it in place.
The packing boxes may now be lifted off the rod. O-rings seal the top and bottom side of the packing boxes.

42. Upper Packing Box Removal
Note the orientation of the upper packing boxes. Place the packing installation cones over the ends fo the piston rods, then carefully lift the upper packing boxes and O-rings off the top of the piston rods. Remove the oil deflector rings from the rods.
This picture shows two styles of packing boxes: one with and one without vent rings.

43. Upper Packing Box Detail
Some boxes have vent rings

44. Upper Packing Box Detail
Some models will have two vent rings and two O-rings on the each packing box. Other models will have only a single O-ring and no vent rings.

45. Upper Packing Box Disassembly
Packing gland
Packing cups with seals
Packing cup gasket

46. Upper Packing Box Disassembly
Removal of the packing gland from the bottom of the packing box will allow the individual packing cups to be removed. Each packing cup will have an O-ring and will contain a packing seal. The number of packing cups and the types of seals they contain may vary from the picture. A gasket fits between the upper packing cup and the top of the packing box.

47. Seal Detail Seal ring pairs Tangential-Tangential Radial-Tangential
Keep seals together
Note match marks
With the snap ring removed, the top washer, the spring, the middle washer, the seal, the bottom washer and retainer ring can all be removed.
The seal consists of three types of rings. One ring is a male ring, next a series of V-rings, then a female ring.
The upper and lower seals are the same. The seal orientation will depend on the operating pressures. The spring and washer, however, always press against the male ring.
The red oil deflector ring fits on the piston rod between the two seals. The holes in the side of the packing box allow the oil deflector ring to be guided onto the rod as the box is installed. TT RT

48. Seal Detail
Most seal rings come in pairs and may be Tangential - Tangential (shown on the left) or Radial-Tangential (shown on the right). They each consist of 3 carbon pieces with a spring around the circumference.
Keep individual seal pairs together. Pay attention to the locating pins and match marks. TT RT

49. Lower Packing Box Removal
Remove hold down screw with spanner
Hold down screw has plastic insert
Packing box O-ring
The packing boxes are secured by a hold down screw which is removed with the same adjustable spanner that was used on the piston nut and piston. Note that the hold down screw also has a nylon insert that keeps it in place.
The packing boxes may now be lifted off the rod. O-rings seal the top and bottom side of the packing boxes.

50. Lower Packing Box Removal
The packing boxes are secured by a hold down screw which is removed with an adjustable spanner. Notice that the hold down screw also has a plastic insert that keeps it in place. Next, the packing boxes themselves may be lifted off the rod. O-Rings seal the bottom of the packing boxes.

51. Lower Packing Box Disassembly
Use a screwdriver handle to depress the spring while removing the retainer ring
V-rings
Spring is next to the male seal ring
Remove the seals ( packing ) from the box as follows.
Use a pair of inside snap ring pliers to remove the top snap ring. A screwdriver handle can be used to depress the spring to make this operation easier.
Turn the packing box over to remove the bottom seal.

52. Lower Packing Box Disassembly
Use a pair of inside snap ring pliers to remove the top snap ring. The handle of a screwdriver can be used to slightly depress the spring to make this operation easier.
With the snap ring out, the top washer, the spring, the middle washer, the seal, the bottom washer and retainer ring can all be removed. The seal consists of three types of rings. A male ring, a series of V-rings, then a female ring. The seal orientation will depend on the operating pressures; however, the spring and washer always press against the male ring.

53. Piston Rod Inspection
Piston rods and tops of the crossheads are visible through the nameplate opening
The piston rods and the top on the crossheads are visible through the opening when the nameplate is removed

54. Piston Rod Inspection
The piston rods and the top of the crossheads are visible through the opening when the nameplate is removed.

55. Crankcase and Crossheads
Gasket fits between crankcase & guide
Access cover & gasket
Connecting rod nuts are removed to take out crosshead & connecting rod
Dipstick
By removing the crosshead guide, access is given to the crosshead / piston rods.
The flat gasket that fits on top of the crankcase may require the use of a flat scraper to remove completely.

56. Crankcase and Crosshead
The crosshead guide may now be removed, exposing the crosshead/piston rod assemblies. Removal of the crankshaft access cover and gasket allows access to the connecting rods. After the bottom cap of the connecting rod has been removed, the piston rod/crosshead and the top half of the connecting rod may be lifted off from above. Keep each connecting rod with its proper cap.
A scraper may be needed to remove the flat gasket that fits on top of the crankcase..

57. Crosshead Never remove piston rod from crosshead Ductile iron rod
Press out wrist pin
Plastic retainer plugs
The connecting rod and crosshead assembly are separated by removing the wrist pin in a bench press. Note that the wrist pin has a plastic retainer plug on each end.
The piston rod is permanently secured to the crosshead at the factory and no attempt should be made to separate them. Final machining is done to the assembled crosshead / rod which precludes their reassembly once separated. The grooves in the crosshead are lubrication channels.
The small end of the connecting rod shown here has a bronze bushing. This is used on some models. Current production for the HD362, 342 and 372 incorporates a steel needle bearing in the connecting rod small end.

58. Crosshead
Remove the wrist pin with a press to separate the connecting rod from the crosshead assembly. The piston rod is permanently secured to the crosshead at the factory and no attempt should be made to separate them. Note the plastic retainer plug on each end of the wrist pin.

59. Connecting Rod Ductile iron rod Split bearing on the crank end
Tabs on bearings fit in slots in rod and cap
Keep rod caps on correct rod and note match marks
The ductile iron connecting rod has a cast in tube to route oil from the big end to the wrist pin.
A precision insert split shell bearing is located at the big [journal] end. Tabs on the bearing shells fit into slots in the rod and bearing cap. These retain the shells and align the oil feeds.
The HD372A uses a bronze bushing on a steel wrist pin at the small end of the conrod. A steel needle bearing is used on some models. The oil admission hole in the bearing or bushing must align with the oil supply hole in the connecting rod small end. When the bronze wrist pin bushing is replaced, it must be honed to final dimension after being pressed into the connecting rod
The rod and cap are matched sets, do not mix. Match marks must align when assembling bearing cap to connecting rod.

60. Connecting Rod
The ductile iron connecting rod is ported to route oil to the wrist pin and the bronze bushing. When the bronze bushing is replaced, it must be honed to the final dimensions after being pressed into the connecting rod. The hole in the bushing must also align with the oil passage port. An automotive type split bearing is on the crankshaft end. Tabs on the bearings fit into slots in the rod and cap. This keeps the bearing from spinning and lines up the hole with the rifle drilled port. Keep each connecting rod cap with its matching rod. Match marks are provided on the rod and cap to ensure proper orientation.

61. Oil Pressure Adjustment
Oil pressure adjustment screw & locknut
Dipstick
Oil pressure gauge
Oil filter
The oil pressure adjustment screw complete with O-ring, lock nut, spring and ball fits into the bearing carrier. Turning the screw inward (clockwise) increases the oil pressure setting.
The oil pickup tube with washers, O-ring and strainer fits in the crankcase under the bearing carrier. If any foreign material is noticed in the strainer, its source should be quickly identified to prevent reoccurrence of the problem.
The pipe plug next to the oil pickup tube opening is the crankcase oil drain.

62. Oil Pressure Adjustment
The oil pressure adjustment screw and locknut fits into the oil pump. Turning the screw inward (clockwise) increases the oil pressure setting.
The oil level dipstick, oil pressure gauge, and external oil filter are all shown in this view.

63. Dipstick Upper and lower oil level marks
The oil pressure adjustment screw complete with O-ring, lock nut, spring and ball fits into the bearing carrier. Turning the screw inward (clockwise) increases the oil pressure setting.
The oil pickup tube with washers, O-ring and strainer fits in the crankcase under the bearing carrier. If any foreign material is noticed in the strainer, its source should be quickly identified to prevent reoccurrence of the problem.
The pipe plug next to the oil pickup tube opening is the crankcase oil drain.

64. Dipstick
Note the upper and lower oil level marks which have been hi-lighted in white in the picture. The oil level must be within these marks.

65. Oil Inlet Strainer Oil strainer - clean when servicing Oil drain plug
The oil pressure adjustment screw complete with O-ring, lock nut, spring and ball fits into the bearing carrier. Turning the screw inward (clockwise) increases the oil pressure setting.
The oil pickup tube with washers, O-ring and strainer fits in the crankcase under the bearing carrier. If any foreign material is noticed in the strainer, its source should be quickly identified to prevent reoccurrence of the problem.
The pipe plug next to the oil pickup tube opening is the crankcase oil drain.

66. Oil Inlet Strainer
The oil pickup strainer screen with washers and O-ring fits in the crankcase under the bearing carrier. If any foreign material is noted on the strainer, its source should be quickly identified to prevent reoccurrence of the problem. The pipe plug next to the oil pickup tube opening is the crankcase oil drain.

67. Oil Pump Oil pump cover Gasket Oil pump
This photo shows the oil pump used in the HD372A. Models HD372B and HD372C use a different pump.
Remove the oil pump cover and O-ring to withdraw the oil pump. Notice the small O-ring on the pump shaft and the bronze bushing in the bearing carrier.
The oil pump cover can be installed with either left or right rotation arrow visible. When installing the cover, make sure that the arrow at the TOP of the cover indicates the desired rotation direction.

68. Oil Pump
Removal of the oil pump filter, cover and gasket allows removal of the oil pump assembly, drive cone, and spring.

69. Oil Pump Detail Oil pump match marks Oil pump drive tab
This photo shows the oil pump used in the HD372A. Models HD372B and HD372C use a different pump.
Remove the oil pump cover and O-ring to withdraw the oil pump. Notice the small O-ring on the pump shaft and the bronze bushing in the bearing carrier.
The oil pump cover can be installed with either left or right rotation arrow visible. When installing the cover, make sure that the arrow at the TOP of the cover indicates the desired rotation direction.

70. Oil Pump Detail
A disassembled oil pump with the oil pressure adjusting screw and the external oil filter.
Note that the oil pump parts have match marks. Also note the drive tab at the back of the pump - this tab fits into a slot in the end of the crankshaft.

71. Bearing Carrier & Crankshaft Removal
Bearing carrier gasket
Oil pump drive slot and crankshaft drive pin
Orient crankshaft
Do not scar surfaces
The entire bearing carrier / oil pump assembly, with gasket, can be removed intact. This allows the crankshaft to be removed.
Note the slot in the end of the oil pump drive shaft. This slot must align with the drive tang in the end of the crankshaft during installation.

72. Bearing Carrier & Crankshaft Removal
The entire bearing carrier / oil pump assembly with gasket may be removed as one. Note the slot in the end of the crankshaft. When the bearing carrier is reinstalled, this slot must align with the drive tab in the oil pump.
The crankshaft is readily removed once oriented correctly. Be careful not to scar the bearing or journal surfaces when removing the crankshaft.

73. Crankshaft Detail Pressure lubrication holes at the journal bearings
Oil spray nozzles on the crankshaft for the crossheads
Remove the crosshead and connecting rod assemblies to proceed with the crankshaft removal. Notice the lubrication holes on the bearing journals. Also note the spray nozzles on the crankshaft. The spray nozzles lubricate the crosshead guide and the main [ roller ] bearings.
The top of the crankcase is fitted with a breather which prevents entry of foreign material into the crankcase but allows the release of crankcase pressure.

74. Crankshaft Detail
Note the lubrication holes on the bearing journals and the spray nozzles on the crankshaft. These holes and the passageways inside the crankshaft must be clean.

75. Bearing Cover Plate Located at flywheel end
Shims adjust main bearing preload
Shims are reusable
Adjusted for new main bearing or new crankshaft
Cover contains crankshaft oil seal
The bearing plate cover is on the flywheel side of the crankcase. Behind this plate are shims which adjust the preload on the main bearings. These shims are normally reusable and the shim thickness will not have to be adjusted unless the crankshaft or main bearings are replaced.
The bearing cover plate also contains a crankshaft oil seal.

76. Bearing Cover Plate
The bearing cover plate is on the flywheel side of the crankcase. Behind this plate are shims which adjust the preload on the main bearings. These shims are normally reusable and the shim thickness will not have to be adjusted unless the crankshaft and/or main bearings are replaced. The bearing cover plate also contains a crankshaft oil seal. x

77. End of Presentation 1809 Century Avenue Grand Rapids, MI, USA 49503
Ph:
Fax:
These slides give a simplified description of the disassembly of a Blackmer HD372A.
The current production model is HD372C. Significant changes are needle bearings at the wrist pin, a larger wrist pin [ 1” instead of 7/8”] and a full-flow, spin-on, oil filter as standard equipment.
With some unimportant differences, this presentation is also appropriate for the other Blackmer 1 and 2 stage models, with the exception of the HD942, double-acting compressor.