1 09/97 CB-259

1
HD372 Compressor
This presentation is a simplified description of
the disassembly of a Blackmer HD372A. The
current production model is the HD372C (March
1997). 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 minor differences,
this presentation is also appropriate for the
other Blackmer 1 and 2-stage models, with the
exception of the HD942, double-acting
compressor. Select one of the following
Hilites Only
Detailed Text
2
HD372 Industrial Compressor
3
LITERATURE

• Have the literature for your machine at hand
• Parts lists
• Installation, Operation and Maintenance manual
• Call your Blackmer distributor for literature

4
LITERATURE

• 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.

5
Tools

• Use standard tools for small machines
• Blackmer spanner (p/n 790535) for valve hold down
  screws
• Blackmer adjustable spanner with 1/4 pins (p/n
  790316)
• Inside snap ring pliers

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 Blackmer p/n 790535 spanner is
  used for valve hold down screws. The Blackmer
  spanner p/n 790316 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.

7
Nameplate

• Model number
• Serial number
• I.D. number
• Defines construction
• Oil capacity
• Rod inspection access

8
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 compressors model
  number, serial number, ID number, and oil
  capacity.
• The compressor ID is a coded number that fully
  describes the compressors construction.
• Make certain that you have these identifying
  numbers when you call your Blackmer distributor
  for parts or service assistance.

9
HD372 Flywheel Side

• Two-stage 20 bhp (11 kw )
• Non-lubricated 400-825 rpm
• Reciprocating air-cooled
• Single-acting various gases

10
HD372 Flywheel Side

• 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 400-825
  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.

11
HD372 Oilpump Side

• Other Models Available
• Liquid-cooled HDL372
• Smaller HD17210 bhp (7.5 kw)
• Larger HD612 and HDL61240 bhp (30 kw)

12
HD372 Oilpump Side

• 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
Head with Standard Suction Valves
The HD372 is a two cylinder compressor. Each
cylinder has a suction and discharge valve. These
operate automatically and independently for each
cylinder.
14
Head with Suction Valve Unloaders

• Loadless starting
• Constant speed operation

15
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 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.

16
Removing Standard Valves

• Cap O-ring
• Remove hold down screw from valve cap

17
Removing Standard Valves

• 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 (such as a Blackmer p/n 790535).
• To prevent possible damage to the valves during
  reassembly, the hold down screws must be
  completely removed from the valve cover plates.
• Note the O-ring under each cap these should be
  replaced rather than reused. The compressor I.D.
  number on the nameplate contains a code for the
  O-ring material used.

18
Valve Cover Plates

• Replace O-rings
• Reassemble covers before installing
• the hold down screws

19
Valve Cover Plates

• Once the valve caps and hold down screws have
  been removed, the cover plates can be removed.
• Note the O-ring under the valve cover plate.
  Typically, O-rings are not reusable and should be
  replaced any time the cover plates are remove.
• During reassembly the valve cover plates must be
  reinstalled first, before the hold down screws
  are installed.

20
Valves

• Valve cages
• Valves
• Always replace gaskets

21
Valves

• Once the cover plates removed, the valve cage,
  valve and gasket may be taken out.
• Make certain the valve gaskets are removed with
  each valve. When they are left in the head they
  may be difficult to see. The valve gaskets are
  normally iron although other materials are used
  as required. Valve gaskets should be replaced
  when the valves are removed.

22
Removing Suction Valves with Unloaders

• O-ring
• Remove hold down screw from valve cap

23
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 valve
  hold down screw can be removed.
• When assembling, make sure the cover plate is
  firmly secured before reinstalling the hold down
  screw.

24
Suction Valve Removal

• Valve cage
• Unloader plunger
• Valve with actuator
• Always replace gasket

25
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, unloader plunger,
  suction valve with unloader actuator, and a valve
  gasket.

26
Suction Valve Unloaders

• PTFE Unloader piston seals
• All Stainless Steel Parts

27
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.

28
Disassembled Valves

• Valve components
• seat
• bumper
• springs
• plate
• post
• nut
• lock washers

29
Disassembled Valves

• 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
Standard Intercooler

• Radiator or Finned tube types
• All steel construction

31
Standard Intercooler

• The intercooler is readily unbolted from the
  cylinder head at two locations. Note the PTFE
  intercooler flange O-rings.
• Earlier models were fitted with the finned tube
  intercooler as shown on the right. Standard
  intercoolers are all steel construction and rated
  for the first stage discharge pressure.

32
Cylinder Head

• O-ring head - to - cylinder seals

33
Cylinder Head

• 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.

34
Piston Removal

• Remove piston nut with 1/4 pin spanner
• Piston nut has nylon locking insert
• Use spanner to unscrew piston
• Washer and shims adjust piston end travel
• Piston rings have expanders

35
Piston Removal

• 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.

36
Piston and Cylinder

• Ring gap is 180o from expander gap
• Stagger ring gaps around piston
• Two O-rings cylinder-to-crankcase
• Under-piston channel between bores

37
Piston and Cylinder

• 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.

38
Packing Box Removal

• Remove hold down screw with spanner
• Hold down screw has nylon locking insert
• O-rings seal packing box at each end

39
Packing Box Removal

• 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.

40
Packing Box disassembly

• Depress spring with screwdriver while removing
  retainer ring

41
Packing Box disassembly

• 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.

42
Rod Seals

• V - ring type
• Spring is next to the convex surface
• Oil deflector ring between seals

43
Rod Seals

• With the snap ring removed, the top washer,
  spring, middle washer, seal rings, 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.

44
Piston Rod Inspection

• Piston rods and tops of the crossheads are
  visible through the nameplate opening

45
Piston Rod Inspection

• The piston rods and the top on the crossheads are
  visible through the opening when the nameplate is
  removed.

46
Crankcase and Crosshead

• Gasket between crankcase and guide

47
Crankcase and Crosshead

• 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.

48
Oil Pressure adjustment, Strainer

• Oil pressure adjustment screw and lock nut
• Clean the oil strainer
• Oil drain plug
• Oil filter now standard

49
Oil Pressure adjustment, Strainer

• 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.

50
Crankcase Access

• Access cover and gasket
• Dipstick
• Remove lower bearing caps, lift crosshead and
  connecting rod assembly

51
Crankcase Access

• The oil dipstick is located adjacent to the
  access cover. In earlier models, it was located
  in the access cover. The oil viscosity and
  capacity are found in the Instruction Manual.
• Removal of the crankcase access cover and gasket
  permits 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.

52
Crosshead and Connecting Rod

• Connecting rod has cast-in lube channels, big
  end to small end
• Connecting rod is Ductile Iron
• Crosshead is now cast iron
• Dont remove piston rod from crosshead

53
Crosshead and Connecting Rod

• 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.

54
Crosshead and Connecting Rod (contd)

• Wrist pin is pressed in or out of the crosshead
• Wrist pin bushing is pressed in and honed to the
  proper bore
• Bushing oil hole must align with connecting rod
  feed hole
• Some models have needle wrist pin bearings

55
Crosshead and Connecting Rod (contd)

• 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 feed
  holes.
• 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.

56
Bearing Carrier

• Carrier and oil pump are removed as an assembly
• Slot in carrier fits into tang at crankshaft end

57
Bearing Carrier

• 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.

58
Oil Pump(HD372A)

• May be installed for either rotation direction
• Rotate cover 180 for opposite rotation direction

59
Oil Pump(HD372A)

• 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.

60
Crankshaft Removal

• Pressure lubrication holes at the journal
  bearings
• Oil spray nozzles on the crankshaft for the
  crossheads
• Crankcase breather vent

61
Crankshaft Removal

• 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.

62
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

63
Bearing Cover Plate

• 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.

64
End of Presentation
1809 Century Avenue Grand Rapids, MI, USA
49503 Ph 616-241-1611 Fax [phone] www.black
mer.com