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COMPRESSION / INTERACTIVE 3D

Reciprocating compressor concept

Inspect the crank, crosshead, packing, grooved piston and four separate valve stacks.

Static preview of the reciprocating compressor concept schematic
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HOW TO READ THIS MODEL

The system, explained.

A reciprocating compressor connects a crank and connecting rod to a piston through a crosshead and piston rod. This original single-cylinder concept distinguishes the crank-end and head-end regions, with separate suction and discharge valve markers at each end. Compare the rod packing with the piston rings, then inspect a perforated seat, plate, guard and spring. The pose is static: gas movement, compression and automatic valve events are not simulated.

Model scope and limits

Original generic static single-cylinder concept with invented proportions, separate crank journals/webs/pin, connecting-rod eyes, crosshead, guide shoes, packing markers, hollow cylinder, grooved piston, split rings, rider band and four simplified valve stacks. No OEM CAD, imagery or product dimensions imported. No cycle, automatic valve events, pressure, gas flow, thermodynamics, rod loads, speed, lubrication, leakage, spring force, rated joints, materials, clearances, threads or full collision qualification. The separate boundary connections are not a complete manifold, package, motor drive, cooling, gas treatment, vent/purge, lubrication, instrumentation or protection system. Revealed and separated views provide no operating or maintenance procedure.

Source links support further study; no affiliation or endorsement is implied.

CHECK YOUR UNDERSTANDING

Which illustrated component connects the small connecting-rod eye to the piston-rod region?

Choose an answer

GUIDED COMPONENT STUDY

Trace the system.

Read each explanation, then focus its component in the explorer. This is a learning route through the model, with no operating or maintenance sequence.

  1. Distinguish the two crank axes

    The main journals share one axis; the crank pin is offset from it. Separate web markers connect their regions. This is one static invented pose, without a motor, balancing, speed or cyclic force calculation.

  2. Follow the connecting rod

    The large annular eye surrounds the offset crank pin; the smaller eye surrounds the crosshead pin. A separate shank joins their regions. Selected export checks compare these axis centres. They do not qualify bearings, retention or a full moving linkage.

  3. Locate the crosshead

    Two side cheeks, a pin, bushing and upper/lower shoe markers distinguish this assembly from the piston. The fixed guide surfaces lie around it. Running clearance, side load, travel and wear are not calculated.

  4. Trace the rod through its boundary

    The piston rod passes through three separate annular packing markers near the crank-end head. Their location differs from the wiper and from the rings on the piston. Real packing segmentation, loading, cooling, venting and sealing behaviour are outside this concept.

  5. Compare the piston grooves

    Two narrow recesses receive separate split-ring markers; a wider central recess receives a rider-band marker. The hollow centre surrounds the rod. These are actual geometric recesses and separate meshes, with invented gaps and no material, wear, leakage or running-fit result.

  6. Distinguish the rider band

    This closed annular marker occupies the wider piston recess. Compare its location with the two split rings. A component label and geometry do not establish loading, wear, lubrication or a qualified piston support arrangement.

  7. Inspect one suction seat

    Eight actual holes pass through this fixed seat marker. The separate annular plate lies on the cylinder side of the illustrated seat. The guard, centre pin and coil remain separate. No pressure-responsive opening, measured lift, gas passage or leakage is calculated.

  8. Compare the discharge stack

    The discharge plate marker lies on the outer-pocket side of its fixed seat, unlike the suction plate relationship. Both stacks are held in a static pose. The blue and teal connection colors identify lesson roles, without a measured flow direction or industry color standard.

  9. Open the pocket-cover joint

    The separate cover and annular flange share four actual stud bores, with distinct smooth studs, washers and bored nut markers. The side opening leads to a hollow boundary neck. Threads, rated retention, manifold connections and pressure-joint qualification are omitted.

  10. Recognize the missing package

    The hollow wall has four geometric valve-pocket openings and separate end closures. This teaching scene omits a complete driver, lubrication, cooling, gas treatment, controls, relief, shutdown and manifold package. Connecting it conceptually to plant equipment does not establish an engineered installation.

ACCESSIBLE COMPONENT REFERENCE

Every part, in plain language.

Search all components ↗Model provenance ↗
Compressor support frame

Invented support frame. No foundation, structural, vibration or load calculation.

Support leg 1

Illustrative support meeting the enclosure/cylinder region. Attachments and loads are not designed.

Support leg 2

Illustrative support meeting the enclosure/cylinder region. Attachments and loads are not designed.

Support leg 3

Illustrative support meeting the enclosure/cylinder region. Attachments and loads are not designed.

Support leg 4

Illustrative support meeting the enclosure/cylinder region. Attachments and loads are not designed.

Support leg 5

Illustrative support meeting the enclosure/cylinder region. Attachments and loads are not designed.

Support leg 6

Illustrative support meeting the enclosure/cylinder region. Attachments and loads are not designed.

Support leg 7

Illustrative support meeting the enclosure/cylinder region. Attachments and loads are not designed.

Support leg 8

Illustrative support meeting the enclosure/cylinder region. Attachments and loads are not designed.

Crankcase floor

Static enclosure floor. Oil level, pump and lubrication circuit are omitted.

Crankcase top cover

Separate enclosure cover, removed only by presentation controls.

Crankcase end wall

Illustrative frame end wall, without qualified casting or ventilation details.

Crankcase guide wall

Frame wall with an actual opening toward the crosshead guide.

Front crankcase wall

Separate frame wall with a bored crankshaft opening. No pressure or casting specification.

Front main bearing

Separate annular bearing marker around the main journal. No oil-film, load or bearing fit qualification.

Rear crankcase wall

Separate frame wall with a bored crankshaft opening. No pressure or casting specification.

Rear main bearing

Separate annular bearing marker around the main journal. No oil-film, load or bearing fit qualification.

Front main journal

Smooth main journal on the crank axis; no speed, balance or bearing duty.

Rear main journal

Second main journal coaxial with the first. Static geometry only.

Front crank web

Original web marker joining a main journal region to the offset crank pin. No balance or stress qualification.

Rear crank web

Original web marker joining a main journal region to the offset crank pin. No balance or stress qualification.

Offset crank pin

Separate crank-pin axis offset from the main journals. One invented static pose; no cycle or rod-load calculation.

Connecting rod big end

Annular connecting-rod end around the crank pin. Split cap, bolts and qualified bearing fit are omitted.

Connecting rod small end

Annular rod end on the crosshead pin axis. No qualified bearing or force transfer.

Crosshead pin bushing

Separate thin bushing marker between the crosshead pin and rod eye. Clearance is invented.

Connecting rod shank

Original straight shank joining the two rod-eye regions. Its shape and section are teaching choices.

Front crosshead cheek

Crosshead side cheek with a real pin bore. Guide and pin relationships are static.

Rear crosshead cheek

Crosshead side cheek with a real pin bore. Guide and pin relationships are static.

Crosshead pin

Smooth crosshead pin coaxial with the small rod eye. No retention or cyclic load calculation.

Upper crosshead shoe

Separate guide-shoe marker. No wear, running-clearance or side-load qualification.

Upper crosshead guide

Fixed guide surface around the crosshead shoes. No dynamic travel is supplied.

Lower crosshead shoe

Separate guide-shoe marker. No wear, running-clearance or side-load qualification.

Lower crosshead guide

Fixed guide surface around the crosshead shoes. No dynamic travel is supplied.

Front guide wall

Separate side enclosure around the crosshead/rod region.

Rear guide wall

Separate side enclosure around the crosshead/rod region.

Piston rod

Smooth rod from the crosshead region through packing to the piston. No thread form, rod load or dynamic motion.

Front distance-piece wall

Open-ended distance-piece enclosure marker. Purge, ventilation, drains and service requirements are unspecified.

Rear distance-piece wall

Open-ended distance-piece enclosure marker. Purge, ventilation, drains and service requirements are unspecified.

Upper distance-piece wall

Separate distance-piece wall; no qualified gas/oil separation or enclosure classification.

Lower distance-piece wall

Separate distance-piece wall; no qualified gas/oil separation or enclosure classification.

Rod wiper housing

Separate hollow wiper location marker. Drain and sealing details are omitted.

Rod wiper marker

Annular wiper marker around the rod; no lip profile, material or sealing result.

Rod packing housing

Hollow housing around separate rod-packing markers. No packing pressure, cooling or vent plan.

Rod packing ring 1

Separate annular packing marker. Real segmentation, spring loading, leakage and material behaviour are omitted.

Rod packing ring 2

Separate annular packing marker. Real segmentation, spring loading, leakage and material behaviour are omitted.

Rod packing ring 3

Separate annular packing marker. Real segmentation, spring loading, leakage and material behaviour are omitted.

Crank-end head

Cylinder closure around the piston rod, with actual central bore. No pressure rating or qualified packing joint.

Crank-end cylinder flange

Hollow cylinder-end flange with separate drilled fastener bores.

Compression cylinder wall

Actual hollow cylindrical wall with four geometric valve-pocket openings. Invented wall thickness, no gas or pressure simulation.

Head-end cylinder flange

Hollow head-end flange with actual fastener bores. No rated facing or joint.

Head-end head

Solid geometric end closure. No head stress, pressure or manufacturing specification.

Crank-end joint stud 1

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Crank-end joint washer 1

Separate washer with an open centre. Not a qualified fastener joint.

Crank-end joint nut 1

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Crank-end joint stud 2

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Crank-end joint washer 2

Separate washer with an open centre. Not a qualified fastener joint.

Crank-end joint nut 2

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Crank-end joint stud 3

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Crank-end joint washer 3

Separate washer with an open centre. Not a qualified fastener joint.

Crank-end joint nut 3

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Crank-end joint stud 4

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Crank-end joint washer 4

Separate washer with an open centre. Not a qualified fastener joint.

Crank-end joint nut 4

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Crank-end joint stud 5

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Crank-end joint washer 5

Separate washer with an open centre. Not a qualified fastener joint.

Crank-end joint nut 5

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Crank-end joint stud 6

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Crank-end joint washer 6

Separate washer with an open centre. Not a qualified fastener joint.

Crank-end joint nut 6

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Crank-end joint stud 7

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Crank-end joint washer 7

Separate washer with an open centre. Not a qualified fastener joint.

Crank-end joint nut 7

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Crank-end joint stud 8

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Crank-end joint washer 8

Separate washer with an open centre. Not a qualified fastener joint.

Crank-end joint nut 8

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Head-end joint stud 1

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Head-end joint washer 1

Separate washer with an open centre. Not a qualified fastener joint.

Head-end joint nut 1

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Head-end joint stud 2

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Head-end joint washer 2

Separate washer with an open centre. Not a qualified fastener joint.

Head-end joint nut 2

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Head-end joint stud 3

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Head-end joint washer 3

Separate washer with an open centre. Not a qualified fastener joint.

Head-end joint nut 3

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Head-end joint stud 4

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Head-end joint washer 4

Separate washer with an open centre. Not a qualified fastener joint.

Head-end joint nut 4

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Head-end joint stud 5

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Head-end joint washer 5

Separate washer with an open centre. Not a qualified fastener joint.

Head-end joint nut 5

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Head-end joint stud 6

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Head-end joint washer 6

Separate washer with an open centre. Not a qualified fastener joint.

Head-end joint nut 6

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Head-end joint stud 7

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Head-end joint washer 7

Separate washer with an open centre. Not a qualified fastener joint.

Head-end joint nut 7

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Head-end joint stud 8

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Head-end joint washer 8

Separate washer with an open centre. Not a qualified fastener joint.

Head-end joint nut 8

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Grooved piston

Original hollow piston marker with two ring recesses and a central rider-band recess. Geometry does not establish a piston material, running clearance or gas performance.

Split piston ring 1

Separate split-ring geometry in a piston recess. Split gap, loading, material and leakage are invented.

Split piston ring 2

Separate split-ring geometry in a piston recess. Split gap, loading, material and leakage are invented.

Piston rider band

Separate closed rider-band marker. Its role differs from the two split-ring markers; no wear or loading result.

Piston retaining marker

Annular retaining marker around the rod. No qualified nut thread, locking or axial retention.

Crank end suction pocket neck

Hollow connection through a drilled cylinder-wall opening toward a separate valve stack. No rated port or simulated flow.

Crank end suction perforated seat

Fixed valve-seat marker with eight actual geometric holes. Not a manufacturer valve or a flow/leakage calculation.

Crank end suction plate marker

Separate annular plate at a fixed illustrated seat relationship. There is no automatic valve event, measured lift, pressure response or leakage result.

Crank end suction guard

Separate bored guard/support marker below the plate in this static concept. Retention and valve lift are unspecified.

Crank end suction spring marker

Original three-turn closed coil marker. Static pose; no valve spring rate, preload, fatigue or event timing.

Crank end suction centre pin

Smooth central guide/attachment marker, without threads or rated valve retention.

Crank end suction outer pocket

Hollow outer pocket above the suction seat or below the discharge seat. Separate boundary necks are illustrative, not a complete manifold.

Crank end suction boundary neck

Hollow boundary connection for the indicated inlet/outlet role. No manifold, support system, gas quantity or process direction simulation.

Crank end suction boundary flange

Open flange marker on the boundary neck; facing, pressure and attachment design omitted.

Crank end suction pocket cover

Separate solid presentation cover on the outer pocket. No qualified pressure or valve-retention joint.

Crank end suction cover flange

Annular pocket-cover flange with actual matching stud bores. No rated facing, preload or pressure-joint qualification.

Crank end suction cover stud 1

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Crank end suction cover washer 1

Separate washer with an open centre. Not a qualified fastener joint.

Crank end suction cover nut 1

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Crank end suction cover stud 2

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Crank end suction cover washer 2

Separate washer with an open centre. Not a qualified fastener joint.

Crank end suction cover nut 2

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Crank end suction cover stud 3

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Crank end suction cover washer 3

Separate washer with an open centre. Not a qualified fastener joint.

Crank end suction cover nut 3

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Crank end suction cover stud 4

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Crank end suction cover washer 4

Separate washer with an open centre. Not a qualified fastener joint.

Crank end suction cover nut 4

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Crank end discharge pocket neck

Hollow connection through a drilled cylinder-wall opening toward a separate valve stack. No rated port or simulated flow.

Crank end discharge perforated seat

Fixed valve-seat marker with eight actual geometric holes. Not a manufacturer valve or a flow/leakage calculation.

Crank end discharge plate marker

Separate annular plate at a fixed illustrated seat relationship. There is no automatic valve event, measured lift, pressure response or leakage result.

Crank end discharge guard

Separate bored guard/support marker below the plate in this static concept. Retention and valve lift are unspecified.

Crank end discharge spring marker

Original three-turn closed coil marker. Static pose; no valve spring rate, preload, fatigue or event timing.

Crank end discharge centre pin

Smooth central guide/attachment marker, without threads or rated valve retention.

Crank end discharge outer pocket

Hollow outer pocket above the suction seat or below the discharge seat. Separate boundary necks are illustrative, not a complete manifold.

Crank end discharge boundary neck

Hollow boundary connection for the indicated inlet/outlet role. No manifold, support system, gas quantity or process direction simulation.

Crank end discharge boundary flange

Open flange marker on the boundary neck; facing, pressure and attachment design omitted.

Crank end discharge pocket cover

Separate solid presentation cover on the outer pocket. No qualified pressure or valve-retention joint.

Crank end discharge cover flange

Annular pocket-cover flange with actual matching stud bores. No rated facing, preload or pressure-joint qualification.

Crank end discharge cover stud 1

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Crank end discharge cover washer 1

Separate washer with an open centre. Not a qualified fastener joint.

Crank end discharge cover nut 1

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Crank end discharge cover stud 2

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Crank end discharge cover washer 2

Separate washer with an open centre. Not a qualified fastener joint.

Crank end discharge cover nut 2

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Crank end discharge cover stud 3

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Crank end discharge cover washer 3

Separate washer with an open centre. Not a qualified fastener joint.

Crank end discharge cover nut 3

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Crank end discharge cover stud 4

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Crank end discharge cover washer 4

Separate washer with an open centre. Not a qualified fastener joint.

Crank end discharge cover nut 4

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Head end suction pocket neck

Hollow connection through a drilled cylinder-wall opening toward a separate valve stack. No rated port or simulated flow.

Head end suction perforated seat

Fixed valve-seat marker with eight actual geometric holes. Not a manufacturer valve or a flow/leakage calculation.

Head end suction plate marker

Separate annular plate at a fixed illustrated seat relationship. There is no automatic valve event, measured lift, pressure response or leakage result.

Head end suction guard

Separate bored guard/support marker below the plate in this static concept. Retention and valve lift are unspecified.

Head end suction spring marker

Original three-turn closed coil marker. Static pose; no valve spring rate, preload, fatigue or event timing.

Head end suction centre pin

Smooth central guide/attachment marker, without threads or rated valve retention.

Head end suction outer pocket

Hollow outer pocket above the suction seat or below the discharge seat. Separate boundary necks are illustrative, not a complete manifold.

Head end suction boundary neck

Hollow boundary connection for the indicated inlet/outlet role. No manifold, support system, gas quantity or process direction simulation.

Head end suction boundary flange

Open flange marker on the boundary neck; facing, pressure and attachment design omitted.

Head end suction pocket cover

Separate solid presentation cover on the outer pocket. No qualified pressure or valve-retention joint.

Head end suction cover flange

Annular pocket-cover flange with actual matching stud bores. No rated facing, preload or pressure-joint qualification.

Head end suction cover stud 1

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Head end suction cover washer 1

Separate washer with an open centre. Not a qualified fastener joint.

Head end suction cover nut 1

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Head end suction cover stud 2

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Head end suction cover washer 2

Separate washer with an open centre. Not a qualified fastener joint.

Head end suction cover nut 2

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Head end suction cover stud 3

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Head end suction cover washer 3

Separate washer with an open centre. Not a qualified fastener joint.

Head end suction cover nut 3

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Head end suction cover stud 4

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Head end suction cover washer 4

Separate washer with an open centre. Not a qualified fastener joint.

Head end suction cover nut 4

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Head end discharge pocket neck

Hollow connection through a drilled cylinder-wall opening toward a separate valve stack. No rated port or simulated flow.

Head end discharge perforated seat

Fixed valve-seat marker with eight actual geometric holes. Not a manufacturer valve or a flow/leakage calculation.

Head end discharge plate marker

Separate annular plate at a fixed illustrated seat relationship. There is no automatic valve event, measured lift, pressure response or leakage result.

Head end discharge guard

Separate bored guard/support marker below the plate in this static concept. Retention and valve lift are unspecified.

Head end discharge spring marker

Original three-turn closed coil marker. Static pose; no valve spring rate, preload, fatigue or event timing.

Head end discharge centre pin

Smooth central guide/attachment marker, without threads or rated valve retention.

Head end discharge outer pocket

Hollow outer pocket above the suction seat or below the discharge seat. Separate boundary necks are illustrative, not a complete manifold.

Head end discharge boundary neck

Hollow boundary connection for the indicated inlet/outlet role. No manifold, support system, gas quantity or process direction simulation.

Head end discharge boundary flange

Open flange marker on the boundary neck; facing, pressure and attachment design omitted.

Head end discharge pocket cover

Separate solid presentation cover on the outer pocket. No qualified pressure or valve-retention joint.

Head end discharge cover flange

Annular pocket-cover flange with actual matching stud bores. No rated facing, preload or pressure-joint qualification.

Head end discharge cover stud 1

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Head end discharge cover washer 1

Separate washer with an open centre. Not a qualified fastener joint.

Head end discharge cover nut 1

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Head end discharge cover stud 2

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Head end discharge cover washer 2

Separate washer with an open centre. Not a qualified fastener joint.

Head end discharge cover nut 2

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Head end discharge cover stud 3

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Head end discharge cover washer 3

Separate washer with an open centre. Not a qualified fastener joint.

Head end discharge cover nut 3

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.

Head end discharge cover stud 4

Smooth stud marker through an actual geometric bore. Threads and qualified bolt load are omitted.

Head end discharge cover washer 4

Separate washer with an open centre. Not a qualified fastener joint.

Head end discharge cover nut 4

Bored nut marker. Its circular bore is unthreaded and does not establish retention or torque.