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Company News · Model reference guide

National JWS-400 Mud Pump Spare Parts

Published by Pratt Oil ·

Pratt OilParts identification
National JWS-400 source expendables reference table

National JWS-400 reference MK-0237-50 identifies a nominal 5-inch liner in the list. Separate the liner requirement from individual piston and valve components, retaining the actual size and fitted arrangement. For a quotation, send the part or drawing number, quantity, pump model and nameplate photo.

Parts List

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42 parts

P/PPart / Drawing No.NamePart / Drawing No.Name
1MK-0237-40Liner, nominal size 4''MK-LL-400-10Long Life (Urethane); nominal piston size 4''
2MKG-0272Liner Packing, nominal size 4''MK-RT-440-10Red Thunder Bonded Pistons; nominal piston size 4½''
3MK-0237-44Liner, nominal size 4½''MK-I44HK10Imperial Piston; nominal piston size 4½''
4MKG-0274Liner Packing, nominal size 4½''MK-I44HKImperial Rubber Kits; nominal piston size 4½''
5MK-0237-50Liner, nominal size 5''MK-RB-440-10Rubber Bonded; nominal piston size 4½''
6MKG-0276Liner Packing, nominal size 5''MK-LL-440-10Long Life (Urethane); nominal piston size 4½''
7MK-0237-54Liner, nominal size 5½''MK-RT-500-10Red Thunder Bonded Pistons; nominal piston size 5''
8MKG-0278Liner Packing, nominal size 5½''MK-I50HB10Imperial Piston; nominal piston size 5''
9MK-1715146Valve Cover GasketMK-I50HBImperial Rubber Kits; nominal piston size 5''
10MK-1561575VALVE (Urethane Insert); suctionMK-RB-500-10Rubber Bonded; nominal piston size 5''
11MK-1561575VALVE (Urethane Insert); dischargeMK-LL-500-10Long Life (Urethane); nominal piston size 5''
12MK-1561561VALVE SEAT; suctionMK-RT-540-10Red Thunder Bonded Pistons; nominal piston size 5½''
13MK-1561569VALVE SEAT; dischargeMK-I54HB10Imperial Piston; nominal piston size 5½''
14MK-1560698VALVE SPRING; suctionMK-I54HBImperial Rubber Kits; nominal piston size 5½''
15MK-1717296VALVE SPRING; dischargeMK-RB-540-10Rubber Bonded; nominal piston size 5½''
16MK-1561577VALVE INSERT (Urethane); suctionMK-LL-540-10Long Life (Urethane); nominal piston size 5½''
17MK-1561577VALVE INSERT (Urethane); dischargeMK-2239-APiston Rod; part no.
18MK-RT-400-10Red Thunder Bonded Pistons; nominal piston size 4''MK-2239-BSub Rod; part no.
19MK-I40HK10Imperial Piston; nominal piston size 4''MK-16-2239Extension Rod; part no.
20MK-I40HKImperial Rubber Kits; nominal piston size 4''MK-24-2239Rod Clamp; part no.
21MK-RB-400-10Rubber Bonded; nominal piston size 4''MK-7403224Piston Rod Nut; part no.
Technical details and source references

Confirm the installed model, drawing revision and dimensions before ordering. Catalogue quantities do not indicate current stock.

Reference documents and scope

  • S1 — Mud King Products, Mud Pump Expendables / Triplex Fluid End Parts (source catalogue edition undated). Reference file: EMSCO-MK-美国泥浆泵.pdf.

PDF page numbers count from the first page of each reference file. Brand names identify the equipment or catalogue source. A listed number does not establish interchangeability, original-manufacturer authorisation, stock or a delivery commitment. Send the nameplate, complete reference, quantity and drawing revision for a parts review.

For a National JWS-400 mud pump parts enquiry, the complete component reference is more useful than the pump model alone. The Mud King Products catalogue separates expendable parts by nominal size, component family and installed arrangement. This guide transcribes the identifiable supplier-number entries associated with National JWS-400, with their original page and table context, so a buyer can assemble a clearer maintenance RFQ.

Liner Packing and G2 Valve References

The JWS400 liner table lists four size-specific packing combinations: for example, MK-0237-40 pairs with MKG-0272 in the 4-inch row, while MK-0237-54 pairs with MKG-0278 in the 5½-inch row. The valve-cover gasket entry is MK-1715146. Keep that component description separate from liner packing even though both are sealing parts.

The G2 valve table differentiates suction seat MK-1561561 from discharge seat MK-1561569 and also separates the two valve springs. These should not be copied from the JWS165/340 table: the shared valve assembly family does not establish identical seats or springs. The rod section lists a piston rod and a sub rod separately, so identify which connection and component the repair requires.

Read the catalogue reference correctly

The accompanying reference list covers the identifiable number-bearing cells in the relevant source tables, not a complete original-manufacturer bill of materials. MK and MKG identify supplier catalogue references; their prefixes, punctuation and combined suffixes are retained. A value marked N/A or left blank is not replaced by an invented number. A shared model heading records the catalogue scope and does not by itself confirm interchangeability on an individual pump.

Information to send for parts matching

Send the pump nameplate and serial number, full reference including its prefix, required quantity and a photograph of the installed or removed component. For liners and pistons, add the nominal size and sealing arrangement. For fluid-end hardware, identify the module configuration and whether an individual component or a studded assembly is required. Keep any original equipment drawing number as a separate field rather than stripping the supplier prefix to assume an OEM match.

Review mud pump spare parts matching, compare liners, pistons, valves and seats, or send Pratt Oil a parts list for review. Matching and availability require confirmation; these references do not establish authorisation, inventory or a delivery promise.

  1. MK-0237-40 — S1 , PDF p. 30 — Liners and liner packing; source row 4''; Mud King supplier catalogue number
  2. MKG-0272 — S1 , PDF p. 30 — Liners and liner packing; source row 4''; Mud King supplier catalogue number
  3. MK-0237-44 — S1 , PDF p. 30 — Liners and liner packing; source row 4½''; Mud King supplier catalogue number
  4. MKG-0274 — S1 , PDF p. 30 — Liners and liner packing; source row 4½''; Mud King supplier catalogue number
  5. MK-0237-50 — S1 , PDF p. 30 — Liners and liner packing; source row 5''; Mud King supplier catalogue number
  6. MKG-0276 — S1 , PDF p. 30 — Liners and liner packing; source row 5''; Mud King supplier catalogue number
  7. MK-0237-54 — S1 , PDF p. 30 — Liners and liner packing; source row 5½''; Mud King supplier catalogue number
  8. MKG-0278 — S1 , PDF p. 30 — Liners and liner packing; source row 5½''; Mud King supplier catalogue number
  9. MK-1715146 — S1 , PDF p. 30 — Gaskets; Mud King supplier catalogue number
  10. MK-1561575 — S1 , PDF p. 30 — MKP-G2; suction; Mud King supplier catalogue number
  11. MK-1561575 — S1 , PDF p. 30 — MKP-G2; discharge; Mud King supplier catalogue number
  12. MK-1561561 — S1 , PDF p. 30 — MKP-G2; suction; Mud King supplier catalogue number
  13. MK-1561569 — S1 , PDF p. 30 — MKP-G2; discharge; Mud King supplier catalogue number
  14. MK-1560698 — S1 , PDF p. 30 — MKP-G2; suction; Mud King supplier catalogue number
  15. MK-1717296 — S1 , PDF p. 30 — MKP-G2; discharge; Mud King supplier catalogue number
  16. MK-1561577 — S1 , PDF p. 30 — MKP-G2; suction; Mud King supplier catalogue number
  17. MK-1561577 — S1 , PDF p. 30 — MKP-G2; discharge; Mud King supplier catalogue number
  18. MK-RT-400-10 — S1 , PDF p. 30 — Piston family Red Thunder Bonded Pistons; size 4''; Mud King supplier catalogue number
  19. MK-I40HK10 — S1 , PDF p. 30 — Piston family Imperial Piston; size 4''; Mud King supplier catalogue number
  20. MK-I40HK — S1 , PDF p. 30 — Piston family Imperial Rubber Kits; size 4''; Mud King supplier catalogue number
  21. MK-RB-400-10 — S1 , PDF p. 30 — Piston family Rubber Bonded; size 4''; Mud King supplier catalogue number
  22. MK-LL-400-10 — S1 , PDF p. 30 — Piston family Long Life (Urethane); size 4''; Mud King supplier catalogue number
  23. MK-RT-440-10 — S1 , PDF p. 30 — Piston family Red Thunder Bonded Pistons; size 4½''; Mud King supplier catalogue number
  24. MK-I44HK10 — S1 , PDF p. 30 — Piston family Imperial Piston; size 4½''; Mud King supplier catalogue number
  25. MK-I44HK — S1 , PDF p. 30 — Piston family Imperial Rubber Kits; size 4½''; Mud King supplier catalogue number
  26. MK-RB-440-10 — S1 , PDF p. 30 — Piston family Rubber Bonded; size 4½''; Mud King supplier catalogue number
  27. MK-LL-440-10 — S1 , PDF p. 30 — Piston family Long Life (Urethane); size 4½''; Mud King supplier catalogue number
  28. MK-RT-500-10 — S1 , PDF p. 30 — Piston family Red Thunder Bonded Pistons; size 5''; Mud King supplier catalogue number
  29. MK-I50HB10 — S1 , PDF p. 30 — Piston family Imperial Piston; size 5''; Mud King supplier catalogue number
  30. MK-I50HB — S1 , PDF p. 30 — Piston family Imperial Rubber Kits; size 5''; Mud King supplier catalogue number
  31. MK-RB-500-10 — S1 , PDF p. 30 — Piston family Rubber Bonded; size 5''; Mud King supplier catalogue number
  32. MK-LL-500-10 — S1 , PDF p. 30 — Piston family Long Life (Urethane); size 5''; Mud King supplier catalogue number
  33. MK-RT-540-10 — S1 , PDF p. 30 — Piston family Red Thunder Bonded Pistons; size 5½''; Mud King supplier catalogue number
  34. MK-I54HB10 — S1 , PDF p. 30 — Piston family Imperial Piston; size 5½''; Mud King supplier catalogue number
  35. MK-I54HB — S1 , PDF p. 30 — Piston family Imperial Rubber Kits; size 5½''; Mud King supplier catalogue number
  36. MK-RB-540-10 — S1 , PDF p. 30 — Piston family Rubber Bonded; size 5½''; Mud King supplier catalogue number
  37. MK-LL-540-10 — S1 , PDF p. 30 — Piston family Long Life (Urethane); size 5½''; Mud King supplier catalogue number
  38. MK-2239-A — S1 , PDF p. 30 — Rod arrangement PART NO.; Mud King supplier catalogue number
  39. MK-2239-B — S1 , PDF p. 30 — Rod arrangement PART NO.; Mud King supplier catalogue number
  40. MK-16-2239 — S1 , PDF p. 30 — Rod arrangement PART NO.; Mud King supplier catalogue number
  41. MK-24-2239 — S1 , PDF p. 30 — Rod arrangement PART NO.; Mud King supplier catalogue number
  42. MK-7403224 — S1 , PDF p. 30 — Rod arrangement PART NO.; Mud King supplier catalogue number

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