National P-Series Mud Pump Crossheads: Models, Reference Numbers and Replacement Manufacturing

When a National P-Series mud pump is due for power-end repair, identifying the correct crosshead is more specific than naming the pump model alone. A triplex pump normally uses different crossheads by position: two center/right-hand units and one left-hand unit. The reference number, pump serial number, manual revision, dimensions and mating components should therefore be checked together before manufacturing or ordering a replacement.

FH Petroleum Machinery manufactures replacement mud pump crossheads and the mating components required to build a coordinated, customer-specific crosshead package for maintenance, overhaul and legacy-equipment support. Together with a custom crosshead, FH can manufacture matching crosshead guide boards or liners, crosshead pins, extension rods and other interfacing power-end parts from the same approved technical basis. Customers can submit a reference part number, approved drawing, sample component or complete dimensional and material specification.

National P-Series Models Covered

The National Type P triplex mud pump family includes 7-P-50, 8-P-80, 9-P-100, 10-P-130, 12-P-160 and 14-P-220. Their published maximum input ratings range from 500 hp to 2,200 hp, with strokes from 7 3/4 in. to 14 in. These ratings identify six different pump sizes; they do not make the crossheads interchangeable.

• 7-P-50: 500 hp, 7 3/4 in. stroke
• 8-P-80: 800 hp, 8 1/2 in. stroke
• 9-P-100: 1,000 hp, 9 1/4 in. stroke
• 10-P-130: 1,300 hp, 10 in. stroke
• 12-P-160: 1,600 hp, 12 in. stroke
• 14-P-220: 2,200 hp, 14 in. stroke

Crosshead Reference Part Numbers by Pump Model

The following numbers are reference identifiers for initial matching. They should not be treated as a substitute for final technical confirmation.

For example, the 14-P-220 parts list distinguishes part number 1295015 for the center and right-hand positions from part number 1295090 for the left-hand position. The same 015 versus 090 position pattern appears across this P-Series family. Because equipment can be rebuilt or modified during its service life, FH asks buyers to confirm the installed configuration rather than relying on the model name alone.

What the Crosshead Does in the Mud Pump Power End

The crosshead transfers the connecting rod's oscillating motion into the guided reciprocating motion required by the piston and extension rod. Its running surfaces travel against the crosshead liners or guides, while the crosshead pin connects the crosshead to the small end of the connecting rod.

Dimensional control is important at the crosshead pin bore, guide or liner contact surfaces, extension-rod connection, lubrication passages, mounting faces and left-hand versus center/right-hand geometry. A replacement should be assessed as part of a system. Worn liners, an out-of-tolerance pin, poor alignment or an incompatible rod connection can affect fit even when the nominal reference number appears correct.

Four Ways FH Can Manufacture a Replacement Crosshead

1. Manufacture from an Approved Drawing

An approved drawing is the clearest starting point when it contains the geometry, tolerances, material, heat-treatment requirements, surface finish and inspection criteria. FH reviews the drawing and identifies information that must be clarified before production.

2. Manufacture from a Physical Sample

For legacy pumps, a usable drawing may no longer be available. FH can evaluate a customer-supplied sample and build a dimensional record. Sample-based work must account for wear: a used component shows the installed configuration, but a worn dimension is not automatically the original design dimension.

3. Match a Reference Part Number

The reference numbers above help narrow the search when the pump model and crosshead position are known. FH will still request supporting information such as the pump nameplate, serial number, parts-book page, photographs or critical dimensions to reduce the risk of a revision mismatch.

4. Build to a Technical Specification

FH can quote against a controlled specification that defines dimensions, tolerances, materials, inspection points, marking, coating, documentation and packing requirements.

From Technical Confirmation to Finished Component

1. Input review: pump model, crosshead position, reference number, drawing revision, sample condition and quantity.
2. Technical clarification: key dimensions, mating parts, material and process requirements, acceptance criteria and documentation.
3. Manufacturing planning: material route, machining sequence, special-process controls and inspection plan.
4. Precision machining: bores, guide surfaces, faces, holes and lubrication features.
5. Inspection: dimensional checks and specified material or process verification.
6. Identification and packing: agreed marking, preservation and export packaging.

The exact route is defined by the approved technical package. FH does not identify or guarantee a component solely from a photograph.

Matched Components for a Custom Crosshead Package

FH can manufacture the components that interface with a customer-specific crosshead as one coordinated package. The custom crosshead and its mating parts are reviewed against the same approved drawing, sample, reference-number information and dimensional requirements to help control fit, alignment and operating clearances.

Crosshead Guide Boards and Crosshead Liners

Guide boards or liners can be manufactured to match the custom crosshead running surfaces, required clearances, material, hardness, lubrication arrangement and installed pump configuration.

Crosshead Pins

FH can manufacture a matching crosshead pin to the confirmed pin-bore geometry, connecting-rod interface, material, heat treatment and inspection requirements of the customer-specific crosshead package.

Extension Rods and Other Interfacing Power-End Parts

Where required, FH can also manufacture matching extension rods and other interfacing power-end parts after the connecting geometry, alignment requirements and technical specification have been confirmed.

Information to Include in Your RFQ

• Pump manufacturer, model, serial number and nameplate photograph
• Required crosshead position: left-hand, center or right-hand
• Reference part number and parts-manual page
• Approved drawing and revision, or available physical sample
• Whether a matched package is required: guide boards or liners, crosshead pins, extension rods or other interfacing parts
• Key dimensions, running clearances and mating-component information
• Material, heat treatment, hardness, coating and inspection requirements
• Quantity, documentation and delivery destination

Frequently Asked Questions

Are all three crossheads in a National P-Series triplex pump the same?

No. Published parts information distinguishes the left-hand crosshead from the center/right-hand crossheads. Confirm the required position before ordering.

Can FH identify the exact pump model from a photograph?

Photographs are useful supporting evidence, but are not enough for a guaranteed identification. FH uses the nameplate, position, reference number, drawing, sample and critical dimensions for confirmation.

Can FH manufacture a discontinued or hard-to-source crosshead?

FH can evaluate replacement manufacture from an approved drawing, a physical sample, a reference number supported by technical data or a complete customer specification. Feasibility depends on the available inputs.

What information helps prevent fit problems?

Crosshead pin, liner or guide, extension-rod connection, lubrication features, running clearances and pump serial/revision information are especially useful.

National and NOV names and reference numbers are used only to identify equipment applications. FH Petroleum Machinery supplies independently manufactured replacement components and does not imply OEM affiliation. Final compatibility is subject to technical confirmation.