Reciprocating Compressors›Rod Load Calculator
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Rod Load & Reversal Calculator

Compression, Tension & Reversal Analysis per API 618

Rod Load Analysis
Calculate compression and tension rod loads for reciprocating compressor cylinders. Verify rod reversal requirements and check against frame load limits per API 618.

Cylinder Geometry

inches
inches

Operating Pressures

psig
psig
psia

Frame Specifications

lbs
Maximum allowable combined rod load

Rod Load Formulas

Parameter Formula
Head End AreaAHE = π × D²/4
Crank End AreaACE = π × (D² - d²)/4
Compression LoadFc = Pd × AHE - Ps × ACE
Tension LoadFt = Pd × ACE - Ps × AHE

Learn the Theory

Understand rod load calculations, reversal requirements, and frame load limits

Read Engineering Guide

Rod Load Notes

Rod Reversal: Required for proper crosshead pin lubrication. Load must reverse direction each stroke.
API 618 Requirement: Minimum 3% reversal recommended. Higher ratios provide better bearing life.
Frame Limit: Combined rod load should not exceed frame manufacturer's rating.

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