INDUSTRY COMPONENT

Crankpin/Eccentric Journal

A precision cylindrical journal on an eccentric shaft that converts rotary motion into reciprocating motion in industrial machinery.

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Component Specifications

Definition
The crankpin or eccentric journal is a precisely machined cylindrical surface offset from the main rotational axis of an eccentric shaft or crankshaft. This offset creates an eccentricity that transforms continuous rotary input into controlled linear or oscillating output motion through connecting rods or linkages. In industrial applications, it serves as the critical interface between rotating shafts and reciprocating components in engines, pumps, compressors, and various mechanical systems.
Working Principle
Operates on the eccentric motion principle where the offset distance (eccentricity) between the journal center and shaft rotational axis creates a crank mechanism. As the shaft rotates, the journal follows a circular path, converting rotational energy into linear displacement through attached linkages. The mechanical advantage depends on the eccentricity radius and angular position.
Materials
Typically forged or machined from alloy steels (AISI 4140, 4340, EN19) with surface hardening (case hardening, induction hardening, nitriding). High-wear applications may use hardened tool steels or incorporate wear-resistant coatings (chrome plating, thermal spray coatings). Corrosion-resistant applications utilize stainless steels (17-4PH, 316L).
Technical Parameters
  • Hardness 55-62 HRC (surface)
  • Roundness 0.005 mm max
  • Cylindricity 0.008 mm max
  • Eccentricity ±0.02 mm
  • Surface Finish Ra 0.4-0.8 μm
  • Diameter Tolerance h6/h7 (ISO)
Standards
ISO 286-2, DIN 748, ISO 1101, DIN 7190

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Crankpin/Eccentric Journal.

eccentric journal crankpin crankshaft component power transmission reciprocating motion industrial shaft mechanical linkage offset journal Crankpin/Eccentric Journal Crankpin/Eccentric Journal in Machinery and Equipment Manufacturing

Parent Products

This component is used in the following industrial products

Eccentric Shaft / Crank

A mechanical component that converts rotary motion into oscillating or reciprocating motion through its offset axis of rotation.

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Engineering Analysis

Risks & Mitigation
  • Fatigue failure from cyclic loading
  • Wear and clearance increase
  • Lubrication failure leading to seizure
  • Imbalance causing vibration
  • Corrosion in harsh environments
FMEA Triads
Trigger: Insufficient lubrication or contaminated lubricant
Failure: Increased friction, overheating, and eventual seizure
Mitigation: Implement scheduled lubrication maintenance, use filtration systems, monitor oil temperature and pressure
Trigger: Cyclic loading exceeding fatigue strength
Failure: Crack initiation and propagation leading to fracture
Mitigation: Proper material selection, surface treatments, regular non-destructive testing (ultrasonic, magnetic particle)
Trigger: Misalignment during assembly or operation
Failure: Uneven wear, increased vibration, reduced efficiency
Mitigation: Precision alignment procedures, use of alignment tools, regular vibration monitoring

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
Geometric tolerances per ISO 1101, dimensional tolerances per ISO 286-2, surface finish requirements per ISO 1302
Test Method
Dimensional verification with CMM, hardness testing (Rockwell/Vickers), surface roughness measurement, non-destructive testing (ultrasonic, dye penetrant), dynamic balancing

Procurement Evaluation Criteria

Not customer reviews or live demand data. These dimensions support RFQ preparation and supplier evaluation.

Technical documentation
4/5
Manufacturing capability
4/5
Inspection readiness
5/5
Supplier transparency
3/5

These scores are example evaluation dimensions, not real customer ratings, country-specific buyer feedback, or live inquiry activity.

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Frequently Asked Questions

What is the difference between a crankpin and eccentric journal?

While functionally similar, crankpins typically refer to components in multi-cylinder engines where they connect rods to crankshafts, while eccentric journals are single-offset features on shafts for creating reciprocating motion in various industrial machines.

How is eccentricity measured and controlled?

Eccentricity is measured as the radial distance between the journal center and shaft rotational axis using coordinate measuring machines (CMM) or dial indicators. Control is maintained through precision machining, balancing, and strict tolerance adherence.

What maintenance do crankpins require?

Regular lubrication, wear inspection, clearance checks, and balancing verification. High-cycle applications may require periodic re-machining or replacement due to fatigue and wear.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

Data Basis

CNFX manufacturer profiles, technical classification, publicly available product information, and ongoing plausibility checks.

Preliminary Technical Classification
This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

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