Locking Jaws: Jaw Opening Width 50-90 mm

Component Specifications

Definition

Locking jaws are precision-engineered mechanical components in fifth wheel coupling systems that engage and secure the trailer kingpin. They consist of hardened steel jaws with specific geometry that close around the kingpin when the coupling handle is activated, creating a positive mechanical lock. The jaws must maintain consistent clamping force under dynamic loading conditions while allowing for controlled release during uncoupling operations.

Working Principle

The locking jaws operate on a cam-and-lever mechanism where the coupling handle rotation translates into jaw closure through a linkage system. When the handle is moved to the locked position, the cam forces the jaws to close around the kingpin with mechanical advantage. Spring-loaded components maintain tension and prevent accidental release, while wear indicators show when replacement is needed.

Materials

Forged or cast alloy steel (typically SAE 4140 or equivalent), heat-treated to 40-45 HRC for core hardness with surface hardening to 55-60 HRC. Corrosion-resistant coatings include zinc plating, phosphate coating, or powder coating.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Wear Limit	Maximum 3 mm jaw wear before replacement
Yield Strength	≥ 600 MPa
Weight Capacity	Up to 36,000 kg (Class 8 trucks)
Tensile Strength	≥ 800 MPa
Jaw Opening Width	50-90 mm
Kingpin Compatibility	2-inch or 3.5-inch standard
Operating Temperature	-40°C to +120°C

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 3584, ISO 3842, DIN 74080, SAE J700

Parent Products

This component is used in the following industrial products

Fifth Wheel Coupling

A specialized coupling mechanism that connects a terminal tractor to semi-trailers, allowing articulation and load transfer.

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Engineering Analysis

Risks & Mitigation

Jaw failure causing accidental uncoupling
Excessive wear leading to reduced holding capacity
Corrosion compromising structural integrity
Improper installation causing misalignment

FMEA Triads

Trigger: Material fatigue from cyclic loading
Failure: Crack propagation leading to jaw fracture
Mitigation: Regular inspection for surface cracks, proper heat treatment during manufacturing, replacement at recommended intervals

Trigger: Abrasive wear from contaminated kingpin surfaces
Failure: Reduced clamping force and potential uncoupling
Mitigation: Regular cleaning of kingpin and jaws, use of wear indicators, timely replacement when wear limits are reached

Trigger: Corrosion in harsh environments
Failure: Material degradation and reduced strength
Mitigation: Proper corrosion-resistant coatings, regular inspection in coastal or chemical exposure areas, protective maintenance

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

Jaw dimensions ±0.5 mm, hardness variation ±2 HRC, surface finish Ra ≤ 3.2 μm

Test Method

Dynamic fatigue testing per ISO 3584, static load testing to 1.5x rated capacity, metallurgical analysis for material compliance, dimensional verification with CMM

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

Check the legal entity, factory address, ownership, certifications, and direct contacts.

CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Locking Jaws

Manufacturer profiles associated with Locking Jaws.

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Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review

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Frequently Asked Questions

How often should locking jaws be inspected?

Locking jaws should be visually inspected before each trip and undergo detailed inspection every 3 months or 50,000 km, whichever comes first. Check for wear, cracks, and proper lubrication.

What are signs of worn locking jaws?

Visible wear grooves exceeding 3 mm, difficulty in locking/unlocking, excessive play in the kingpin connection, abnormal noises during coupling, or visible cracks in the jaw material.

Are locking jaws interchangeable between different fifth wheel brands?

No, locking jaws are typically brand-specific due to differences in geometry, mounting systems, and compatibility requirements. Always use OEM or certified replacement parts.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

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.

Locking Jaws