Fifth Wheel Coupling for Terminal Tractors | Specifications & Standards

Product Specifications

Technical details and manufacturing context for Fifth Wheel Coupling

Definition

The fifth wheel coupling is a critical component of terminal tractors (also known as yard trucks or shunt trucks) that enables the secure connection and articulation between the tractor and semi-trailers. It serves as the primary interface for load transfer, steering control, and stability during yard operations such as trailer spotting, container handling, and short-distance transport within logistics facilities. The coupling is designed to engage with the trailer's kingpin, providing a pivot point that allows the tractor to maneuver trailers through tight spaces while maintaining load-bearing capacity. Constructed from high-strength alloy steel, forged steel components, and hardened wear plates, the coupling is built to withstand the demanding conditions of frequent coupling and uncoupling cycles. Key parameters include a rated load capacity of 20–50 tonnes (ISO 1726), an adjustable coupling height of 1100–1300 mm to match trailer kingpin heights, and a standard kingpin diameter of 50.8 mm (ISO 337). The operating pressure range is 1.0–1.6 MPa, and the operating temperature range is -40 to 85°C. The main plate material is S355J2+N (EN 10025), with a zinc-nickel plating of 8–12 μm (ASTM B841) for corrosion resistance. The coupling weighs between 150 and 250 kg, depending on configuration and options. The locking mechanism is automatic, with a manual release available as an option, and the mounting type is bolted directly to the tractor frame. For any specific application, it is essential to verify model-specific values and standards with the legal manufacturer or supplier.

Working Principle

The fifth wheel coupling operates through a locking mechanism (typically a jaw assembly) that engages with the kingpin mounted on the semi-trailer. When the tractor reverses under the trailer, the coupling's locking jaws close around the kingpin, securing the connection. The coupling's plate design allows for vertical and horizontal articulation while maintaining load-bearing capacity, enabling the tractor to maneuver trailers through tight spaces. The locking mechanism is automatic, and a manual release is available as an option. The coupling height is adjustable to match the trailer kingpin height, ensuring proper engagement. The operating temperature range of -40 to 85°C is specified; outside this range, material properties degrade.

Common Materials

High-strength alloy steel, Forged steel components, Hardened wear plates

Technical Parameters

Parameter	Typical range	Notes & selection driver
Rated Load Capacity	20–50 t	Maximum vertical load on the fifth wheelISO 1726
Coupling Height	1100–1300 mm	Adjustable to match trailer kingpin height
Kingpin Diameter	50.8 mm	Standard 2-inch kingpinISO 337
Operating Temperature Range	-40–85 °C	Outside this range, material properties degrade
Material Grade	S355J2+N	High-strength structural steel for main plateEN 10025
Surface Treatment	Zinc-nickel plating 8–12 μm	Corrosion resistance for outdoor useASTM B841
Weight	150–250 kg	Depends on configuration and options
Locking Mechanism Type	Automatic	Manual release available as option
Mounting Type	Bolted	Direct mount to tractor frame

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

Components / BOM

Coupling Plate Part
Primary load-bearing surface that supports trailer weight and allows articulation

Material: High-strength steel
Locking Jaws Part
Mechanism that engages with trailer kingpin to secure connection

Material: Forged alloy steel
Release Handle/Mechanism
Control system for disengaging the coupling from the trailer

Material: Steel with protective coating
Mounting Brackets Part
Structural components that secure the coupling to the tractor frame

Material: Structural steel

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Fifth Wheel Coupling.

Applied To / Applications

This component is essential for the following industrial systems and equipment:

Terminal Tractor

View system integration details

Manufacturers of Fifth Wheel Coupling

Manufacturer profiles associated with Fifth Wheel Coupling.

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Frequently Asked Questions

What is the rated load capacity of this fifth wheel coupling?

The rated load capacity is 20–50 tonnes, as per ISO 1726. This is a reference range; the exact capacity for a specific model must be confirmed with the manufacturer.

What is the standard kingpin diameter for this coupling?

The standard kingpin diameter is 50.8 mm (2 inches), as per ISO 337. This is a common standard for semi-trailers.

What is the operating temperature range?

The operating temperature range is -40 to 85°C. Outside this range, material properties may degrade, so it is important to verify suitability for extreme environments.

What surface treatment is applied for corrosion resistance?

The surface treatment is zinc-nickel plating with a thickness of 8–12 μm, as per ASTM B841. This provides corrosion resistance for outdoor use.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records.

Preliminary Technical Classification

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pressure:	N/A (mechanical load bearing)
other spec:	Max vertical load: 40,000 kg, Max articulation angle: ±15°
temperature:	-40°C to +80°C

Fifth Wheel Coupling

Product Specifications

Industry Taxonomies & Aliases

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Industrial Ecosystem & Supply Chain Structure

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