GB/T 6974.4-2008 is Part 4 of the crane terminology series, specifically governing the terms and definitions for jib cranes.

Standard Scope and Terminology Framework

GB/T 6974.4-2008 is the fourth part of the GB/T 6974 "Cranes — Vocabulary" series, dedicated to standardizing terminology for jib-type cranes. Jib cranes come in a wide variety of configurations with significant structural differences — from portal cranes to floating cranes to mast cranes — and each type has its own terminology system that shares common ground while retaining type-specific terms. The standard covers approximately 160 specialized jib crane terms across six categories: crane type, main structure, mechanisms and devices, safety devices, performance parameters, and operational terms. Standardized jib crane terminology is essential for technical communication and safety management in shipyards, ports, and heavy equipment installation sectors.

Jib Crane Type Terminology

The standard defines terminology for each jib crane configuration: Portal crane — a crane mounted on a gantry structure with a slewing jib system, allowing railway vehicles or road vehicles to pass through the portal base. Mast crane — a crane whose jib is mounted on a slewing mast (column) stabilized by guy ropes. Floating crane — a crane installed on a barge or pontoon, used for port loading/unloading and offshore lifting operations. Deck crane — a slewing jib crane mounted on a ship's deck for handling the vessel's own cargo. Cantilever crane — a fixed-base jib crane (wall-mounted or column-mounted) with a slewing jib at a fixed or adjustable working radius. Railway crane — a crane mounted on a railway vehicle chassis, capable of traveling and operating on rail tracks.

Main Structural Component Terms

The standard precisely defines the terminology for the main structural components of jib cranes: Portal base — the portal-shaped structure unique to portal cranes, comprising legs, cross beams, and diagonal struts, which carries the full load transmitted from the slewing platform above. Jib system — includes the main boom, the fly jib (where applicable), and the connecting tie bars or suspension ropes. Slewing platform — the rotating structural component that carries the jib, hoisting mechanism, luffing mechanism, and counterweight, connected to the base/portal via the slewing bearing. Counterweight — weights mounted at the rear of the slewing platform or on the balance arm to offset part of the load moment and reduce the overall overturning moment. Guy rope — steel wire ropes used on mast cranes to keep the mast stable, typically arranged with 4 or more ropes evenly spaced. Ground anchor — the fixing point for guy ropes, either buried in the ground or secured to counterweight blocks.

Mechanism and Safety Device Terms

The standard specifies terminology for jib crane mechanisms and safety devices: Luffing mechanism — the mechanism that changes the working radius of the jib (wire rope luffing / rack-and-pinion luffing / hydraulic cylinder luffing). Grab (grab bucket) — a double-jaw load-handling device for bulk cargo, operated by coordinated hoisting and closing drum action to grip and release material. Load moment limiter (LML) — a combined safety device that monitors both lifting capacity and working radius parameters (mandatory on jib cranes). Radius limit switch — a safety device that prevents the jib from luffing beyond the maximum or minimum allowable working radius. Anti-tipping-back device — a mechanical or hydraulic device that prevents the jib from tilting backward beyond its limit position under no-load or light-load conditions. Luffing speed-limiting valve — a hydraulic control valve in the luffing system that prevents excessive lowering speed. In Kelude technical communications, all jib crane technical characteristics are described using the standard terminology specified in GB/T 6974.4.

Jib Crane Terminology Classification Table

The comparison table below lists the core parameter configuration of the jib crane terminology classification, for reference by selection and operating personnel.

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