Jib Crane Product

Overview

A jib crane is a fixed crane consisting of a vertical pillar and a horizontal cantilevered arm that rotates (slews) about the pillar axis. A hoist trolley travels along the arm, so the hook covers an annular area — typically a 270° to 360° circle of 2 to 10 m radius. Jib cranes handle the short, repetitive lifts that would otherwise monopolise an overhead crane: loading machine tools, serving welding benches, tending presses. Capacities run from 125 kg ergonomic units to 10 t workshop columns, with 500 kg to 2 t the dominant class.

The machine divides into a structural set — Pillar (Mast), Jib Arm, Foundation Interface — and a mechanism set: the Slewing Unit, the Hoist Trolley, and the Electrification Kit that powers a hoist such as an electric chain hoist hung from the trolley.

Structure and load path

Every load on the hook produces two actions at the mast: a vertical force and an overturning moment equal to load times radius. A 1 t load at 4 m radius applies roughly 40 kN·m of moment, and it is this moment — not the vertical load — that sizes everything below the hook. The Boom Track Beam is a rolled IPE or W-shape whose bottom flange doubles as the trolley track; tip deflection is limited to about span/150 at rated load so the trolley does not run downhill. Free-standing designs carry the boom root on a welded Arm Connection Bracket; braced designs add a Tie Rod Brace from the mast top to mid-boom, which permits a lighter beam but obstructs hook approach near the mast.

The Mast Tube resists the moment in bending. At its foot, four or more Base Gusset Rib ribs spread the wall stress into the Base Flange Plate, and eight Foundation Anchor Bolt studs carry the moment as a push-pull couple into the concrete. The footing is large — commonly 1.5 to 3 m square and up to 1.2 m deep — because soil bearing, not steel strength, usually governs. Erection uses Levelling Nut Set sets to plumb the mast within 1:1000 before Non-Shrink Grout is rammed under the plate; an out-of-plumb mast makes the arm self-rotate toward the low side.

Slewing

The arm rotates on a Slewing Ring Bearing — a single-row, four-point-contact ball bearing with bolted rings, the same family of component used in excavator turntables. One bearing simultaneously reacts thrust (the vertical load), radial force, and the full tilting moment, which is why it replaced the older arrangement of separate top and bottom pivot bearings. Ring bolts are grade 10.9, torqued and re-checked annually, since bolt preload is what keeps the raceway geometry true.

Cranes up to about 2 t are slewed by hand: the operator simply pulls the load, and an adjustable Slew Friction Brake friction pad damps the motion so the arm does not coast. Larger or higher cranes use a Slew Drive Unit — a gearmotor whose Slew Pinion meshes with teeth cut into the slewing ring, turning the arm at 0.5–1 rpm. A Slew Limit Switch cuts the drive before the rubber Slew Buffer stops are struck. Standard cranes are limited to 270°–300° by the Rotation Limit Stop because the power cable rises through the mast and would wind up; full 360° endless slewing requires a slip-ring collector at the mast head.

Trolley and electrification

The Hoist Trolley is a four-wheel carrier whose flanged Wheel Assembly wheels run on the angled underside of the boom flange. Two Trolley Side Plate plates hang on a crossbar — the Hoist Suspension Bar — from which the hoist is suspended; Trolley Spacer Set washers adjust the plate gap to the flange width. Push trolleys suffice to about 2 t; beyond that a motorised trolley travels at 10–20 m/min.

Power reaches the moving hoist through the Electrification Kit kit: a galvanised Festoon C-Rail C-rail under the boom carries Festoon Cable Trolley cable carriers, each supporting a loop of Flat Festoon Cable. The festoon extends and gathers as the hoist travels. A lockable Mains Isolator Switch at the mast base provides maintenance isolation per EN 60204-32.

Variants

Wall-mounted (cantilever) jibs bolt to a building column and swing about 180°, saving floor space and foundation cost but requiring the column to take the moment. Articulating jibs use two hinged arm segments so the hook can reach around obstructions and inside machines. Foundationless models spread the moment over a wide bolted base on an existing 150–200 mm slab, trading radius and capacity (typically ≤1 t at ≤5 m) for installation cost. Stainless and food-grade versions are specified to EN 13001 with crane group classification matched to duty, while North American practice follows ASME B30.11 with a 15% impact allowance and span/150 deflection limit.