Workstation Bridge Crane

Overview

A workstation bridge crane is a light overhead crane that covers a rectangular work area, lifting and positioning loads anywhere within it. It works like a scaled-down version of an industrial bridge crane: two parallel runway rails run the length of the area, a bridge spans between them and rolls along the runways, and a hoist hangs from a trolley that crosses the bridge. Between the two motions, the hook can be placed over any point in the rectangle. The defining feature is lightness: built from cold-formed enclosed track rather than heavy I-beams, the whole crane rolls so freely that an operator can position a load of a few hundred kilograms by hand, which is what makes it an ergonomic handling tool rather than a heavy lifter.

The crane is built from the Runway Track System that defines the travel length, the Bridge Beam that spans the width, the End Truck carriages that link the two, the Hoist that lifts, the Hoist Trolley that carries the hoist across the bridge, the Ceiling Suspension that hangs the system, and the Electrical and Control that powers it.

Runway and enclosed track

The Runway Track System sets the length the crane can cover. It is a pair of Enclosed Track enclosed-track rails, a style where the wheels run inside the track section rather than on top of an exposed flange, which keeps the running surface clean and lets the bridge roll with very low effort. Sections are joined by Track Joint splices that keep the surface smooth, Runway End Stop stops limit travel at the ends, and the rails hang from Runway Hanger hangers. The low rolling resistance of enclosed track is the reason a worker can push a loaded bridge along the runway by hand.

Bridge and end trucks

The Bridge Beam spans the two runways. It is a Bridge Track enclosed section chosen for low deflection, since a bridge that sags would make the trolley want to roll to the middle, and Bridge End Stop stops keep the trolley on the beam. At each end an End Truck carriage with End-Truck Wheel wheels runs the bridge along a runway. Most workstation cranes are pushed by hand, but a powered version adds a Bridge Drive with a Servo Motor for motorized bridge travel where spans or loads are larger.

Hoist and trolley

Lifting is done by the Hoist, almost always an electric chain hoist on a crane this size. A Hoist Motor drives a Hoist Gearbox and a Load Chain that raises the Hook Block, whose forged Lifting Hook carries a Safety Latch to keep a sling captive. A Hoist Brake holds the load when the motor stops, a Chain Container collects the slack chain as the hook rises, and Limit Switch switches stop the hoist at the ends of travel. The hoist hangs from a Hoist Trolley that rides the bridge on Trolley Wheel wheels, moved by hand or by a powered Trolley Drive, with Trolley Bumper bumpers at the ends.

Suspension and support

A workstation crane carries no columns of its own when ceiling-hung, so the Ceiling Suspension is what holds the whole system up. Hanger Rod rods drop from Ceiling Bracket brackets fixed to the roof structure, setting the runway at the wanted height, and Sway Brace diagonal braces stop the suspended assembly from swinging as the bridge accelerates and stops. Where the roof cannot take the load, the same runway is carried on a freestanding frame of columns instead, which makes the crane independent of the building.

Electrical and control

The Electrical and Control system keeps operation simple. A Conductor Bar busbar along a runway feeds power to the moving bridge, a Festoon Cable cable feeds the trolley along the bridge, and a Control Panel holds the contactors and control board. The operator drives bridge, trolley, and hoist from a hanging Pendant Control, and a Emergency Stop cuts all motion at once. Manual-travel cranes need only the hoist supply and its pendant.

Use and place in the fleet

Workstation bridge cranes are made for ergonomic, repetitive handling in a fixed work area: feeding an assembly line, loading machines, or moving parts between benches without a worker lifting them. They cover a full rectangle, which a Wall-Mounted Jib Crane cannot, since one jib sweeps only an arc, yet they are far lighter and cheaper than a full industrial bridge crane and can often be moved or extended as a plant layout changes. Their limit is capacity, since the light enclosed track and hand-push design suit loads up to a couple of tonnes rather than the tens of tonnes a heavy bridge or gantry crane handles. Within that range they are the standard tool for taking the strain out of repeated lifting at a workstation.