Overhead cranes can move objects weighing dozens of tons. They are indispensable to factories, mills, and refineries. Yet few people know how they work.
Here is a quick guide to the three main components of industrial overhead cranes.
1. The Bridge
The bridge is the track for the crane. There are two different types of bridges for industrial overhead cranes.
A single girder design uses one girder. Single girder designs allow for easier movement, and they are low maintenance and easy to install. But a single girder cannot support large weights.
A double girder bridge uses two girders. Double girders permit a higher height to hoist objects, and they support very large weights. But double girders are heavy, so they need support within the building foundation.
2. The Trolley
The trolley is the vehicle that travels on the bridge. There are three types of trolleys.
A plain trolley is the simplest design. The operator pushes or pulls the trolley into position. The operator grabs the load by hand and positions it along the bridge.
A geared trolley is more complicated. The hoist operator pulls on a chain hanging from the trolley, which has gears attached to the chain. The trolley then rolls along the bridge.
A motorized trolley has a motor attached to its wheels. A control pendant hangs from the bridge, and the operator presses buttons to move the trolley along. Motorized trolleys are fast, so you need to take safety precautions.
3. The Hoist
The hoist lifts the load up and down. You can customize your hoist according to your needs.
You need to know how much your loads weigh. Pick a hoist that can more than carry your objects. If you work with one-ton loads, purchase a hoist that lifts two tons.
Determine the amount of lift you need. Subtract the resting location of your load from the hanging location of your hoist. Purchase more than enough chain and rope to lift the load up and down.
Then determine the speed you need. If your objects are fragile, pick a low-speed hoist.
You can install your hoist on top of or beneath your bridge. Top running hoists permit greater lifting heights, while under running hoists reach loads in shorter periods of time. Double girder designs usually use top running hoists.
You can suspend your hoist from a hook or from a lug. Many hoists use lug suspensions, as lugs are smaller than hooks. Pick a lug if you want more flexibility to move and secure loads.
Go to the Experts on Industrial Overhead Cranes
Parts make up the whole. Industrial overhead cranes work because their parts work together well.
The bridge is the track or tracks the crane runs on. The trolley is the vehicle that runs on the bridge. The hoist is what lifts objects up and down.
These three simple components are what make industrial cranes work. But they can only work if you maintain them. Read this checklist on maintaining your crane.