The same goes for cranes and hoists. Impossible to separate, the two are integral parts of overhead lifting and handling of large, heavy, and bulky loads that can’t easily be maneuvered or elevated by ground-based equipment. They’re relied upon throughout a broad range of industries, including manufacturing, automotive, shipping, energy, construction, transportation, food processing, and many more.
There are several different types of crane and hoist combinations. At their most basic, an indoor overhead crane is built to cover three axes, transporting a load side to side, backwards, and forwards as directed by an operator via manual, wired pendant, or remote controls. Two fixed runways, positioned parallel to each other, support a perpendicularly placed bridge beam known as a girder.
The bridge girder spans the distance between the two runways and rides on end trucks. It moves the load forward and backward. Depending on the application requirements, the bridge may be mounted on top of the runways (called a top-running crane) or suspended from the bottom flange of the runways (called an under-hung or under-running crane).
Suspended from the bridge is the hoist, which is attached to a trolley that rolls across the bridge girder. The trolley moves the load side to side, while the hoist provides the lifting and lowering function as directed by the operator. Hoists are outfitted with wire rope or chain and are operated manually, electrically, or pneumatically.
Different Types of Cranes
Cranes themselves come in a variety of configurations. These include:
- Single Girder Crane – A crane with a single bridge girder mounted between and supported by end trucks at each runway.
- Double Girder Crane – A crane with two bridge girders mounted between and supported by end trucks at each runway.
- Gantry Crane – A crane similar to an overhead crane except that the bridge for carrying the trolley (or trolleys) is rigidly supported on two or more legs running on fixed rails or a runway embedded in the floor.
- Jib Crane – A crane design whereby the bridge girder (often called a boom) is fixed at one end, typically mounted to a wall or a post (free standing) via a hinge to allow rotation of 180 to 360 degrees around the axis. This design enables the opposite end to cantilever over the load. The fixed end generally is hinged to allow rotation.
Specifying a Crane/Hoist Combo
To ensure the proper combination of crane and hoist will serve a unique application, the Crane Manufacturers Association of America (CMAA) and Hoist Manufacturers Institute (HMI) have each developed a list of service classifications. These are based on a variety of performance capabilities, including speed, lift cycles, and travel distance, as well as operating conditions, load magnitude, and standard maintenance requirements.
CMAA crane classifications range from Class A – Infrequent Use to Class F – Continuous/Severe Service. Likewise, HMI’s list of service classifications for self-contained or packaged “off-the-shelf” hoists ranges from H1 to H5. HMI hoist classifications generally align with CMAA’s crane service classifications, with Class A cranes typically using H1 hoists, and so on. The exception is Class E and Class F cranes typically require a custom-engineered hoist. To help companies determine the best fit for their application, American Crane has published an eBook on “How to Choose the Right Crane,” and a separate eBook on “How to Choose the Right Hoist.”
Based on the requirements of an application, it’s critical to specify the right pairing of crane and hoist to ensure the safety of those working with and around it, as well as to maximize the functional lifespan of the system. Some situations are suitable for a standard, off-the-shelf combination of the two; others require custom design and engineering of both components to match the load movement needs.
I’ll be discussing how to select a crane and hoist in my next post. In the meanwhile, American Crane offers a comprehensive library of in-depth educational resources — including more eBooks, brochures, and a glossary of crane terms — to help you better understand and assess the options. Plus, our experts are always available to help you determine the optimal solution for your overhead handling challenge. Connect with a project specialist to discuss your application today.