Terminology
Below are a collection of terms and terminology that is used on our Website and frequently throughout the lifting and mechanical handling industry. You may find it beneficial to study the below before indulging in to and making enquiries on equipment should your knowledge of terms be brief or insufficient.
SWL- Safe Working Load
WLL- Working Load Limit
HOL- Height of Lift
EOTC- Electric Overhead Travelling Crane
OTC- Overhead Travelling Crane
MPM- Meters Per Minute
Overhead Crane Terminology
Overhead Girder Cranes come in various shapes and sizes, but they all share the same or similar terminology, important information that must be known by the buyer before making such enquiries. These include the dimensions, capacities and details of the crane which are vital in order to gain an accurate price quotation. The buyer should be aware of the major crane components in order to ensure the correct equipment is ordered.
Crane Beam/Bridge- This is the central main beam of the crane which will support the hoist and load, usually the heaviest part of the crane structure and the largest part, spanning the width of the load area in order to take full advantage. This is supported by two end carriages, the main beam can be under slung or over slung. Under slung or under hung cranes are usually used in applications where there is height restrictions. Overhead cranes can feature a single bridge or a double bridge beam.
End Carriages- Two end carriages support the span of the crane bridge beam and provide the power to transport the crane up and down the length of the building or workshop enabling full coverage of the desired area.
Trolley- The moving frame in which the hoist in fitted to, the trolley features wheels which allow horizontal traverse of the trolley along the crane beam.
Hoist- The hoist is fitted to the trolley enabling horizontal traverse along the cranes span, the hoist features a hook which lifts and lowers the load up to the stated capacity.
General Hoist & Crane Terminology
Capacity/SWL- The maximum weight that the crane or hoist is required to lift
Span- The length of crane beam, bridge or girder
Height of Lift/HOL- The distance from the bottom of the hoist to the load level
Hoist, Bridge, Trolley & Lifting Speeds- The speed at which the item operates at, usually measured in meters per minute (MPM) the buyer may specify one of two speeds of operation dependant upon the application. For example someone hoisting in the glass industry may opt for two speeds of operation; one fast or normal speed for clear operation and one slow speed for inching and edging in to place where precision is key.
Control Types
Pendant Control- This is the traditional and most cost effective method of controlling an overhead crane or hoist, a hard-wired hand unit is connected to the hoist unit via low voltage flat form cabling enabling the user to control all motions of the crane from the palm of their hand. One of the down sides to pendant operated control is that the operator must travel with the load as the pendant control travels with the hoist unit which the load is underneath.
Radio Control- A favourite choice in overhead crane applications where it is safer for the operator to work at a distance from the load such as is the nuclear industry where it would be a danger for the operator to be so close to the load. Radio control operates exactly the same as a pendant control in terms of features but runs on a rechargeable battery and sends its signals over radio frequency.
VDF Variable Frequency Drive- can be used in conjunction with a pendant, used to vary the frequency of the motors controlling the motions of the crane, allowing for a smoother acceleration and deceleration.