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Synchronizing two hoists eases handling of long loads

Friday, May 22, 2015

Hoists operate simultaneously with stepless variable speed control to ensure safe and efficient material handling.

Lifting and moving long and bulky loads can often present a problem in industrial or manufacturing material handling applications but member companies of the Hoist Manufacturers Institute (HMI) have overhead solutions based on simultaneous operation of hoists.

Typically when two independent hoists are operated in parallel, the differences in starting and stopping times causes the hoist lift or trolley travel to loose synchrony. As the operator tries to rectify the situation they have to turn one hoist on to move the load back to the level position or reposition the hoist or trolley. This slows the process and if the operator does not manually perform the required leveling it can lead to uneven lifting and possibly load slipping, which can cause damage to loads or property and can put personnel in danger.
A solution recently demonstrated by an HMI member company takes advantage of encoder feedback on the hoist and trolley and CANbus communication between the hoists to ensure that when the units are in simultaneous operation, lifting and traveling are always synchronized.

In addition, with other solutions using conventional controls without feedback, one hoist overload may trip, turning the hoist off, while the other hoist continues to lift. If the operator does not recognize this situation, it could lead to further overloading of the hoists or tipping of the load. With this particular solution, the internal communication ensures that if one hoist is overloaded, then both hoists will stop.

HMI, an overhead lifting equipment product group within MHI, provides end users with access to manufacturers which produce the best hoists on the market. The units chosen for this application come standard with stepless variable speed control. Similar to the accelerator in a car, the harder the driver pushes, the faster the car will go. This feature gives the operator full control and is very helpful when lifting and positioning long materials.

The standard controls on many new hoists are ideal for lifting applications that require simultaneous and independent lifting with the two hoists. They provide standard features and benefits that are not available from conventional parallel connection of two hoists. The result is increased throughput and improved operator safety.

The Hoist Manufacturers Institute members are the industry’s leading suppliers of hoisting equipment including hand chain hoists, ratchet lever hoists, trolleys, air chain hoists, air wire rope hoists, electric chain hoists, and electric wire hoists for the manufacturing and distribution sectors.


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