• Wire rope hoists are NOT required to have any type of overload protection
• Electric Chain hoists ARE required to have some form of overload protection
• There are several brands of overload protection that will fit almost all brands of hoist

The topic of the day is a particular type of “overload protection”, that involves cranes with two hoists. We frequently are asked to supply a crane that has two hoists for flipping dies. In this case either hoist may be required to lift the full load, lets say 5 tons, but never will the sum total of the lift be 5 tons. In other words, we have to supply a 5 ton crane with two 5 ton hoists. This may sound like a ticking time bomb, but with modern controls, there is an easy and economical answer.

LOAD SUMMING

Most hoist manufacturers and several third party after market control manufacturers now supply a small control system that is installed into the hoist control panel that constantly sums the total weight lifted by the two hoists. With this, either hoist can lift the full 5 tons or can share the 5 tons in any combination. As long as the aggregate total does not exceed the 5 ton load limit. the units operation is totally transparent, but in the event 5 tons is exceeded, the hoist will cease to lift and only operate in the down direction.

Dr. Frazier Crane
PhD in Craneology (Piled High and Deep)