Many decades ago, reverse plugging was an extremely effective way to control the speed of a crane when you needed to slow and even stop a load. What is reverse plugging? In essence, this practice of the operator using the reverse button while a crane was moving forward would slow down the crane, helping to control the speed. Older cranes, with their huge motors and contactors were able to handle reverse plugging and the heat that it produces from the friction of the reverse button being engaged. Today, however, crane motors and contractors are compact and smaller, and the heat from reverse plugging speed control could cause serious problems with the motor and the crane’s electrical system. Reverse plugging speed control is no longer an option.
According to section 1917.45(f)(13) of the regulations for cranes and derricks as set forth by the United States Department of Labor’s Occupational Safety and Health Administration, “Each independent hoisting unit of a crane shall be equipped with at least one holding brake, applied directly to the motor shaft or gear train.” You can read the complete regulations document for cranes and derricks online here. What does that have to with reverse plugging speed control? Well, before the 1970s, cranes were not mandated by OSHA to have breaks. Today, the brake system can (and should) be used to control speed.
That said, there are problems with a load suddenly being stopped. Reverse plugging is still thought to be an option for some because suddenly stopping a load that was moving in one direction can cause it to swing uncontrollably and even become imbalanced. This can cause the crane to tip over, crane boom (arm) collapse, wire cable breaking, and other problems. So, for many, slowly decelerating was a much better answer, and reverse plugging made that possible. However, as this website discusses, today’s new inverter-controlled hoists don’t have this problem. Every time you use the brakes, the crane uses a deceleration curve. This is similar to slowly going on the brakes in a car. You’ll slow down slowly and eventually stop without spilling your passenger’s coffee or, in this case, without making the load swing. It is a much safer way to deal with speed control.
Therefore, reverse plugging is truly an outdated practice in most cases. With most newer cranes, in fact, it doesn’t even work – you have to be stopped before you can use the backwards button. In any case, the important thing is that you are trained on the crane you are using. Older cranes require certain speed control techniques while newer cranes require completely different operations. Just because you’ve operated a crane in the past does not automatically mean that you are qualified to run a new crane. Every year, many workers are injured while operating cranes. Review these tips from the National Institute for Occupation Safety and Health, but remember, you need on the job training as well. Part of this training should cover speed control, as knowing how to properly slow and stop a load could help you avoid potentially fatal accidents. If you have been injured in a crane accident due to reverse plugging contact a crane accident lawyer today.