The idea for this mobile crane poster came from somewhat harsh assessment that you have to be a “blockhead” to operate a mobile crane without an anti-two block device. Two-blocking can lead to serious accident, injury, and even death. And yet, on average, two out of ten sites we visit are found operating a stiff boom crane that is missing the A2B switch. Why? This bad habit is often a result of ignorance (the operators didn’t know it was required, and “we are really careful”) or laziness (they knew they needed it but lacked the time, and “we are really careful”). I tell them that won’t go over well with OSHA. Besides that, it is dangerous. So don’t be a blockhead and avoid two-blocking. Inspect them, test them, never operate without them.
According to OSHA: Two blocking means a condition in which a component that is uppermost on the hoist line such as the load block, hook block, overhaul ball, or similar component, comes in contact with the boom tip, fixed upper block or similar component. This binds the system and continued application of power can cause failure of the hoist rope or other component.Too often we see mobile cranes missing anti-two blocking devices.