This Rayco Wylie R147 wireless anti two block system is designed to warn the crane operator of an impending two block or A2B situation.  If the crane is equipped with a lockout solenoid this can also be automatically activated to shut off the cranes motion until the A2B situation is resolved.  The Rayco R147 A2B system has been specifically designed to fit on telescopic cranes, boom trucks, derrick trucks and conventional lattice cranes with minimal effort and time requirement. There are two main components for this A2B system

The R147 display and unit in the cab is able to monitor two radio anti two block switches, either of which can activate the signal to activate the lockout functionality.  The A2B display comes standard for 12V or 24V negative body cranes.

The anti two block switch itself is installed at the boom tip, and optionally at the end of the jib if dual A2B switches are required.  The boom tip switch detects the potentially dangerous two-block condition and send the warning signal to the display unit via wireless signal, no cumbersome cable reels are needed.