Most serious accidents involving mobile cranes are caused by loss of stability. Loss of stability is due to reasons such as overloading and over-hoisting. To prevent accidents, the following safety devices must be installed: torque limiter, hoisting limit switch, radius indicator, level indicator, anti-boom tilting device, outrigger retraction locking device, slewing positioning device, reverse alarm device, protective covers for moving parts, and rain covers for electrical equipment.
(1) Torque Limiter: Its function is to limit the overturning moment of the crane, preventing mobile cranes from overturning due to excessive torque. It consists of a force sensor, boom length and boom angle sensors. When the crane's lifting weight reaches the rated value, it sends a signal, displays a red light, and then stops working.
(2) Hoisting Limit Switch: This device prevents over-hoisting of the crane boom. When the boom approaches its maximum angle, the limit switch opens and sounds an alarm.
(3) Radius Indicator: A circular indicator dial with a movable pointer is suspended on the crane boom. It indicates the lifting capacity at various radii during luffing.
(4) Level Indicator: This instrument mainly controls the outriggers by measuring the levelness of the crane chassis in the front, back, left, and right directions, keeping the crane level.
(5) Anti-Boom Tilting Device: This ensures that the boom is prevented from tilting backward even if the limit switch of the luffing mechanism fails.
(6) Outrigger Retraction Locking Device: This ensures that the crane outriggers are reliably locked when retracted.
(7) Slewing Positioning Device: This keeps the upper structure in a fixed position when the crane is traveling.
(8) Reverse Alarm Device: When the crane is moving in reverse, it should quickly emit an audible alarm signal and flashing light signals.
(9) Protective Covers for Moving Parts: These cover exposed moving parts on the crane that could cause injury.
(10) Rain Covers for Electrical Equipment: These cover the electrical equipment on the crane to prevent rain from affecting its performance.
