Safety Devices of Construction Hoists
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Safety Devices of Construction Hoists
The safety of construction hoists is paramount. It is essential to ensure that they are installed correctly, rigorously tested, and inspected regularly to guarantee the reliability of all safety devices. The primary safety devices of construction hoists include buffers, limit switches, overload protectors, limit switches, fall arrestors, and safety hooks, each serving a specific function.
Buffers: Located on the bottom frame of the hoist, buffers ensure a soft landing and contact with the ground in the event of a "runaway" situation.
Limit Switches: Used to control the travel and limit protection of mechanical equipment, limit switches are electrical devices that switch circuits based on the position of moving parts. They consist of a normally open and a normally closed set. Inspection standard: power off when the door is opened.
Limit Switches: Cut off the main power supply. The principle is that the connecting rod can cut off the power when it is pushed up or down. If the upper and lower limit switches fail, the limit bump iron acting on one end of the standard section will cut off the power. It is an emergency stop switch that cannot be automatically reset. Inspection standard: power off when pushed.
Fall Arrestors: Fall arrestors are the most critical safety device on construction hoists and are installed inside the hoist cage. Their function is to limit the overspeed operation of the hoist cage. When the hoist cage overspeeds due to a malfunction, the fall arrestor activates, increasing torque, and gradually braking the cage within a certain distance to prevent it from falling and ensuring the safety of personnel and equipment.
Overload Protectors: An axial shaft sensor is installed at the connection between the hoist cage and the drive plate (connecting pin shaft). It measures the weight by causing the axial shaft sensor to slightly deform due to the weight of the hoist cage. The weight signal is then converted and transmitted to the weight limiter. Function: When the hoist is overloaded, it can alarm the hoist operator and cut off the circuit when the limit weight is reached, preventing startup. Inspection standard: overload startup.
Safety Hooks: Safety hooks are installed to prevent the hoist cage from continuing to run upward when it reaches the preset position and the upper limit switch and upper extreme limit switch fail to operate, which could cause the cage to collide with the top surface of the guide frame and tip over. Safety hooks are the last line of defense. They ensure that the hoist cage does not tip over when it reaches the top of the guide frame's safety protection facility.