The cable pull switch (Cable Pull Switch), commonly known as the "emergency stop switch," is used in belt conveyor sites when a shutdown is required, stopping the conveyor by actuating the switch.
Introduction
The cable pull switch is divided into manual reset and automatic reset types, and it needs to meet the required IP level set by the country.
Automatic reset: After action, it can automatically return to the initial position but may cause unintentional restart.
Manual reset: After action, there is a self-locking device to keep it in the operating position. The reset handle needs to be operated manually to return it to the initial position.
The cable pull switch is an essential safety device for belt conveyors, preventing the escalation of accidents and significant losses. Due to easy installation and reliable switch conversion, it is widely used in belt transportation sites.
Principle
The cable pull switch is composed of a pull rod, reset handle, cam, locking groove, and microswitch.
The cable pull switch is installed on the frame on both sides of the belt conveyor, and the switch is connected by a wire rope along both sides of the conveyor. When an emergency occurs in the conveyor equipment, the wire rope is pulled at any point along the site, pulling the driving arm to rotate. The precision cam undergoes displacement through the torsion spring, driving the microswitch to cut off the control circuit, stopping the conveyor's operation.
Installation Adjustment
The cable pull switch should be installed in a place with maintenance access on both sides of the conveyor, and the installation position should ensure convenient operation for maintenance personnel in emergency situations.
1. Fix the cable pull switch on the frame.
2. The distance between the two switches on one side is about 50m, connected by a wire rope with a diameter of Φ4, with moderate tension.
3. To reduce the influence of the weight of the wire rope on the switch start, install a support ring on the frame every 3m to support the wire rope.
4. The other end of the wire rope is tied to the tension spring (fixed with a rope buckle). Use a tightener to tension the rope on both sides without affecting normal use, ensuring balanced tension on both sides.
(Note: For the climbing section of the conveyor, the switch spacing and rope length should be shortened as much as possible.)
Precautions
1. Cut off the main power supply first, and then use a multimeter to find the live wire. The switch must be installed at one end of the live wire.
2. Cut the live wire in a suitable place, and there will be two joints. The cable pull switch also has two joints.
3. Peel the two joints of the live wire to expose the metal wires, and connect them to the two joints of the switch arbitrarily.
4. Cut off the excess metal wire at the connected joints to prevent the two metal wires from colliding and shorting.
5. Rotate the cover of the cable pull switch, and you can see a metal shaft with a hole at one end.
6. There is also a hole on the side of the plastic shell of the cable pull switch. First, pass the rope through the hole in the plastic shell to lead the rope into the cable pull switch, then lead one end of the introduced rope into the shaft, tie a knot, and cut off the excess rope after tying.
7. Finally, screw the cover of the cable pull switch to prevent electric shock.
Scope of Application
The cable pull switch is a switch-type sensor (i.e., a no-contact travel switch), mainly used for conventional belt conveyors, shuttle conveyors, skirt edge feed conveyors, bucket elevators, packaging production lines, material stacking/retrieval systems, cranes, excavators, ship loading and unloading systems, horizontal feeders, and other equipment on-site emergency stop protection devices. When an emergency occurs, pulling the cable at any point along the site can send a stop signal, achieving the protection of personnel and equipment.
Because it has the characteristics of both travel switches and micro switches, as well as sensing performance, and has reliable action, stable performance, fast frequency response, long service life, strong anti-dry-worry ability, waterproof, shockproof, corrosion-resistant, etc. It is widely used in belt conveyor systems used in industries such as machinery, mining, textiles, printing, chemicals, metallurgy, light industry, valves, power, security, railways, transportation, cement, and ports.
