What Are the Safety Protection Devices for Conveyor Belts?

What Are the Safety Protection Devices for Conveyor Belts?

Conveyor Belts (commonly used in mining, ports, power plants, chemical industry, and other fields) are core equipment for material conveying. 

However, during operation, they are prone to equipment damage or safety accidents due to faults such as deviation, slipping, overload, and tearing. 

Therefore, targeted safety protection devices must be equipped, which can be divided into 10 categories by function.

Note: A summary table is provided at the end of the article for quick overview.

I. Belt Deviation Protection Devices

When a belt deviates from the center line, it may cause minor issu

es such as edge wear and material spillage, 

or more serious problems like jamming and shutdown. Belt deviation protection devices are divided into two categories: "

monitoring and alarm" and "automatic correction".

Functions and Characteristics

Deviation Switch (Monitoring Type)

Equipped with two-stage triggering: When the belt deviates 10-30cm from the center line (first stage), an audible and 

visual alarm is activated to prompt intervention; when the deviation exceeds the safety threshold (second stage), emergency shutdown 

is enforced to prevent fault escalation.

Structure: Mechanical contacts or photoelectric sensing, installed on both sides of the belt, with a response time ≤ 0.5 seconds and 

resistance to dust interference, acting like an "electronic guardrail" for the belt.

Automatic Deviation Correction Device (Correction Type)

It can actively "pull back" the deviated belt through mechanical/hydraulic structures without shutdown:

Self-aligning idler: Pure mechanical design, which uses the friction of the belt to drive the idler rotation for passive deviation correction

 (low cost and maintenance-free); 

Hydraulic deviation corrector: Active drive with stronger correction force, suitable for wide belts (e.g., 1.8m-wide coal conveying belts in ports).

Application Scenarios

All conveyor belts, especially long-distance (>100m) and wide-width (>1.2m) belts (e.g., main transportation belts in mines, coal conveying belts in power plants).

II. Belt Slipping Protection Devices

When the friction between the belt and the driving drum is insufficient, the phenomenon of "slow belt and fast drum" (slipping) will occur, 

which may cause minor material accumulation or more serious problems like overheating and fire due to friction. This device monitors the 

speed in real time to intercept risks in advance.

Functions and Characteristics

When the belt speed drops to 70%-80% of the rated speed (customizable), it first gives an alarm for early warning; if slipping persists, 

it enforces shutdown to prevent the risk of fire caused by friction between the belt and the drum.

Structure Types

Speed sensor: Magnetoelectric type (contact-type synchronous speed measurement with the belt) or photoelectric type (non-contact, 

identifying marks on the belt surface), with a speed measurement accuracy of ±0.5%, acting like a "speedometer" for the belt;

Drum-linked detector: Directly connected to the driven drum, with mechanical triggering, strong resistance to dust and humidity (suitable for 

humid underground environments in mines), and no need for complex calibration.

Application Scenarios

High-load and high-speed belts (e.g., underground coal conveying belts in mines, ore conveying belts in ports), to prevent slipping caused by 

material overload and drum material adhesion.

III. Belt Tearing Protection Devices

Sharp edges of ores, metal impurities, and other substances are likely to scratch the belt, causing longitudinal tearing. 

If shutdown is not performed in time, the tear will spread rapidly, leading to the scrapping of the entire belt. 

This device can quickly intercept tearing faults.

Functions and Characteristics

Once a belt tear (tear >50mm) is detected, it immediately triggers shutdown + alarm to prevent the tear from spreading.

Structure Types

Contact type (steel cable/plate type): Steel cables are embedded in the belt, and the switch is triggered when the cable breaks due 

to tearing; the switch is triggered when the plate is squeezed by the torn belt, featuring high mechanical reliability but requiring direct contact with the belt;

Non-contact type (ultrasonic/infrared type): Ultrasonic waves scan the internal structure of the belt, and infrared rays identify changes in surface flatness, 

with no wear and long service life, suitable for high-dust environments (e.g., raw material belts in cement plants), acting like performing a "CT scan" on the belt.

Application Scenarios

Belts conveying materials with sharp impurities (e.g., ore belts in mines, construction waste treatment belts), to accurately intercept "invisible hazards".

IV. Emergency Shutdown Protection Devices

In case of emergency situations such as personnel straying into the area, equipment jamming, or fire, the belt needs to be "shut down with one key". 

This device is the final safety line and is divided into three types: along-the-line pull rope, emergency stop button, and emergency pull cable.

Functions and Characteristics

Pull rope switch: One switch is installed every 30-50m along the belt; pulling the pull rope at any position triggers instant shutdown, 

covering the entire length, like wrapping a "safety rope" around the belt;

Emergency stop button: Red mushroom-head buttons are installed in the operation room and at the head/tail of the belt; pressing the button cuts off

the power immediately, with a response time <0.1 second, enabling more convenient "one-key shutdown";

Emergency pull cable: Made of steel cable (tensile strength ≥500N), suitable for complex paths such as curves and slopes; pulling the steel cable triggers shutdown,

filling the protection blind spots in special terrains (e.g., mountain belts in mines).

Application Scenarios

Pull rope/button: All belts (mandatory standard configuration by the state);

Emergency pull cable: Belts in the wild and complex terrains (e.g., mountain belts in mines), solving the problem of "unreachable and unpressable".

V. Overload Protection Devices

Belt overload will cause motor overload and belt stretching deformation. This device equips the belt with overload protection devices 

from three dimensions: flow, tension, and current, which can detect problems in time and reduce potential safety hazards.

Functions and Characteristics

Belt scale (flow monitoring): Dynamically weighs the material; when the weight exceeds the limit, it first gives an alarm and then links 

with the feeder to reduce the feeding amount (closed-loop control), acting like an "electronic scale" for the belt;

Tension sensor (tension monitoring): Monitors the belt tension in real time; when the tension exceeds the threshold due to overload, 

it directly shuts down the belt to protect the "skeleton" of the belt;

Motor overload protector (current monitoring): Monitors the working current of the motor; when the current exceeds 1.2 times the rated current, 

it automatically cuts off the power supply, featuring low cost and easy maintenance, acting as a "current bodyguard" for the motor.

Application Scenarios

High-flow belts (bulk cargo in ports, grain reserves, raw material belts in cement plants), to prevent chain faults caused by material accumulation.

VI. Anti-Reversal Protection Devices

Core Logic

After the shutdown of an inclined belt (inclination angle >15°), the gravity of materials is likely to cause the belt to reverse, 

which may lead to minor material backflow or more serious belt stacking and tearing. The anti-reversal protection device can firmly lock the running direction.

Functions and Characteristics

Ratchet backstop: Pure mechanical structure (ratchet + pawl), no power dependency, with a reliability >99%, suitable for medium and low-speed belts 

(e.g., underground hoisting belts in mines), acting like a "mechanical lock" for the belt;

Belt-type backstop: Realizes braking through the friction between the brake belt and the drum, featuring simple structure and low cost, 

but with slight wear during braking, suitable for light-load belts;

Hydraulic backstop: Hydraulic drive, with stable braking and small impact force, suitable for high-speed (>2m/s) and heavy-load inclined belts 

(e.g., ore hoisting belts in ports), acting like a "hydraulic brake" for the belt.

Application Scenarios

Inclined belts (underground hoisting in mines, inclined raw material conveying in cement plants, sand and gravel conveying belts in hydropower stations), 

solving the problem of "material backflow".

Appendix: Summary Table of Conveyor Belt Safety Protection Devices (Quick Reference Version)