-
-
PRODUCTS
-
Safety Operating Procedures for Electric Hoists
Release time:
2021-05-07
An electric hoist is a type of lifting machinery that has a relatively small lifting capacity and a simple structure, yet it is very practical. It is generally installed on the tracks of straight or curved I-beams for lifting and transporting heavy objects. The electric hoist consists of two main parts: the lifting mechanism (hook) and the moving device (trolley), which are driven by two cage-type electric motors.
Composition of the electrical equipment circuits of the electric hoist
The electric hoist is a type of lifting machinery that is lightweight, simple in structure, but very practical. It is generally installed on the tracks of straight or curved I-beams to lift and transport heavy objects. The electric hoist consists of two parts: the lifting mechanism (hook) and the moving device (trolley), which are driven by two squirrel-cage motors.
The main circuit has two motors, M1 and M2. M1 is used to lift goods and is braked by an electromagnetic brake FB1; M2 drives the electric hoist to move horizontally to transport goods. M1 and M2 are controlled for forward and reverse rotation by contactors QA1 to QA4, thus achieving the lifting, lowering, and horizontal movement of the hook. The main circuit is protected against short circuits by fuse F1 and is connected to the three-phase power supply through switch Q1.
The auxiliary circuit power is derived from L1 and L2. The entire auxiliary circuit is divided into two parts: lifting control and moving control. Each part consists of two branches to achieve forward and reverse control of M1 and M2. S1, S2, S3, and S4 are suspended composite buttons, which have the advantage that when the operator leaves, the electric hoist automatically stops to avoid accidents. At the same time, the composite buttons can be interlocked to prevent misoperation. S5, S6, and S7 are limit switches used for the terminal protection of the lifting and moving mechanisms.
After starting the hoist, there is no response, and the hoist does not work. The usual causes are that the power supply is not connected, or the electrical components of the main control circuit of the hoist are damaged and need to be repaired in the factory. A voltage lower than 90% of the rated voltage can also cause the hoist to not work after being turned on.
During the operation of the electric hoist, abnormal noises occur. (1) Abnormal noises occur in the control circuit, usually due to a fault in the AC contactor or the voltage not meeting standards. (2) The motor produces abnormal noises. If the above situations occur, work should be stopped immediately, and the motor should be checked for single-phase operation, bearing damage, coupling damage, or motor sweeping. Generally, such situations should be handled by professionals to ensure the safe use of the hoist.
When braking, the distance of descent exceeds the specified requirements. The cause is that when the electric hoist has been unused for a long time, someone may have mistakenly adjusted the brake adjustment nut, or the brake ring has worn excessively, reducing the pressure of the brake spring and lowering the braking force. When stopping, the braking is unreliable, and the descent distance exceeds the specified requirements. In this case, simply readjusting the brake nut according to the hoist manual is sufficient. However, during work, it is prohibited to adjust, check, and repair the brake while lifting heavy objects. Sometimes, even after adjusting the brake nut, the descent distance still exceeds the specified requirements. In such cases, other reasons should be considered. First, disassemble the brake ring and check if there is oil or dirt on the braking surface. If there is oil or dirt, the friction coefficient will decrease, causing slippage during braking and exceeding the specified descent distance. Simply adjusting the brake nut will not be very effective.
Next
Related News
2024-02-23
Address: East Section of Weishili Road, Lifting Industrial Park, Changyuan City, Henan Province
QR Code
Copyright © 2025 Zhongtian Heavy Industry