Five cases of electric hoist need to stop operation

1. Overloading or unclear weight of objects, such as lifting and pulling up buried straight objects with unclear weight or pulling force, and oblique pulling and slanting, etc.; 2. Defects or damages of structures or parts that affect safe work, such as failure of brake safety device, damage of hook and nut anti-loosening device, and wire rope reaching scrap standard;

2021-10-28

Causes of electrical system failure

Because the crane in the normal operation, the resistance group in the resistance box is put into operation most of the time, which generates a lot of heat, so that the temperature of the resistance group is higher. In a high temperature environment, both the resistor itself and the resistor connection terminal are susceptible to deterioration. At the same time, the bridge crane in the working process of a variety of AC contactor switching frequency is particularly high, the contact is easy in the frequent switching damage, aging, resulting in part of the contact resistance becomes larger or lack of phase phenomenon, so that the motor winding series resistance value imbalance. As a result, the crane will cause damage to the motor when it is heavily loaded or working for a long time.

2021-10-28

Brief Analysis of General Working Principle of Electric Hoist

Electric hoist is commonly used in monorail crane, jib crane and single beam crane, because the electric hoist structure is simple, convenient manufacturing and maintenance, good interchangeability, easy operation, so widely used in the factory. Electric hoist according to the purpose can be divided into general electric hoist and special electric hoist two, two kinds of electric hoist working principle is as follows: Start the lifting motor first to lift the heavy object to an appropriate height, then start the running motor to transport the heavy object to the designated position, and the running trolley walks on the lower edge of the single I-beam beam. When walking, a motor is used to drive the wheels on both sides of the car. Because the walking speed is relatively small, the running car generally does not have a braking mechanism. When the running car is walking, in order to prevent heavy objects from falling, an electromagnetic brake is set on the lifting mechanism. Braking relies on the pressure of the spring to compress the inner and outer discs. The principle is similar to that of the friction clutch. When it is released, the electromagnet is energized and the outer disc is sucked to loosen the inner and outer discs.

2021-10-28

How to solve abnormal motor start

When an HBT60A concrete pump stops and starts again after pumping, the motor cannot start. It sounds as if the power is insufficient. At the same time, the AC relay of the star-connected motor power supply "snaps" and snaps. At first, it is suspected that the power supply voltage is insufficient or the phase is small. After inspection, the three-phase voltages are very stable. When we replace the AC relay, the relay no longer beats, but the starting sound of the motor is still abnormal. After the motor power supply is converted into triangular connection, the starting sound of the motor returns to normal, but the pressure in the main oil circuit of the machine remains high, while the pumping operation is normal. After stopping pumping, the pressure in the main oil circuit remains high, indicating that the main pump is not unloaded. It is speculated that the abnormal start of the motor may be due to the start of the motor with load, and the fault is not on the electrical appliance. When the motor starts normally, the main oil circuit is impossible to have pressure. If the hydraulic oil is not clean, the main oil circuit electro-hydraulic reversing valve is blocked, which will lead to the failure of the oil circuit, causing the motor to start with load.

2021-10-28

The motor does not rotate after starting, and heavy objects cannot be lifted.

The main reason treatment method (1) excessive overload does not allow overload use (2) the voltage is more than 10% lower than the rated voltage and other voltages return to normal (3) electrical appliances are faulty, wires are disconnected or poor contact is required to repair electrical appliances and circuits (4) the brake wheel and rear end cover are corroded and bitten, the brake wheel cannot be detached, the brake wheel is removed, and the corroded surface is cleaned (5) the motor sweep bore is according to serial number 9

2021-10-27

Unreliable braking, sliding distance exceeding specified requirements

(1) The spring pressure is reduced due to large wear of the stop ring or other reasons. (2) The contact between the brake ring and the tapered surface of the rear end cover is poor. (3) The brake surface is oily. (4) The brake ring is loose. Replace the brake ring (5) The pressure spring is fatigued. (6) The coupling does not move well or is stuck. Adjust and remove the grinding. Remove the cleaning and replace the spring to check the coupling part.

2021-10-27

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