What Is an Electric Hoist?

Electric hoist is a special lifting equipment, installed on overhead cranes and gantry cranes. Electric hoist has the characteristics of small size, light weight, simple operation and convenient use. It is used in industrial and mining enterprises, storage, docks and other places.

The lifting weight is generally 0.3 to 80 tons, and the lifting height is 3 to 30 meters. by

Electric hoist is mainly divided into: chain electric hoist, wire rope electric hoist (

Application areas: lifting, pulling, loading and unloading heavy objects, oil tank flip welding, such as the installation and movement of various large and medium-sized concrete, steel structures and mechanical equipment, suitable for construction and installation companies, civil engineering of factories and mines and bridge construction Machinery, equipment for infrastructure projects such as power, shipbuilding, automobile manufacturing, construction, highways, bridges, metallurgy, mines, slope tunnels, and well control.

(1) Inspection before use

a. There should be no obstacles and floating objects in the walking range of the operator, the sight range, and the route through which the heavy objects pass.

b. The up and down, left and right directions of the manual control button should be accurate and sensitive, and the motor and reducer should have no abnormal sound.

c. The brake should be sensitive and reliable.

d. There should be no foreign matter on the electric hoist running track.

e. The action of the upper and lower limiters should be accurate and sensitive.

f. The hook stop nut should be fastened firmly.

g. The hook should be flexible to rotate in the horizontal and vertical directions.

h. The hook pulley should rotate flexibly.

i. The steel wire rope should have no obvious cracks, be neatly arranged on the reel, no signs of disengagement of the pulley groove, random twisting, overlapping buckle, etc., and good lubrication.

j. There are no abnormalities in lifting aids.

k. The working environment temperature of electric hoist is -25 + 40

l. Electric hoist is not suitable for places full of corrosive gas or relative humidity greater than 85%. It cannot replace explosion-proof hoist. It is not suitable to lift molten metal or toxic, flammable and explosive materials.

(2) Electric hoists must not be hoisted and unloaded side by side, and overloading is prohibited.

(3) During use, the operator should check the wire rope for random buckling, knotting, troughing, abrasion, etc. at any time. If it occurs, it should be eliminated in time, and the rope guide and limit switch should be checked frequently for safety and reliability.

(4) Do not use limiters artificially in daily work to stop lifting heavy objects or stop equipment operation.

(5) After the work is completed, turn off the main power switch and cut off the main power.

(6) Special maintenance personnel shall be set up to check the main performance and safety status of the electric hoist once a week, and remove the faults in time.

1. For electric hoists that are newly installed or installed after disassembly and inspection, the empty car trial operation should be performed several times first. But before the installation is completed, do not turn on the test drive.

2. Before normal use, a static load test with a rated load of 125% and a lifting distance of about 100 mm from the ground for 10 minutes should be performed to check whether it is normal.

3. The dynamic load test is based on the rated load weight, repeated lifting and left-right movement tests. After the test, check whether the mechanical transmission part, electrical part and connection part are normal and reliable.

4. In use, it is absolutely forbidden to use in the environment that is not allowed, and under the rated load and the rated closing times per hour (120 times).

5. During installation, debugging and maintenance, it is necessary to strictly check whether the limit device is flexible and reliable. When the hook is raised to the upper limit position, the distance between the hook shell and the drum shell must be greater than 50mm (10t, 16t, 20t must be greater than 120mm). When the hook is lowered to the lower limit position, the wire rope safety ring on the drum should be guaranteed. The effective safety ring must be more than 2 turns.

6. It is not allowed to press two flashlight buttons that move the electric hoist in opposite directions at the same time.

7. After the work is completed, the main gate of the power supply must be opened to cut off the power supply.

8. The electric hoist should be operated by a special person. The operator should fully grasp the safety operation regulations.

9. In use, the electric hoist must be checked regularly by specialized personnel, and measures should be taken in time to find faults, and carefully recorded.

10. When adjusting the brake slip of the electric hoist, ensure that the brake slip is S V / 100 under the rated load (V is the distance for stable lifting within the next minute of the load).

11. Scrap standards for wire ropes: Inspection and scrap standards for wire ropes are implemented in accordance with CB / T5972-1986 "Practical Code for Inspection and Scrap of Wire Ropes for Lifting Machinery".

12. In the use of electric hoist, it is necessary to maintain sufficient lubricant, and keep the lubricant clean, and it should not contain impurities and dirt.

13. When using steel wire rope, you should use a hard brush or a small piece of wood. It is strictly forbidden to directly oil the working wire rope by hand.

14. When the electric hoist is not working, it is not allowed to suspend heavy objects in the air to prevent permanent deformation of the parts.

15. During use, if a failure is found, immediately cut off the main power.

16. Pay special attention to the wearing parts during use.

17.10 to 20 tons of hoist may automatically power off after a long period of continuous operation. This is an overheating protection function of the motor. At this time, it can be lowered. After a period of time, the motor can continue to work after it has cooled down.

Electric hoists are generally equipped with multi-directional protective devices to ensure the safety of personnel and work, but the protective devices should also have some basic requirements.

1. It has the function of preventing danger, suitable for the operating conditions of electric hoist, without hindering production and operation.

2. Firm installation, reliable performance, sufficient strength and rigidity, accurate movement and stable performance.

3. Durable, does not affect hoist adjustment, repair, lubrication and inspection.

4. The protective device itself should not cause harm to the operator.

Inspection work before using electric hoist

Before the electric hoist is used, simple safety inspection is necessary to avoid abnormal problems of some parts and do danger prevention work in advance.

1. The direction of the buttons on the operating handle, the brake, and the limiter are sensitive and accurate.

2. The steel wire rope has no defects, is well lubricated and arranged neatly.

3. There is no abnormal sound when the motor and reducer rotate.

4. There are no obstacles in the electric hoist track and the walking area of people.

5. The hook and pulley can rotate flexibly.

Installation precautions of electric hoist

The installation of electric hoist is a very important task. Not only must you prepare well before installation, but you must also pay attention to the specific matters needing attention during installation.

A. In order to ensure that the electric hoist does not derail when it runs to both ends of the track or prevent collision and damage to the body, elastic buffers should be provided at both ends of the track.

B. When installing the electric hoist, check whether the plug for fixing the wire rope is loose.

C. A ground wire shall be provided on the track or the connected structure. The ground wire may be bare copper wire of 4-5mm or metal wire with a section of not less than 25mm².

D. The resistance of all electrical circuits of the electrical device to the ground of the control circuit must not be less than 10000 per volt working voltage.

Comprehensive inspection after installation of electric hoist

After the electric hoist is installed, a comprehensive safety inspection is required, which is very necessary from a safety perspective:

1. Whether the electrical equipment of the electric hoist is suitable for the type of current and working voltage at the installation site.

2. Whether the electrical circuit connection is correct and reliable.

3. Whether the limit mounting operation is correct, flexible and reliable.

4. Whether all lubricating parts are filled with lubricating oil separately.

5. Whether the wheel and track joints are reliable.

6. When selecting the power supply cable, you must ensure that the power supply voltage at the line end of the hoist motor is not lower than the rated voltage ^[1]

1. After starting, the motor does not rotate and cannot lift heavy objects

Excessive overload, overloading is not allowed

The voltage is more than 10% lower than the rated voltage.

(3) The electrical appliance is faulty, the wire is disconnected or the contact is poor, and the electrical appliance and the circuit are overhauled.

The brake wheel and the rear cover are rusted and bite, the brake wheel cannot be disengaged, remove the brake wheel and clean the rusted surface

Motor blasting, deal with according to fault number 9

The wire is too thin, replace the wire

2. Braking is unreliable, and the sliding distance exceeds the specified requirements

The spring pressure is reduced due to large wear of the brake ring or other reasons, and the spring pressure is adjusted

The brake ring has poor contact with the tapered surface of the rear end cover.

The brake surface is oily, remove it for cleaning

The brake ring is loose, replace the brake ring

Pressure spring fatigue, replace the spring

Coupling is not working or stuck, check the connection part

The amount of movement of the conical rotor is too large, adjust it according to regulations

3.The temperature of the motor is too high

Overload use, underload use

Too frequent operations, reduce the number of operations

(3) The brake clearance is too small, and the brake ring is not completely disengaged during operation, which is equivalent to an additional load. readjust

4.The reducer is too loud

Poor lubrication, disassembly and maintenance

5.The motor buzzes when starting

Lack of power and motor phase, repair or replace the contactor

6. The weight is lifted into the air, and it cannot be restarted after parking.

The voltage is too low and fluctuates greatly. Wait until the voltage is restored before starting.

Overload lifting, load reduction use

7. Can't stop after starting, or stop at the extreme position

The contact of the AC contactor is welded, and the main power is cut off quickly.

The limiter fails, replace the AC contactor

The end of the limiter is connected incorrectly, and the line of the limiter is overhauled

8.Reducer oil leakage

Between the box and the cover, the seal ring is badly assembled or damaged, remove it for repair or replace the seal ring

The connection screws are not tightened. Tighten the screws.

Excessive refueling, refueling according to regulations

9. The gap between the conical rotor or the stator of the motor is too small to cause collision (called sweeping)

The factory products are not allowed to "broom". The main reasons for "brooming" are: wear of the bearing ring on the motor shaft, axial displacement of the rotor core, or custom core displacement. Remove and replace the support ring, so that there is a uniform gap between the cone surfaces of the stator rotor, each side is 0.35 ~ 0.55mm (small motor clearance is small) or return to the manufacturer for repair.

The domestic electric hoist has been produced and developed in imitation form since the 1950s.

July 1949 Shanghai's first trial production successfully imitates German company 1.5t and 3t general purpose

1. Operators must undergo professional studies and receive safety technology training, and be assessed and verified by the national or business competent authority before they can obtain the "Special Operator's Operating Certificate" issued by the local competent authority before engaging in command and operation. Unlicensed operations are strictly prohibited .

2. Before using the electric hoist, check the safety and technical conditions of vulnerable parts such as hooks, wire ropes, and reducers.

3 When the electric hoist is in use, no one is allowed to enter the hoisting danger area and send special personnel to take care of it.

4 The electric hoist must be placed or bundled during hoisting to meet the requirements of hoisting regulations.

5. It is forbidden to operate the crane when the brakes, safety devices fail, damage to the hook nut anti-loosening device, or damage to the wire rope reaches the scrap standard.

6. Lifting operations should not be carried out when the hanging objects are tied, hanging poorly or unbalanced and may slide, and there is no padding between the hanging object edges and the wire rope.

7. Do not perform lifting operations when the site, hanging objects and command signals cannot be clearly seen.

8. Hangers, baskets, slings and ropes must be suspended in the air during shutdowns or breaks.

9. When working with lifting appliances, they must not be inspected and repaired. The brakes of the lifting mechanism must not be adjusted under load.

10 It is strictly forbidden to fall freely (slide) when lowering hanging objects. Do not park with limit position limiter ^[1] .