What are the factors that affect the lifting weight of a jib crane and how to choose a gantry crane from Chunhua Group
If the voltage fluctuates beyond this range, it will cause the motor to generate heat to varying degrees, resulting in reduced motor strength and reduced lifting weight. The diameter and length of the wire rope are often neglected factors. If you choose a wire rope with a large diameter or a long length, the diameter of the drum will increase, because the speed of the motor is constant, which will inevitably lead to an increase in speed, which will reduce the motor's strength and the lifting weight. Try to choose the appropriate wire rope when using it. The wire rope should also be selected with a suitable length, and a few more wire ropes with different lengths should be used. If the angle between the inclined arm and the column exceeds 45 degrees, the lifting weight will also decrease. The angle between the inclined arm and the column is controlled within 45 degrees.
The smaller the angle, the better. There are many other factors, as long as the heat dissipation of the motor is not good, causing the motor to overheat, the motor will naturally be weak. Generally, it is necessary to strengthen the heat dissipation, remove the shell of the host, and increase the heat dissipation of the blower.
How to choose a gantry crane? A gantry crane is a variant of a bridge crane, also called a gantry crane. It is mainly used for loading and unloading of outdoor cargo yard, material yard and bulk cargo. Gantry cranes have the characteristics of high site utilization, large operating range, wide adaptability and strong versatility. They have been widely used in port cargo yards. Its metal structure resembles a gate-shaped frame. Two feet are installed under the main beam, and it can directly walk on the ground track. The main beam can have outriggers at both ends. Divided into gantry cranes and cantilever gantry cranes with single main beam, double main beam derrick beams and box beams. The application form can be divided into ordinary gantry cranes, gantry cranes, gantry cranes, shipbuilding gantry cranes, container gantry cranes, model 1, standard gantry crane code, rated lifting weight, span, and working level. The four main elements feature the model. Second, the single girder gantry crane has the symbols: MDG, MDE, MDZ, MDN, MDP, MDS. Such as: MDN—Single Girder Single Trolley Grab Hook Gantry Crane. 3. The symbols of double beam gantry crane are:
How to choose a gantry crane
It complies with the relevant regulations of general gantry crane GB / T14406-1993 and GB5905-86.
In general, the lifting capacity is below 50t and the span is within 35m. There is no special use requirement, and the single main beam type should be used. If the width of the door legs is required to be large, the working speed is high, or heavy and long pieces are often hoisted, a double-beam gantry crane should be selected.
Second, span and cantilever length Gantry crane span is an important factor affecting the crane's own quality. In the selection, the span should be reduced as much as possible on the premise that the equipment use conditions are met and the span series standards are met.
Third, the determination of the track (a) can meet the stability requirements of the mast along the crane track;
(B) the overall dimensions of the cargo must be able to pass through the flat steel frame of the legs smoothly;
(C) Pay attention to make the wheelbase B proportional to the span S. Generally, take the wheelbase B = (1 / 4-1 / 6) S.
Fourth, the gantry crane spacing size determination 
In work, there should be a certain space size between the external dimensions of the gantry crane and the cargo and transportation vehicle passages in the yard to facilitate loading and unloading operations. When loading and unloading within the span of a general transportation vehicle, the distance from the door legs should be kept at least 0.7m. When not working, the spreader should have a distance of more than 0.5m from the transport vehicle, and the cargo should have a distance of more than 0.5m when it passes through the door legs.
Gantry crane maintenance I. The working performance and life of each mechanism of the lubrication crane depend to a large extent on lubrication.
For lubrication, maintenance and lubrication of electromechanical products, please refer to the user's manual, and trolleys, cranes, etc. should be filled with grease once a week. The hoist is filled with industrial gear oil (SY1172-80) 200, and the oil level should be checked frequently and added in time.
Second, the wire rope should pay attention to the broken wire situation. If the broken wire, broken strands or abrasion amount reaches the scrap standard, the new rope should be replaced in time. The steel wire ropes that can be selected include phosphate coated steel wire rope, galvanized steel wire rope and smooth steel wire rope.
Third, the spreader must be checked regularly.
4. The pulley unit mainly checks the wear of the rope groove, whether the rim is cracked, and whether the pulley is stuck on the shaft.
Fifth, the wheel regularly checks the rim and tread. When the rim part is worn or chipped to a thickness of 10%, it should be replaced with a new wheel.
When the difference between the diameters of the two driving wheels on the tread exceeds D / 600, or if serious scars appear on the tread, the car should be relighted.
Six, the brake should be checked once every shift.
The brake should be accurate and the pin should not be jammed. The brake shoe should fit the brake wheel correctly, and the brake shoe clearance should be equal when the brake is released. 
Seven. Reasons for oil leakage from reducers and preventive measures There are three common reasons for oil leakage from reducers:
1: Due to the manufacturer's unreasonable design: design defects such as lack of special vent holes or too small vent holes during the design process will cause imbalance in the internal and external pressure of the reducer and cause leakage leakage, which will eventually cause the lubricant of the reducer to leak out. malfunction. There may also be leakage caused by improper sealing of the reducer's connection surface during long-term use.
2. Due to the limited level of processing technology, the precision of the contact surface of the box is insufficient, which causes poor sealing performance and oil leakage.
3. Due to improper maintenance performed by the operator or maintenance staff during daily use, the internal pressure is higher than the external pressure due to multiple internal blockages. At the same time, too much oil and the fasteners are not tightened will cause a gap between the two boxes. Inadequate joint surfaces can cause oil leakage.
In order to effectively prevent the oil leakage of the reducer, the manufacturer should improve the technological level and optimize the design scheme: a venting device can be added to the filler hole cover to ensure that the internal and external pressure is balanced and unobstructed. At the same time, the precision of the process between the joint surfaces of the two cabinets should be improved during the design process, so as to prevent oil leakage due to the inadequate contact surfaces. At the same time, during the daily use, maintenance work should be done well, and the ventilation holes, oil volume, box, fasteners, etc. should be checked regularly to see if they are in a normal state.
MDS—Three-purpose portal crane with single main beam trolley.