(1)Advantages
a. One-piece steel plate welded with another makes box-girder gantry crane very stable 
b. High wind-resistance, high rigidity and low deflection make it very safe
c. Use winch to lift objects easily
d. Proven, professional technique and good performance make it famous all over the world
e. HUAZHONG use high-quality electronic components which improve the efficiency and safety of the whole machine
f. The classical and traditional style has been widely accepted by all people.
(2)working principle
Girder and outrigger parts constitute subject steel structure of the gantry crane which stands on the ground track by two sides outrigger., realizes longitudinal traverse by travelling mechanism and horizontal movement by trolley mechanism, the lifting and lowering of suspended objects by hoisting winch.
(3)structure of the crane
1. main girder 
be welded of steel plates, connected by high-strength precision bolt. there are sliding rail for trolley to travel upper the girder which is fixed on outrigger by high-tension precision bolt
2. outrigger
a. consist of rigid outrigger and flexible outrigger, all connection points are connected by high-tension bolt
b. the ladder is used by operator to enter into cab or arriving at winch
c. when the span>30m,there need a flexible leg aiming at reducing the lateral thrust the trolley has to the rail when the girder load objects
3.travelling mechanism
consist of driving gear box and passive wheel box
a. the driving gear box supplies power to realize the crane’s travelling
b. what the difference between driving gear box and passive wheel box is that passive wheel box lacks transmission structure such as dynamo, reducer and a pair of exposed gear
4. trolley with hoist
be made up of trolley frame, winch and pulley block
a. trolley frame welded of steel plate  is the loading and travelling mechanism of trolley with hoisting
b. winch is the lifting mechanism of trolley..when it works, wire  rope affects the pulley as rising and falling movement, which makes suspended objects lifting and lowering
Warning: wire ropes need to be examined regularly and changed in time if there is a 10% broken wires, loosen wires and wearing down.
5. Cab 
a. glass window through which one can watch overall working condition is installed in the front and two sides of the cab 
b. Electric cabinet as a group of independent cabinet , fixed outside of cab is connected by control cable and linkage station which is set up in the cab
6. Electrical system
a. lifting motor, crane travelling motor and hydraulic power motor are included. The whole electrical system is controlled by PLC.
b. Two ways to operate the crane: cab operating and remote controlling.
c. Electric components are imported from Schneider in Germany 
7. Platform
platform is installed in order to maintain the crane, the protective guard is added to protect the safety of servicemen.
(4)technical parameters
 
（5）Attention
1. Keep safety first in mind
2. Employees can operate the crane only after strict training
3.It is required to use lifting sling with more than 5 times of safety factor, binding steel wire with more than 10 times of safety factor
4. It is forbidden for workers to stay under structural member ,crane jib or stress rigging when the crane is hoisting objects,
5. It is forbidden for installation work when the wind speed is above category 5
6. Lifting of structural member should be stable and slow to avoid vibrating and swing
7. All the workers need to learn about installation plan and technology, be familiar with operating steps before construction. During the process, anyone can not change operational requirement without permission, if necessary, there must be some measures to ensure the safety of the whole project.
8. When install the steel strand, the floor safe area should be divided to avoid unnecessary casualties caused by attached objects dropping, it is the same case with formal lifting,during the process of lifting, specially-assigned person should observe the working condition of ground anchor, safety anchor, hydro-cylinder, steel strand and cable, if there is abnormal, call the control centre
9. Before work ,It is needed to examine whether all chain block, wire rope, pulley, winch and the like are qualified
10.Electrical workers cannot change electrical appliance without permission, there must be standard distribution box and full-time electrician on the site. Laying of cable should be in accordance with related regulation.
11. When commanding the crane, the signal should be clear and uniform; when the crane is working, anybody cannot access to cab except the operator; when the crane stops working, the lifting hook should be fitted on solid objects
12. The command system for high altitude, floor and operating must be uniform
13. The crane can loosen hook only when the heavy loads is firmly connected, otherwise it is forbidden.
 
（6）After-sale service
1.We promise to provide brand-new and quality guaranteed products 
2.we promise to provide practical solution to settle the problem the user encounters