（1）Range of application:
The instruction applies to electrical double-girder, single-girder and hoist block gantry cranes.
(2) Purpose and characteristics:
i. The gantry crane is usually used in outdoor working environment. According to the different occasions, it can be classified as various types including the hook, grab, electromagnetic, hook-grab, hook-electromagnetic etc. The working temperature is -10℃~ +40℃，and the altitude is not exceeding 200m. It will be a special order while it doesn’t match the mentioned working environment. During the crane working, the wind speed must be less than or equal to grade 6.
ii. Gantry Crane of Series MG is the patented product designed specifically for bridge building purpose by our company. Considering the characteristics of bridge building, like smaller operation batch, bigger unit weight, short of power supply, frequent moving of working site, and so on, we try our best to gain the goal of a simpler structure, convenient mounting and dismounting, easy operation, and energy saving in the design. After absorbing some strong points of the existing foreign equipment and with repeated improvement, our product has been featured with the following characteristics:
a, unique design of cellular beam, originated by our company, with lighter empty weight, higher load, strong wind-resistant capability, and other strong points;
b, matured pin-connection-mechanism with not only higher firmness and reliability but also fast assembling (merely several minutes to set one steel pin);
c, flexible lever of supporting post, which may be dismounted into single pieces and thus facilitates transportation;
d, minimum installed capacity, that solves the difficulty of power supply shortage in the field operation.