The bridge erecting machine is the equipment to place the prefabricated beam on the prefabricated pier. The bridge erecting machine belongs to the category of crane, because its main function is to lift the beam, then transport it to the position and put it down.

Bridge erecting machine is very different from crane in general sense. It requires harsh conditions, and there is a beam on the line, or called longitudinal movement. Bridge erecting machine is divided into highway bridge, conventional railway bridge and passenger dedicated railway bridge.

It is a kind of bridge construction machinery which runs on highway and railway track and is used for erecting small span beam. Because of its high efficiency, it is considered as the design principle in the standard design of railway bridges in China. The fuselage is huge and beyond the railway transportation limit, so it must be disassembled and transported, and then assembled and used after arriving at the construction site.

There are three kinds of bridge erecting machines in China, most of which are used for erecting reinforced or prestressed concrete beams.

Single beam bridge erecting machine

One of the bridge construction machinery, its boom is a box beam, which overhanging forward, in front of which there is a folding column (composed of left and right legs). The machine can drive into the bridge position automatically under no-load condition, and then straighten the front column and support on the front pier. When the supported beam (or the whole beam) moves along the boom, the boom is close to the simply supported beam. When erecting a bridge, the machine can drive into the bridge position automatically under no-load condition. First, the beam pieces must be transferred from the railway flat car to the special beam carrier by using the special gantry crane, and then the beam carrier and the rear end of the bridge erecting machine are aligned, and the beam pieces are lifted by two beam trolleys running on the crane arm of the bridge erecting machine, and then they move forward along the crane arm to reach the bridge position and drop the beam. In order to adapt to curved bridge erection, the boom of the crane can swing a little in the horizontal plane. The positioning method of the beam is the same as that of the double cantilever bridge erector (moving the beam or moving the track). The advantages of the machine are: canceling the balance weight, no need of locomotive pushing, no need of bridge fork line for beam feeding, improved mechanization degree and improved safety performance. The Shengli Bridge Erecting Machine with a lifting capacity of 130 tons is of this kind.

Double cantilever bridge erecting machine

This type of bridge construction machinery was used earlier in the Soviet Union. When it was introduced in 1948, its front and rear arms were made of steel plate beams, with lifting weights of 45 tons and 80 tons. In the 1950s, the double arms were changed into frames, and the lifting capacity was developed to 130 tons.

This kind of bridge erecting machine can't be driven by itself, so it needs to be pushed by locomotive. The forearm is used to lift the beam, and the rear arm is used to lift the balance weight, so the front and rear arms can not swing in the horizontal plane. When erecting a bridge, it is often necessary to use a special 80 ton flat car to transport the beam under the hook of the forearm of the bridge erecting machine (called "beam feeding"); In order to make shunting operation convenient, it is necessary to lay bifurcated line at bridge head. After the girder is lifted by the bridge erecting machine, the axle load will increase, and the new embankment at the bridge head is relatively soft. Therefore, reinforcement measures must be taken for the section where the girder is lifted by the bridge erecting machine, such as using heavy vehicles to press the road, adding sleepers, etc.

Double beam bridge erecting machine

Hongqi type bridge erecting machine and Liaoyuan type bridge erecting machine belong to this kind, and the lifting weight is also 130 tons. The boom is composed of left and right box girders, which run through the fuselage and extend forward to the rear end. There are folding columns composed of two legs at both ends. The middle distance between the two beams of Hongqi type is 3.4m, while that of Liaoyuan type is 4.8m. There are two truss cars across the two box girders, which can travel along the boom longitudinally. The trolley is placed on the truss car and can travel along the truss car. The beam to be erected (or the whole beam) can be directly sent to the rear arm of the bridge erecting machine by the railway flat car, lifted by the beam trolley, moved forward by the truss trolley, then moved horizontally by the beam trolley, and then dropped into place. The front and rear ends of this kind of bridge erecting machine can lift and drop beams; When changing the direction of beam erection, there is no need to turn around; In order to adapt to the curve beam, both the front and rear arms can swing in the horizontal plane; When erecting in pieces, the beam can be in place without moving the beam or shifting the track“ "Beam feeding" also does not need the bridge branch line or special beam carrier.

Track laying should be done immediately after girder erection, so that the bridge erecting machine can continue to work forward. The latter two kinds of bridge erecting machines can generally hoist the pre assembled track rows in place, so that the beam erecting work will not be delayed due to track laying.

In addition to the above-mentioned standing bridge erecting machines, the construction unit sometimes makes various temporary bridge erecting machines as required. For example, during the construction of the approach bridge on the South Bank of Jiujiang Bridge, a special bridge erecting machine capable of lifting 300 tons was made to erect a 40 meter span Ballastless sleeper free prestressed concrete beam. Some construction units often use standing steel scaffold members, dismounted beams or military beams to form a simple bridge erecting machine to complete the bridge erecting task in time.