Things You Need to Know Before Buying an Overhead Bridge Crane

Things You Need to Know Before Buying an Overhead Bridge Crane

Bridge cranes are characterized by their ability to lift and move heavy loads—whether suspended from a hook or other lifting device—vertically or horizontally through space. A bridge crane consists of a lifting mechanism and mechanisms that drive the trolley and the main carriage. Through the coordinated actions of these components, heavy objects can be lifted and transported within a defined cubic workspace. Common examples of this type of crane include bridge cranes and gantry cranes.

A bridge crane consists of two main components: the bridge and the hoisting trolley. At both ends, the bridge is supported directly on elevated rails via its running mechanism, allowing it to move longitudinally along the tracks. Meanwhile, the trolley itself travels horizontally along dedicated trolley rails mounted on the bridge’s main girder. Bridge cranes are classified into two types: single-girder bridge cranes and double-girder bridge cranes. A single-girder bridge crane features a single main beam, while a double-girder bridge crane is equipped with two parallel main beams.

Bridge cranes primarily consist of a lifting mechanism, a traveling mechanism, and a metal structure. The lifting mechanism is the crane's core working component, typically comprising a hoisting system and a trolley—but some models also utilize hydraulic systems to raise and lower heavy loads.

The running mechanism is used to move heavy objects horizontally or adjust the crane's working position; it typically consists of an electric motor, a gearbox, a brake, and wheels.

The metal structure serves as the crane's skeletal framework. , The main load-bearing components include bridge girders, boom structures, and gantry frames. The bridge girder's metal structure consists of a main beam and end beams, categorized into two types: single-girder bridges and double-girder bridges. The main beam and end beams are rigidly connected, with wheels mounted at both ends of the end beams to support the bridge girder as it travels along elevated tracks. Additionally, a rail is installed on the main beam to guide the operation of the lifting trolley. Gantry frames can be designed as box-type, truss-type, or even plate-web structures; some may also utilize structural steel sections as supporting beams.

The large vehicle's running mechanism employs individual drives, with two active wheels each equipped with a pair of symmetrical, independent drive units. These drive units primarily consist of components such as electric motors, brakes, gear reducers, and wheels.

The small frame is welded from steel plates and equipped with a lifting mechanism and a traveling mechanism.

The crane's lifting mechanism is mounted on the upper part of the trolley frame. To ensure safe and reliable operation, a braking device is installed on the high-speed shaft of the gearbox, and a hoisting height limit switch is fitted to the bearing housing at one end of the drum.

The trolley's running mechanism is driven by an electric motor connected to a gearbox. The low-speed shaft of the gearbox is linked to the driving wheels via a centralized drive system, while the other end of the motor shaft is equipped with a brake. Crane operation can be categorized into two main types of drive systems: one is the centralized drive, where a single electric motor powers a long transmission shaft that drives the active wheels on both sides. ; Another type features independent drive, meaning each of the two front wheels is powered by its own electric motor.

Understanding the structure and importance of each component of a bridge crane is essential to selecting the most suitable crane for your needs.