I. Trolley Traveling Mechanism
The tower crane trolley achieves horizontal movement (left and right) through its traveling mechanism. The principle behind this is that the chassis of the trolley, consisting of a pair of drive wheels and a pair of fixed wheels on each side, is driven by a motor. This motor's power is transmitted through a combination of gears and chain drives, enabling the trolley to move forward or backward along the jib. Furthermore, under the action of a screw drive and a flywheel speed regulation system, the motor speed is varied by a frequency converter to achieve different travel speeds, thus realizing the horizontal movement of the trolley body. The traveling speed of the trolley can be adjusted by the frequency converter, allowing for accurate and stable speed control.
II. Luffing Mechanism
The tower crane trolley achieves luffing (changing the working radius) through its luffing mechanism, also known as the radius changing system. This is a crucial active mechanism on the tower crane, composed of a fixed part and a moving part. The moving part is responsible for altering the angle of the jib (horizontal arm), while the fixed part is securely connected to the mast (vertical column). The main components of the luffing mechanism include limit switches, gears, shafts, retaining rings, and hydraulic cylinders (in some designs).
The luffing of the tower crane trolley can be achieved in two primary ways:
Luffing by Jib Raising and Lowering: In this method, the entire jib structure pivots upwards or downwards at its connection point with the mast. This change in the jib's angle directly alters the horizontal distance the trolley can reach, thus changing the working radius. The hoisting mechanism, responsible for lifting the load, often plays a role in controlling the jib's angle through a system of ropes and drums.
Direct Luffing Control by Hydraulic Cylinder: Some tower crane designs utilize hydraulic cylinders directly to control the luffing angle of the jib. These cylinders are typically attached between the mast and the jib. Extending or retracting the hydraulic cylinders directly pushes or pulls the jib, causing it to pivot and change its angle, thereby adjusting the working radius of the trolley.
The range of the luffing angle can be adjusted according to the required working radius for handling different loads and reaching various points on the construction site.
In summary, the horizontal movement and luffing principles of the tower crane trolley are both achieved through the collaborative operation of various mechanisms including electric motors, gears, frequency converters, chain drives, and hydraulic systems (in some luffing designs). The coordinated function of these components allows the tower crane trolley to move freely left and right along the jib and to adjust its working radius, enabling it to adapt to diverse and complex working conditions and achieve efficient and safe transportation of goods.