The drum group is the primary component of lifting machinery. The drum is used in the hoisting mechanism to wind the wire rope for power transmission.

Composition of the drum group:
The drum group consists of components such as the drum, drum group, gear coupling, and bearing supports. The drum shaft is connected to the reducer through a gear coupling. For the fixation of the wire rope on the drum, the crane uses a double-grooved drum, with spiral grooves at both ends in opposite helical directions. The two ends of the wire rope are separately fixed on the outer ends of the left and right helical grooves. The wire rope is generally fixed on the drum using pressure plates, which is a simple method and convenient for disassembly. To ensure safety, reduce the pressure on the fixed pressure plates or the force on the wedges, and ensure that the load-handling device can be lowered to the limit position, in addition to the fixed rope loops, at least 2 loops of wire rope should be retained on the drum. These loops are called safety loops, also known as load-reducing loops.

Material of the drum group:
Generally, cast iron not lower than HT20—40, cast steel ZG25 or ZG35, or steel plates Q235B or Q345B for welded construction are used.

Drum machining process:
Plate blanking → rolling the cylinder body and welding the longitudinal seam → inspecting the longitudinal weld and geometric dimensions of the cylinder body: diameter, length, inner diameter ovality tolerance, etc.; for large-diameter drums, add temporary stiffening ribs according to technical procedures → machining the annular bevel of the cylinder body; for processes requiring rough machining of the outer diameter, machine the outer surface → extension welding of the cylinder body. For drums that require temporary stiffening ribs at both ends, perform according to technical procedure requirements, and inspect the quality of the circumferential welds and the machining allowance → final dimensioning of the drum length and machining of the end rabbets or bevels → welding the end flange plates, shaft, inner support rings, etc.

Safety requirements for the drum group:

1. When the load-handling device is at the upper limit position, the wire rope should be fully wound in the helical grooves; when the load-handling device is at the lower limit position, there should be 1.5 to 2 loops of grooves for fixing the wire rope and more than 2 loops of safety grooves at each fixed end.

2. The operating condition of the drum group should be regularly inspected:

• Check that the drum and shaft have no cracks. If cracks are found, they must be scrapped and replaced immediately.
• When the drum wall wear reaches 20% of the original wall thickness, the drum should be scrapped and replaced immediately.
• The drum hub must have no cracks, and its connection with the drum should be firm without loosening.
• The fixation of the wire rope tail end should be reliable, and the fixing device should have anti-loosening or self-tightening performance.

1. The deviation angle between the drum and the wire rope paying off should not exceed 3.5 degrees for single-layer winding mechanisms, and should not exceed 2 degrees for multi-layer winding mechanisms.
2. For drum groups using multi-layer winding, the drum ends should have flanges. The flanges should be higher than the outer layer of wire rope or chain by twice the diameter of the wire rope or the width of the chain. Single-layer winding single drums should also meet the above requirements.