JB/T 10221-2014 Wire Rope Electric Hoist Drum Standard
JB/T 10221-2014, "Electric Hoist Drums," is the product standard governing drums specifically designed for electric hoists. It defines the classification, technical requirements, test methods, and inspection rules for wire rope electric hoist drums, and is applicable to drums used in the hoisting mechanisms of CD1 and MD1 electric hoists.
Drum Construction and Technical Requirements
Electric hoist drums differ from those used on general-purpose cranes—they are smaller in diameter, shorter in length, and more compact, with the motor and gearbox arranged in-line on the same shaft. The standard specifies HT250 grey cast iron for drums up to 50 t (55 US tons) and Q345B steel welded construction for larger capacities above 50 t. Wall thickness is determined by wire rope diameter and lifting capacity, with a minimum of 8 mm.
The standard imposes tight tolerances on rope groove machining. The groove radius R≈0.53–0.55d, pitch p≈d+2 mm, and depth h≈0.35–0.4d. Surface roughness must not exceed Ra 12.5 μm, and the spiral groove must transition smoothly with no sharp edges. The drum diameter D must be at least 20d—a critical factor in ensuring the bending fatigue life of the wire rope. The drum's outer surface and rope grooves must be machined in a single setup to maintain concentricity.
Drum wall thickness is determined not only by strength requirements but also by castability. For HT250 grey cast iron drums, the minimum wall thickness is generally 8 mm; for cast steel drums, it is 10 mm. Walls that are too thin can cause poor molten metal flow during casting, leading to cold shuts and porosity. Excessively thick walls, on the other hand, add unnecessary dead weight and cost. Proper matching of drum diameter to wire rope diameter is a key factor in maximizing wire rope service life.
The D≥20d requirement is based on wire rope bending fatigue test data—when the D/d ratio falls below 18, bending stress in the rope increases sharply and service life drops exponentially. For demanding applications such as gantry cranes, the standard recommends D/d≥25. Machining accuracy of the drum grooves directly affects rope spooling quality and wear uniformity; a groove radius that is too large or too small accelerates wire rope wear.
Wire Rope Fixing and Safety Requirements
Wire rope ends are secured to the drum using clamp plates, with at least two plates per end spaced no less than 50 mm apart. The rope must be spooled evenly onto the drum, leaving at least two safety wraps. For multi-layer winding, flanges at both drum ends must extend at least two rope diameters above the outermost layer. Drum bearing housings require regular lubrication, and operating temperature must not exceed 80°C.
Q345B Welded
Load-Dependent
Reduces Bending
2 Clamp Plates per End
h≈0.35–0.4d
Wall Thickness Loss >20%
| Parameter | HT250Drum | Q345B (≈S355J2)welded drum |
|---|---|---|
| applicable tonnage | ≤50t | >50t |
| wall thickness | 10~16mm | 8~14mm |
| rope groove radius | R≈0.53d | R≈0.53d |
| Surface Treatment | Aging+Rust Preventive Paint | Hot-Dip Galvanizing+topcoat |
The number of safety wraps of wire rope on the drum is a fundamental safety requirement. Even when the hook is lowered to its lowest working position, at least 2 wraps of wire rope must remain on the drum. These safety wraps prevent the rope-end clamping plate from bearing the full rope tension, which could otherwise loosen the plate and cause the rope to slip off. The wire rope should be wound evenly and tightly on the drum, with no cross-over or pinching allowed during multi-layer winding.
Testing and Inspection Requirements
Each drum undergoes a Factory Acceptance Test (FAT) individually, covering visual inspection (free from cracks, porosity, and burrs), dimensional verification (outer diameter, length, and rope groove parameters), and static balancing. The type test includes a 1.25× static load test (held for 10 minutes) and a 1.1× dynamic load test. During service, rope groove wear should be checked every 500 working hours; the drum must be scrapped if cracks are found or if wear exceeds 2 mm.
| inspection items | technical requirements | Cycle | Judgment |
|---|---|---|---|
| Appearance | None Casting Defect | factory | Conforming |
| Dimension | wall thickness/rope groove | factory | Tolerance Internal |
| Wear | rope groove≤2mm | 500h | Over Limitscrapping |
| static load | 1.25Times×10min | type test | None Deformation |
Kelude Heavy Industry supplies electric hoist drums in all specifications to match your crane system.
Electric Hoist Drum FAQ
Q: What materials are commonly used for electric hoist drums?
A: Drums are manufactured from HT250 gray cast iron for light- and medium-duty applications (≤50 t) or from Q345B steel (≈S355J2) welded construction for heavy-duty applications (>50 t). Gray cast iron suits general operating conditions, while Q345B welded drums are recommended for demanding environments such as metallurgy and foundry work. Minimum wall thickness is 8 mm.
Q: What are the machining parameters for drum grooves?
A: Rope groove radius R≈0.53–0.55d, pitch p≈d+2 mm, groove depth h≈0.35–0.4d, and surface roughness Ra≤12.5 μm. The spiral groove features a smooth transition with no sharp edges and is machined on CNC lathes. Flanges are fitted at both ends for multi-layer winding.
Q: How does drum diameter relate to wire rope diameter?
A: Standards require a drum-to-rope diameter ratio of D≥20d. A smaller drum diameter reduces the rope bending radius, increasing bending stress and accelerating fatigue fracture. Bridge cranes require D≥20d, while gantry cranes require D≥25d.
Q: What are the discard criteria for crane drums?
A: A drum must be taken out of service if any of the following conditions are present: cracks, rope groove wear exceeding 2 mm in depth, wall thickness reduction greater than 20%, deformation causing wire rope derailment, or missing or cracked flanges. Repair welding on load-bearing areas is not permitted.
