GB/T 25120-2010 Electric Hoist Standard Guide
GB/T 25120-2010, "Electric Hoists for Lifting Appliances," is the general product standard for wire rope electric hoists. It defines the classification, technical parameters, safety requirements, and test methods for wire rope electric hoists with rated loads from 0.5t to 100t, and serves as the design & manufacturing basis for models such as CD1 and MD1.
GB/T 25120-2010 is the dedicated standard for electric hoists used in lifting appliances. It specifies the classification, technical requirements, test methods, and inspection rules for electric hoists. As core components of light and small lifting equipment, electric hoists are widely used for material handling in workshops, warehouses, and maintenance facilities.
Electric Hoist Classifications and Key Parameters
GB/T 25120-2010 classifies electric hoists by structural type into: Fixed electric hoists — mounted on a stationary support, capable of hoisting only with no horizontal movement, suitable for fixed lifting point applications. Traveling electric hoists — mounted on an I-Beam rail, capable of moving horizontally along the rail, representing the most commonly used configuration. By hoisting speed, hoists are classified into: Standard-speed electric hoists (CD1 type) — single-speed hoisting, typically at 7–8 m/min. Standard/slow-speed electric hoists (MD1 type) — two-speed hoisting, with standard speed of 7–8 m/min and slow speed of 0.7–0.8 m/min, designed for applications requiring precise positioning. The standard specifies the following main parameter series: rated loads of 0.5t, 1t, 2t, 3t, 5t, 10t, 16t, 20t, 32t, 50t, and 100t — 11 ratings in total. Lifting heights of 6m, 9m, 12m, 18m, 24m, and 30m — 6 standard heights (higher lifts available on request). Work duty classifications per ISO 4301 range from M3 to M6 (with M3 representing light duty and M6 representing heavy duty).
Technical Requirements for Core Components
The standard specifies requirements for each major hoist component: Hoisting motor — a cone rotor motor with an integrated brake. The motor duty classification is S3 (intermittent periodic duty) with a duty cycle of FC = 25%–40%. The motor must deliver sufficient starting torque (starting torque / rated torque ≥ 2.0) to prevent load slipping during full-load startup. Reducer — a three-stage helical gear unit with gears made of 20CrMnTi steel (carburized and quenched to HRC 58–62) and gear accuracy of Grade 7 or better. The reducer must be properly sealed, run smoothly, and produce no abnormal noise. Drum — the drum-to-wire-rope diameter ratio must be D/d ≥ 20. The drum's rope capacity must accommodate the rated lifting height, and the drum ends must be fitted with flanges to prevent the wire rope from slipping off. Wire rope — line-contact wire rope (e.g., 6×19W or 6×36WS construction) with a safety factor ≥ 5. Hook — forged hooks selected in accordance with the GB/T 10051 standard. Travel mechanism — the travel motor is a cone rotor or side-mounted brake motor, with travel speeds typically of 20–30 m/min. The wheel tread hardness must be HB ≥ 300. The standard also requires electric hoists to be equipped with limit switches (for both upper and lower travel limits) and an overload limiter.
Brake System and Safety Devices
The standard sets out the following requirements for brakes and safety devices: Cone rotor brake — the conical brake ring at the rear of the hoisting motor engages with the conical surface of the motor rotor. When energized, the electromagnetic force draws the rotor into the stator, automatically releasing the brake; when de-energized, spring force pushes the rotor outward, engaging the brake. The brake ring friction material must provide a service life of at least 300,000 braking cycles (approximately 2 years of service at 120 starts per hour). Brake slip distance after ring wear — the full-load brake slip distance must be ≤ 100 mm for lifting heights ≤ 12m, or ≤ 200 mm for lifting heights exceeding 12m. When the brake slip distance exceeds the specified limit, the brake spring compression must be adjusted or the brake ring replaced. Overload limiter — when the load exceeds 110% of the rated capacity, the overload limiter must cut off the hoisting-up motion (allowing lowering only) and simultaneously trigger an audible and visual alarm. Limit switches — the upper final limit switch must automatically stop the hoisting-up motion when the hook reaches its highest position, and the lower final limit switch must stop the lowering motion when only 2 wraps of wire rope remain on the drum. All electric hoists supplied by Kelude are manufactured in compliance with the GB/T 25120 standard.
Testing and Inspection
Test items specified by the standard: No-load test — each mechanism of the hoist is operated without load to verify running smoothness, noise level (must be ≤ 85 dB), and correct operation of the limit switches. Static load test — the hoist is subjected to 1.5 times its rated load for 10 minutes; after unloading, all components are inspected for permanent deformation or damage. (The 1.5× static load test factor is higher than the 1.25× factor used for general cranes because the load-bearing structure of an electric hoist is more compact and demands a greater safety margin.) Dynamic load test — the hoist is subjected to 1.25 times its rated load through three complete hoisting and lowering cycles to verify braking reliability and electrical system stability. Type test — includes a fatigue life test (≥ 100,000 continuous hoisting and lowering cycles at rated load), noise test, temperature rise test, and durability test. Every hoist undergoes a no-load test and a static load test at the factory, while the dynamic load test is performed on a batch sampling basis (10% of each batch).
| Parameter | CD1Normal Speed Type | MD1 Type Two-Speed |
|---|---|---|
| Lifting Speed | 7~8m/min | Normal Speed7~8+Slow Speed0.7~0.8 |
| Work Duty / Classification | M3~M5 | M3~M6 |
| brake slip distance | ≤100mm | ≤100mm |
| Static load test | 1.5Times | 1.5Times |
| Application Scenarios | Standard Lifting and transport | Precise Positioninginstallation |
Electric Hoist FAQ: Duty Classification, Speed, Braking & Troubleshooting
Q: How is the work duty of an electric hoist classified?
A: The work duty of an electric hoist is classified into 8 levels, from M1 to M8, in accordance with the GB/T 3811 Crane Design Standard. The classification is determined by the frequency of use and the load spectrum factor. M1 to M3 are applicable to light-load, intermittent duty (e.g., maintenance hoists); M4 to M5 suit general material handling in workshops; M6 to M7 are intended for production lines with frequent duty cycles; and M8 is for continuous heavy-load operations. When selecting a hoist, match the duty classification to your actual service conditions — choosing too low a classification leads to motor overheating and premature component wear, while over-specifying results in unnecessary cost.
Q: How do I choose the right lifting speed for an electric hoist?
A: The lifting speed of an electric hoist is determined by your usage requirements: standard single-speed hoists typically offer a lifting speed of 4–8 m/min (suitable for general lifting operations); two-speed hoists provide a fast-to-slow speed ratio of 4:1 to 6:1 (with the slow speed ideal for precise positioning); VFD hoists offer stepless speed regulation within a range of 0.5–10 m/min (suited to precision installation and frequent start-stop cycles). Higher lifting speeds demand greater motor power and generate more heat in the brake. Kelude Heavy Industry offers electric hoists in three lifting speed configurations — single-speed, two-speed, and VFD — to meet diverse application needs.
Q: What are the braking torque requirements for an electric hoist?
A: The standard requires that the braking torque of the hoisting mechanism brake be no less than 1.5 times the rated hoisting torque. The brake must be of the normally closed type — closed by spring force and released electromagnetically — ensuring automatic braking in the event of a power failure. The friction coefficient of the brake lining must be ≥0.30 (in dry conditions), and the surface hardness of the brake wheel must be ≥HB280. The brake must be capable of at least 500,000 braking cycles (for M4 duty) or 1,000,000 cycles (for M6 and above). Kelude Heavy Industry electric hoist brakes are designed with a 1.8x safety factor, and the brake linings use asbestos-free, environmentally friendly materials.
Q: What are the common faults in electric hoists and how are they resolved?
A: Common faults and their troubleshooting methods: 1) Motor fails to start — check the power supply, confirm the emergency stop button is reset, and inspect the motor wiring for loose connections; 2) Weak lifting or load slipping — the brake gap is excessive or the brake lining is worn beyond limits; adjust the gap or replace the lining; 3) Trolley drifts or runs off-track — uneven wear on the trolley wheels or excessive rail straightness deviation; inspect and realign; 4) Abnormal noise — low gearbox oil level or worn gears; check the oil level and gear condition; 5) Limit switch malfunction — the limit switch cam has shifted or the contacts are sticking; readjust the limit switch position. A thorough examination is recommended every 500 operating hours.
