JB/T 6391 Crane Reducer Standard Explained
JB/T 6391 — Reducer Standard for Cranes is a key technical specification in the crane industry. Developed as a machinery-sector standard, it defines the requirements for special reducers used in crane applications.
The standard provides a unified technical basis for design engineers, inspection bodies, and end users. Kelude strictly follows the technical requirements set out in this standard throughout product development and manufacturing, ensuring compliance and reliability of all equipment.
Scope and Application of the Standard
JB/T 6391 specifies the technical requirements and safety indicators for crane reducers, covering all types of lifting appliances with a Rated Lifting Capacity above 0.5t. The standard governs not only the design and manufacturing of new equipment but also provides clear technical guidance for the inspection, maintenance, and modification of cranes already in service. As a critical component of the crane standard system, it aligns with the EN 13001 Crane Safety Standard series and ISO 4309 Wire Rope Inspection Standard, together forming a comprehensive framework of technical specifications. The core technical parameters and Safety factor requirements defined in the standard give designers a clear design basis and provide third-party inspection bodies with quantifiable acceptance criteria for Type Tests and Factory Acceptance Tests.
Core Technical Parameter Framework
Under the technical provisions of JB/T 6391, the design and manufacturing of crane reducers must satisfy a stringent set of technical parameters. These parameters are established based on extensive test data and safety engineering theory, covering the entire process from material selection to structural design. The Safety factor ranges specified in the standard take full account of fatigue life and limit load conditions under demanding operating conditions.
Comparative Analysis of Key Technical Parameters
| Item | technical requirements | Description |
|---|---|---|
| Contact Safety SH | ≥1.25(ISO Class 6 (cleanroom)336 Gear load capacity calculation standard) | Includingdynamic load Kv Service KADistribution KHβ |
| Bending Safety SF | ≥1.50 | Carburizing and Quenching HRC58~63 |
| bearing life | L10h≥5000h(rated load) | According to ISO 281 Rolling bearings — Dynamic load ratings and rating life Calculation |
| Efficiency | ≥92%(Third Stage)/≥88%(Fourth Stage) | Including Oil Churning Loss80°C |
| Noise | ≤80dB(A)/Distance1m | 5Average of Measuring Points |
| Enclosure Protection | IP55Dustproof Water Jet Proof | Double Oil seal Static Surface Sealing Compound |
Inspection Requirements and Intervals
Factory Acceptance Tests are performed on every unit by the quality inspection department at the manufacturer's facility. Each unit that passes inspection ships with a detailed inspection report and a Certificate of Conformity. Type Tests are conducted when a new product enters production, when manufacturing moves to a different facility, or when significant structural changes are introduced. For equipment already in service, the periodic inspection interval is determined by the work duty classification and operating environment, typically not exceeding 12 months.
| Item | technical requirements | Description |
|---|---|---|
| Lubricating Oil | Oil Level/Oil Quality/Oil Temperature | Weekly+Per500hOil Change |
| Gear Meshing | Contact pattern≥60%Face Width | Semi-annual Cover Inspection |
| Bearing | Vibration/Temperature/Noise | Quarterly Vibration Measurement≥10m/s²Replacement |
| Sealing | Output Shaft/Joint Surface Leakage | Monthly+Leakage Replacement Oil seal |
Safe Operation and Management Requirements
The standard places strong emphasis on operator qualification and training, requiring that all operators complete specialized training and obtain the necessary certifications before being allowed to operate the equipment. User units are expected to establish a comprehensive equipment file management system that documents the full history of installation, operation, maintenance, and inspection. Any safety hazards identified must be addressed through the rectification procedure specified in the standard, ensuring that equipment remains in a safe and controllable condition at all times.
FAQ
Q: What are the required safety factors for gears (SH and SF) under the JB/T 6391 crane gearbox standard?
A: Contact safety factor SH ≥ 1.25, bending safety factor SF ≥ 1.50. Materials: 20CrMnTi / 17CrNiMo6, carburized and quenched to HRC 58–63.
Q: What are the rated life and selection requirements for gearbox bearings under the JB/T 6391 standard?
A: L10h ≥ 5,000 h at rated load with 90% reliability. Tapered roller bearings on the input shaft with C3 clearance class.
Q: What efficiency and noise limits does the JB/T 6391 standard specify for gearboxes?
A: Three-stage gearboxes: ≥ 92%; four-stage: ≥ 88%. Measured at an oil temperature of 80°C, including churning losses.
Q: What does the JB/T 6391 standard require for gearbox lubrication and oil change intervals?
A: Splash lubrication with oil immersion depth of 2–3 times the module. Use VG220/320 synthetic oil. Oil change every 500 hours.
Kelude Heavy Industry — Specialized in crane design and manufacturing, with products strictly compliant with the JB/T 6391 standard system and backed by full lifecycle service.
