Interpretation of the TB/T 2628 Standard, “General Specifications for the Design of Railway Cranes”
⚠️ TB/T 2628, “General Specifications for the Design of Railway Cranes,” is an industry-recommended standard for the design of complete railway crane systems. It covers key technical requirements such as general layout, structural design, selection of mechanisms, electrical systems, and safety protection, and applies to the design, development, and type testing of rail-mounted railway cranes.
TB/T 2628 is a fundamental technical specification in the field of railway crane design. Developed under the leadership of the China Academy of Railway Sciences, it applies to railway cranes operating on standard-gauge railways. Unlike general-purpose bridge crane design standards, this standard fully accounts for special operating conditions such as railway clearance constraints, track horizontal and vertical alignment conditions, subgrade bearing capacity, and the operation of coupled locomotives and rolling stock. During the research and development of its railway cranes, Krud Heavy Industry strictly adheres to TB/T 2628 as the design benchmark to ensure that its products meet the operational safety and reliability requirements of the railway system.
Overall Layout and Clearance Constraints
The standard sets forth specific requirements for the overall layout of railway cranes. The overall dimensions of the crane must comply with the rolling stock gauge specified in GB 146.1; on straight track, the outermost points of all components must not intrude upon the gauge contour line. Regarding the connection method between the car body and the bogie, the standard recommends a structural configuration that combines side bearings and a center disc, with the side bearing clearance controlled within the range of 2 to 4 mm.
Regarding axle load distribution, the standard requires that the deviation in axle load for any given axle under full-load conditions not exceed ±4% of the average axle load, to ensure uniform distribution of the track load. For multi-axle bogies, the standard also specifies principles for matching the stiffness of the primary and secondary suspensions, recommending that the ratio of vertical equivalent stiffness be maintained between 1:3 and 1:5 to balance ride comfort and curve-running performance.
Key Points of Structural Design
TB/T 2628 adopts an analytical framework based on the limit state method for the design of steel structures for railway cranes. Major load-bearing members must be verified for fatigue strength, and the fatigue design load spectrum should be based on data regarding the frequency distribution of loads collected during actual operation. The standard specifically states that stress analysis using the finite element method must be performed on critical joints—such as the hinge seat at the base of the boom, the slewing bearing seat of the turntable, and the outrigger housing—taking into account the effects of geometric stress concentration at welds.
Regarding material selection, the standard recommends using Q345qD or Q370qE bridge structural steel for the primary load-bearing structure, with low-temperature impact toughness meeting the requirement of KV₂(-40°C) ≥ 47 J. For components such as booms that are subjected to significant dynamic loads, the standard also specifies additional requirements regarding the fatigue crack propagation rate to ensure that no fatigue failure occurs over the 25-year design life.
Equipment Selection and Performance Parameters
The hoisting mechanism is the core working mechanism of a railway crane. Standards require that railway cranes with a rated lifting capacity of ≥100 t be equipped with a dual-winch hoisting system, in which the two drums are linked via a synchronizing shaft or electronically controlled synchronization. The recommended hoisting speed range is 0.5 to 3.0 m/min (under full load); when unloaded, the speed may be increased to 6.0 m/min or higher. The slewing mechanism shall employ a hydraulic motor drive system equipped with a normally closed brake, with a continuously adjustable slewing speed of 0.1 to 0.5 r/min.
The outrigger system is critical to ensuring operational stability. The standard stipulates that railway cranes must be equipped with a four-outrigger extension support system, with the maximum load capacity of each outrigger designed to be 1.5 times the rated outrigger reaction force. The hydraulic locks on the outrigger cylinders must comply with the requirements of ISO 4413 and be capable of reliably locking in the event of a hydraulic line rupture. The standard also requires the installation of a leg extension status detection switch; hoisting and slewing operations are prohibited when the legs are not fully extended.
Electrical and Safety Protection Systems
The electrical system design shall comply with the relevant requirements of TB/T 3021, “Electrical Equipment for Railway Rolling Stock.” The standard stipulates that the control system shall employ a dual-loop redundant design, with the main controller and backup controller monitoring each other via hardware watchdogs. The torque limiter shall be capable of collecting boom angle, reach, and load data in real time; it shall issue a warning signal when the actual load reaches 90% of the rated load, and shall automatically cut off hoisting and boom swing operations when the load reaches 110%.
In terms of safety protection, the standard requires the installation of an anemometer (alarm threshold: 13.8 m/s; automatic shutdown threshold: 20.7 m/s), an anti-tipping torque limiter, an outrigger settlement monitoring device, and a lighting system for nighttime operations. For operations on electrified railway sections, the safety distance requirements for the overhead contact line must also be met; the safety distance between the highest point of the boom and the live parts of the overhead contact line must be no less than 2 m.
| Design Elements | Requirements of TB/T 2628 | Design Basis | Verification Methods |
|---|---|---|---|
| Boom Cross-Section Types | Box-shaped/U-shaped cross-section | Finite Element Optimization + Buckling Analysis | 1:5 Scale Model Stress Test |
| Slewing Bearing | Three-row roller type | DIN ISO 281 Service Life Calculation | Verification of the Overturning Moment Test Stand |
| Outrigger Span | ≥1.5 times the track gauge | Calculation of Support Reactions Under the Most Adverse Conditions | Load Testing of Vehicle Outriggers |
| Hoisting Mechanism | Dual Winches + Synchronized Control | GB/T 3811 Design of Hoisting Mechanisms | 1.25x Dynamic Load Test |
| Cabin Noise | ≤85 dB(A) | GB/T 25685 | Sound Level Meter A-Weighted Measurement |
| Electrical Protection | IP54 or higher | GB/T 4208 | Dust and Water Resistance Testing and Validation |
| Test Items | Testing Standards | Inspection Frequency | Acceptance Criteria |
|---|---|---|---|
| Static Load Test | 1.25 times the rated load | Type Testing/Factory Release | No permanent deformation |
| Dynamic Load Test | 1.1 times the rated load | Type Testing/Factory Release | Movement is normal; no abnormalities. |
| Stability Testing | 1.25 times + wind load | Type Testing | Does not tip over |
| Leg Settlement | ≤3 mm/30 min | Factory Testing | Hydraulic Lock Effectively Maintains Pressure |
| Boundary Check | GB 146.1 | Factory Testing | Non-intrusive limit |
| Torque Limiter Calibration | Accuracy: ±5% | Factory Inspection + Annual Inspection | Over 1101 TP3T Automatic Shutdown |
Track gauge: 1,435 mm
Multiple levels available
≤6.0 m/min (no load)
Stepless Speed Control
Fatigue Life Verification
SIL 2
Frequently Asked Questions
Q: To which railway cranes does the TB/T 2628 standard apply?
Answer: This standard applies to self-propelled railway cranes operating on standard-gauge (1435 mm) railways and covers a series of products with rated lifting capacities ranging from 60 t to 160 t. This standard does not apply to road-rail dual-purpose cranes or track cranes that operate exclusively in fixed positions within rail yards. The specific scope of application shall be determined in accordance with Chapters 1 and 4 of this standard.
Q: What are the key considerations in the design of a railway crane boom?
Answer: The core of boom design encompasses three aspects: first, buckling stability, which requires both linear and nonlinear buckling analysis; second, fatigue strength, which requires verifying the fatigue life of critical welds based on measured load spectra; and third, clearance limits, whereby the coverage area of the boom across its full swing range must comply with railway clearance requirements. TB/T 2628 contains explicit technical provisions for all three of these aspects.
Q: What specific requirements does TB/T 2628 set forth for torque limiters?
Answer: The standard requires that the torque limiter have a three-level warning function: a yellow warning at 90% of the rated load, an audible and visual alarm at 100%, and automatic shutdown of hoisting and boom swing operations at 110%. The system must also include a "black box" recording function that stores data from the most recent 1,000 operations, including lifting capacity, boom length, boom angle, and timestamps.
Q: What tests must be completed for the factory inspection of a railway crane?
Answer: Factory inspections must include, at a minimum: a 1.25-times static load test (no permanent deformation for 10 minutes) , a 1.1x dynamic load test (each mechanism operated through its full stroke three times), an outrigger settlement and pressure retention test (settlement ≤ 3 mm within 30 minutes), a clearance test, calibration of the torque limiter accuracy (error within ±5%), and functional testing of all safety devices.
