Portal Crane Design Parameters & Safety per GB/T 29560-2013
GB/T 29560-2013 "Portal Cranes" is the product standard governing the design and manufacturing of portal slewing cranes. The standard specifies type parameters, technical requirements, safety devices, and test methods, covering the complete technical specification for general-purpose portal cranes used at port terminals and power stations.
GB/T 29560-2013 is the general product standard for portal cranes, published and implemented in 2013. A portal crane is a slewing jib crane whose portal base allows railway or road vehicles to pass underneath. It incorporates four working mechanisms — hoisting, luffing, slewing, and traveling — and is widely used for lifting operations at port terminals, power stations, shipyards, and construction & installation works. Compared with the port-specific standard GB/T 17495, this standard has a broader scope of coverage and applies to the design, manufacturing, and acceptance of all general-purpose portal cranes. Kelude Heavy Industry portal cranes are designed and manufactured to this standard.
Type Classification and Basic Parameters
The standard classifies portal cranes into three categories based on application and structural type. General-purpose portal cranes — for routine cargo handling at port terminals and storage yards, with rated lifting capacity of 5–100 t and maximum working radius of 25–45 m. Power-station portal cranes — for equipment installation and maintenance at hydroelectric and thermal power plants, with lifting capacity up to 200 t or more and relatively smaller working radius. Shipyard portal cranes — for hull block hoisting and assembly on slipways, featuring high lifting capacity (100–500 t) and high lifting height (up to 70 m or more). The standard also defines two structural configurations based on the slewing bearing arrangement: the column-supported type, where the slewing section is supported on the portal frame through a slewing column, and the turntable type, where the slewing section is mounted on a slewing platform connected to the portal frame via a slewing bearing. The column-supported type offers a simple structure and high load-bearing capacity, making it suitable for large portal cranes; the turntable type provides a compact structure with a low center of gravity, suited to small and medium portal cranes.
On basic parameters, the standard specifies a rated lifting capacity series of nine grades: 5 t, 10 t, 16 t, 25 t, 40 t, 63 t, 100 t, 160 t, and 200 t. The maximum working radius series covers seven grades: 20 m, 25 m, 30 m, 35 m, 40 m, 45 m, and 50 m. Lifting height ranges from 20–30 m for port-type cranes, 30–50 m for power-station types, and 50–70 m for shipyard types. Mechanism speed parameters: lifting speed 10–40 m/min (two-speed configuration with heavy-load low speed and light-load high speed), derricking speed 30–60 m/min, slewing speed 1.0–2.0 r/min, and travel speed 20–30 m/min. The duty classification of the complete crane is not lower than A6, and the hoisting mechanism not lower than A7. The portal frame headroom must accommodate the height limit of vehicles passing underneath — not less than 5.5 m for railway traffic and not less than 4.5 m for road traffic. The clear width of the portal frame must satisfy the vehicle width plus safety distance on both sides.
Metal Structure and Mechanism Requirements
The metal structure of a portal crane consists of the portal frame (portal legs plus bottom cross beam), slewing platform, A-frame, jib (boom), and counterweight spreader beam. The standard sets strength and stiffness requirements for the design of main structural components. Strength calculations for the portal frame must consider both vertical loads (compression from dead weight and lifting load) and horizontal loads (bending moments from wind load and slewing centrifugal force). The jib typically uses a box section or lattice section; jibs exceeding 30 m in length require nonlinear stability analysis. The A-frame must have sufficient strength and stiffness to withstand the maximum force exerted by the luffing mechanism. The slewing platform must provide adequate torsional stiffness and mounting surface accuracy. The anti-overturning stability of the complete portal crane must be verified under three operating conditions: working condition (rated load at maximum radius plus wind load), non-working condition (maximum wind load plus dead weight), and erection/dismantling condition. The stability factors for these three conditions must be no less than 1.4, 1.5, and 1.3, respectively.
On mechanisms, the standard sets individual requirements for the hoisting, luffing, slewing, and travel mechanisms. The hoisting mechanism must adopt a double-brake configuration (service brake plus safety brake) with a braking torque of no less than 1.5 times the rated hoisting torque. The ratio of drum diameter to wire rope diameter (D/d) must be no less than 25 for duty classification A7 and above. The luffing mechanism should use either rack-and-pinion or hydraulic luffing, with the luffing rack strength safety factor no less than 5. The luffing mechanism must be equipped with bidirectional buffer devices to decelerate at the luffing travel limits. The slewing mechanism uses a planetary reducer to drive the slewing bearing, whose load-bearing capacity is selected based on the overturning moment and axial force at maximum working radius. The travel mechanism adopts individual drive configuration, with each drive wheel fitted with an independent brake. The anti-wind safety device should use an electric rail clamp interlocked with an anemometer to automatically clamp the rail when the working wind speed exceeds the limit.
Safety Devices and Electrical Requirements
Portal cranes require a more comprehensive safety device configuration than standard overhead type cranes, owing to their four independent working mechanisms and demanding operating environments such as high-wind port terminals. Mandatory safety devices include: an Overload Limiter (with dual limiting on both lifting capacity and working radius), a Lifting Height Limit Switch (dual-configuration with mechanical and electronic units), a lowering limit switch, a luffing limit switch (set separately for maximum and minimum radius), a Slewing Limit Switch (restricting slewing revolutions to prevent cable twisting), an Anemometer (alarm at wind speeds above 16 m/s, automatic shutdown of working power above 20 m/s), a Wind Rail Clamp (interlocked with the anemometer, the Electric Rail Clamp automatically engages when power is lost), and emergency stop buttons located in the operator cab, on the slewing platform, and at ground level. The standard also specifies that portal cranes shall be equipped with an Anti-Collision Device to prevent boom interference when multiple cranes operate in the same area.
For the electrical system, portal cranes use a cable reel power supply method — the cable runs from the dock-side power supply box and is automatically paid out and retracted by the Cable Reel as the crane travels. The cable reel's retrieval speed must match the crane's travel speed to prevent the cable from being pulled taut or tangling. The Electrical Control System uses a PLC for logic control and Fault Diagnosis of each mechanism. Each mechanism's motor employs Variable Frequency Speed Control for smooth speed regulation and precise positioning. The operator cab shall be equipped with air conditioning and heating to maintain a comfortable interior temperature. Vibration acceleration in the cab shall not exceed 0.5 m/s². The electrical room shall be fitted with heating and dehumidification equipment to protect against salt-spray corrosion. Outdoor electrical components shall have a Protection Rating (IP) of no less than IP55. The Earthing Protection resistance of the portal crane shall not exceed 4 Ω, and each mechanism's motor shall have independent Short-Circuit Protection and Overload Protection. The standard further requires a lightning protection system for the entire crane, with the Lightning Rod's Grounding Resistance not exceeding 10 Ω.
Test Methods and Factory Acceptance
The standard specifies requirements for both the routine test before delivery and the Site Acceptance Test for portal cranes. Before delivery, each crane shall undergo a No-Load Test with all mechanisms running continuously for 1 hour at rated speed, with no abnormal noise or temperature rise. The Rated Load Test (100% SWL) involves lifting the rated load at each typical working radius and performing full-cycle hoisting, lowering, luffing, and slewing operations while measuring boom-end Deflection and the brake slip distance of each mechanism. The Dynamic Load Test requires lifting 1.1 times the rated load and performing each action no fewer than 5 times at maximum mechanism speed, checking that structural components show no abnormal Deformation and Weld Seams show no cracking. The Static load test involves lifting 1.25 times the rated load and holding it stationary at maximum radius for 10 minutes to measure permanent deformation of the structure. For the overall stability test, the crane shall not overturn when lifting 1.4 times the rated load at maximum radius. The Slewing Bearing gear clearance shall be measured and recorded before delivery as baseline data for subsequent inspections.
Test Methods and Factory Inspection
The standard specifies the factory and site acceptance test requirements for portal cranes. Each crane undergoes a No-Load Test before delivery, with all mechanisms running at rated speed for 1 hour. The Rated Load Test (100% SWL) is performed at each typical working radius with full-cycle operation, measuring Deflection and brake slip distance. The Dynamic Load Test uses 1.1 times the rated load with each mechanism action repeated no fewer than 5 times. The Static load test uses 1.25 times the rated load held stationary at maximum radius for 10 minutes. The overall stability test requires that the crane shall not overturn when lifting 1.4 times the rated load at maximum radius. Slewing Bearing gear clearance is measured and recorded before delivery as the baseline for future inspections.
Portal Crane Design Parameter Comparison Table
The comparison table below lists the core parameters for portal crane design configuration, for reference by selection and operation personnel.
| Parameter Name | technical requirements | Acceptance Standard | Application Notes |
|---|---|---|---|
| Lifting Capacity | Rated Lifting Capacity≥design value | Load test1.25Timesstatic load | Including Lifting spreader Weight |
| working radius | Maximum/Minimum radius Compliancedesign requirements | Actual Measurement Comparison | Including Luffing range |
| Lifting Height | Above Rail/Below Rail Height Meets Process Requirements | Actual Measurement Verification | Includingspreader height |
| Work Duty / Classification | A5~A8Per Application Frequency Selection | Per GB/T 3811 Crane Design Standardverification | Height Strength Height Selection Grade |
| Anti-Wind Anti-Slip | Rail clamp+Anchor device Interlocking | clamping force Testing | Wind Speed≥6Classearly warning |
FAQ: Portal Crane Standards, Operation & Inspection
Q: What is the difference between GB/T 29560 and GB/T 17495 for portal cranes?
A: GB/T 29560 is the general standard for portal cranes, covering all types used in ports, power stations, and shipyards. GB/T 17495 is the dedicated standard for harbor portal cranes, focusing on the special requirements of port terminal operations. The general standard serves as the foundation, while the dedicated standard provides supplementary specifications.
Q: Why must luffing operation not be performed under load on a portal crane?
A: Luffing under load changes the boom angle, which in turn alters the relationship between working radius and load moment, creating a risk of overload and overturning. Standard requirements mandate that luffing operation be carried out only when the crane is at no-load or with a light load (not exceeding 70% of the rated lifting capacity).
Q: What are the setting requirements for the slewing limit switch on a portal crane?
A: The slewing limit switch should restrict the slewing angle to no more than 1.5 to 2.5 revolutions to prevent excessive cable twisting. After the limit switch is activated, the crane should be able to slew in the reverse direction to reset. For portal cranes powered via a central collector ring, the slewing limit switch may be omitted, but the slip ring must be subject to periodic inspection.
Q: What periodic inspection items are required for portal cranes?
A: Monthly inspection covers safety devices and brakes on all mechanisms. Quarterly inspection covers weld seams on the metal structure and the slewing bearing gear. A comprehensive inspection is performed annually, including load tests, flaw detection on the structure, and accuracy calibration of the load moment limiter.
