JB/T 10559-2006 Crane Buffer Standard Guide
JB/T 10559-2006, the industry standard for crane buffers, governs the design, manufacturing, and inspection of buffer systems for lifting appliances. The standard defines the structural types, technical parameters, performance requirements, and test methods for four primary buffer types—spring, hydraulic, polyurethane, and rubber—and applies to the end-of-travel buffering of both the crane travel mechanism and trolley travel on bridge cranes, gantry cranes, and portal cranes.
JB/T 10559-2006 is the industry standard for crane buffers, specifying the classification, technical parameters, and inspection rules for spring, hydraulic, and polyurethane buffers. The buffer serves as the final protective device that prevents a crane from impacting the rail end stop.
Buffer Types and Working Principles
JB/T 10559-2006 categorizes buffers into four types based on working principle and material: Spring buffers absorb impact energy through elastic deformation of a helical spring. They offer a simple design, are unaffected by temperature, and provide low restoring force (the spring recovers slowly after compression). They are suitable for standard bridge cranes with travel speeds up to 1.5 m/s. Typical buffer stroke ranges from 100 to 600 mm, and the buffer force is proportional to compression (linear characteristic). Hydraulic buffers dissipate energy through the damping action of hydraulic oil passing through an orifice. They provide high energy absorption, smooth braking, and a nearly constant buffer force (non-linear characteristic), making them ideal for applications with higher travel speeds (>1.5 m/s) or where low impact forces are required.
Hydraulic buffers are available in piston-type and plunger-type configurations. Polyurethane buffers absorb energy through the non-linear compressive deformation of polyurethane elastomer. They feature a compact structure, light weight, easy installation, and excellent weather resistance, making them the most widely used buffer type today. Rubber buffers absorb energy through elastic deformation of rubber material. They offer the simplest construction and lowest cost, but their energy absorption capacity is limited and performance is temperature-sensitive. They are suitable only for small cranes with travel speeds up to 0.7 m/s.
Technical Parameters and Selection
The standard defines the core selection parameters for buffers: Rated absorption energy—the maximum impact kinetic energy the buffer must absorb over its rated stroke, expressed in kJ. This value is calculated based on crane mass, travel speed, and braking deceleration. Rated buffer stroke—the distance the buffer travels from its free state to full compression, expressed in mm. Rated buffer force—the maximum reaction force generated at the end of the rated stroke, expressed in kN.
The standard requires that the crane end stop (buffer mounting base) withstand 1.5 times the rated buffer force without permanent deformation. The selection calculation formula is: E = 0.5 × m × v² × η (where E is the required energy absorption, m is the crane (or trolley) mass, v is the impact velocity (typically taken as 70%–85% of rated operating speed), and η is the kinetic energy correction factor (generally 1.0–1.25)). The buffer's rated absorption energy must be no less than 1.25 times the calculated energy—this is the safety margin.
Kelude cranes come standard with polyurethane buffers. Hydraulic buffers can be supplied on request to meet the buffering requirements of high-speed applications.
Linear buffer force
Near-constant force
Excellent weather resistance
Lowest cost
calculated energy
rated buffer force
Buffer Installation and Layout
The standard sets out the following principles for buffer installation and layout: Installation quantity—at least two buffers must be installed on each crane rail (one at each end of the crane). For bridge cranes with a span of 30 m or more, two buffers at each end (four in total) are recommended to reduce eccentric loading during a one-sided impact. Installation height—the buffer centerline must align with the top of the crane rail (or the impact height of the stop center), with a deviation of no more than ±10 mm, to prevent angular impacts that could damage the buffer. Mounting base—the buffer must be mounted on a sturdy structural component capable of withstanding the impact force and impact load.
Buffers at both ends must contact the end stop simultaneously (one-side-first contact is not permitted), as uneven contact creates a turning moment that can cause wheel flange wear or derailment. The contact surfaces between the buffer and the end stop must be flat and perpendicular; if contact is uneven, the stop face must be adjusted. When buffers are used on the trolley, one buffer is installed at each end of the trolley, positioned on the centerline of the trolley rail.
The standard also recommends installing a limit switch near the buffer. When the buffer is compressed to 75% of its rated stroke, the limit switch should cut off power to the travel mechanism, providing both electrical and mechanical protection.
Inspection and Performance Testing
The inspection items specified in the standard include: Visual inspection—the buffer's external surface must be free of cracks, bubbles, shrinkage cavities, and flash. Dimensional inspection—the buffer's mounting dimensions must conform to the drawings, with a tolerance grade of no lower than IT14. Static compression test—the buffer is subjected to 1.5 times its rated buffer force for 5 minutes. After unloading, the buffer must show no permanent deformation or damage (spring buffers must show no residual deformation; polyurethane and rubber buffers must have residual deformation of no more than 3%).
Impact test—the buffer is mounted on a test bench and struck at 1.1 times the rated operating speed. The buffer stroke and buffer force curve are measured, and the buffer must show no damage. Temperature test—polyurethane and rubber buffers must be conditioned at −20 °C and +50 °C for 4 hours before undergoing the static compression test, and must still meet performance requirements. Fatigue test—the buffer is compressed and released 1,000 times at 75% of its rated stroke. Performance changes are then evaluated (for polyurethane and rubber buffers, the buffer force attenuation after fatigue testing must not exceed 15%).
Buffer Maintenance and Replacement
The maintenance points recommended by the standard are: Spring buffers—periodically check the spring for permanent deformation or fatigue fracture (replace if the free length has shortened by more than 5%), and check for severe corrosion on the spring surface (replace if pitting deeper than 0.5 mm is found). Hydraulic buffers—check for hydraulic oil leaks and verify that the oil level meets requirements. Over extended service, the seals in hydraulic buffers will age and fail, causing oil seepage. If seepage is detected, replace the seals or the entire buffer immediately.
Polyurethane buffers — inspect the elastomer surface for cracks (fine surface crazing does not affect performance, but any split deeper than 3 mm requires replacement). Prolonged exposure to UV light causes polyurethane to harden, lose elasticity, and age prematurely; for outdoor installations, we recommend replacing polyurethane buffers every 2–3 years. Rubber buffers — in oily or greasy environments, rubber swells or softens rapidly; replace immediately if the rubber becomes soft, tacky, or shows surface blistering. Any buffer that develops cracks, fractures, permanent deformation, or visible aging during service must be replaced immediately — a failed buffer allows the crane to strike the end stop at full speed, which in severe cases can cause the crane to derail or sustain structural damage.
| Parameter | Spring buffer | Hydraulic buffer | Polyurethane buffer | Rubber buffer |
|---|---|---|---|---|
| Buffer Characteristics | Linear Progressive | Approximately Constant Force | Non-linear | Non-linear |
| Maximumspeed | ≤1.5m/s | >1.5m/s | ≤2.0m/s | ≤0.7m/s |
| Energy Density | Low | High | Medium | Low |
| Temperature Effect | None | ≥-20°C | -30~+80°C | -10~+60°C |
| maintenance Requirement | Low(Inspection Spring) | Medium(Replacement Sealing) | Low | Low |
| Service Life | 5~8Years | 3~5Years | 2~3Years | 1~2Years |
Buffer FAQ: Selection, Installation & Maintenance
Q: Why does a spring buffer produce rebound force?
A: The rebound force occurs when the spring releases the impact energy it stored during compression. For cranes with a travel speed exceeding 50 m/min, a hydraulic buffer is recommended over a spring buffer. Hydraulic buffers absorb energy through oil throttling, producing no rebound force while delivering smooth, high-capacity energy absorption.
Q: What should be considered for hydraulic buffers in low-temperature environments?
A: Below -20°C, use low-temperature hydraulic oil (L-HV32) and run the buffer through a warm-up cycle before operation to raise the oil temperature. Check the oil level and condition every six months. Kelude offers Low-Temperature Type hydraulic buffers that ensure reliable operation down to -30°C.
Q: What is the allowable shaft alignment deviation for buffer installation?
A: The deviation between the buffer centerline and the bumper plate centerline must not exceed 10 mm, and the stroke difference between two buffers on the same side must not exceed 5 mm. Perform an inspection quarterly. To verify alignment, coat the bumper plate with red lead powder and perform a low-speed impact — the contact pattern will indicate the alignment condition.
Q: How often should polyurethane buffers be replaced?
A: Replace them when cracking, permanent deformation, or a noticeable loss of elasticity is observed. The typical service life is 2 to 3 years. All buffers should undergo a functional test monthly — a low-speed impact to confirm proper compression and reset.
