JB/T 7854-2016 Hydraulic Buffer for Cranes
JB/T 7854-2016 "Hydraulic Buffers for Cranes" is the product standard governing hydraulic buffers used on cranes. The standard defines the structural types, technical parameters, performance requirements, and test methods for hydraulic buffers, and is applicable to hydraulic buffers used for end-of-travel protection on the bridge travel mechanisms of overhead, gantry, and portal cranes.
JB/T 7854-2016 is the product standard for hydraulic buffers on cranes, specifying their classification, technical requirements, test methods, and inspection rules. Hydraulic buffers are critical safety devices mounted at the ends of a crane's travel mechanism. They absorb the kinetic energy generated when the crane impacts the buffer stop, protecting both the crane structure and the rail end from damage.
Buffer Types and Working Principle
JB/T 7854-2016 classifies crane buffers into four types. Spring buffers rely on the compression of coil springs to absorb impact energy; they feature a simple design and low cost, making them suitable for low-speed (≤50 m/min) cranes with small tonnage. Hydraulic buffers dissipate energy through the damping effect created as hydraulic oil is forced through orifices; they offer high energy absorption and smooth braking, making them ideal for medium- to high-speed (≤120 m/min) cranes with large tonnage.
Polyurethane buffers absorb energy through the compressive deformation of a polyurethane elastomer. They are leak-free, maintenance-free, and corrosion-resistant, making them well suited for general-purpose applications on small- and medium-tonnage cranes. Hydraulic-spring combination buffers integrate both hydraulic and spring buffering for maximum energy absorption, designed for very large tonnage and high-speed cranes. The buffer type should be selected based on the crane's working speed, mass, and impact frequency.
Technical Requirements and Performance Parameters
Key performance parameters defined by the standard include: Rated absorbed energy — the maximum energy the buffer can absorb at rated stroke and rated speed (in kJ). Buffer stroke — the displacement of the buffer from initial contact to full compression (in mm). Maximum buffer force — the peak reaction force generated during buffering (in kN), which must not exceed the design load-bearing capacity of the crane structure and the rail foundation.
Reset requirements — after unloading, the buffer must automatically reset under spring force, with a reset time of ≤30 s for hydraulic types. The operating temperature range is -20°C to +80°C. Under rated conditions, the service life of hydraulic buffers must be ≥100,000 cycles, while spring buffers must achieve ≥50,000 cycles. Hydraulic buffers use L-HM32 anti-wear hydraulic oil.
Installation and Commissioning Requirements
Installation requirements specified in the standard: Buffers must be mounted on the impact side of the crane bridge end carriage or on the rail end stop. The buffer axis must align with the direction of impact, with a maximum axis deviation angle of 2°. When two or more buffers are used in parallel, their installation heights must be identical (height difference ≤2 mm) to ensure simultaneous contact with the stop. Mounting bolts must be Grade 8.8 high-strength bolts.
Commissioning requirements: After installation, a no-load impact test must be performed — manually push the crane into the stop at low speed to verify smooth buffer operation and proper reset. Before first use, air must be purged from the hydraulic cylinder of hydraulic buffers (by repeatedly pressing the push rod to expel air bubbles). Kelude offers buffer selection calculation and on-site commissioning services.
Maintenance and Inspection
Routine maintenance: Perform a monthly inspection of the buffer's external condition, checking for oil leaks, push rod damage or corrosion, and proper reset. Every six months, check the hydraulic oil level (top up with L-HM32 hydraulic oil if low) and the condition of seals. Conduct an annual buffering performance test — measure buffer stroke and maximum buffer force at rated impact speed, and compare against factory values with a permissible deviation of ≤±15%.
Replacement criteria: Replace hydraulic buffers when oil leakage cannot be repaired; when the push rod is bent or severely corroded; when buffering performance noticeably degrades (impact force increases by ≥30%); and when spring buffers exhibit permanent deformation or spring fracture. Replace polyurethane buffers when cracking or permanent deformation (residual compression deformation ≥10%) is observed.
Impact Energy
0.5–100 kJ
Configurable
Stroke Range
50–500 mm
Max. Reaction Force
10–500 kN
Reset Method
Spring Reset
Automatic
Operating Temp.
-20°C to +80°C
Service Life
≥100,000 cycles
Kelude Heavy Industry: Overhead & Gantry Crane Solutions
Kelude Heavy Industry specializes in the design, engineering, and manufacturing of heavy-duty overhead cranes, gantry cranes, and electric hoists. Our product range covers a wide spectrum of industrial lifting applications, from single-girder and double-girder bridge cranes to versatile gantry systems and explosion-proof hoists. With a strong focus on safety, performance, and longevity, our equipment is built to meet the rigorous demands of workshops, warehouses, and production lines.
What Are Overhead & Gantry Cranes?
Overhead cranes, also known as bridge cranes, feature a movable bridge carrying a hoist that travels along rails mounted on the building's load-bearing walls or columns. This design allows for efficient lifting and horizontal movement of heavy loads within a defined rectangular area. Gantry cranes, in contrast, are supported on legs running on ground rails, making them ideal for outdoor yards, storage areas, and sites where a building structure cannot support an overhead runway.
Both crane types are essential for optimizing material flow, reducing manual handling, and improving workplace safety. They are available in various configurations, including single-girder, double-girder, and specialized designs like low-headroom or explosion-proof models, to suit specific operational needs.
Q: What is the difference between an overhead crane and a gantry crane?A: An overhead crane runs on overhead runways mounted to the building structure, while a gantry crane is supported by legs that travel on ground rails. Gantry cranes are often used outdoors or where building support is unavailable.
Q: How do I determine the right capacity for my crane?
A: You need to consider the heaviest load you will lift, including the weight of any lifting attachments. It's recommended to add a safety margin to account for dynamic loads and future needs. Our engineers can assist you in calculating the appropriate capacity.
Q: Can you provide cranes for explosion-proof environments?
A: Yes, we offer explosion-proof crane systems designed for hazardous areas. These cranes feature specialized electrical components and materials that prevent ignition, complying with relevant safety standards.
Q: What is the typical lead time for a custom crane?
A: Lead times vary depending on the complexity and specifications of the crane. Standard models may be available in a few weeks, while custom-engineered solutions typically take 8-16 weeks from design approval to delivery.
Q: Do you offer installation and training services?
A: Absolutely. We provide full installation services by our qualified technicians, along with comprehensive operator and maintenance training to ensure safe and efficient use of the equipment.
Q: What kind of after-sales support do you provide?
A: We offer extensive after-sales support, including spare parts availability, maintenance contracts, and technical assistance via phone or on-site visits. Our goal is to ensure your crane operates reliably throughout its lifespan.
Contact Kelude Heavy Industry
A: Ready to enhance your material handling capabilities? Contact our team today to discuss your requirements and receive a tailored solution. We look forward to partnering with you.
| Type | working principle | Features | Applications |
|---|---|---|---|
| Spring buffer | Spring Compression Energy Absorption | Simple Structure, Low Cost | Low Speed, Small Capacity |
| Hydraulic buffer | Hydraulic Oil Throttling Compression Energy Absorption | High Energy Absorption, Smooth Operation | Medium-High Speed, large tonnage |
| Polyurethane buffer | Elasticity Volumetric Compression Energy Absorption | Leak-Free, Maintenance-Freemaintenance | Universal for Small-Medium Capacity |
| Hydraulic Spring Composite | Hydraulic+Spring Combined | Maximum Energy Absorption | Speciallarge tonnage |
Hydraulic Buffer FAQ: Working Principle, Selection & Maintenance
Q: How does a hydraulic buffer work?
A: A hydraulic buffer consists of a cylinder body, piston, hydraulic oil, and a return spring. Upon impact, the piston rod is compressed, forcing hydraulic oil through the orifice from the high-pressure chamber into the low-pressure chamber. This converts kinetic energy into heat, which is then dissipated. Once the impact ends, the return spring pushes the piston back to its initial position. The orifice is designed to keep the buffer force nearly constant throughout the stroke, ensuring smooth deceleration.
Q: What factors determine hydraulic buffer selection?
A: Selection is based on the following: impact mass (total crane weight + rated load), impact speed (typically 70%–100% of Long Travel Speed), buffer stroke (determined by available installation space), and impact frequency (number of impacts per hour). Standards require that the buffer absorb total energy at maximum impact speed equal to or greater than the impact kinetic energy multiplied by a safety factor of 1.25.
Q: What are the installation requirements for hydraulic buffers?
A: Buffers should be mounted on the crane bridge end carriage (impact side) or on the rail end stop. The buffer axis must align with the direction of impact (misalignment angle ≤ 2°). When two or more buffers are used in parallel, they must contact the buffer stop simultaneously. After installation, the piston rod should extend and retract freely without sticking, and the return action should operate normally.
Q: How should hydraulic buffers be maintained and when should they be replaced?
A: Perform a monthly inspection to check for oil leaks, piston rod damage or corrosion, and proper return action. Check the hydraulic oil level every six months, topping up with L-HM32 Hydraulic Oil as needed. Conduct buffer performance testing annually. Replacement is required when: leaks cannot be repaired, the piston rod is bent or severely corroded, or buffer performance noticeably degrades (resulting in increased impact force).
