JB/T 1307-2012 Electric Single-Girder Suspension Crane Standard
Product Classification & Technical Parameters
JB/T 1307-2012 applies to electric single-girder suspension cranes that operate on the lower flange of an I-beam rail. The underslung crane is mounted directly to the lower flange of the factory roof truss or runway beam, eliminating the need for independent runway columns and thereby saving valuable floor space. The rated lifting capacity ranges from 0.5t, 1t, 2t, 3t, to 5t, with spans from 3 to 12 meters.
Lifting speed is 8 m/min (single-speed) or 8/0.8 m/min (two-speed), and travel speed is 20/5 m/min (two-speed). The crane runs on an I-beam rail (I20a–I45a) welded to the factory roof structure, with a levelness deviation of ≤1/1000.
Technical Requirements & Safety Devices
The standard specifies structural requirements for the main girder, which is fabricated from an I-beam or a built-up I-section, with the lower flange serving as the runway for the electric hoist trolley. The main girder is designed with a camber of S/1000 to S/500. End carriages are connected to the main girder using high-strength bolts. The crane travel mechanism employs a three-in-one gear reducer, with the drive wheels directly driven by the reducer output shaft.
Wheel materials are ZG310-570 cast steel or 65Mn forged steel, with tread surfaces hardened by quenching to HB300–380. Safety devices include a lifting capacity limiter (which automatically cuts off hoisting when the load exceeds 110% of the rated capacity), a lifting height limit switch, crane travel limit switches, and buffers. The control voltage is safety extra-low voltage of 36V or 48V. The standard sets out specific requirements for the structural components of electric single-girder suspension cranes.
The main girder is made of an I-beam (I20a–I45a) or a built-up I-section, with the lower flange acting as the running surface for the electric hoist trolley. The main girder must have a camber of S/1000 to S/500 under no-load conditions to ensure that deflection under rated load remains within acceptable limits. End carriages are of welded structural steel and are bolted to the main girder with high-strength bolts.
The standard requires that the mid-span deflection of the main girder under rated load not exceed 1/400 of the span, which is critical to ensuring smooth hoist travel and positioning accuracy. The crane travel mechanism must use a three-in-one gear reducer (integrating motor, reducer, and brake) mounted on the end carriage. Drive wheels are driven directly by the reducer output shaft, while driven wheels are connected to the end carriage via wheel axles.
Wheel materials are ZG310-570 cast steel or 65Mn forged steel, with tread surfaces induction-hardened to HB300–380. Wheel diameter is determined by the rated lifting capacity—Φ100 to Φ200 mm for capacities from 0.5t to 5t.
Safety devices include a lifting capacity limiter (which automatically interrupts hoisting when the load exceeds 110% of the rated capacity), a lifting height limit switch (which automatically stops hoisting when the hook reaches its highest position), crane travel limit switches (which automatically stop the crane at both ends of the rail), and buffers (which absorb impact energy at the rail ends). The control circuit operates at safety extra-low voltage of 36V or 48V.
| Lifting Capacity(t) | Span(m) | I-Beam | Hoist Model | Operation Mode |
|---|---|---|---|---|
| 0.5 | ≤6 | I20a | CD1-05 | Manual/Electric |
| 1 | ≤8 | I25a | CD1-10 | Electric |
| 2 | ≤10 | I28a | CD1-20 | Electric |
| 3 | ≤12 | I32a | CD1-30 | Electric |
| 5 | ≤12 | I45a | CD1-50 | Electric |
Test and Inspection Requirements
Routine factory tests include a no-load test (full travel cycle run at least 5 times), a rated load test (3 cycles each for hoisting and bridge travel), a 1.25× static load test (held for 10 minutes), and an insulation test (insulation resistance ≥1 MΩ). A type test is conducted every 2 years and covers all routine factory test items plus a durability test. In-service comprehensive safety inspections are performed every 6 months. Cranes with a lifting capacity of 3 t or more are subject to regulatory inspection as special equipment.
Factory tests performed according to the standard include a no-load test (full travel cycle run no fewer than 5 times to verify smooth operation), a rated load test (3 cycles each for hoisting and bridge travel), a 1.25× static load test (held for 10 minutes to confirm no permanent deformation), and an insulation test (insulation resistance ≥1 MΩ). The type test, carried out every 2 years, covers all routine factory test items plus a durability test (continuous operation for ≥100 hours to assess the reliability of each mechanism).
In-service comprehensive safety inspections are conducted every 6 months, covering functional tests of safety devices and inspection of main structural components. Cranes with a lifting capacity of 3 t or more are subject to regulatory inspection as special equipment — registration for use must be filed with the special equipment supervisory authority before commissioning or within 30 days after the crane is put into operation. A comprehensive inspection is required every 2 years.
Routine maintenance focuses on checking the tightness of crane rail connection bolts, wear on trolley wheels of the hoist trolley, and the response sensitivity of all limit switches. Kelude Heavy Industry can provide supporting services for underslung cranes according to the standard.
| inspection items | technical requirements | Cycle | Standard |
|---|---|---|---|
| No-Load Test | Full Travel≥5Times | factory | §6.1 |
| rated load | Hoisting / Lifting/Each Operation3Times | factory | §6.2 |
| Static load test | 1.25Times (Multiplier)×10min | Annual | §6.3 |
| insulation test | ≥1MΩ | Semi-Annual | §6.4 |
| safety inspection | thorough examination | Semi-Annual | §7.1 |
FAQ
Q: What is the difference between an Electric Single-Girder Suspension Crane and a standard LD Type crane?
A: An underslung crane is mounted directly to the lower flange of the factory roof truss or runway beam, eliminating the need for independent runway columns and saving valuable floor space. It is applicable to lifting capacities up to 5t and spans up to 12m. The LD Type crane operates on its own dedicated runway rails and supports capacities up to 20t. Suspension cranes are ideal for light-duty hoisting applications, while LD Type cranes are better suited for general-purpose lifting tasks.
Q: What are the rail installation requirements for an underslung crane?
A: The crane rail consists of an I-beam (I20a to I45a) welded to the factory roof structure. Levelness deviation must not exceed 1/1000, and straightness deviation must stay within ±3mm over the full rail length. Joint gaps should be no more than 2mm, with a maximum height difference of 1mm at each joint. The rail system must be properly grounded. The lower flange serves as the running surface for the crane wheels and must be kept clean and free of oil or grease.
Q: What safety devices are fitted on an underslung crane?
A: Standard safety equipment includes a load limiter (cuts power to hoisting at 110% of rated capacity), a hoisting height limit switch, and crane travel limit switches with buffers. Cranes rated at 3t and above are classified as special equipment and subject to regulatory inspection. The control grip operates on low-voltage control (36V or 48V), and remote control operation includes an emergency stop button.
Q: How is the electric hoist mounted on an underslung crane?
A: The electric hoist is mounted on a trolley that travels along the lower flange of the I-beam. The wheel treads sit flush against the lower flange, while side guide rollers prevent lateral sway. Before installation, verify that the I-beam section matches the trolley specifications. Trolley travel should be smooth, with no binding or rail-catching during operation.
