When evaluating the quality of manual hoists (manual cranes) in operation, it is important to focus on four core dimensions: structural safety, operational performance, reliability of core components, and effectiveness of safety protection devices. The following are specific quality risk points and analysis:

1、 Structural safety risks

Welding defects and deformations

Problem manifestation: Structural components (such as frames, cranes, and support legs) have virtual welding, cracks, or deformation after long-term use.

Risk: Causing equipment to break or become unstable during operation, leading to overturning accidents.

Testing method: visually inspect whether the welding points are uniform and free of pores; Use a laser rangefinder to detect the verticality and levelness of structural components.

Material fatigue

Problem manifestation: After high-frequency use, metal components such as chains and hooks may experience microcracks or decreased elasticity.

Risk: The risk of fracture increases exponentially with the number of uses.

Testing method: Magnetic particle inspection to detect surface cracks on the chain; Tensile testing machine tests the tensile strength of the hook.

2、 Operational performance defects

Insufficient sensitivity of the handle

Problem manifestation: There is a jamming and delayed rebound phenomenon in the operating handle.

Risk: Causing unstable lifting actions, leading to cargo swinging or equipment loss of control.

Detection method: Record the time from the maximum stroke of the handle to reset, with a standard of ≤ 0.5 seconds.

Visual obstruction

Problem manifestation: The design of the operation cabin is unreasonable and there are blind spots in the field of vision.

Risk: Failure to observe the surrounding environment in a timely manner increases the risk of collision.

Detection method: Simulate the work scenario and test the operator's recognition distance of ground obstacles.

3、 Reliability of core components

Chain wear exceeds the standard

Problem manifestation: The wear of the chain diameter exceeds 10% of the original size.

Risk: Decreased carrying capacity, prone to breakage.

Testing method: Measure the pitch and diameter of the chain with a caliper and compare them with the factory standard.

Brake system failure

Problem manifestations: brake pad wear, oil contamination, or insufficient spring tension.

Risk: Failure to stop the equipment in a timely manner, resulting in overloading or falling.

Testing method: Conduct a no-load test on the braking distance, with a standard of ≤ 50mm; disassemble and inspect the thickness of the brake pads.

Gearbox oil leakage and abnormal noise

Problem manifestation: Failure of gearbox seal leading to oil leakage or abnormal noise during operation.

Risk: Insufficient lubrication accelerates gear wear, leading to transmission failure.

Testing method: visually inspect whether the oil seal is aging; The decibel meter tests the operating noise (should be ≤ 85dB).

4、 Failure of safety protection device

Limit device malfunction

Problem manifestation: The up/down limiter fails and cannot automatically stop.

Risk: Causing the chain to over roll or the equipment to overturn.

Detection method: Simulate over limit operation and test the accuracy of triggering the limiter.

The safety rope is broken

Problem manifestation: The safety rope material is aging or the connection is loose.

Risk: Operator falling risk.

Testing method: Tensile test to test the breaking force of the safety rope (should be ≥ 22kN).

Warning signs are missing

Problem manifestation: No warning signs such as maximum load capacity and operating taboos have been set up.

Risk: Accidents caused by operator misoperation.

Testing method: Check whether the equipment is labeled with the warning symbol specified in GB/T 191-2008.

5、 Maintenance defects

Insufficient lubrication

Problem manifestation: Components such as gears and bearings lack regular lubrication.

Risk: Increased wear and tear, shortened equipment lifespan.

Testing method: Check whether the lubrication point is dry and whether the oil quality has deteriorated.

bolt loosening

Problem manifestation: The structural connection bolts are not tightened regularly.

Risk: Causing component detachment or equipment disassembly.

Testing method: Use a torque wrench to test the tightening torque of key bolts.

6、 Insufficient environmental adaptability

Insufficient ground bearing capacity

Problem manifestation: The ground below the support legs is soft or has potholes.

Risk: Causing equipment to overturn.

Testing method: Use pressure sensors to test the ground bearing capacity (should be ≥ 1.5 times the total weight of the equipment).

Extreme temperature effects

Problem manifestation: Use in environments below -20 ℃ or above 50 ℃.

Risk: Material embrittlement or lubrication failure.

Testing method: Check the temperature range indicated on the equipment nameplate.

The main equipment produced by Hebei Makita: stage electric hoist, electric chian hoist, wire rope electric hoist，Hand chain hoist, lever hoist, pneumatic hoist and other lifting equipment