Operational skills of bridge crane from novice to expert

What are the operational skills required to transition from a novice to an expert in operating bridge cranes? Let's find out together with the editor from the bridge crane manufacturer.

From novice to expert, operating a bridge crane involves five stages: mastering basic specifications, training precise control, handling complex scenarios, enhancing efficiency, and internalizing safety culture. Through systematic training and experience accumulation, operational efficiency can be improved by 30%-50%, and the accident rate can be reduced by over 80%. Below are the phased operational tips and key points:

1. Novice stage: basic norms and safety bottom line

"Three checks" before operation

Equipment inspection: Confirm the status of key components such as brakes (brake pad wear ≤50%), steel wire ropes (number of broken wires ≤10% of total wires), limiters (sensitivity error of upper and lower limits ≤5mm), and tracks (levelness deviation ≤1/1000).

Environmental inspection: Observe that there are no obstacles (such as pipes, beams) above the work area, no water on the ground (anti-slip), and no personnel staying (safety distance ≥3m).

Load inspection: Check the weight of the lifted object (not to exceed 90% of the rated load), shape (if the length-to-width ratio is greater than 3:1, a balance beam should be added), and center position (if the center deviation exceeds 10%, the lifting point needs to be adjusted).

"Four slow" principle for basic operations

Slow startup: When lifting the main hook, first perform a trial lifting (height ≤ 0.5m) to confirm the reliability of the brake, and then slowly lift it (speed ≤ 0.5m/s).

Slow amplitude change: When the crane/trolley is 1m away from the end point, slow down to 0.2m/s in advance to avoid impacting the limiter (the impact force can increase the damage rate of the limiter by 3 times).

Slow rotation: When starting and stopping the slewing mechanism, the "inching-slow stopping" mode is adopted (each inching time ≤2s) to prevent the load from swinging (if the swinging amplitude exceeds 0.5m, readjustment is required).

Slow landing: When the lifted object is 0.5m above the ground, pause to observe whether the ground supports (such as wooden beams and pads) are stable. After confirming that everything is correct, slowly lower the object to the ground (at a speed of ≤0.3m/s).

"Three-step method" for emergency response

Power off: In case of emergencies (such as wire rope breakage or brake failure), immediately press the emergency stop button (response time ≤ 0.1s).

Warning: Activate the audible and visual alarm device (volume ≥ 85dB) and keep it sounding for more than 30 seconds to remind nearby personnel to evacuate.

Isolation: Set up a warning line (height ≥1.2m) around the crane, and prohibit unauthorized personnel from entering the danger zone (radius ≥1.5 times the height of the lifted object).

II. Advanced Stage: Precise Control and Efficiency Enhancement

Micro-motion operation skills

Handle control: Adopting the "touch-hold-release" mode, micro-speed movement of 0.1m/s is achieved by adjusting the handle opening (10%-30%) (e.g., when precision assembly is required, the positioning error of the lifted object should be controlled within ±2mm).

Pulse control: For variable frequency speed regulation cranes, pulse signals (with a frequency of 5-20Hz) are utilized to achieve stepless speed regulation, reducing mechanical impact (with impact force reduced by 60%).

Coordinated operation: When operating the three mechanisms of the main hook, crane, and trolley simultaneously, the "main hook priority" strategy is adopted (first stabilize the height of the main hook, then adjust the horizontal position) to avoid swinging of the lifted object.

Load control technique

Dynamic balance: When lifting long objects (such as steel beams), adjust the lengths of the steel wire ropes at the two lifting points (with a length difference of ≤50mm) to ensure that the horizontal deviation of the lifted object is ≤1° (otherwise, it is prone to tipping).

Inertia compensation: When braking the crane/trolley, release the handle 0.5-1s in advance to utilize mechanical inertia to achieve a smooth stop (reducing the braking distance by 30%).

Wind load response: During outdoor operations, lifting should be stopped when the wind speed is ≥ level 6 (10.8-13.8m/s). When the wind speed is < level 6, the impact of wind force can be resisted by adjusting the center of gravity of the lifted object (lowering the center of gravity by 0.5m) and reducing the operating speed by 50%.

Multi-machine collaboration skills

Signal synchronization: During dual-crane lifting, unified command is provided through wireless intercoms (dedicated channels) or hand signals (international ISO standard) to ensure that the speed difference between the two cranes during lifting/lowering is ≤0.1m/s.

Load distribution: According to the rated load of the crane (e.g., crane A with a capacity of 50t and crane B with a capacity of 30t), the load is distributed proportionally (crane A bears 60% and crane B bears 40%), to avoid overload of a single crane.

Space avoidance: When multiple cranes are operating in a cross-directional manner, maintain a horizontal spacing of ≥3m and a vertical spacing of ≥5m to prevent collisions (the collision energy can reach 10kJ, which is sufficient to damage structural components).

III. Expert Stage: Complex Scenarios and Fault Prediction

Operation under special working conditions

High-temperature environment: In high-temperature areas such as steel mills (temperature > 50°C), regularly inspect steel wire ropes (apply high-temperature lubricating grease every 2 hours) and brakes (cool down every 4 hours) to prevent performance degradation caused by thermal aging.

Corrosive environment: In corrosive environments such as chemical workshops (pH value < 4 or > 9), stainless steel wire ropes (made of 316L material) and anti-corrosion coatings (epoxy resin) are used to extend equipment life (the lifespan of ordinary steel wire ropes is reduced by 50%).

Narrow space: In narrow areas such as ship cabins and tunnels (with a clear height of less than 5m and a clear width of less than 3m), the "low speed + multiple fine adjustments" strategy (with a speed of ≤0.3m/s) is adopted, assisted by laser range finders (with an accuracy of ±1mm) for positioning.

Fault prediction and troubleshooting

Abnormal noise identification: Determine the fault location by listening to the brake friction sound (normally "rustling" sound, abnormally "clunking" sound) and the steel wire rope sliding sound (normally silent, abnormally "squeaking" sound).

Vibration analysis: Monitor the motor vibration value (normal ≤ 4.5mm/s, abnormal > 7.1mm/s) using a vibration sensor (frequency range 10-1000Hz) to detect bearing wear or coupling looseness in advance.

Temperature monitoring: Use an infrared thermometer (accuracy ±2℃) to detect the surface temperature of the brake wheel (normal ≤100℃, abnormal >150℃) to prevent brake failure.

Energy-saving optimization techniques

Regenerative braking utilization: For variable frequency speed regulating cranes, enabling the regenerative braking function (which feeds back the braking energy to the grid) can reduce energy consumption by 20%-30%.

Light-load high-speed mode: When lifting light loads (less than 30% of the rated load), switch to high-speed gear (speed increased by 50%), thereby shortening the operation cycle (single cycle time reduced by 20%).

No-load low-speed mode: During no-load operation, the low-speed gear (speed ≤ 0.5 m/s) is used to reduce mechanical wear (wear amount reduced by 40%).