The allocation of usage time for lever chain cranes should be based on equipment characteristics, load conditions, safety regulations, and maintenance cycles, and follow the principles of "scientific planning, dynamic adjustment, and safety priority". The specific strategies are as follows:

1、 Basic time allocation framework

Single continuous use duration

Standard scenario: A single continuous operation should not exceed 2 hours to avoid performance degradation or malfunction of the chain and braking system due to overheating; When the load is high (≥ 75% of the rated load), the single use time is shortened to 1 hour and cooled with a 15 minute interval.

Special scenarios: such as high temperature, humidity, or corrosive environments, the single use time needs to be further shortened (such as 30 minutes), and the cooling and inspection frequency needs to be increased; Preheat the equipment in low temperature environments (<5 ℃) to avoid cold brittle fracture.

Total daily usage time

Routine homework: The total daily usage time should not exceed 8 hours to avoid excessive equipment fatigue; When working in multiple shifts, it is necessary to arrange equipment maintenance and cooling time of more than 2 hours.

High intensity operations, such as construction sites, port loading and unloading, require rotating multiple equipment or increasing rest intervals (such as stopping for 1 hour every 4 hours) to reduce equipment wear and tear.

2、 Dynamic adjustment strategy

Load driven adjustment

Light load (<50% rated load): The single use time can be appropriately extended (such as 3 hours), but the chain temperature, braking performance, and structural tightness need to be checked every 2 hours.

Heavy load (≥ 75% rated load): Strictly limit the single use time and add a brief shutdown check every 30 minutes (such as chain tension and hook stability).

Overload (>rated load): Do not use, immediately stop the machine and investigate the cause; If temporary overloading is required, it needs to be evaluated by professional engineers and strengthened measures should be taken (such as adding support structures and using double machine lifting).

Environment driven adjustment

High temperature environment (>35 ℃): Reduce the single use time to 1 hour and add cooling fans or shading measures; Check the condition of hydraulic oil and lubricating grease every 2 hours to avoid oxidation failure.

Low temperature environment (<5 ℃): Preheat the equipment (such as electric heating blanket wrapped around the chain) before starting to avoid cold brittle fracture; Maintain a constant speed during operation to avoid sudden pulling or stopping that may cause impact loads.

Wet/Corrosive Environment: Use rust proof grease and increase equipment cleaning frequency (such as wiping chains and hooks after each shift) to avoid corrosion affecting performance.

3、 Embedding maintenance and repair time

Daily maintenance time

After each shift: check chain wear, brake clearance, and structural tightness; Clean the surface of the equipment and lubricate rotating parts (such as chains and bearings); Record device status data (such as temperature, vibration values).

Before the end of each day: Conduct a 15 minute comprehensive inspection, including electrical system insulation testing, hydraulic system oil level inspection, and functional verification of safety devices (such as overload protection and limiters).

Regular maintenance schedule

Weekly: Conduct a 1-hour in-depth inspection, including chain fatigue crack detection (such as magnetic particle inspection), brake friction plate wear measurement, and structural weld non-destructive testing (such as ultrasonic testing).

Monthly: Conduct 4-hour comprehensive maintenance, including changing lubricating grease, adjusting brake clearance, checking hydraulic system sealing, and testing safety device sensitivity.

Annual overhaul: Conduct comprehensive disassembly and maintenance for more than 8 hours, including chain replacement, gearbox cleaning, electrical system upgrade, and structural anti-corrosion treatment; After major repairs, a static load test with a rated load of 125% is required to ensure the recovery of equipment performance.

4、 Reserve safety and emergency time

Safe buffer time

Before operation: Reserve 15 minutes for equipment preheating, environmental inspection, load assessment, and safety device verification.

During operation: reserve 5 minutes every hour for brief shutdown checks (such as chain temperature and braking performance); High risk operations such as high-altitude lifting and heavy loads require increased inspection frequency.

After operation: Reserve 10 minutes for equipment cooling, cleaning, status recording, and safety device reset.

Emergency response time

Fault shutdown: When abnormalities are detected (such as chain jamming or brake failure), immediately shut down and initiate a 15 minute emergency inspection process to investigate the cause of the fault; If on-site resolution is not possible, it is necessary to call for backup equipment or contact a professional maintenance team.

Accident handling: In the event of a safety accident (such as a falling object or equipment collapse), immediately initiate a 30 minute emergency response procedure, including personnel evacuation, on-site blockade, accident reporting, and preliminary rescue; Detailed accident investigation and rectification must be carried out for at least 24 hours in the future.

5、 Industry Cases and Best Practices

Construction site: adopting a "three ship exchange system", with each shift lasting no more than 6 hours, and 2 hours of equipment maintenance and personnel rest arranged in between; During high load operations, use dual machines to lift and distribute the load to below 75%.

Warehouse logistics: Adopting a "short-term high-frequency" mode, with a single usage time not exceeding 1 hour and a total daily usage time not exceeding 6 hours; Cooperate with automation systems (such as AGV) to achieve precise positioning and rapid turnover.

Energy facilities: In scenarios such as wind farms and power towers, modular time allocation is adopted to adjust usage time based on operational stages (such as blade lifting and tower assembly), and safety buffers and emergency response times are embedded.

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