When operating a manual hoist (manual crane) in a low clearance environment, special attention should be paid to equipment selection, operating standards, safety protection, and environmental adaptability to ensure efficient and safe operation and avoid structural damage. The following is a classification analysis of key precautions:

1、 Equipment selection and configuration

Low clearance dedicated design

Compact structure: Choose a hoist with a low head height and adjustable chain/wire rope travel (such as the German Yale C Series and the Japanese KITO ER2 series), which reduces the body height by 30% to 50% compared to traditional models.

Folding design: using foldable handles or telescopic chain boxes to reduce space occupation in non working states.

Lightweight materials: Aluminum alloy or high-strength plastic shell is preferred to reduce overall weight (such as the TOYO AL-LIGHT series in Japan, which is 40% lighter than steel hoists).

Load and travel matching

Rated load redundancy: The actual load should be less than 80% of the rated load of the hoist (if 500kg needs to be lifted, a 1-ton hoist should be selected).

Effective lifting height: Accurately calculate the sum of clearance height (ground to obstacle distance) and load height, and choose a model with a chain/wire rope travel slightly greater than this value (for example, when the clearance is 3 meters, use a 3.5-meter travel hoist).

Travel extension plan: If the travel of a single hoist is insufficient, multi-stage hoist series connection or pulley group doubling travel can be used (note that the efficiency loss is about 10%~15%).

Safety device verification

Overload protection: Confirm the sensitivity of mechanical overload clutch or electronic load limiter (error ≤± 5%).

Braking system: Test the ratchet pawl brake driven by the bracelet to ensure that the displacement is ≤ 2mm within 5 minutes when fully loaded and stationary.

Limit device: Install a travel limit switch to prevent the chain/wire rope from derailing beyond the travel limit (such as the German JDN PROFI-TI series with built-in double limit).

2、 Operating standards and procedures

Pre inspection and debugging

Appearance inspection: Focus on checking the wear of the chain/wire rope (replacement is required if the diameter decreases by ≥ 7%), and the deformation of the hook (scrap if the opening degree increases by ≥ 15% or the torsion is ≥ 10 °).

No load test run: Operate forward and reverse three times each to confirm no abnormal noise, jamming, or brake failure.

Load test lifting: Lift 50% of the rated load 100mm off the ground and let it stand for 10 minutes to check the settlement (≤ 5mm is qualified).

Lifting path planning

3D space scanning: Use a laser rangefinder or BIM model to confirm the distribution of obstacles (such as beams and pipelines) in the lifting path, and mark the minimum clearance coordinate points.

Dynamic obstacle avoidance strategy:

Vertical obstacle avoidance: Adopt inclined lifting (angle ≤ 5 °) or segmented lifting (adjust position by translation after each lifting).

Horizontal obstacle avoidance: Use steerable suspension points (such as universal swivel rings) or track type hoists (such as the German STAHL CraneSystems SH EX series).

Emergency channel reservation: Ensure that there is an operating space of ≥ 0.5m around the lifted object for easy intervention in emergency situations.

Collaborative homework requirements

Unified signal: Use standard gestures and walkie talkie double confirmation, with a command transmission delay of ≤ 1 second.

Partition operation: Designate a dedicated person to monitor the status of the hoist body, lifting points, and loads, and prohibit cross operation.

Load stability control:

Rigid load: Use anti sway devices (such as hydraulic dampers) to limit the swing amplitude within ± 2 °.

Flexible load: Adopting double point lifting (spacing ≥ 1/3 of the load length) and pre tensioning balance.

3、 Security Protection and Emergency Response

Personal Protective Equipment (PPE)

Head protection: Wear an impact resistant helmet (EN 12492 standard, lateral deformation ≤ 40mm).

Hand protection: Use cut resistant gloves (EN 388 standard, cutting resistance level ≥ 3).

Fall protection: When the working height is ≥ 2m, fasten a double hook safety belt (load-bearing ≥ 15kN) to an independent anchor point.

Environmental risk control

Temperature management:

Low temperature environment (below -20 ℃): Select low-temperature steel chains (such as ASTM A341 Class D) and preheat the hoist to above 10 ℃.

High temperature environment (≥ 60 ℃): Increase the viscosity of the lubricating grease (such as using lithium based No.2 grease) and shorten the inspection cycle to once a week.

Corrosion protection:

Acid alkali environment: The surface of the gourd is coated with polytetrafluoroethylene coating (thickness ≥ 50 μ m).

Salt spray environment: Use 316L stainless steel components and clean corroded areas monthly.

Dust protection: On the basis of IP54 protection level, install a positive pressure dust cover (filtration efficiency ≥ 99.97%).

Emergency plan

Mechanical failure: Equipped with a spare hoist (of the same specifications) and quick replacement tools (such as hydraulic chain disassemblers).

Load loss control: Set up a safety rope interception net (with a load capacity of ≥ 5 times the load) below the lifting path.

Trapped personnel: Install escape routes (such as foldable aluminum alloy ladders) and emergency communication equipment (explosion-proof intercoms).

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