Conceptual analysis framework for chain hoist (manual hoist)

1. Definition and core functions

Essential attribute: Chain crane is a light and small lifting equipment that uses manual pulling of the chain to drive the gear transmission system, achieving vertical lifting or horizontal movement of heavy objects. It belongs to the category of manual lifting machinery.

Functional positioning: mainly used in scenarios without power supply or requiring flexible operation (such as factories, warehouses, construction sites, ship maintenance, etc.), undertaking tasks such as cargo loading and unloading, equipment installation, maintenance lifting, etc. The rated load is usually between 0.5 tons and 20 tons, and the lifting height generally does not exceed 6 meters.

2. Structural composition and working principle

Core components:

Chain system: including lifting chains (load-bearing chains) and hand zippers (driving chains), made of high-strength alloy steel (such as 20Mn2, 25MnV) that has been heat-treated and surface galvanized/chrome treated. The diameter and pitch design of the chain links need to balance strength and flexibility.

Gearbox: It includes planetary gears, ratchet and pawl mechanisms, and brakes (such as friction plate brakes) to achieve the transmission and self-locking function of the chain.

Hooks and connectors: The upper and lower hooks should be equipped with anti detachment devices, and the connecting pins should be made of high-strength materials and securely fixed.

Shell and handle: The shell protects the internal mechanism, and the handle is used for manual operation. Some models are equipped with explosion-proof handles.

Working principle: Pull the hand zipper to drive the planetary gears inside the gearbox to rotate, and drive the lifting chain to move vertically through the sprocket; The brake automatically locks when it stops pulling, preventing heavy objects from sliding down; The ratchet and pawl mechanism ensures one-way transmission and avoids reverse sliding.

3. Classification and standard system

By driving mode: manual hoist (pull/pull), electric hoist, pneumatic hoist, hydraulic hoist.

According to the chain structure: single chain (lightweight), double chain (high load), multi chain (special scenario).

By application scenario: industrial grade (factory/warehouse), building grade (construction site), ship grade (marine anti-corrosion), explosion-proof type (flammable and explosive environment).

Standard certification: Adhere to international standards such as ISO 3077, EN 818, AS 2321, as well as domestic regulations such as GB/T 10054.1-2021 and TSG 51-2023 "Safety Technical Regulations for Cranes". It is necessary to pass safety certification (such as CE, CCC) and indicate the rated load and safety factor (usually 4-6 times).

4. Performance influencing factors

Materials and processes: Chain material (such as 100 grade alloy steel), heat treatment process (quenching+tempering), surface treatment (galvanizing/electroplating hard chromium), welding quality directly affects tensile strength, wear resistance, and corrosion resistance.

Design parameters: chain ring diameter, pitch, number of sprocket teeth, gear module, brake friction coefficient, etc. need to be optimized through mechanical calculations to ensure load-bearing capacity and safety redundancy.

Environmental adaptability: Temperature (-25 ℃ to+40 ℃), humidity (≤ 85%), corrosive gases/liquids, dust, ultraviolet rays and other environmental factors affect the fatigue life and surface protection effect of metals.

Operation and maintenance: Improper operations such as overloading, diagonal pulling, emergency stop and start, and impact loads accelerate chain wear; Regular lubrication, cleaning, crack detection, and static/dynamic load testing are key to extending the lifespan.

5. Analysis of advantages and disadvantages

Advantage:

Portable and flexible, no need for power supply, suitable for narrow spaces or temporary operations.

Simple structure, low maintenance cost, and low threshold for operation training.

High safety factor (through brake self-locking and ratchet mechanism anti slip), in compliance with safety standards in multiple countries.

Limitations:

High labor intensity, slow improvement speed, not suitable for high-frequency or large-scale operations.

The risk of overloading is high, and it is necessary to strictly comply with the rated load and operating specifications.

The chain is susceptible to environmental corrosion and wear, and requires regular maintenance and replacement.

6. Safety regulations and regulatory requirements

Pre operation inspection: equipment integrity (chains, hooks, brakes), environmental safety (stable support points, no obstacles), load confirmation (no overloading).

Standard operation: Trial lifting confirmation (check stability 10-20cm above the ground), vertical suspension of chains, avoiding diagonal pulling and hard pulling, uniform speed operation, and prohibiting personnel from staying under heavy objects.

Post operation maintenance: clean and lubricate, store in a dry and ventilated environment, conduct regular tests (static/dynamic load), and meet scrap standards (chain wear exceeding 5% or elongation exceeding the standard).

Regulatory basis: TSG 51-2023 specifies the qualifications of renovation units, requirements for supervision and inspection, and principles for calculating rated lifting capacity (such as including detachable lifting equipment in the weight calculation). Mobile operation lifting machinery needs to frequently relocate their work locations.

7. Development Trends and Innovation Directions

Material innovation: Using carbon fiber composite materials or high-strength aluminum alloys to reduce weight and improve corrosion resistance.

Intelligence: Integrate sensors to monitor load, chain tension, and brake status, and achieve remote monitoring and fault warning through the Internet of Things.

Modular design: It can quickly replace components such as chains and hooks to meet different operational needs.

Greening: Using environmentally friendly lubricants and recyclable materials to reduce environmental impact.

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