Low-clearance chain-type electric hoists are compact, lightweight lifting devices that are smaller in size and lighter in weight than wire-rope electric hoists, making them widely used in industrial settings such as factories, docks, and warehouses. Compared with wire-rope electric hoists, low-clearance chain-type electric hoists feature a simpler structure, easier installation, higher reliability, and a broader range of applications. These hoists represent an optimized design that builds upon the manually operated chain hoists and wire-rope electric hoists, resulting in the LCK and LCR series of lightweight chain-driven electric hoists that are even more portable and practical. A key distinguishing feature of this optimized design is its rational structural configuration and excellent stability.

1. The low-headroom chain-type electric hoist is developed by upgrading and modifying imported chain-type electric hoists from overseas. This new type of electric hoist primarily features the following characteristics:

1.1. Disc-brake motor, replacing the manual chain and brake components, offering sensitive, precise, and reliable braking.

1.2. A planetary gear reducer is used to reduce speed and increase torque; it features a high transmission ratio, compact size, light weight, and stable, reliable performance.

1.3. A torque limiter is employed to prevent overloading, protect the disc-type motor and transmission system from damage, and ensure the crane’s stability and reliability.

1.4. Enhancing the Structure and Product Varieties of Chain Electric Hoists

A chain-type electric hoist consists of an electric motor, a transmission mechanism, and sprockets. Unlike wire-rope electric hoists, it replaces the wire rope with a chain, thereby overcoming the latter’s drawbacks of large size and heavy weight. Its rated lifting capacity typically ranges from 0.5 to 35 tonnes, with a lifting height of 3 to 120 meters.

2. Structural Design of Low-Space-Requirement Electric Chain Hoists

2.1. Transmission System Design

The main transmission structure of the LCR series chain-driven hoist comprises the following components.

1) Motor: Equipped with a thermal protection device to prevent the motor from burning due to overheating.

2) Braking: Equipped with mechanical brakes using copper-asbestos-based friction materials, the brake can stably support the load once the motor has stopped.

3) Reducer: Used to reduce rotational speed, increase torque, and transmit power.

4) Limit switches: Use upper and lower electronic limit switches to prevent the chain from becoming overly tight.

5) Torque limiter: Allows the motor to idle in the event of overload or excessive tightening, thereby preventing damage to the motor and the mechanical transmission system caused by overload or over-rotation.

6) Hooks and Chains: The hooks are forged from alloy steel and undergo a rigorous heat-treatment process, ensuring they will not fracture under overload and will open gradually. The chains, after heat treatment, exhibit excellent wear resistance, corrosion resistance, and long service life.

2.2. Geometric Parameter Design of Gear Drives

Geometric Parameter Design of Gourd-Body Gear Transmission

Low-headroom electric chain hoists typically employ helical gears to ensure reliability, minimize meshing-induced impacts and vibration, and thereby extend service life. The gears’ specialized design enhances durability, and they are manufactured from alloy steel that undergoes micro-heat treatment to achieve higher strength.