I. Basic Concept
A screw crane is a mechanical lifting device that raises and lowers heavy loads through the screw drive between a screw and a nut. It features a simple structure and strong self-locking capability, and is commonly used for short-stroke, heavy-duty applications requiring long-term load support.
II. Working Principle
The screw is rotated manually or by a motor, causing the nut (or the screw) to move vertically in a straight line, converting rotational force into vertical lifting force.
Key feature: The trapezoidal thread is inherently self-locking, preventing the load from sliding down automatically, ensuring safety and stability.
III. Main Classification
1. Manual Screw Crane (Screw Jack)
- Compact and portable, driven manually by a hand crank
- Common load capacities: 3t, 5t, 10t, 20t, 32t, 50t, etc.
- Used in vehicle repair, equipment installation, and emergency lifting
2. Electric Screw Crane
- Consists of motor, worm gear reducer, and screw
- Supports synchronous control of multiple units, used in production lines, platform lifting, and precise positioning
IV. Advantages
- Simple structure, low failure rate
- Reliable self-locking, enabling long-term support without continuous force application
- Free from oil leakage and hydraulic failure
- Some models can be installed horizontally or upside down
V. Disadvantages
- Slow lifting speed
- Lower efficiency than hydraulic types
- Less competitive for long strokes and extra-heavy loads
VI. Typical Applications
- Vehicle maintenance, mechanical installation and leveling
- Support for building components, adjustment of bridge bearings
- Industrial equipment lifting platforms, automated production lines
- Lifting operations in field environments without power supply
