Guide to Screwnut Lifting Systems Principles and Applications

Imagine elevators that no longer require massive machine rooms, feature simplified installation processes, and significantly lower maintenance costs. This isn't science fiction—it's the reality being delivered by screw-nut elevator systems. This emerging vertical transportation technology is gaining traction in small-scale projects due to its unique advantages.

Screw-Nut Elevator Systems: An Overview

Screw-nut elevator systems, also known as screw-driven lifts, utilize threaded rod mechanics to achieve vertical movement. Compared to conventional hydraulic or traction elevators, these systems boast simpler structures, reduced space requirements, and easier maintenance. Their core components include:

• Electric motor
• Threaded steel rod (screw)
• Large drive nut
• Power supply system

The streamlined design typically eliminates the need for a machine room (MRL configuration), minimizes footprint requirements, and avoids deep pit excavations—dramatically reducing construction modification costs.

Working Mechanism

The operation principle is remarkably straightforward. The elevator car or platform connects to the drive nut. When activated, the motor rotates the nut along the screw's threads: clockwise rotation lifts the car while counterclockwise movement lowers it. This threaded engagement ensures smooth, reliable vertical motion.

Lubrication plays a critical role in maintaining quiet operation. Some designs, like the Gartec platform lift, incorporate an oil reservoir at the screw's base. As the drive nut descends to its lowest position, it dips into this reservoir, automatically distributing lubrication along the screw.

These systems accommodate various lift configurations. Open-platform models (e.g., Gartec 7000) utilize L-shaped carriers that visibly traverse the shaft, while enclosed cabin versions (e.g., Gartec 9000) resemble traditional elevator boxes.

Component Breakdown

Motor

The system's power source determines lifting speed, capacity, and stability. AC or DC motors paired with precision control systems enable accurate speed and position management.

Screw Rod

Manufactured from high-strength alloy steel with specialized surface treatments, this central component affects operational smoothness and noise levels through its thread precision and surface finish. Length dictates maximum lifting height.

Drive Nut

Typically bronze or other wear-resistant materials minimize friction. Design considerations include load capacity, durability, lubrication efficiency, and thread compatibility.

Control System

This "brain" incorporates PLCs, sensors, encoders, and variable frequency drives for precise operation monitoring, safety functions, and diagnostics.

Safety Features

• Overload protection: Halts operation when exceeding weight limits
• Limit switches: Prevents overtravel at shaft extremes
• Safety brakes: Mechanically engages during uncontrolled descent
• Emergency stop: Immediate system shutdown capability

Lubrication System

Oil-bath or automatic lubrication methods reduce friction between screw and nut components.

Advantages and Limitations

Benefits

• Simplified maintenance with fewer components
• Lower installation and operating costs
• Compact footprint ideal for space-constrained locations
• Inherent safety through mechanical self-locking
• Rapid installation (often 2-3 days for modular units)

Drawbacks

• Reduced speed (typically below 0.15 m/s for open platforms)
• Limited capacity (approximately 500 kg standard)
• Height restrictions (generally under six stories)
• Continuous button pressure required for some open-platform models

Application Scenarios

• Residential: Ideal for villas and duplexes assisting elderly or mobility-impaired users
• Accessibility: Public space modifications in hospitals, stations, and shopping centers
• Industrial: Small-scale warehouse and factory cargo transport
• Entertainment: Stage elevation mechanisms
• Domestic: Increasing home elevator market penetration

Selection Criteria

• Required lifting height
• Weight capacity needs
• Desired operational speed
• Available installation space
• Safety certification compliance
• Budget constraints
• Long-term maintenance requirements

As this innovative technology continues evolving, screw-nut elevator systems demonstrate significant potential for small-scale vertical transportation solutions. Their unique combination of compact design, cost efficiency, and safety features positions them as compelling alternatives in appropriate applications.