Linear actuators and screw jacks both solve the task of converting rotary motion into linear motion. Yet their design differences lead to entirely different strengths. This guide helps you make the right choice.
Linear Actuator: Compact All-Rounder
In mechanical engineering, the term "linear actuator" typically refers to an electric linear drive in a compact design. The defining characteristic: motor, spindle device, and guide element are housed in an integrated enclosure.
Structure of the Linear Actuator
A standard linear actuator consists of:
- Electric motor – typically DC motor, stepper motor, or servo (AC/DC)
- Gearbox – usually worm gear or planetary gear
- Ball screw or trapezoidal screw – converts rotation into stroke
- Linear guide – usually ball rail or plastic guide
- Push rod or nut – depending on design, the rod or screw nut moves
This integrated design enables space-saving installation. Linear actuators are ready to use immediately – no complex assembly required.
Practical Tip from TEA:
Linear actuators are particularly well suited for applications where space constraints are critical. Think of medical devices, laboratory automation, or compact industrial machines. The pre-calibrated accuracy also saves commissioning time.
Screw Jack: Modular Flexibility
The screw jack is a modular solution made up of individual components. It consists of a separate drive unit (motor + worm gear) and a downstream lifting element unit (spindle + guides).
Structure of the Screw Jack
A typical screw jack consists of:
- Drive – electric motor (typically 1–15 kW)
- Worm gear – generates high reduction and torque
- Trapezoidal screw or ball screw – converts torque into lifting force
- Guide rails – stabilize the load during the stroke
- Load attachment device – can be individually customized
Modularity is the great advantage: you can select motor size, gear ratio, spindle, and guides completely independently. There is an optimal combination for every individual case.
Practical Tip from TEA:
Screw jacks allow the use of synchronization elements (driveshafts, belts) for exact coordination of multiple strokes. This is standard in printing presses, presses, and production systems.
Direct Comparison
| Criterion | Linear Actuator | Screw Jack |
|---|---|---|
| Max. lifting force | Up to approx. 100 kN | 500 kN and higher |
| Stroke length | 100–1000 mm (constrained) | 100–5000 mm (freely selectable) |
| Stroke speed | 5–50 mm/s typical | 10–200 mm/s and higher |
| Positioning accuracy | ±0.5–1 mm standard | ±0.1–0.5 mm (depending on spindle) |
| Synchronization of multiple drives | Difficult, electronic only | Mechanically via shafts/belts possible |
| Design costs | €€ (catalog product) | €€€ (custom assembly) |
| Maintenance effort | Low | Medium to high |
| Scalability | Limited | Very flexible |
Application Scenarios in Practice
When Is the Linear Actuator the Best Choice?
Medical technology: In blood analyzers and dental treatment units, space savings are critical. Linear actuators with compact design and precise positioning are ideal.
Laboratory automation: Pipetting robots and sample handlers benefit from the fast commissioning and precisely calibrated kinematics of the linear actuator.
Lightweight assembly: For loads under 50 kN and stroke lengths up to 500 mm, linear actuators are economically unbeatable.
When Is the Screw Jack the Right Solution?
Heavy-duty applications: Hydraulic presses, sheet metal technology, and stamping tools require the high forces and torques that only screw jacks deliver.
Synchronized multi-axis strokes: In printing presses (plate stroke, counter motion) and automated storage systems, multiple spindles must run in exact synchronization. The screw jack offers a robust mechanical solution via driveshafts.
Long and variable strokes: Strokes of 2–6 meters are no problem. Modularity allows adaptation to spatial requirements.
Selection Criteria for Your Application
The following questions help you make the right decision:
- How high is the required lifting force? If it exceeds 100 kN, the screw jack is the first choice.
- Is synchronization of multiple strokes necessary? If yes: screw jack with mechanical coupling.
- What are the space conditions? Tight installation space → linear actuator. Plenty of space → both solutions possible.
- What stroke length is required? > 1 m: screw jack is more economical.
- How critical is commissioning time? Short time required → linear actuator as catalog solution.
- What budget is available? Small budget, low requirements → linear actuator. Large budget, high requirements → screw jack.
TEA Recommendation
There is no universal "best" solution. Both systems have their place. Linear actuators are perfect for fast, cost-effective solutions with moderate requirements. Screw jacks enable high-load, synchronizable, long-stroke applications. The decision depends on your specific requirements. Get advice from our application engineering team on sizing – we help you find the economically and technically best solution.
Which Solution Fits Your Task?
Our application engineers analyze your requirements and recommend the most economically optimal solution – linear actuator or screw jack.
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