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Screw Jacks
What types of screw jacks are there?
What are screw jacks?
Screw jacks are true all-rounders in drive technology. There are hardly any applications where they are not discussed as a driving element. We have been manufacturing screw jacks since 1945. The basic principle is simple yet brilliant: a rotational motion is simply converted into axial motion - and all in a tight space.
This is achieved as follows: an electric motor drives a worm shaft, which rotates a worm gear. The worm gear is equipped with a threaded spindle (standard: trapezoidal thread; special version: ball screw) - and the screw jack is ready to go.
You have the choice: 4 types of gearboxes to choose from
The right gearbox type for your application depends on various factors: the required load capacity, the load case, and the space available. In principle, each gearbox can be provided in two versions:
- As a basic version: The spindle performs the linear lifting motion.
- As a travelling nut version: The nut performs the linear lifting motion.
We cover this wide range of loads with our proven screw jacks: from 0.5 kN to 2000 kN.
An overview of Screw Jack types
Cubic Screw Jacks - from 2.5 kN to 500 kN
The housing shape is already indicated in the name: it's cubic, resembling a cube. All surfaces in this design offer many attachment options for various constructions. We can realize load capacities from 2.5 kN to 500 kN and provide many customization possibilities.
The cubic screw jacks are designated as MJ or BJ. In total, there are 11 standard sizes available in the basic configuration.
Classic screw jacks - from 0.5 kN to 2000 kN
The housing shape of these screw jacks is indicated in their name: Classic. In contrast to the cubic design, the linear actuators of the MC series can withstand higher loads up to 2,000 kN. Due to the design, it's not possible to attach construction elements to the housing.
The classic screw jacks are designated as MC. There are 14 sizes available, with each size also offered in travelling nut and basic versions.
High-performance screw jacks HMC - from 5 kN to 1000 kN
The name itself indicates what's inside these gearboxes. These high-performance screw jacks are tailored for special dynamic and demanding applications, where standard screw jacks are not suitable due to their simple design.
As a result, we can achieve higher speeds and loads. The high-performance gearboxes are designated as HMC. They can lift loads ranging from 5 kN up to 1,000 kN.
High-speed Screw Jacks - from 15kN to 90kN
As an addition to our screw jack program, GROB High-speed gearboxes provide an expansion of the applications for our screw jacks. Unlike traditional screw jacks, they utilize bevel gear transmissions.
The offering includes three sizes with gear ratios of 1:1, 2:1, and 3:1. The overall efficiency of GROB High-speed Gearboxes is approximately 75% with ball screw spindles and approximately 40% with trapezoidal screw spindles.
This is what a worm gear actuator looks like from the inside
GROB Antriebstechnik GmbH
Pros and Cons
Cons
✘ Speed Limitation: In many cases, screw jacks are slower compared to other motion systems, which can be problematic in high-speed applications.
✘ Complexity: The design and installation of screw jacks can be complex and often require specialized knowledge.
✘ Maintenance Requirement: Screw jacks require regular maintenance to ensure optimal performance and lifespan.
✘ Cost: High-quality screw jacks can be expensive, especially when customized.
Pros
✔ Precise Motion Control: Screw jacks enable precise control of linear motion, which is crucial in applications where accuracy is important.
✔ High Load Capacity: Screw Jacks are capable of lifting or moving heavy loads, making them ideal for high-load applications.
✔ Energy Efficiency: They can facilitate efficient power transmission, allowing for energy savings and lower operating costs.
✔ Versatility: There are various types of screw jacks, such as spindle actuators, worm gear actuators, and high-speed screw jacks, suitable for different applications.
✔ Long Lifespan: Well-maintained linear actuators can have a long lifespan, making them cost-effective in the long run.