A linear actuator is a self-supporting structural system capable of reworking a circular motion generated by a motor right into a linear motion alongside an axis. Helping to produce movements such because the pushing, pulling, elevating, lowering or inclination of a load.

The commonest use of actuators entails combining them with multi-axis Cartesian robot systems or using them as integral parts of machines.

The principle sectors:

industrial automation

servos and pick-and-place systems in production processes


packaging and palletisation

Certainly, just think of applications akin to plane, laser or plasma slicing machines, the loading and unloading of machined items, feeding machining centres in a production line, or moving an industrial anthropomorphic robot along an additional external axis to be able to broaden its range of action.

All of these applications use one or more linear actuators. In accordance with the type of application and the efficiency that it should assure in terms of precision, load capacity and velocity, there are various types of actuators to select from, and it is typically the type of motion transmission that makes the difference.

There are three predominant types of motion transmission:


rack and pinion


How can you ensure that you select the suitable actuator? What variables does an industrial designer tackling a new application need to take into consideration?

As is usually the case when talking about linear motion solutions, the important thing is to consider the issue from the precise viewpoint – namely the application and, above all, the results and performance you might be expecting. As such, it is worth starting by considering the dynamics, stroke length and precision required.

Let’s look at these in detail.

High Dynamics

In many areas of industrial design, akin to packaging, for instance, the calls for made of the designer fairly often need to do with pace and reducing cycle times.

It’s no surprise, then, that high dynamics are commonly the starting point when defining a solution.

Belt drives are often the best solution when it involves high dynamics, considering that:

they allow for accelerations of up to 50 m/s2 and speeds of as much as 5 m/s on strokes of so long as 10-12m

an X-Y-Z portal with belt-driven axes is typically capable of dealing with loads ranging from extremely small to approximately 200kg

based on the type of lubrication, these systems can provide particularly long upkeep intervals, thus ensuring continuity of production.

Wherever high dynamics are required on strokes longer than 10-12m, actuators with rack and pinion drives are usually a wonderful solution, as they permit for accelerations of as much as 10 m/s2 and speeds of as much as 3.5 m/s on doubtlessly infinite strokes.

The selection of a special type of actuator wouldn’t assure the same results: a screw system, which is undoubtedly a lot more exact, would certainly be too sluggish and wouldn’t be able to deal with such lengthy strokes.

Long Strokes

Systems created by assembling actuators within the typical X-Y-Z configurations of Cartesian robotics typically, in applications similar to pick-and-place and feeding machining centres alongside production lines, have very long strokes, which may even reach dozens of metres in length.

Plus, in lots of cases, these lengthy strokes – which often involve the Y axis – are tasked with dealing with considerably heavy loads, typically hundreds of kilos, as well as quite a few vertical Z axes which operate independently.

In these types of applications, the only option for the Y axis is certainly an actuator with a rack and pinion drive, considering that:

thanks to the inflexibleity of the rack and pinion system, they’re capable of operating along potentially unlimited strokes, all whilst maintaining their inflexibleity, precision and effectivity

actuators with induction-hardened steel racks with inclined teeth which slide along recirculating ball bearing rails or prismatic rails with bearings are capable of handling loads of over one thousandkg

the option of installing a number of carriages, each with its own motor, permits for quite a few unbiased vertical Z axes.

A belt system is ideal for strokes of up to 10-12m, whilst ball screw actuators are limited – within the case of long strokes – by their critical speed.

Positioning Repeatability

If, alternatively, the designer is seeking maximum precision – like in applications such because the meeting of microcomponents or certain types of handling within the medical area, for instance – then there’s only one clear choice: linear axes with ball screw drives.

Screw-driven linear actuators supply one of the best efficiency from this perspective, with a degree of positioning repeatability as high as ±5 μ. This efficiency can’t be matched by either belt-driven or screw-pushed actuators, which both attain a maximum degree of positioning repeatability of ±0.05 mm.