Linear Actuators
For lifting loads of up to 500kN, so far...

Our Linear Actuators are used to lift and position load using the mechanical advantage gained from a rotating lead screw. So-named due to the linear direction of the force provided.

In its simplest form, a Linear Actuator is a device which can apply force acurately along a single axis. At Kelston Actuation, we specialise in the Electromechanical type of Linear Actuators, which rely on the mechanical advantage of lead screws and gearing, driven by an electrical input to achieve actuation.

Our Electromechanical Linear Actuators provide force by translating a rotational input (typically provided by an attached motor or servo) into linear motion. The motor is permitted to drive an attached gearbox, which can alter the direction or speed of rotation and relay it directly to a lead screw. Using the mechanical advantage of a lead screw, increased linear force can be applied from the rotational input torque. 

Linear Actuators are typically sealed units, and in order to achieve this, a ram tube will cover the lead screw and actuate with the lifting nut. This tube will run between seals and guides, housed in a secondary, outer, tube. The rotation of the tube can also be fixed by guiding the ram tube along a keyway or similar.

Linear Actuators are used in a variety of different applications from home appliances to industrial systems. On a small scale, you might find a linear actuator in a home printer, or garage door closing system. At industrial levels, Linear Actuators are used to apply a controlled force to a load or product. For instance, automated load testing, conveyor belt tracking, industrial presses, valve operation, machine simulation, pharmaceutical manufacturing and much, much more.

Whilst there is an almost endless number of real-world applications for Linear Actuators, Kelston Actuation frequently manufactures custom designs for the automotive, pharmaceutical, aviation, manufacturing, defence, and energy sectors of industry.

Electromechanical Linear Actuators are not the only type in existance. Although we at Kelston do not supply them, Hydraulic and Pneumatic set ups are regularly implemented in various industries. All types of Linear Actautor share the same goals though, it is only the method of force application that differs. We of course would argue that there are plenty more benefits to Electromechanical lifting though!

Whilst the fundamental action of a Linear Actuator doesn’t change (delivering a linear force along an axis) there are various dynamic differences in how they can achieve this – including the travel speed and length, the repeatability and positional accuracy of the action. 

The functional nature of an actuator is heavily dependent on the design of the lead screw. There are various styles available such as machine (trapezoidal), ball or roller screws. Each style has its own characteristic qualities and would be more appropriate for different scenarios. For example, a ball screw is more applicable for an action requiring high repeatability and accuracy. Trapezoidal screws, however, are extremely durable and are inherantly self-locking.

Linear Actuators can feature different forms of mounting such as trunnion, single clevis, double clevis, foot, or gimble. Each having benefits for a specific application and being possible to implement on all types of Actuator. All of our Actuators also utilise our Gearboxes, which can be used to change speed and direction of the rotational input. The materials used to manufacture an Actuator can also differ, depending on the structural, environmental, or cosmetic preferences you as a customer may have, with a multitude of paints, coatings and surface treatments also available.

Linear Actuators are commonly used as alternatives to standard Screw Jacks, which are limited when sealed units are desired. There are several key advantages they offer:

1. Safety

As Linear Actuators are typically fully sealed sysems, the only moving external part is the sliding tube, or ram. Consequently, there is a low risk of debris ingress which would otherwise increase wear, decrease life, or irrepairably damage a system. Having a covered rotating screw also drastically limits risk of injury to any personnel responsible for operation. Personnel in charge of the system can also control the power source directly and adjust positioning whilst monitoring travel, speed, and load from a safe distance. The sealed nature of Electromechanical Linear Actuators also means there is less threat of operational failure through tampering or accidental damage. 

2. Accuracy

Ball and roller screws are often used as the main load bearing components in Electromechanical Linear Actuators and can be used to effectively position loads with smoother translation and greater precision than could be achieved with a standard Screw Jack utilising a trapezoidal lead screw. This can be advantageous if you handle fragile goods and components or require high accuracy where motion control is concerned.

3. Low Maintenance

As the entirety of a Linear Actuator is sealed, there is little to no ongoing maintenance required to keep them running effectively. This is mainly due to the wiper seal arrangement in the top of the outer tube which drastically limits any loss of grease/lubricant. As such, with proper operation and handling, these units are unlikely to incur any long-term maintainance costs, especially when compared to the open-screw of a standard Screw Jack.

4. Cost effective

Linear Actuators often produce a higher initial cost when compared to a standard Screw Jack, but due in part to the low required maintenance, will have much lower running costs. This is also achieved by utilising high efficiency components such as roller screws, which often reduce the input power required for operation when compared to a much lower efficiency lead screw. Many motors used with these units will have static brakes built in which will allow the operator to turn off an Actuator when not in use, but still under load. Once again, this will reduce power consumption and consequently running costs.

5. Synchronisation

Another key advantage of Linear Actuator design is the ease at which they can be incorporated into synchronised systems. It is common place to use several actuators in a given system to position or move load. This can be achieved using driveshafts and couplings or by synchronising the servos driving them.

AB Dynamics supplies advanced production testing and R&D systems to the global motor industry. The company asked Kelston Actuation to design and manufacture specific linear actuator components for their trademark Suspension Parameter Measurement Machine (SPMM).

The SPMM measures the kinematic characteristics of a vehicle’s suspension and steering system. It is powered by a set of six actuators that perform linear movement on five different axes. Each actuator is driven independently by its own servo motor drive.

The actuators are fitted with positional control switches, which along with the servo motor, integrate with the SPMM control panel.

Each bespoke actuator consists of a spiral bevel gearbox rotating a worm and wheel gear set – which drives a high precision ball screw.