A linear actuators manufacturers directory including electric actuators, electric linear actuators, positioning tables, positioning stages, linear motion components, linear positioners, electrical actuators, precision linear actuator, miniature linear actuator, electromechanical linear actuator, pneumatic linear actuators, mechanical linear actuator and automotive linear actuators.  

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About Linear Actuators

Linear actuators are devices that produce mechanical motion by converting various forms of energy into mechanical energy. A drive screw is rotated using either a synchronous timing belt drive, worm gear drive or direct drive. The turning of the screw pushes a drive nut along the screw, which in turn pushes the rod out. Rotating the screw in the opposite direction will retract the rod. The drive screw of linear actuators is either an ACME or ball thread or is belt-driven. The drive nut is plastic or bronze or is a ball nut. A cover tube protects the screw nut from environmental elements and contamination. Radial thrust bearings permit the screw to rotate freely under loaded conditions.

Linear actuators are typically part of motion control systems and usually are computer-controlled. Control systems use linear actuators to move or control objects. Linear actuators could also act as servomechanisms to provide and transmit a precise amount of energy to work another mechanism. The various forms of energy that run linear actuators include hydraulic, pneumatic, mechanical and electrical. Linear actuator manufacturers serve a wide range of industries, including robotics, aerospace and factory automation. Some linear actuators and units operate in vacuum, radiation, cryogenic, corrosive and underwater environments.

Linear actuator manufacturers can produce hydraulic actuators, pneumatic actuators and electromechanical actuators. Hydraulic actuators have brute strength, essentially no compressibility and excellent power-to-weight ratio. However, they tend to leak, have lower reliability, are higher maintenance, expensive and loud, use flammable fluids and generate heat. Even though pneumatic actuators are inexpensive, have rapid response and are simple and easy to control, they are also loud and use compressible fluid, and their position is difficult to control. Electromechanical actuators are fast replacing pneumatic actuators because they save money by reducing unnecessary energy consumption within plants, have vastly improved control and flexibility, are especially beneficial for multi-positional tasks and provide no health and environmental issues due to high noise levels. However, the tendency of these electrical linear actuators to spark limits their use in hazardous environments, and they have lower power and torque-to-weight ratios. Research has been moving forward on piezoelectric linear actuators and other forms of technology, which use active materials, but this has been primarily focused on micro-actuators and micro-manipulation.

When choosing from linear actuator manufacturers, consider several factors, including the speed, stroke length and load rating of the linear actuators produced. Also evaluate the duty cycle accuracy and programmability of linear actuators. Decide what the desired lifetime of the end product of the linear actuator system will be. Are there particular safety mechanisms required, environmental concerns to be addressed or space issues to deal with? If the linear actuator system is not battery-run, the size and kind of motor (AC, DC or special) are important considerations. Compare the different available motors, which include stepper, brushed DC or brushless servomotors. Design system flexibility is determined by the anticipated specification revisions.

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Featured Articles

“Hybrid Linear Actuators: Technical Overview”
http://www.hsi-inc.com/hybrid_actuators.php

“Straight Talk on Linear Actuators: Ball Screw or Belt Drive? Let the Application
Decide”
http://www.machinedesign.com/ASP/viewSelectedArticle.asp?strArticleId=57000&strSite=MDSite&catId=0

Image Provided by Haydon Switch and Instrument, Inc.

Types of Linear Actuators

• Actuators are devices that convert various forms of energy into rotating or linear mechanical energy.
  
• Air cylinders are pneumatic linear actuators that are either single-acting with spring return or double-acting. Air cylinders are actuated by pressure differential within the cylinder chambers.
  
• Diaphragm pneumatic linear actuators achieve valve actuation by using a diaphragm in a closed piston to enable control from a low pressure pneumatic (air) supply, similar to the way air cylinders (http://www.air-cylinders.com) work. Coiled springs of diaphragm pneumatic linear actuators provide quick and dependable valve shutdown that is independent of flowline pressure, ensuring a fail-safe position.
  
• Electric actuators convert electricity into mechanical energy.
  
• Electric linear actuators convert electricity into linear mechanical energy.
  
• Electrohydraulic thrusters are linear actuators that consist of motors and closed-loop hydraulic systems for the driving and operating of brakes, levers, dampers and safety mechanisms for a variety of industrial equipment.
  
• Electromechanical linear actuators, or electrical linear actuators, are basic linear actuators. These terms denote that electrical power is used to achieve mechanical force through the actuator.
  
• Hydraulic linear actuators utilize some sort of hydraulic fluid to achieve the positioning movement. Typically, electricity is used to start the positioning process.
  
• Linear cylinders are simple cylinders that have a pin-ended rod connecting to a crank arm, which then rotates the shaft. A fail-safe linear cylinder is spring-loaded to ensure the return of the shaft to a safe position.
  
• Linear thrusters provide cyclical linear motion via double-acting air or hydraulic cylinders attached to plates and shafts.
  
• Miniature linear actuators typically used in small spaces that require large payloads.
  
• Piezoelectric actuators produce a small displacement with a capacity for high force when voltage is applied.
  
• Planetary actuators consist of a piston assembly and shaft assembly and have planetary rollers on a piston located between the helical shaft and housing grooves. Piston movement causes the roller to follow the helical grooves into the housing, forcing piston rotation, while the rollers follow helical grooves into the shaft, causing shaft rotation.
  
• Rack-and-pinion actuators make use of fluid pressure to move a piston connected to a gear rack, which rotates a pinion. The output torque of rack-and-pinion actuators can be doubled with two parallel piston-rack units.
  
• Rod linear actuators are electric actuators that have an output rod which provides linear motion through a motor-driven ball or ACME screw assembly. The load of the rod linear actuator is typically unsupported but could be attached to the end of a screw or rod.
  
• Rodless linear actuators have a barrel of extruded anodized aluminum and are formed with a longitudinal slot, permitting a connection between the piston and mounting carriage. A hardened stainless steel band pneumatically seals the cylinder, while a second stainless steel band on the exterior closes the slot and avoids contamination to the interior of the cylinder; a system of slide rails divides the two bands in the pressure-free zone between the two piston seals, allowing the mounting carriage to move.
  
• Rotary actuators are compact, simple and efficient actuators that rotate an output shaft through a fixed arc to produce oscillating power. They require limited space and simple mountings and can produce high instant torque in either direction.