Linear Actuators

Linear Actuators Buying Guide

Where a linear actuator fits. Most of the material handling equipment in this store is a finished machine you push, ride, or hang a load from. A linear actuator is the opposite: a component you design into your own equipment to give it a controlled stroke. It replaces the hand crank on an adjustable frame, the hydraulic cylinder on a positioner you would rather run on electricity, or the manual pin and hole on a guard that now indexes at the push of a button. If your problem is holding work at a set height, a self-contained lift table is the packaged answer and usually the cheaper one. Reach for an actuator when the motion has to live inside a frame you are building or modifying, when several axes need to run from one control panel, or when you are converting hydraulic motion to clean electric drive. That framing, component rather than appliance, is what separates this collection from everything else on the floor.

Acme or ball screw: the first fork in the road. Every unit here converts rotary motion to linear travel through a screw, and the screw type decides most of the behavior. Acme, or machine-screw, actuators run a threaded nut on a trapezoidal screw. The high thread friction wastes some input as heat, which caps their speed, force, and duty cycle, but it buys the single most useful trait in lifting work: the screw is self-locking and will not back-drive, so the load stays put when power is cut, with no brake required. Ball-screw actuators run recirculating bearings between nut and screw, cutting friction so efficiency can reach the high eighties or better. That yields more speed, more force, and a longer duty cycle from the same motor, at the cost of the self-locking property. A vertical ball-screw actuator will back-drive under load when power is removed, so it needs a holding brake or constant motor power to stay in position. Match the screw to the job: slow, load-holding positioning that sits still for long stretches wants acme, while fast, high-cycle motion wants ball screw with a brake.

Size to force, stroke, and load direction. Three numbers size an actuator. Capacity is the force it must exert, and it should clear your heaviest real load with margin, the same discipline as any rated lifting gear. This line spans a wide band, from a 27 lb unit for light positioning through 250 and 500 lb mid-range models to 1,500 lb units for structural moves. Stroke is how far the rod travels, set by the actual open-to-closed distance your mechanism needs. Longer strokes cost travel time and can invite column buckling in compression, so specify the shortest stroke that does the job. Load direction is the number people forget. Actuators are built to push and pull along their own axis, in tension and compression, and they hate side load: a rod pushed off-axis wears the bushings and bends the screw. Mount so the force runs straight through the rod, use clevis or trunnion ends that let the unit pivot with the mechanism, and if the geometry swings through its travel, let the actuator float rather than fight a fixed pin.

Power supply and duty cycle. Power comes in two families here. The 12 and 24 volt DC units suit mobile, off-highway, and battery equipment, or any panel already running low-voltage control, and they make up the bulk of this line. The 115 volt AC models plug into standard industrial single-phase power for stationary gear. Whichever you pick, read the duty cycle before you trust the capacity. Duty cycle is the share of a given period the actuator can run before it needs to rest and shed heat, and it is not a fixed figure: a unit run well under its rated load stays cool and tolerates long on-times, while the same unit at full rating heats fast and wants more rest between strokes. Sealed, weather-rated units also give up some practical duty cycle to their own insulation. If the application cycles hard all shift, size the force generously so each stroke runs cool, or step up to a ball-screw model built to move the heat, rather than an acme unit run past its comfortable window.

Environment, mounting, and controls. Last, settle the environment and the wiring. An actuator's ingress rating, the IP number, tells you what it shrugs off: a control-cabinet unit is happy indoors and dry, while washdown, dust, and outdoor duty want a sealed housing rated for the exposure. Confirm the temperature range if the machine lives in a freezer or near an oven. On control, decide up front how the stroke stops and reports itself. Built-in limit switches end travel cleanly at each end of stroke, and potentiometer or Hall-effect feedback lets a controller land the rod at any point in between for repeatable positioning. Those choices ripple straight into the panel, so pin them down before wiring day. Actuators like these often build motion into equipment that also carries forklift attachments or machine-moving gear, so keep voltage, connector, and control scheme consistent across the whole build instead of specifying one unit at a time.