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A linear drive converts rotational movements to linear movements and vice versa. Linear actuators are key components for motion control in many mechanical systems and mechanical engineering. Often, this conversion is needed to convert power and motion generated by motors and other rotating equipment into translation (linear motion). The drive is industrially realized with motors or also by hand. The article introduces frequently used and common concepts and lists the design criteria. Lastly, we will discuss examples for mechanical engineering applications.
Mechanical engineering relies on various concepts to convert a rotational motion to a linear motion. The efficiency of motors in industrial environments is high and can be converted into linear movements by various mechanisms. The rotation of the motor can be used both rotationally and translationally.
The most common principles are:
The slider crank mechanism consists of a driven crank, a coupling (also called connecting rod) for power transfer, and a linearly guided slider. The drive is powered by a rotational movement that rotates the crankshaft and thus the crank. The connecting rod has a rotary linkage on both ends. The slider can only be moved in a translational manner. The constrained motion of the crank and slider creates a transmission that generates translation from rotation.
The lead screw drive is a screw gear consisting of a rotating lead screw and a linearly guided carriage. The lead screw is driven by a motor and the lead screw pitch causes the carriage to move translationally. The guided movement and defined, uniform translation permit very precise and easy-to-control motion.
Lead screw drives and other screw gears are often powered by hand to adjust objects.
Cam gears are non-uniform transmissions. The rotary motion is converted by a powered, defining transmission geometry (e.g., a cam disc) and a scanner. The scanner is guided linearly.
Cam gears are classified by locking method, among other things. They are distinguished into friction locking and interlocking.
The eccentric mechanism consists of a control disc constructed with an eccentricity (offset to the axis of rotation) and a connecting rod. The eccentric mechanism is a coupling gear and acts like the slider crank. The control disc is the crank. The design often allows for a smaller installation space and has smoother operating properties due to higher masses.
Drives with rotary movements can also follow other principles. In principle, belt conveyors and traction drives also transform rotation to translation. However, these implementations are not suited for translation into rotation and are therefore not considered further.
The design of linear actuators differs by the employed mechanisms. In principle, linear actuators are gears that convert a gear ratio from a rotary motion to a translation.
The application of linear actuators in mechanical engineering is diverse and multiple embodiments can often be implemented for one application. Examples of linear motion in mechanical engineering are:
When synthesizing a linear drive, such as a slider crank, the MISUMI shop has the right connectors, such as hinge bolts and hinge bearing blocks, for supporting rotational movements, as well as articulated arms, connecting rods and spherical bearings for designing the gear ratio.
The components that cannot be replaced by standardized parts and purchased parts can be ordered on meviy. The meviy page is a contract manufacturing form where you can use CAD models to place an order - all without drawing derivation. The page will detect from the uploaded model whether it is a sheet metal part, turned part, or milled part and will calculate your price and lead time.
