Build my rack app plus#
M = moved mass includes the application load, plus any system components that are being moved, such as the pinion, gearbox, motor, etc. In addition, if the application involves any external pressing forces, those are included in the tangential force calculation. In a horizontal application, the rack experiences two forces due to the movement of the mass: a force created due to the moved mass acting against the coefficient of friction of the guide rails, plus a force that results from accelerating the mass. Tangential force on the rack: horizontal application And compared to other linear drive options, rack and pinion drives are relatively simple to select, integrate, and operate.Ĭase in point: Unlike ball screw sizing - which must take into account factors such as characteristic and critical speeds, end bearing considerations, and the effects of preload, in addition to basic thrust force and drive torque calculations - rack and pinion drive sizing is primarily based on three factors: the force the rack sees (referred to as the “feed force” or “tangential force”), the torque the pinion sees, and the rotational speed of the pinion. This is good news for designers and engineers who are faced with applications that require any combination of long stroke, high thrust force, high speed, and challenging environmental conditions. Image credit: Atlanta Drive Systems, Inc. Unlike ball screw assemblies, rack and pinion drives can provide high speeds and high thrust forces regardless of length or mounting factors. In fact, manufacturers of linear actuators commonly offer rack and pinion drive versions, and several profiled rail guide manufacturers offer integrated rack and pinion systems, with the rack ground into the guide rail profile or the guide rail mounted directly on the rack.įurther evidence that rack and pinion drives aren’t going away is the investment that manufacturers continue to make in the technology - from developing improved methods for tooth grinding to researching new materials with better hardness and surface finish for reduced wear, higher efficiency, and reduced weight. While the rack and pinion drive is sometimes dismissed as old technology, a look at the market for linear motion solutions demonstrates that this isn’t the case. But rack and pinion drives are the often-overlooked workhorses behind gantry and transport applications that require long travel, high acceleration rates, and high thrust forces at a relatively low cost - a performance-price combination the other drive technologies have difficulty achieving. In linear motion applications, ball screws are widely recognized for their ability to provide high thrust forces, while linear motors are gaining market share in high-speed applications, and belt drives continue to maintain their reputation as the best solution for long travel lengths.