Techno Linear Motion Catalog8Technical InformationBacklashis defined as the dead band experienced when changing directions. This phenomenon is causedby a clearance between interactive elements in a drive train and/or bearing system. Backlash is typicallyfound between gears or between a nut and screw. A common and less technical description of backlash isdefined to be the amount of play or slop in a system. The largest contributing factors to backlash stemfrom the drive train and bearings being imprecise or worn. Preloading the drive train and bearings willremove excess play in a system, and this type of system is generally referred to as anti-backlash.Resolutionis defined as the smallest attainable increment of adjustment or positioning. The minimumamount that a positioning system can be moved is referred to as the system resolution. Among the factorsthat determine resolution are the type of motor and control used, and mechanical advantages found withinthe drive train.Lifetimeis defined as the cumulative number of linear inches of travel guaranteed by the manufacturer ofa linear motion system. This specification varies greatly with load and speed so care should be taken toconfirm operating conditions.Frictionis defined as a nonconservative force that acts in the opposing direction of a motion. By means ofheat dissipation, friction results in the loss of useful energy and contributes to system wear. As a result offriction, systems become inefficient, inaccurate, and expensive to maintain. Friction due to rolling contactis far less than that due to sliding contact. This should be considered when selecting load bearings anddrive trains. For example, lead screws and plain bearings have higher friction forces than ball screws andball and roller bearings.Static analysisis defined as force and torque analysis of a body or system of bodies when they are at rest(or when they are at equilibrium). Although acceleration forces are present in all gravitational fields, theyare counteracted by equal and opposite forces in a static system and motion is constrained. A static loadis a load acting on a body or system of bodies that is supported by an equal and opposite force. This typeof system is analyzed using Newtons 2nd Law in the case where the accelerations acting on all bodies areequal to zero.Dynamic analysisis defined as force, torque and motion analysis of a body or system of bodies when theyare not at rest (or when they are not at equilibrium). A dynamic system will have force and torque actingthat are not counteracted, resulting in motion of the body or bodies. A dynamic load is a load that is notsupported by an equal and opposite force and results in a dynamic, or changing system with respect tomotion. This type of system is analyzed using Newtons 2nd Law in the case where the accelerations actingon all bodies may be nonzero. Note that dynamic conditions complicate load and life calculations becauseof shock loads and vibrations.Case 3: Not Accurate and not Repeatable(Mean ¹ Absolute Position, s large)12 10 8 6 4 2 0 MeanPosition¯¯XAbsolutePosition3 Error 3Case 4: Accurate but not Repeatable(Mean =~ Absolute Position, s large)12 10 8 6 4 2 0 AbsolutePositionMeanPosition¯¯X3 3 Error