LinearLibraryItem - Helix Screw Load Definitions

Helix Screw Load Definitions

Helix Screw technical glossary, definitions and diagrams


BACKLASH - Backlash (lash) is the relative axial clearance between a screw and nut without rotation of the screw or nut. Backlash information for Helix precision lead screws and nuts is listed within the data section of this catalog. Lash will always increase with use. Helix Linear Technologies has developed several unique ways to reduce or remove the lash between the screw and nut.

STATIC LOAD - The maximum thrust load – including shock – that should be applied to a non-moving nut assembly. Actual maximum static load may be reduced based on end machining and screw mounting hardware.

DYNAMIC LOAD - The maximum recommended thrust load which should be applied to the lead screw and nut assembly while in motion. PV LOAD - Any material which carries a sliding load is limited by heat buildup caused by friction. The factors that affect heat generation rate in an application are the pressure on the nut in pounds per square inch of contact area and the surface velocity in feet per minute at the major diameter. The product of these factors provides a measure of the severity of an application.

TENSION LOAD - A load that tends to “stretch” the screw.

COMPRESSION LOAD - A load that tends to “squeeze” the screw.

THRUST LOAD - A load parallel to and concentric with the axis of the screw.

OVERTURNING LOAD - A load that tends to rotate the nut radially around the longitudinal axis of the screw.

SIDE LOAD - A load that is applied radially to the nut.

Figure 1