Vlier S57N Threaded Spring Plunger 5/16-18 Steel Locking

Product Description

The VLIER S57N is a threaded spring plunger designed for indexing, positioning, and light-duty locking applications in mechanical assemblies. It features a 5/16-18 unified coarse thread with 1 inch of thread length and a standard-length steel body measuring 1 inch. The spring-loaded nose extends 3/16 inch in projection, with a minimum plunger diameter of 0.133 inches and a maximum of 0.135 inches. An integrated locking element secures the plunger in the threaded bore after installation, preventing back-out under vibration. Initial end force is 1.5 pounds and final end force is 4.5 pounds, giving the plunger a defined resistance curve suited for repeatable positioning tasks.

This spring plunger installs into tapped holes in machine components, fixtures, jigs, tooling plates, and industrial equipment where a retractable, spring-loaded detent is needed. Typical applications include panel latching, slide positioning, and assembly-line fixture work in manufacturing and automation environments. A licensed machinist or mechanical technician typically handles installation in production tooling contexts, while field maintenance techs handle replacement in existing assemblies.

Key Features

• 5/16-18 thread for direct installation into standard tapped holes
• 1 inch thread length and 1 inch body length for secure engagement depth
• 3/16 inch plunger projection provides consistent detent travel
• 1.5 pound initial end force and 4.5 pound final end force for defined resistance
• Steel nose and steel body for durability in industrial environments
• Integrated locking element prevents plunger back-out under vibration

Compatibility

Designed as an OEM-style replacement or new-installation spring plunger for any assembly using a 5/16-18 tapped hole requiring a standard-length threaded spring plunger with a locking element.

Installation Notes

A hex key or appropriate slotted driver is typically used to thread the plunger into a pre-tapped 5/16-18 hole. Ensure the mating bore is clean and free of chips before installation. The locking element engages upon final tightening, so do not overtighten in a way that damages the thread or locking feature. De-energize or lock out any powered equipment before servicing assemblies containing this plunger.