Vlier PH55A Threaded Spring Plunger 1/4-28 1in Thread

Product Description

The VLIER PH55A is a standard threaded spring plunger designed to provide controlled, spring-loaded contact force in positioning, indexing, and light-duty locking applications. The steel body and steel nose deliver consistent durability in industrial and mechanical assemblies. Thread size is 1/4-28 UNF with a thread length of 1 inch and a plunger projection of 3/16 inches. Initial end force measures 1 pound, final end force measures 4 pounds, and middle end force is 2.5 pounds, giving the installer a predictable force progression across the plunger stroke. This part is installed by machinists, mechanical assemblers, and maintenance technicians working on fixtures, jigs, and precision mechanical components.

The PH55A is used in applications where a spring-loaded ball or nose must engage a detent or register a part position. Typical installations include machine tool fixtures, assembly jigs, tooling plates, and light-duty indexing mechanisms in both industrial and commercial manufacturing environments. The 1/4-28 fine thread allows for secure installation in tapped bores where vibration resistance is required. No locking element is present, making this a straightforward press-and-release plunger suitable for frequent cycling applications.

Key Features

• 1/4-28 UNF fine thread for secure engagement in tapped bores
• 1 inch thread length and 1 inch body length for standard depth installations
• 3/16 inch plunger projection with a plunger diameter range of 0.117 to 0.118 inches
• Force progression: 1 pound initial, 2.5 pounds middle, 4 pounds final end force
• Steel body and steel nose construction for industrial durability
• No locking element - suitable for high-cycle positioning and indexing use

Compatibility

Designed as a standard 1/4-28 threaded spring plunger for use in tapped holes in machine fixtures, tooling plates, assembly jigs, and similar mechanical components requiring spring-loaded positioning or detent engagement.

Installation Notes

Installation requires a properly tapped 1/4-28 UNF blind or through hole in the mating component. Use an appropriate hex key sized for the 0.079 inch hex drive to thread the plunger in by hand or with a screwdriver-style tool, then torque to the fixture manufacturer specification. Ensure the bore is clean and free of debris before installation to prevent damage to the plunger nose. De-energize or lock out any automated equipment before servicing plungers in active fixtures.