Pollak 21-517 Precision Ball Switch – Normally Closed (NC), .250" Blade Terminals

Reliable Precision for Heavy-Duty Safety & Control Systems

The Pollak 21-517 Precision Ball Switch is a high-performance sensing component engineered for the demanding environments of the transportation, trucking, and industrial sectors. This Normally Closed (NC) switch remains in a closed-circuit state until the ball plunger is depressed, making it an essential choice for safety interlocks, neutral sensing, and specialized lighting controls that require "break-on-contact" functionality.

Universal .250" Blade Terminal Connectivity The 21-517 features high-conductivity .250" (1/4 inch) blade terminals, designed for easy integration with standard female push-on connectors. This "exposed terminal" design provides a secure electrical connection while offering maximum flexibility for technicians to perform quick field repairs or custom harness installations without proprietary plugs.

Built to Outlast in Extreme Conditions Engineered by Pollak, the industry leader in precision switches, the 21-517 is built with a rugged, corrosion-resistant body and includes an O-ring seal (based on the 21-456 design) to protect against moisture and contaminants. With a mechanical life of 1,000,000 cycles and a wide operating temperature range of -40°F to +250°F, this switch is designed to survive the high-vibration and high-heat environments of modern truck transmissions and chassis.

Key Specifications:

• Circuitry: Normally Closed (NC)

• Termination: .250" Blade Terminals (Exposed)

• Thread Size: 9/16-18

• Hex Size: 7/8"

• Voltage Rating: 5.0 - 24.0 VDC

• Current Rating: 0.01 - 5.0 DC Amp

• Operating Temperature: -40°F to +250°F (-40°C to +121°C)

• Cycle Life: 500,000 Electrical / 1,000,000 Mechanical

• Mating Connector: Rectangular Receptacle Terminal