Product Overview
High-Capacity SPDT DC Magnetic Blowout Basic Switch
Condition
New old stock (NOS). Stamped date code 8904. Body markings and terminal labels are fully intact and clear. Brass screw terminals show zero installation wear or wire marks. Sourced as unused surplus.
Ships same or next business day from our Idaho warehouse. Honest pricing, no nonsense.
Online since 1999. We are here for our customers, with a no-hassle satisfaction guarantee.
Product Overview
Micro Switch MT-4R-A28 basic snap-action switch manufactured in Freeport, Illinois. Designed with internal magnetic blowout capability for handling high-energy DC and AC electrical loads without contact degradation. Features a pin plunger actuator, single pole double throw (SPDT) non-polarized switching arrangement, and heavy-duty brass screw terminals with a slotted fiber circuit barrier.
Key Features
- Electrical rating: 10 A at 125 VAC/VDC, 1/4 HP at 125 VAC/VDC
- Contact configuration: SPDT (Single Pole Double Throw)
- Actuation type: Pin plunger mechanism
- Magnetic blowout design extends contact life during DC arc interruption
- Non-polarized internal contacts
- Termination: Heavy-duty brass screw binder head terminals
- Fiber terminal barrier stamped for normally open and normally closed leads
- Chassis mount via two standard through-holes
Applications
- Replacing worn travel-limit switches on vintage machine tools, lathes, and mill tables.
- Controlling direct-current traction motors, battery-powered lifts, or winches where DC inductive arcs destroy standard contacts.
- Integrating into custom CNC builds, safety interlocks, or shop-floor automation jigs that demand rugged physical position sensing.
- High-voltage hobbyist bench supplies and kinetic art projects requiring positive tactile snap action under DC loads.
Frequently Asked Questions
What does the magnetic blowout feature do?
The internal magnet generates a flux field that quickly deflects and stretches the electrical arc away from the contact points when switching DC circuits, dramatically reducing contact pitting and premature failure.
Are mounting fasteners or wiring screws included?
The integrated brass terminal screws and circuit barrier shown in the photos are attached to the unit. External mounting chassis screws are not included.
Why choose an individually photographed unit instead of hunting surplus lots?
You receive the exact unused Freeport-made switch shown, clean and ready to drop directly into your equipment without guessing at terminal condition or storage wear. Orders clear dispatch from our Idaho warehouse the same or next business day.
A rugged classic from the Freeport line, ready to handle heavy inductive sparks and keep heavy machinery doing honest work.
Need more than one? More pieces cost less each - the price-break table on this page shows what each quantity costs.
Shipping? This one clears the free-shipping line on its own - and it leaves the Idaho warehouse the same or next business day.
