Precision Switching Products & Linear Position Sensors

J4 Ball Switch – A Study in Hardness & Durability

Ball and Plunger Switches

Sometimes in engineering design, you just get it right. The right combination of materials, simplicity and elegance. Just the right amount of cleverness. Sometimes it even looks pretty. Sure as time goes on you make tweaks here and there, but if your basic design is sound, reinventing the wheel is seldom necessary.

Such is the case with the CPI J4 Ball Switch, the gift that keeps on giving as it were. Originally designed for military applications on armored vehicles and tanks, this reliable, virtually indestructible waterproof ball switch with our patented seal mechanism keeps getting design win after design win in a variety of control and sensing applications such as:

  • Neutral safety detection on commercial or military vehicles
  • Door Open/Closed sensing on everything from military jeeps to submarine’s
  • Boom travel detection on Forklifts and Emergency Vehicles.
  • Cab down detection on trucks and military vehicles
  • Transmission Gear Range Detection – For closed loop feedback on military vehicles.
  • Outrigger lock detection – for construction, agricultural, and emergency vehicles
  • Air Shut Off Switch – This uses the plunger variation of our ball switch on large compressors
  • Anti Two Block – for crane operation and safety.

Most recently the J4 Ball received another design-in at a major manufacturer of armored vehicles. This time it will see use in a transmission sensing application where it provides feedback on gear range inside the transfer case (low, med, high).

J4 Ball Switch Operational Niche

Our ball switch has a few defining characteristics that make it an excellent choice for certain high endurance applications

  • Completely Waterproof, Sealed Design. – When a ball or plunger switch depresses, it is the perfect opportunity for particulates to leak into the housing. Just a little bit of sand, mud or wind dust and your switch becomes all but useless. But in the CPI J4 ball switch we use a custom designed exclusion seal and our patented ball carrier that is tightly dimensioned to the plunger bore. In this proven configuration, our switch completely eliminates liquid and contaminate ingress.
  • Ball and Plunger Switch Variations – Our J4 Plunger variation uses the same ball seal mechanism as our ball switch and is equally reliable and tough.
  • Extended Temperature range operation – Many competitor switches will simply freeze up in one position or another when things get really chilly. In our qualification testing, our J4 ball switch is held in actuated position, then submerged in cold water in a -40C freeze chamber. Just before the switch completely freezes into a block ice, the switch is released. In our testing our J4 switch deactivates every time.
  • Extreme electromechanical endurance – Because our switches are often used in critical man/machine safety systems, we’ve qualified versions of this switch to over 5 million cycles.

CPI Ball and Plunger Switches for Harsh Duty Applications

Tough and durable is what we make and who we are. All our products are designed and manufactured in the USA.

If you think your application is tough enough for our switches, give us a call today.

Originally published at

Make The "Switch" to CPI

If your momentary switch application demands high performance, we think you should demand CPI. Please call us today to speak with our engineering team about your needs.

(973) 887-9400