Sometimes, the best engineering advances arise out of failure. To quote Thomas Edison “I have not failed. I’ve just found 10,000 ways that don’t work!”
Indeed as one looks at the development history of CPI’s patented J4 ball switch, its current category leading performance did not come without decades of trial and error, and improvement. Perhaps the best way to illustrate this is through the story of our use on one of the military most famous military vehicles of the the last 30 years, the Hummer.
In the late 80’s and 90’s the Hummer or Humvee was born. Tipping the scales at 10,000 lbs and getting less than 10 miles per gallon, the military version came to the publics attention when it saw action in the 1989 invasion of Panama, and the first Persian Gulf War. A civilian version of the vehicle dubbed the “Humvee” was first released in 1992 and shot to fame, embraced by celebrities like Arnold Shwartzenegger who went on to own a whole fleet of them!
A Technical and Reliability Challenge
Even the smaller commercial versions of the Humvee faced some challenges owing to the massive size and power of the transmission and drive train, supporting all that weight under extreme operating conditions. One such problem had to do with the detection of neutral in the transmission, the so-called “neutral-safety” application
Neutral safety refers the need to detect when a vehicle transmission is not in gear. Certain actions in the vehicle are only permitted when the vehicle is in neutral and there is no danger of sudden movement. Detection of neutral is one of the most critical safety systems in a vehicle and is present in almost all modern vehicles, both military, and in regular automobiles.
In the Humvee, detection of neutral safety was becoming a big headache for its maker (AM General Corp, and later GM). Qualification requirements for neutral safety required an extremely robust “ball-switch) type design that was waterproof, vibration resistant, could even operate when frozen in ice! It also had to have low profile and extremely high electromechanical endurance over hundreds of thousands of cycles.
But when the makers of the HUMVEE came to CPI, nothing they had tried was surviving the qualification requirements.
Where Other Switches Fail, The J4 Evolves and Succeeds.
While the J4 was already a robust, class leading all stainless steel switch, the requirement to operate when frozen in ice was particularly problematic, as were the mounting considerations for this application.
Learning heavily from the failures of many different manufacturers parts, CPI engineers came up with an entirely new (patented) ball carrier that had the potential to solve both the freezing problem, while simultaneously increasing the endurance of the switch. It works as follows:
In the new J4 design a “double seal” is employed. As pictured below, this sealing mechanism actually seals the actuator both before, and the second seal, seals it during actuation. Not only does this prevent liquid and small particulates from entering the housing, but upon release any unwanted liquids or particulates that have entered the outer chamber are forced back out of the switch.
The seal design has the additional effect of preventing “freeze-up” in the housing by double insulating the contacts from the freezing effects that plagued competitor switches. The J4 ball switch was the only switch Humvee ever tested that was able to operate successfully while completely frozen in ice.
After meeting these electrical and operational requirements, CPI further expanded the base product with a variety of mounting threads and lengths for installation into transmissions and ultimately CPI created a variation of the original ball switch design – the J4 plunger switch, which was used in the Military’s cab tilt limit application, where once again, nothing else survived the qualification requirements.
When You’re Done Messing Around, Try A Real Waterproof Switch
If your application calls for a robust waterproof ball switch or plunger type switch, you won’t find a more durable, or easily mounted, truly waterproof limit switch solution than the CPI J4 series.
Samples are available for qualified applications. Please call the factory.