CPI Thermals Take the Heat in Military Vehicles.

CPI Pendant Switches on Marine Humvee

While change often comes slowly in the vast military industrial complex, there’s often good reason for that. That’s at least partly because battlefield conditions continue to dictate many of the same unique and complex operating requirements for vehicles, machines, guns, and support equipment that they always have. Survivability of man and machine in forward areas continues to drive extreme requirements back into electronic components and subassemblies related to durability, high performance and accuracy, extended operating temperatures, and long life coupled with fail-safe operation. That’s just not going to change any time soon.

In military applications requiring standalone thermal detection, CPI’s three lines of thermal switch products continue to see widespread use in military vehicles, guns, aircraft and equipment, in both retrofit and new designs. Our product line covers reliable thermal switching from 0 to 1750°F, with products that are proven in the field, made completely in the USA, simple to deploy and integrate, and just plain hard to kill out in the world. They were designed that way for the military over 70 years ago and while they have evolved and improved significantly over that time, their original take-no-prisoners design philosophy hasn’t changed one bit.

Military subcontractors and designers continue to find new ways to deploy our 3 thermal switch lines in applications where cheap sensors and control systems just aren’t tough enough. Here are a few examples.

CPI SnapStat, 0-300F, Bi-Metal Snap Disc, Extreme Vibration Immunity.

Application: ENGINE OVERHEAT SENSOR – The M939 by AMG is a logistical workhorse for the US military, and friendly militaries around the globe. With over 32,000 M939 variations in service around the world, the truck handles transport of both troops and equipment in well over a dozen configurations with a hauling capacity of over 4500 kg or 5 tons.

M939 Military vehicle Thermal SwitchesKey to the operation of the vehicle is the Cummins 6CTA8.3 504 c.i.d. turbocharged engine, producing 240 hp (745 ft-lbf@1500 rpm). This is an engine that does some serious work when pulling a heavy load in the desert so when AMG was looking for a reliable thermal sensor to add to their engine over-temperature control system, the CPI AD series was the only choice. Part of the SnapStat Series of CPI thermal switches, this thermal sensing device is particularly suited to military vehicle applications owing to its 300°F temperature range, its tight setpoint tolerance, and most of all its almost complete immunity to vibration and shock. CPI’s SnapStat thermal switches have a bimetal snap disc that actuates a miniature microswitch . This double snap action makes these switches virtually immune to shock and vibration. Epoxy sealing or glass to metal hermetic sealing makes them ideal for demanding industrial or military applications.

CPI PlugStat, 0-650°F, Slow Make-and-Break, Close Tolerance.

Application: LUBE OIL OVERHEAT SENSOR – The M1 Abrams battle tank has been a guardian of infantry for almost 40 years since its introduction in 1980. It is used by allies around the world and the current version, the M1A2C, extends the production run of this design, adding features  like an active protection system, armor reinforcement and station independent targeting.

Military Grade Thermal Switches

Also present on the M1 Tank is the CPI M2 Thermal Switch (Naming is a coincidence, honest…). The CPI M2 is part of our PlugStat Series of sensors with a temperature range up to 650°F, and hermetic sealing that allows partial immersion in oil as required by the application. As a slow make and break device, the CPI M2 will not chatter at the setpoint and allows graceful switching control as oil temperatures reach their limits and again when they decrease. Made inside a 100% stainless steel body, the device also maintains excellent vibration immunity, and electromechanical endurance of over 50,000 cycles is standard.

CPI Rod & Tube, 0-1750°F, Ultra-High Temperature Thermal Switch

Application: Smoke Generator X2 – Part of the survivability equation for groundCPI switches for Smoke Generation vehicles are tactics for avoiding acquisition once they are spotted. The latest version of the smoke system used on US tanks employs CPI X2 series high temperature thermal switches .  Part of the Rod & Tube series of Thermal Switches, these thermals represent among the highest temperature ranges in the world, boasting high durability along with very rapid response times.

The smoke generator heats what is essentially engine oil to the point of evaporation, and combines it with cool air, in a controlled manner, causing it to condense.  CPI’s X2 thermal switches control the start of the system, sensing that the heating chamber has reached the appropriate temperature.  This is a high-vibration environment, not unlike that of a chain saw.  Additionally, once started, the smoke generator runs with internal temps over 1,000F, no problem for our X2 with its temperature range up to 1750°F.

CPI Rod&Tube Thermal Switches

In our rod & tube thermal switch design, the outer tube expands at a faster rate than the inner rod allowing for movement of one set of a spring & contact assembly towards another set. Setpoint temperature is calibrated by position of the calibration screw which moves the position of the spring & contact assembly opposite of the moving contacts. Electrical circuit configuration is determined by use of insulators. In our MIL connector designs, the terminal screws are replaced with an inner pin and wire assembly that are connected to related terminals on the MIL connector.

Final Thoughts on Thermal Switches for Military Applications.

As a DOD approved contractor, CPI has never stopped making the kinds of ultra-hardened Thermal Switching products that our military demands. Products that help keep our military the most effective and modern in the world. For certain applications in the military world, designers keep coming back to CPI for robustly engineered, field proven thermal products that are made in the USA.

Shiny technology objects will come and go but on the battlefield some things never change.

CPI reliability is one of them.