Hi-Endurance Switching, Sensing
& Linear Position Sensors

Truck Builders do the Electric Slide

If you haven’t been to a wedding lately you will be horrified to know that most wedding DJ’s are still dragging out the “Electric Slide” as a sure crowd pleaser and dance floor favorite. Being in technology however (and not being much of a dancer) we here at CPI interpret the “electric slide” somewhat differently.

And we are not alone. Client companies around the world are converting systems formally driven by gas powered components to electric solutions. This gives them greener options for system power including solar, battery power, or even hydrogen based fuel cells which are actively under development.

And while electric cars are well established and getting better every year, fully serviceable fleet electric trucks with their higher power requirements, more robust operating environments and greater weight, remain a challenge. Still there are companies out there, chipping away at solutions, one axle at a time.

CPI Limit Switches Find a Home in the Electrification of Trucks

With no engine to speak of, electric trucks need a source of propulsion. Electricity may be the truck’s fuel, but it can’t move the vehicle forward by itself, something has to stand in for the engine. In electric cars, a traditional driveshaft and axle system driven by a centralized electric motor can still work, but In many electric trucks, it’s the axle that must bear this burden. Enter the so-called “eAxle.” Designed as a drop-in replacement for existing truck axles, electric axles have evolved to accommodate fully electric medium-duty truck and bus applications, and long-haul hybrid vehicles as large as class 6.

e-axles can use CPI Switches
Typical eAxle courtesy SAE International

One such manufacturer recently contacted CPI with a problem: How can they safely service these axles, given the high currents and voltages in use by the motors? It turns out that our E1 series Waterproof Limit Switches are often used in applications that require detection of doors or hoods opening, or service panels being removed. In this case, the idea is that once the eAxle cover is removed for service, the high voltage supply will automatically shut off while allowing the low voltage supply to feed through for diagnostic purposes. Simple right?

This kind of application is completely in our switch wheelhouse of course, however we must confess that looking at the environmental requirements may have given us a moment of pause: ie. “…switch must endure a regular spray of hot oil by demonstrating ability to survive complete submersion in hot oil at 120C (the absolute upper end of the range) for at least 500 hours.”

Uh… Yea sure, no problem?

Investigating the Limits of Our Limit Switches

CPI started out back in 1946 making Limit Switches for the military. On tanks, troop carriers, Humvee’s, military aircraft, inside shipboard guns, and even on submarines, our limit switches have found homes doing a wide variety of things over the years. To meet these requirements, CPI developed two variations of their basic waterproof pendant switch. Our normal version of the switch is sealed in santoprene and boasts a temperature range from -40F to 220F, more than enough for almost all industrial and military applications. Occasionally however, the military has needed extreme cold weather performance and so our switch can be sealed in Neoprene rubber which improves its cold weather performance and extends its temperature range all the way down to -65F.

CPI E1092-B9111

For our eAxle application, we’re clearly in a Santoprene world and our team tested a configuration consisting of our E1092 simulated Roller Angle Mount Bracket, used with our B9111-12 sealed waterproof switch. The switch is basically our off-the-shelf switch with a small internal mod to use a Zytel plastic actuator button better temperature performance.

As far as temperature goes, if you did the math in your head, you will note that the customer required temperature range (120C = 248F) is slightly outside our stated range by about 28F, but being extremely conservative with our specs, we felt confident that our switch would survive.

Really, we did.

Fast Forward Five Hundred Hours

In mid-December slightly before Christmas, we fetched a few of our switch assemblies out of a vat of hot motor oil that had been sitting in a temperature chamber at 120C for 500 hours. The team nervously hooked them up to our test fixture and depressed the bracket lever.

But there was nothing to be nervous about. All switch assemblies activated/deactivated perfectly and continued to operate perfectly over continued cycles until our fingers got tired. Honestly did you think we’d write this whole blog just to tell you it failed?

We probably won’t change our posted Santoprene temperature range as a result of this test, but it’s nice to know that we have a pretty big cushion when it comes to meeting our advertised specs.

Keep on Truckin’

Trucks will continue to do their own version of the electric slide. There will be many challenges both technological and economic, in getting large scale adoption for fleet vehicles etc… but we will get there, there is no doubt.

For more information on how CPI switches and sensors can help with your most demanding applications, give us a call today.


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