A Single Actuator Button, at each location is all that is needed,
aside from 2 Resistors and some Cat-5-Cable.
Push-On / Push-Off
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This is not hard to push even with Welding-Gloves on ................
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View attachment 324154

Hi,

It sounded to me like the idea was to be able to change the speed of a motor for a pump, not just turn it on or off. Did you have something else in mind.

 

Hi,

You mean you are willing to take responsibility for the workings of fire trucks for two entire countries? That's guts

I mean that the circuit I suggested with the relay that I specified will provide the correct control functions for the specified application, if it is assembled correctly. Copies made by others are subject to separate evaluation.

 

The objective,
with the extremely limited information that we have to work with,
is to simply create 2-Voltage levels at a particular Micro-Controller's Input-Pin.

The first Voltage-Level should be probably ~1-Volt, which commands Governed "Idle-RPM",
this first Voltage-Level must have some adjustability, at first with a Pot,
and when the desired Idle-RPM is agreed upon, the Pot could be replaced by a 2-Resistor-Voltage-Divider.

The "3-way-Light-Switch-Circuit" will simply disconnect, or connect,
the Engine's ECM / Micro-Controller-Ground-Connection to the Voltage-Divider,
rendering either a pre-set Low-Voltage for Idle,
or the full "5-Volts-Ref" Voltage to the Engine's ECM / Micro-Controller, RPM-Input-Pin,
which will result in Maximum-Governed-RPM from the Engine.

At either station, and in any sequence, each press, of either Button,
will result in the Engine alternating between a Governed-Idle-RPM, and Maximum-Governed-RPM.

Super-simple.
And, only requires cutting the Ground-Wire going to
the existing Speed-Control-Pot mounted on the Engine, and removing it's Knob so that it won't be used
for anything other than semi-permanently setting the Idle-RPMs.
The Factory Speed-Control-Knob will never be needed for any other use,
except possibly for returning the Engine to the Factory-Stock-configuration if ever desired.

Nothing to break,
If a break in a Wire occurs, the Engine will default to
Maximum-RPM-operation, with no Idle-Speed-Mode available.
If a Short to Ground occurs in any Wire, the original Speed-Control-Pot will function as normal, if it is retained.
If the original Speed-Control-Pot is physically removed,
a Short-Circuit to Ground, in one of the Wires, may render an Idle-Speed-only condition.

But, of course, no open-Circuit, or Short-Circuit, will ever occur, because the Wiring,
and the mounting of the Heavy-Duty, Industrial-Quality, Push-Buttons,
will be performed by a Competent-Mechanic using approved methods and materials,
and completed in a "workman-like-manner".
( Whatever that is. I always laugh when I see this last, supposedly "precisely-descriptive" phrase ).

No Electronics competency is required by the installer, or anyone needing to work on the Engine.
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I believe that the TS has gone AWOL already.

 

I mean that the circuit I suggested with the relay that I specified will provide the correct control functions for the specified application, if it is assembled correctly. Copies made by others are subject to separate evaluation.

Hi,

Well, I am not sure that makes any sense, but ok.

 

I believe that the TS has gone AWOL already.

Ha! Figures. Maybe he got the hint about a professional team doing the project instead of random internet people
I help lots of people with lots of projects through different media and in-person meetings, but the importance of this project seems to suggest a team of experts should be working on it rather than just one or two who have no direct responsibility to the success of the project.

 

While your aspirations are noteworthy. I suggest you turn this over to an insurance underwriter before you spend additional time and effort. Once you get an idea of insurance costs you can then make an intelligent decision as to how to proceed. Modifying Fire Apparatus is second only to modifying medical equipment. The cost of failure in either instance is greater than the cost of establishing residence on Venus

 

While your aspirations are noteworthy. I suggest you turn this over to an insurance underwriter before you spend additional time and effort. Once you get an idea of insurance costs you can then make an intelligent decision as to how to proceed. Modifying Fire Apparatus is second only to modifying medical equipment. The cost of failure in either instance is greater than the cost of establishing residence on Venus

As for insurance underwriters, the policy of "CYA" no matter how much it prevents the application from even functioning is fairly well known.

 

While your aspirations are noteworthy. I suggest you turn this over to an insurance underwriter before you spend additional time and effort. Once you get an idea of insurance costs you can then make an intelligent decision as to how to proceed. Modifying Fire Apparatus is second only to modifying medical equipment. The cost of failure in either instance is greater than the cost of establishing residence on Venus

Hi,

I tried to get this point across with a little comical line about asking for help designing and building a laser eye surgery machine (ha ha).
The point being that some things are much more critical than others. Try building a rocket ship that puts a satellite in orbit.

Maybe less so would be asking for help designing and building a cell phone from scratch. A lot of priority stuff there.

Now that I think about it even more, there may be a lot of regulations for the fire truck thing too. It's not just a case of bringing it in for Show and Tell and having it rejected.