detroit used the air shut off for years, as an emergency shut down and it is effective
the problems i see with fuel rack shutdowns are they (the fuel rack itself) can sieze or jamb causing a runaway, very dangerous and scarey
and a solenoid to move the rack to shutdown would be ineffective, (the thing is siezed or stuck at full fuel)
the decompressor to me is questionable in that a runaway engine may exhibit some valve float, and some stretch in the rod/piston and cause the
valves to contact the piston, may cause unnecessary damage.
the air shut down will kill the engine dead without damage, and at the very least should be seriously considered by anyone wanting to add
emergency shutdown capability to the engine.
if it is setup as normally closed (spring) and the solenoid has to be activated to open the air valve, then any interuption in electrical power will cause
it to close and stall the engine.. interupting the electrical power opens possibilities to numerous other protection components being incorporated or daisy
chained into the circuit.
i know the last part is repeating myself, but it bears repeating,, it was used successfully for many years on many millions of engines and it works
without fail. you become a believer the first time you hear a detroit go for the sky (4000+ rpm and it takes alot of rpm to float the valves in a detroit!) you reach
for the emergency shutdown and it dies right now, no damage, no fuss , no muss.
detroit used a cable pull emergency with a lock and sear, and if you did any engine work you first made damn sure the system would trip,,,
the example i gave however would be tested each and every time you start the engine, if it failed the engine would not start , to start with.
thoughts?
bob g