Hello! I was turned to this website by my dad who informed me that theres a whole section of HAMBers who're firefighters. SO, I love restoring old cars, motors and detailing are my p***ions. But what I'm getting at here is I'd like to know if there's anyone out there that can help me better understand the mechanical workings of fire apparatus?
well...why is the pump operations tied to the position of the transmission on the fire engine. for instance in order to pump water it must be in neutral to avoid an aweful griding noise...why is that???
well when i started years back , we put wet stuff on the red stuff, but i still play with cars when not holding a nozzle
Hopefully i can explain.. A fire engine uses the actual diesel engine that powers the truck to operate the pump, when you put the truck into neutral you then go ahead and engage the pump which to my understanding is a transfer of power from the drive shaft to the shaft of the fire pump itself, its just kind of like switching gear in a standard transmission only you do not have a clutch and that is why you get the grinding sound, because your forcing that gear into another one when engaging the pump. hopefully that is clear as mud and answers your question.
To further answer your question..if you do get the grinding noise you are doing something wrong!! it should be a smooth process that when you stop the truck, put the truck into neutral set your air brakes, engage the pto switch(engaging fire pump)and then putting the truck into drive gear it should be a nice smooth process that only takes a couple of seconds to do and when you are all done pumping water you just reverse your steps and drive away.
The Jalopy Journal
