You might think that all those emergency vehicles are perfect, but guess what they brake down and have flaws when new just like our motorhomes. Having worked for a fire apparatus builder as a service and warranty manager and also as a delivery and training tech they are not perfect. The trucks build in the 50's to 80's were simple trucks with mechanical engines and transmissions and basic 12 volt and 110 systems. For the most part easy to troubleshoot and repair.
Then in the 80's engines and transmissions became electronically controlled, safety interlocks became required to help prevent operator errors. Multiplexing became the way to wire the 12 volt and 110 systems. Now you needed special equipment and tools to check out and make repairs. We went from simple replays and switches that you could replace in the field to controllers and computers. If one failed you had to contact the manufacture and wait for a replacement.
If it was equipped with a commercial chassis ex. Ford, Navistar, GM and it broke down you hopefully could get the local dealer to push you to the front of the list for repairs. That's if they would touch a large truck chassis. After all they did not like to tick off their good customers that relied on there cars. Also most chassis used for ambulances and fire trucks would have special larger alternators and cooling systems. Most local dealers would not stock them. Special order and wait for parts.
If on a custom chassis ex. Spartan, HME, Duplex or builders own chassis. You still would have to order parts and what for it to ship in. And guess what the chassis builders would some times have to wait for the parts to ship from their suppliers. All this was great on a truck that was new, but fire departments keep trucks for in some cases 30 years. Try getting parts for 20 year old trucks.
On last thing to think about. Most new ambulances start in the $100,000 range for a van conversion. Low end unit. The cut away type will be easily be $200,000 range. A new fire apparatus will start at $200,000 plus and go up to over a million dollars with equipment. Each one of those pieces of equipment can have its own problems that takes the truck out of service.
Just like our motorhomes we hope the builders, dealers and techs find the problems and correct them before we get the units. If not we hope the dealers and techs have what it takes to correct the problems as fast as possible, and the parts that are needed will not take for ever to get.
Personally the dealer I purchased from is not a good one, at least not to me. They missed so much stuff it should not have been delivered to us. Some of the repairs they made caused other problems. Luckily the local Ford dealer and Coach builder have been great to work with. That and the fact I can make some of the repairs and mods myself.
Sorry for the long post.
2014 Coachmen Pursuit 31BDP
2016 Ford C-Max Energi
1987 Chrysler LeBaron Convertible
FMCA Member #F438633 - Good Sam Life Member
Coachmens Owners Group Member