Almost everyone knows someone who has, at one point or another, depended on a firefighter to help them during a frightening, uncertain time. Which means that almost everyone knows someone who has also counted on a firetruck to be ready and waiting.
“It's not the law or anything, but the standard says that we do annual aerial testing [and] annual pump testing to ensure that the pump [is] moving to their rated capacity, and we're looking for any diminishing returns on any of those,” Sims noted. This testing also extends to voltage drop testing on relays and circuit breakers, and if there’s any drop in efficiency, they have to be replaced. “That’s unheard of anywhere but in the fire service,” Sims added.
Some fire stations also rely on oil sampling, as well as hydraulic tests for aerial systems, generators, or foam systems, Sims continued.
Faults to look out for
Due to their weight and how fire engines tend to drive, this can cause specific issues to crop up for trucks, especially in the suspension and electrical systems.
For suspension systems, fire departments are increasingly moving to air ride suspension systems because they’re easier to service and less expensive, said Warren Miller, shop supervisor for the City of Loveland. But this doesn’t mean that leaf spring suspensions have been fully phased out, meaning that fire department technicians need to keep an eye out for certain wear and tear.
“We actually do quite a few front springs on our apparatus, because [on] the packs, all the springs touch, and then you get a lot of corrosion issues in between,” Lane explained. “So it actually breaks the spring, not from being overloaded or overweight, but from the corrosion.”
Then, Sims added that even with air suspension systems, technicians still need to keep an eye on a truck’s ride height, as failing to do so “can definitely lead to premature wear and tear on your suspension system.”
Then for electrical systems, fire engines also tend to see a lot more alternator and battery issues than OTR or vocational trucks, Gaskin said, just because they tend to put more loads on the electrical system between cab features and lights, AC, etc. This means that technicians always need to keep in mind the impact of those systems when running diagnostics.
For instance, Gaskin outlined a situation where a fire truck is running through batteries at a high rate. So, a technician might use a multimeter to test the alternator with the truck at idle and nothing on except the daytime running lights, finding that the truck is drawing 80-95A at idle, and the alternator is putting out 160-180A. This might indicate to the technician that the issue is something else entirely, since the alternator is meeting the truck’s needs.
“Well, that's great, but what the technician didn't do is he didn't turn on the emergency warning lights and he didn't turn on the air conditioning,” Gaskin explained. “So you turn those on, and you start to see that maybe the truck is now drawing 140 or 150 amps or more.”
Taking into consideration this 12V high-lumen scene lighting, plus the number of those lights turned on at night, plus idling and emergency warning lights and the AC, now the truck could be drawing 230-240A at idle, outstripping the alternator and causing the issue. And the solution to the problem?
“You change batteries and alternators,” Gaskin asserted, alongside teaching the crew to use the high-idle switch, which would boost alternator output, and train them to plug their trucks into shoreline power at home to keep the batteries charged. And in the specification phase, departments should understand the capabilities of various vehicle systems and the demands on the vehicle to avoid creating issues later.
Beyond electrical and suspension issues, firetrucks also tend to see problems with the compartment door as firefighters go in and out, as well as the overall corrosion from road salt. And the design of firetrucks can stress their components, too.
“One of our big issues is with the cabover design of a fire apparatus in these newer engines, there's a lot of heat in the engine compartment, and heat really has nowhere to go,” Lane explained. “So we have a lot of problems with coolant hoses blowing or splitting, and our engine harnesses, the covering will get hard and brittle, and then we'll have wires rubbing on metal and causing a check engine light.”
This can require some specialized maintenance during annual inspections, including cleaning the EGR passages and the exhaust pressure sensor to avoid breakdowns. Lane said they also tend to replace all the coolant hoses every other year due to the heat in the engine compartment to avoid blown coolant lines, “and that’s really helped with our breakdowns.”
Fire apparatuses are not only critical vehicles to the community, they are unique vehicles with specialized needs, too. With dedicated technicians who know what to look for when caring for them, they'll always be ready when the time comes.