Ask Ernie - Our ... Fire Apparatus Go To Guy

CarolinaFireJournal -

07/05/2011 -

Should pump transmission fluid be changed every six months in a reserve engine as in the busy rigs?

 Commonly, we utilize the manufacturer’s recommended procedures.  Every six months is overkill to the old seasoned EVT unless you have issues with high humidity that indicates a need to change more often.  If the pumps are run for long periods of time, the heat generated in the gearcase will cook off moisture in the pump transmission.  If water from the firefighting pump is entering the pump transmission, corrective action MUST be taken to prevent further intrusion of water into the gearcase.  Utilizing spectrochemical analysis of the gear oil on an annual basis has lead to oils going out to 5 years with no issues.  Synthetic gear oils are recommended. 


What causes cracks in the rotors on the wheels?

Very simply put: HEAT is the culprit.  The brakes, of course, generate heat to perform the stopping process.  Temperatures can rise to extreme high levels in our vocational use.  By the very nature of our response efforts, we can exercise the brakes to levels not usually seen in Over-the-Road (OTR) trucks.  The extremes of heat generations are an issue, not only with disc brake rotors, but with brake drums as well.  Over time, the disk rotor or drum can break down and crack.  To be very clear, there are types of cracks that need to be addressed. Heat stress cracks in the area of shoe/pad contact is one.  The stress cracks are of little/no issue so long as they are within the shoe/pad contact area and do not radiate out from the contact area and do not crack through the rotor or drum.  The crack process can be accelerated by inducing cold water onto the rotor or drum.  Issues of washing out the wheelwell area upon arrival back at the station before the brakes have cooled is well documented as a cause for rotor and drum cracking.  If you can see a steam column rise from the wheelwell when washing out the wheelwell, you could be heat stressing the rotor or drum.   A crack through the rotor or drum is cause for immediate correction by a certified brake technician as mandated by the Code of Federal Regulations (CFR) 396.25.

What is the proper method of performing a pump service test on my apparatus?

 If you are not in possession of NFPA 1911: Standard for the Inspection, Maintenance, Testing, and Retirement of In-Service Automotive Fire Apparatus, get a copy.  This is your Bible for all things related to the fire apparatus testing and maintenance.  All pumps should be tested to NFPA and manufacturer’s performance standards at least annually or whenever the any component related to pump performance could be compromised.  Things like: pump overhaul, engine overhaul, transmission overhaul.  Pump related activation circuitry issues that have been addressed and supposedly corrected.  The proper method is well spelled out in NFPA 1911 and Manufacturer’s Operator Manuals.  The process requires a well maintained fire apparatus, in good operating condition, clean water devoid of debris, and reliable draft pit equipment.

What are the advantages/disadvantages of a rear mount or rear mount ladder?

 Both rear and mid mount aerials perform the same function at the Fire/Rescue scene.  The mid-mount offers a lower profile than the rear mount and is therefore able to fit into fire stations with low overhead height restrictions.  The Mid-Mount is usually more complicated in its’ design and has a huge rear tail ‘swing’ that can lead to driver training issues. The rear mount has a generally higher overall height. The rear mount will usually have one less fly section than the mid mount and is thus less complicated.  Both rear and mid mount aerials have their pros and cons.  Research well before making decisions. 

Why do we need to know hydraulics in the volunteer service?

Very simply put, for the same reason that full time paid fire service personnel need to know fireground hydraulics.  The firefighter at the end of the hose needs to know that Firefighter/Engineer supplying water for firefighting purposes can provide an adequate flow and pressure to result in an effective extinguishing nozzle performance to do the intended job function.  Too little pressure/flow and the firefighter can be injured.  Too much pressure and the firefighter could be injured.  Practice, practice, practice.  Practice to acceptable standards and you will perform at the scene to a level where everybody goes home at the end of shift.  If you take shortcuts in training practices, you will take shortcuts at the scene with a high probability of injury.

What type of nozzle was it that was used on the 2.5 handlines in the TV show Emergency?

 Not sure if the picture will come through but you can make your own call on it at the video here at the 1:56 minute mark.  Ernie is going to take a stab at it and say that it was one of the first design breakaway Elkhart Select-O-Matic combination fog/straight stream nozzles first used on the west coast  by LACoFD. Ernie’s archived Elkhart Brass Nozzle Company product manuals don’t go back that far.  I had to toss some stuff to keep the house from sinking from the weight of that old printed material.

How much air do you need in the rear tires?

 By the engineering standards set by each tire manufacturer, the vehicle is to be weighed and the air pressure to be put in each tire should match the required pressure to support the actual load on those tires.  The information as to exacting tire air pressure can be found in the engineering data manual suppled by each individual tire manufacturer. The tire engineering data books can be found online.  A sample is: and because we typically use a 22.5 rim, go to page 68 to see how different air pressures affect weight carrying capability.  Typically, tire failures occur due to an overload condition created by actual vehicle overloading or by too little air for the weight carried.  Air pressure must be inspected at nominal ambient temperature and NOT immediately after the apparatus returns from the road with elevated casing temperatures.  With all that being said, the seasoned EVT, through years of experience, will many times increase tire pressures to extend tire mileage and provide for a more stable tire casing in our particular vocation where responses are not straight down the road, but typically are aggressive twist/turn/acceleration/braking operations. The seasoned EVT will never over-inflate the tire past maximum stated pressures on the sidewall of the tire.

At  what point is it okay for firefighters to work on the apparatus — lightbulbs, SCBA Bracket repair, wiring accessories?

 Firefighters are permitted to perform any task to which they have been properly trained.  In-station repairs performed my firefighters is the normal process throughout our volunteer service.  Without that ability, our system of firefighting in the world would not work.  But, as stated, only properly trained personnel should be allowed to perform those functions.  The AHJ (Authority Having Jurisdiction)  takes on the role of risk management for the agency when tasks are assigned to ANY individual, whether a qualified EVT or an assigned firefighter.  Decisions are made at the AHJ level and jobs proceed.  The most critical of issues is brake inspection, maintenance and service.  Any trained person can inspect for brake adjustment.  ONLY properly trained personnel may adjust that same brake.  Code of Federal Regulation (CFR) 396.25 regulates this process and legality.


Answers provided by EVT TechTalk.
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