Ask Ernie “The Apparatus Maintenance Expert”

CarolinaFireJournal -

04/23/2012 -

What is the required in service testing for engines in service for yearly certifications?

You must perform an annual safety inspection of the chassis. You must perform annual inspections of the aerial device, up to but not including the five year Non-Destructive Testing (NDT). However, after the first or second five year aerial NDT inspection testing, it is my recommendation to perform a five year inspection as wear and tear becomes accelerated as time and mileage accumulate.

Remember that you must also maintain the chassis to each component’s manufacturer’s recommendations. If the apparatus has a tank and pump, the pump must be tested to the pump certification capabilities annually. There are many more items for inspection and compliance to the Uniform North American “Out-of-Service” criteria as listed in NFPA 1911; “Standard for the Inspection, Maintenance, Testing, and Retirement of In-Service Automotive Fire Apparatus, 2007 Edition.” Use it as your bible of minimum required inspections and testing.


What kind of maintenance can I do to prolong the life of my on-board charging system?

The simple answer is: housekeeping. Let’s go to the three primary members of the electrical system:

  1. Battery. Without the battery, you cannot power up the starter.
  2. Starter. Without the starter you cannot start the motor.
  3. Electrical power generation unit: Alternator/Generator. Without the alternator or generator, you cannot re-supply the battery to full charge and run the electrical system.

Properly engineered, once the engine is running, the alternator/generator must supply 100 percent of the electrical load even down to engine curb idle. To keep the three members in pristine condition, you must first confirm that the battery(s) are clean, terminals have NO corrosion, and are tested using the best test equipment available. I like the Midtronics electric test equipment, which can perform a number of diagnostic tests of the system.

Once the battery system is confirmed to be in acceptable condition, move on to the starter and all associated cables and connections. Perform a voltage drop test to confirm that all is well with the system and that the starter draw is within specifications.

Once the starting system is confirmed to be within specs, move on to the charging system. What is the condition of the belt(s)? Belts are cheap in comparison to a call out to take corrective action and the possibility the apparatus did not arrive on scene because of lack of inspection and attention to the belt(s). How about belt tension? Are the belts slipping? Like a bad radiator cap, automatic belt tensioners can lose tension over time. Check it and compare it to specs.

What is the charging system output at idle and at high operating temperatures? Does it meet or exceed specifications? All charging systems today should be specified to handle all anticipated loads on the apparatus. The charging system must be fully loaded with all electrical loads during the annual In-Service pump test. So, when performing the annual pump test, you should see all lighting and electrical loads in operation. I like to use a non-contact heat gun to record the operating temperatures of the alternator under full apparatus electrical loads during the pump test and compare it from year to year.

What type of voltage (amperage) draw does my onboard equipment draw?

Ahah! So you think you were going to catch ol’ Uncle Ernie on this one, did ya? Did you desire the figures for Low voltage (14VDC) or Line voltage (120/240VAC) systems?

Of course, voltage drop is associated with amperage loads. What amperage draw does your apparatus create? Who knows? You can provide yourself with a list of individual loads of each component and add up the total to determine the anticipated load whether you are dealing with Low voltage systems or Line voltage systems. Know your system. A clamp-on digital meter will give you the actual amperage draw figures you are looking for.

Are there any tech websites or forums to help us with fire truck troubleshooting?

Yes, there are a few. I like the longest running and worldwide EVT bulletin board which is specifically intended for Emergency Vehicle Technicians. You can find the EVT TechTalk bulletin board at: Sign up, scroll and enjoy. The website is overseen by moderators that keep it clean. The reason for registering is for the website moderator to keep out any Trojan horses and viruses. If any are found, the registered member’s hacked account is quickly found and the member is notified that they have sent attached viruses. Go, take a look.

Have you had an issue with an apparatus that you could not resolve? Go to your brand of apparatus and see what others have done in your situation. If you do not find the answer there, post your own specific question and watch the help arrive on your screen. Enjoy!

For ISO compliance what should my daily check-offs and monthly check-offs contain?

Some of the very best templates for you to use for the daily/weekly/monthly checks are found in the back of the IFSTA “Pumping Apparatus-Driver/Operator Handbook” and the back of the IFSTA “Aerial Apparatus Driver/Operator Handbook.” If you do not have a systematic form at your facilities, I recommend you use the many forms listed there as a guideline for formulating your own guidelines. If you do not have a copy of the CVSA North American Standard Out-of-Service Criteria (2012 Handbook and Out of Service Pictorial Edition), you may obtain one from J.J.Keller at Go to their transportation issue or type in CVSA and find the latest edition available.You will find it indispensable.

Explain GVW of a vehicle.

The Gross Vehicle Weight (GVW) of the vehicle is more correctly stated as the actual weight carried. However, did you want to know: What is the Gross Vehicle Weight Rating (GVWR) of my apparatus? GVW is mandated not to exceed the Gross Axle Weight Rating (GAWR) of ANY axle on the apparatus. Overloading of the GAWR is illegal in any U.S. state and Canadian Provinces. NFPA also stipulates that side-to-side loading shall not vary by more than seven percent GAWR is considered to be the least capable component of chassis, suspension, wheel, and tire ratings. If a combined tire rating of 21,000# was installed on a GAWR of 24,000#, then the actual rating capability of that axle is 21,000#. Make sure that when you install/replace tires that the tire rating matches or exceeds the GAWR for that axle. In heavy apparatus, combining the GAWR for each axle will determine the posted Gross Vehicle Weight Rating (GVWR). Many states offer special exemptions for fire apparatus and emergency services vehicles. Know your particular state laws before making any assumptions.

How can I check for which roll up door is causing an open compartment warning light?

This is another question with no simple answer. What manufacture of roll-up? What type of switching equipment? Is the system a typical hard-wired system, or is it multi-plex’d? In some cases, you will need a magnet to check for proximity switch operations — for some a digital VOM, and for others, a computer. Know your system. The easiest is to close all doors then open and close each, one by one to see if the interior lighting goes on/off, if the switch controls each compartment light. Mechanical switches can be checked with the VOM. And, of course, know your apparatus.

What is the difference in circuit breaker versus a relay?

Circuit breakers interrupt the circuit flow if it exceeds the load rating of the circuit breaker. Circuit breakers come in either manual or automatic reset features. Each type is installed for specific reasons. If a circuit is overloaded and additional overloads can create cumulative electrical circuit damage, a manual reset circuit breaker is desired for issues like computer or multiplex’d supply circuits. If an overload circuit breaker may need to reset for safety reasons, an automatic reset breaker may be desired as in a headlight circuit. The relay is a completely different animal. Take for instance a starter relay (solenoid) that may take a 25-amp actuation current to engage a starter drawing 400 amps. Without the starter relay, the wiring necessary to carry the starter load would be substantial for any mechanical starter switch. All relays perform this same basic task of utilizing low amperage switches to activate a relay capable of much higher amperage flows.

Relays perform many specific functions including delays in time actuation, called “time-delay” relays. The list goes on and the original manufacturer of the chassis/fire apparatus picks and chooses the specific relay for the specific function. Before you go swapping relays, make sure you utilize the exact same function relay.

How do I test my Allison Transmission by using the touch pad?

There are two specific functions that can be accomplished with the modern day Allison touch pad or “T” handle shifter.

For the touch pad, once you have the transmission at full operating temperature, you can check the fluid level without the need for pulling the dipstick. Park the vehicle, set the parking brake and place the transmission in “N” neutral. Simultaneously push the up AND down arrows and note the change in the display window. Wait for the display to indicate fluid level. If all is correct, it will display “OLOK” indicating that the Oil Level is OK. If it should state OLLO2, the Oil Level is Low by Two Quarts. The same indication for too high may be something like OLHI2 indicating Oil Level High by 2 Quarts.

The oil level transducer in transmission, if functioning correctly, will indicate levels in quarts up to six quarts in volume. If things appear to be out of sync or do not change when adding or reducing levels, the transducer may not be operating correctly. If your readout is indicating more than one quart too high or too low, double check with the Allison transmission dipstick. If you push the up and down arrows and the system enters a “D” function, you have entered the Diagnostic readout and your system does not have auto level check.

Also, any of the shift pad units can enter the Diagnostic mode. Know your system. Also, if you do have the auto level check and get some code numbers instead of the level check, compare the codes with the diagnostic checklist associated with your transmission. Those codes will be in the owners operating manual supplied with the apparatus when delivered to your agency.

What does the relative humidity indicator on my aerial swivel actually tell me?

This one stirred my grey matter. There are two major manufacturers of aerial swivels — Amity and Hydromotion. We all know that moisture in any electrical circuit can doom the circuit contacts to a death sentence. Hydromotion, the larger volume supplier utilizes an electrical grade silicone in the electrical contactor cavity to ward off any issues of moisture in the swivel.

I suspect that your swivel is made by Amity, which used a relative humidity desiccant plug in the electrical cavity that changes color to indicate an issue with moisture within the cavity. There may be more and newer equipment in the use of swivels, but I am not privy to those changes. If you know better, let me know.

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