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The Pressure Governor Broke…Now What???

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  • HFDCLanger
    replied
    Resq14:

    The common problems I have heard about typically deal with a bad pressure sensor on the governor, or a faulty circuit board.
    Exactly my point (bold added for emphasis).


    I have been told that you can not incorporate a mechanical linkage throttle (the old knobs) with a newer electronic engine. When you see throttle knobs on newer trucks, they are typically electronic versions of the old mechanical throttle.
    This is correct.


    Annaville's beasts have such a setup I believe
    Yes, this is the setup used for Annaville's rigs, as well as 82 Houston engine companies.


    Rescue101:

    If you have yet to experience one of these failures,stand by;at some point in your career you will.
    Yes, I have already had a governor fail on me in several instances. In each case it was a failure of the governor itself.

    If it's just the pressure govenor messin'up, yes your override will work.If it's the Electronic control module,the ONLY chance is a reboot.
    Of course. My point is that the vast majority of "governor failures" will be with the governors themselves, therefore the override would successfully overcome each of these situations.


    As Resq14 points out, if it is a voltage issue, you probably won't be able to run the engine at all. If it is an ECM issue, the "stepping on the gas" method definitely won't work, especially seeing as how the pedal is locked out in pump mode on newer rigs. You're only chance in this situation would be some fluke with the manual pump engage override and the like.

    The manual override/throttle/relief valve setup is by far the safest, fastest, sanest, and most efficient protection, and will probably save you in the vast majority of pump control failures.

    Leave a comment:


  • Rescue101
    replied
    Hand throttle?

    Clanger,What hand throttle?If it's just the pressure govenor messin'up, yes your override will work.If it's the Electronic control module,the ONLY chance is a reboot.Since the ECM takes input from two different sources(Cab foot throttle and pump throttle),it was clever of the MFGs to remove one of our options.You might be able to engage the cruise control,or if you're lucky your override MIGHT work.But if it's in the ECM input you're SOL!Best way to check is with the engineer who built your specific vehicle.Although all are built with similar parts all can/are programmed differently along with associated wiring.If you have yet to experience one of these failures,stand by;at some point in your career you will.Have a back up plan in place.Drive by wires great until it messes up then it's not so much fun.Lot to be said for old mechanical stuff,clothespin,visegrips,would almost always get you out of a scrape.Ah,modern technology!T.C.
    Last edited by Rescue101; 06-19-2003, 09:59 AM.

    Leave a comment:


  • BLACKSHEEP1
    replied
    We had Christine try to go into pump and road at the same time, this was when we were driving down the road at 40 mph.
    I firmly believe that the last real firetrucks were MACK CF600's there has never been a better truck. They were simple, they worked and we still have 2 on our department that were built in 1974, almost 30 years ago!!, but it's hard to get parts for them these days. I really don't see anything we have today being around 30 years from now.

    Leave a comment:


  • Resq14
    replied
    Re: Overriding a ECM

    If it's the electronics on the engine, I don't think you have too many options. The common problems I have heard about typically deal with a bad pressure sensor on the governor, or a faulty circuit board.

    If the pressure sensor (or cable) goes bad, the truck can still be operated in "RPM" mode, though you will have to constantly monitor and adjust pressure as you would on a conventional pump. We have had this happen on one of our trucks.

    If the circuit board goes bad, you might be able to manually operate the truck in "RPM" mode. Or you might not. It depends on what has failed. Both of these problems can be replaced in the field by maintenance personnel.

    I have been told that you can not incorporate a mechanical linkage throttle (the old knobs) with a newer electronic engine. When you see throttle knobs on newer trucks, they are typically electronic versions of the old mechanical throttle.

    Could you have a backup electromechanical throttle installed that you could switch to, along with a manual relief valve? Yup, there are lots of these floating around. Annaville's beasts have such a setup I believe (hopefully someone in the know can chime in, and correct me if I'm wrong). All this is assuming a problem in the electronic governor or sensor, and NOT in the engine itself. IF the truck is experiencing voltage issues, it is a very real possiblity that the engine WILL shut down, and no type of throttle/governor/computer can fix this. The computer (and consequently the engine) will not function without regulated voltage in a narrow operating range.

    Since the truck IS running at idle in the example given, it doesn't sound like a voltage issue. But while you're trying to get water to the crew from a secondary source, it couldn't hurt to shut down all ancillary electrical loads, disengage the pump, shut down the truck, then restart the truck and re-engage pump. Again, I'd tend to think that if it was a voltage isssue the engine itself would quit, not just the governor. Sooo, perhaps this wouldn't accomplish a thing.

    As far as using the accelerator pedal to "throttle" the pump... if the pump is engaged, an interlock should disable the cab accelerator. This is a required feature to conform with standards. If this didn't happen, the risk of a truck suddenly driving off is increased. An interesting question to me, is how is the interlock configured. Is it on the Road-Pump valve, or is it a sensor located somewhere else that relies on the pump actually becoming engaged? Someone above hinted that perhaps you could manually engage the pump, then use some type of throttle control (accelerator, high idle, cruise control, etc). Sounded like a creative solution to me.
    Last edited by Resq14; 06-18-2003, 02:19 PM.

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  • HFDCLanger
    replied
    I just thought it might be nice to have a system that would work for 99% of your “governor malfunctions”.

    After all, the governor is the least tested system on the fire truck and has the worst track record. The electronic engine is installed in the hundreds of thousands of heavy trucks world-wide, while the engine governor is only in a few thousand fire apparatus, at best.

    “Just how exactly do you think you're going to install an override?”

    Simple: The override switch cuts power to the governor and powers the hand throttle. Leave the relief valve pre-set 20psi above your standard handline pressure. The governor craps the bed, throw the override switch, and you’re back in business.

    Seeing as how you just drove the truck to the fire, I don’t think that it’s a problem with the electronic engine controls themselves. After all, when was the last time you had the throttle kick out on you while you were driving down the road? Now compare this to the number of times it has happened AFTER you put the pump into gear. Yeah, sounds like it will most likely be a governor problem to me.

    Seems quite logical to me. Much more likely to work than having somebody jump in the cab and step on the gas (which will probably not work if the override didn’t work anyway, and would not work with most newer apparatus when in pump gear), doesn’t require the extra person, and gives much more control and sanity to the operation.

    Makes much more sense that conducting some ridiculous relay operation with a pump that most departments won’t have until 20 minutes after the guys are already toast.

    This having been said, it’s hard to believe that anyone would buy a fire truck today without one.

    Leave a comment:


  • 5pts384
    replied
    The more I read on this post the more I like our 30+ year old trucks. These eloctronics are scary.

    stay safe

    Leave a comment:


  • captstanm1
    replied
    Halligan....tried that..works some times. Has to be a design flaw in that circuit and seems to be a consistent problem for more than one manufacturer...

    Leave a comment:


  • Halligan84
    replied
    //Also...anyone ever had the problem with the apparatus wanting to "jump" as it goes down the road if you do not keep steady pressure on the pedal?//

    Cap.. try pressing your boot up against the engine cover, it seems to keep your foot from bouncing everytime you hit a bump, works fairly well for us.

    Leave a comment:


  • BLACKSHEEP1
    replied
    Ok, the hydrants around here flow about 70 psi, so, if the guys inside had smooth bores they might still be ok, they could also go to a smaller tip. The automatic guys may or may not have a problem because the auto will try to compensate for low pressure, and will, to a point, below, that point they're history. The 100 psi fog guys are in trouble, but they might buy some time by changing the gpm ring on the nozzle to the lowest setting and maybe get some form of stream back, the 75 psi fog guys are in the best shape for the fog tips because they operate off of a lower pressure and they can spin the gpm ring down as well. Still, none of this will work if the pressure drops below about 40psi. We have an engine that used to pull this stuff all of the time, it was a Pierce, we named it Christine after the haunted car. Still in service and hasn't acted up in awhile, but you're right, we had an early electric throttle and you could step on the gas pedal. The new ones, no way will that help you.
    Good question though.

    Leave a comment:


  • captstanm1
    replied
    Here's one.... may take a second to accomplish...but...

    Step 1..order evacuation....NOW

    Step 2..have another pumper hook to your other intake and pump through you with their tank water. in the mean time have them hook to the hydrant ...take the hydrant water and continue to "pump through" your pumper...

    Yes..I hate the electronic throttle.... Provides no escape in this kind of emergency. Also...anyone ever had the problem with the apparatus wanting to "jump" as it goes down the road if you do not keep steady pressure on the pedal? (I know this is another subject).. Only way to fix it while driving is to let off accelerator or.....increase speed.

    Leave a comment:


  • Resq14
    replied
    Thanks for all these great posts and discussions, Lt. It's so nice to be learning things, rather than reading about dashlights, etc.

    Leave a comment:


  • CaptainGonzo
    replied
    Originally posted by HFDCLanger
    Spec'ing a manual override/throttle/relief valve could just save your butt in this case. Many departments are spec'ing these already.


    Figure the standard department runs two engines and a ladder on the first alarm. One attack engine, supplying handlines (craps the bed) and one engine at the hydrant. Where does your "relay engine" come in? Is that on the second alarm from your neighbors 10 miles away? Hmmm, sounds like a good argument for a QUINT. HAHAHAHAHAHAHAHAHAHAHA.

    What's that? Not worth the extra money? Never use it? How about if it saved a firefighter's LIFE? ONCE? Perhaps this is just one example of why so many departments use the "just in case" phrase when they decide to put pumps on their aerials.

    Nobody needs to comment on this post. I just needed to strike while the iron was hot.
    Does Hubba Hubba Hubbardston have Quint?

    Leave a comment:


  • ullrichk
    replied
    Assuming for the moment that the pressure governor went south and it wasn't the ECM/throttle body, could you hit the high idle switch?

    Granted high idle switches are supposed to be "locked out" when the pump is engaged, but when electronics get screwed up all bets are off. (And is the lockout still effective when the pump is manually engaged?)

    It wouldn't be pretty, but you might get enough flow for the hose teams to bail out.

    Leave a comment:


  • Rescue101
    replied
    Overriding a ECM

    Well I'll comment.Just how exactly do you think you're going to install an override?If your problem is the ECM going to idle there is no "override"unless you want to install another complete wiring harness and ECM(Engine control module).There is no way to do this unless perhaps you could tap into the field service mode which would give you a fixed idle of say 1000-1100 rpm.When the module throws a head fit you have NO throttle control,nix nada,zippo!I know of no way currently available to overcome this problem.If the problem is the relief valve/govenor yeah maybe,if it's the module it ain't gonna happen.T.C.

    Leave a comment:


  • hfd66truck
    replied
    ...and everything was going along so nicely.....

    Leave a comment:

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