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  • Ind. front Susp.

    HELP!!! My Dept, is in a battle for a new engine and the battle is over Indipendant Front Suspension or I beam suspention. The City Councel is adiment about I Beam and the Department wants I.F.S. I need testing info on safety of the IFS vs I beam. I also need turning radious and brakeing distance info. or any info, or web sights on IFS for fire apparatus. Please no cool aid WE ARE IN A SERIOUS FIGHT, Thanks to all!!!

  • #2
    I have no personal pro's or con's to add, but I do remember that it more than likely adds height to your apparatus. If you have a restriction keep this in mind. Additionally, there is a cost difference when compared to a standard front axle assembly.

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    • #3
      *More Weight
      *Increased Cost
      *Reduced Cramp Angles
      *Reduced turning radius
      *More moving parts equal more maintenance.

      Improved ride is marginal and subjective at best. I would stick with the straight beam.

      -- I should note this info is from when we were looking at a Spartan. Not sure how the others fare.

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      • #4
        Out of almost 50 trucks in service, my dept has one with IFS. It's a Pierce. I can paraphrase from our garage supervisor.

        Parts are expensive. Pierce wants you to go to them for parts. They don't tell you who's making the parts for them, that way you can't just call up and get parts from a competitor.

        After buying the first set of parts from them, you get the part numbers off the box, then take those numbers to your parts supplier and he/she can cross reference them so you can buy them cheaper.

        Plus he says servicing the brakes are a real pain compared to traditional I-Beam & drums.

        The benefits do not, in my opinion, out weigh the costs and trade offs.

        I say stick with an I-beam that carries the weight you need, plus a little extra, and push for the maximum cramp angle you can get.

        Here's a quick primer: Understanding Vehicle Maneuverability
        The American people will never knowingly adopt Socialism. But under the name of 'liberalism' they will adopt every fragment of the Socialist program, until one day America will be a Socialist nation, without knowing how it happened. --Norman Mattoon Thomas, 6 time presidential candidate for the Socialist Party of America

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        • #5
          Several years ago, we (the apparatus committee at work) made the decision to start using IFS on all of our apparatus, to include engines, tower ladders, and heavy rescues.

          Based on input from the personnel assigned to these various rigs, we made the decision to stop putting IFS on the engines last year. The biggest complaints we got there the feeling that the rig was "floating" (especially when on the interstate), lack to ability to "feel" where the rigs were going through curves, and there was less ability anticipate weight shift and braking needs.

          However, we have elected to leave the IFS on the tower ladders and the heavy rescues. We've found that the heavier and/or longer wheelbase on the vehicle, the more or an advantage that the IFS is.

          Based on my full time employment, part time employment, and volunteer experience, I've driven close to 100 different apparatus from every manufacturer. I, personally, far prefer a straight axle on the front versus IFS.

          What are the reasons you all want IFS?
          Career Fire Captain
          Volunteer Chief Officer


          Never taking for granted that I'm privileged enough to have the greatest job in the world!

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          • #6
            Outside of my own department, most of my experience with fire trucks is delivering them over the road. When I get into one, it's a pretty good bet that I'll be in it for 1,000 miles or more, much of that on interstate highways. So I don't get to experience them much in local roads, etc.

            In all that, I have driven one Spartan with IFS. It just happens that I got the same truck (a demo) twice and put nearly 2,500 miles on it altogether. The IFS was nicer, to be sure, but not $14,000 nicer.

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            • #7
              Ifs

              Get a hold of your Spartan Regional (not the dealer) but the actual RSM for your area. At one time they had a form that showed the braking difference with IFS with Disc brakes and MFS with disc. The meritor with disc is far superior stopping than IFS. The reason why braking is better with a solid beam is due to less deflection in the suspension. Maintenance is far less expensive with the solid beam. Also watch out how manufacturers label their cramp angles, typically with IFS you end up with larger tires either 385 or 425 depending on manufacturer. Usually a 315 tire with an 18k axle will give you 48 degrees left 44 degrees right depending on the cab and chassis manufacturer. Also if you are concerned about turning radius you need to consider the following: Front bumper extension, cab overhang (centerline of axle to front of cab) and wheel base. I apologize for the dissertation, i have driven both, the solid beam is still the tried and true product.

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              • #8
                You need to look at the bottom line for maintenance and repair costs, and the people doing it. Some of the old "salts" may not know how to correctly inspect the IFS, but are damn good with the I-beam. Some may need to be educated. Ride quality is slightly better with IFS compared to an I Beam, but that isn't a good gauge to go from one to another versus cost.

                Taking into account your street conditions, weather conditions, the IFS will get abused more, and fail more often, than an I-beam system. As for braking statistics, I don't think there is an advantage over one or the other. Spec your brakes accordingly.

                Personally, I don't see any reason to get an IFS, except for bragging rights, when all is said and done.


                FM1
                I'm the one Fire and Rescue calls, when they need to be Rescued.

                Originally posted by EastKyFF
                "Firemens gets antsies. Theys wants to goes to fires. Sometimeses they haves to waits."

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                • #9
                  I'm siding with majority opinion on this one- solid axle.

                  C6

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                  • #10
                    The few IFS equipped trucks I have driven, you really couldn't tell the difference unless you drive over curbs a lot. Then the IFS was better. And if you drive over curbs a lot, you are going to have tire problems and shocks wear out quickly. The big 17" disc brakes on the solid axles stop as well as any. Solid axle the best choice in my opionion.

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                    • #11
                      (insert knowing smile here)

                      ....but if you don't spec (brand specific trademark) or IFS, you can't succesfully exclude other bidders!

                      j/k. Couldn't resist.

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                      • #12
                        The american heavy truck world moves on solid front axles. Tried and true, parts available many places, and cheaper.

                        Difference in ride may be a factor for IFS, I can't comment.

                        When looking at breaking distances READ THE FINE PRINT. I know of a major manufacture that has data to show much improved braking with IFS. In the fine print it states the tests were a solid axle with 15" discs vs IFS with 17" discs. Get a comparison with equal brakes installed for a real test.
                        We do not rise to the occasion. We fall back to our level of training.

                        Comment


                        • #13
                          Counsel wants it!!

                          Why does your council feel qualified to make this decision over the desires of the Fire department. My dept.'s newest engine has IFS and most prefer driving it over our older I-beam units. Try talking to a couple sales reps., I'm sure they'll get you any info you need to get the deal done.

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                          • #14
                            Of course a sales rep will tell you IFS is better. It's more expensive , hence more profit in his pocket.

                            In some applications IFS will improve ride & handling, in other types of terrain it will scare the bejesus out of you.
                            If you are running on flat level roads that are all paved it's probably ok.
                            if not stay away from it as you will never know what it's going to do next.

                            Comment


                            • #15
                              Well, so far, it looks like more FD's prefer the I-beam over the I.F.S.

                              Doesn't sound like the OP is going to get the help he wants from here. Hope his Council does not see this thread!
                              "This thread is being closed as it is off-topic and not related to the fire industry." - Isn't that what the Off Duty forum was for?

                              Comment

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