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  • #16
    Basing on my knowledge of HEAVY chassis,this rig acts the same as our medium wheelbase heavy wrecker only exaggerated.With a heavy load on the underlift you'll get a light "hammering"with ours at just about 35mph,goes away either side of that.You can also get this condition with a dump truck when the chassis is too short or the centerpoint of the rears is too far ahead.The underlift shifts a lot of weight to the rear and unloads the front. Not knowing what this ladder has for suspension or centerpoint I can't speculate further.However,ten years of wrenching in heavy truck would lead me to believe this problem is deeper than just springs and shocks.Waaay too much flexing going on.Be interesting to see if anyone ever figures it out.Looks like Valleybreeze is looking for a key change.Fixes all known automotive problems.Either way it's not a vehicle I could put a lot of faith in,given that it's a new EMERGENCY vehicle. T.C.

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    • #17
      Do any of you guys think that the pulsations from throttle harmonics could be causing this chassis flexing? From the video the rig doesn't look like it is going all that fast. I've experienced it around 30 MPH. And once the throttle harmonics set in the pulsations do get pretty rough until you let off of the throttle. I know from experience. I wonder if someone could tell us if the engine is pulsing while the rig is flexing?
      I can't believe they actually pay me to do this!!!

      One friend noted yesterday that a fire officer only carries a flashlight, sometimes prompting grumbling from firefighters who have to lug tools and hoses.
      "The old saying is you never know how heavy that flashlight can become," the friend said.
      -from a tragic story posted on firefighterclosecalls.com

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      • #18
        Originally posted by IronsMan53 View Post
        Do any of you guys think that the pulsations from throttle harmonics could be causing this chassis flexing? From the video the rig doesn't look like it is going all that fast. I've experienced it around 30 MPH. And once the throttle harmonics set in the pulsations do get pretty rough until you let off of the throttle. I know from experience. I wonder if someone could tell us if the engine is pulsing while the rig is flexing?

        That's a great observation. I have had that happen many times to me in our E One 1000 gal pumper tanker, it's a long wheel base I believe Hurricane chassis. It responds like that.
        Last edited by MurphysFireKC; 01-17-2007, 10:29 AM.

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        • #19
          Flex-e-Flier

          It looks like a way too flexible frame and a harmonic being set up by a combination of the road surface frequency, the spring rate of the tires, front and rear suspension spring rate and the shock dampening. Maybe some throttle bounce thrown in.

          Years ago we had a snorkle aerial that would bounce you out of the drivers seat if you kept the speed constant at about 35 mile an hour. The chassis manufactuer, Hendrickson (now gone) changed the front tires from a Goodyear cement mixer type front tire to a Michelin Pilote type tire and about 90% of it went away. By changing to a different type of tire it changed the spring rate of the front suspension system and changed the frequency of the harmonics.

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          • #20
            throttle

            I'm down with the Throttle bounce theory.
            I wonder if the department or dealer has investigated that possibility. If it is throttle bounce, Lifting your foot off the throttle for a split second will make it all go away. The combination of a rough road, an air ride driver's seat, and not having the heel of your boot on the floor can result in the "bounce" - leave your foot on the throttle after sensing the bounce - and go for a bumpy ride.

            That's my guess.

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            • #21
              Not the throttle bounce theory

              I know anyone from ALF would love to make this a driver issue but this is very much not a throttle problem. This truck has been driven by many people and it does it not matter how you have the seat positioned, full up or full down, foot plasted to the side of the dog house and the throttle looked at over and over. If it was just driver error then ALF would not be sending a flat bed to take it back to the factory to see if they can find out what is wrong with it. And they are doing this only after the stories showed up on the local news, newspapers, here and other internet forums. The Chief has been trying for over a year to get them to address this issue.

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              • #22
                >"And they are doing this only after the stories showed up on the local news, newspapers, here and other internet forums."

                and they don't want it replaced with a Pierce.

                But the damage has been done to ALF.

                Good Luck!!!

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                • #23
                  ALF Problems

                  We purchased an ALF 75' Telesqurt in 2003. It has a 1500 Waterous mid-ship pump. Soon after taking delivery, we started to notice a "bounce" in the front end of the truck.

                  We had the driveline replaced since it was thought that it was out of balance - that didn't cure the problem.

                  Next idea was that a rim on one of the steer tires was bent - nope that wasn't the problem either.

                  Next was to have the transmission and engine checked while driving - these two test didn't reveal anything substantial.

                  Around 20 - 40 mph, the front end starts to "bounce" and while I was out with the local Detroit Diesel tech, we had it "bouncing" so bad that I swear the front end jumped off the ground.

                  ALF states that there is no problem with the truck - typical response from a factory.

                  Our longtime Pierce sales rep who has been repairing fire trucks for the past 20 yrs stated that the problem is "frame flexing". Our chassis has no reinforcements due to the length of the truck (220" WB). We have a 1994 Pierce Dash with a 198" WB and the frame is doubled back to the duals and we don't experience this "bounce".

                  Seems as though we can not convince the good people at ALF that this is or could be the problem. If this is the problem, I'm not sure what they would do to correct the problem or do anything at all for that matter.

                  http://www.americanlafrance.com/inte...=21&nd=1&x=380
                  If the above link worked, you will see our truck.
                  Jim Shultz
                  Oshtemo Fire Dept
                  Fleet Maintenance Specialist

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                  • #24
                    anyone have any updates what the outcome of the town meeting was?

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                    • #25
                      Video tape it.
                      This space for rent

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