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Caster flutter on a Permobil M5-DME supplier cannot seem to fix

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  • #16
    The reason dog hair was preventing flutter in my casters is because it was filling up the extra space that was there from broken bearings. I didn't go into detail because broken bearings aren't a concern for a new chair. It was just an example of how increasing resistance can reduce flutter. Having said that, your chair will "settle in place" as it ages.

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    • wchair
      wchair commented
      Editing a comment
      I see now. Thanks

  • #17
    Okey-doke, he's going to get all new caster hardware and give that a try. It's one of those things that's really ticked me off. There are a couple primary selling points to getting an M5 instead of an M3. And there is also a big cost differential. The biggest selling point for me is the speed upgrade from 6 mph to 7.5 miles an hour. Now he's explained that any time you get up around 7 and one of the casters loses contact… And by losing contact he means rolling over a leaf or a twig… You'll get caster flutter. That would've been helpful information in the beginning. What's the point in being able to go 7.5 mph if you can only do it in a perfectly flat hallway or in 100 yards spurts until you rollover a pebble.
    The demo chair didn't have this problem. And mine didn't do this for the 1st month and a half or so either.

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    • #18
      Originally posted by wchair View Post
      Okey-doke, he's going to get all new caster hardware and give that a try. It's one of those things that's really ticked me off. There are a couple primary selling points to getting an M5 instead of an M3. And there is also a big cost differential. The biggest selling point for me is the speed upgrade from 6 mph to 7.5 miles an hour. Now he's explained that any time you get up around 7 and one of the casters loses contact… And by losing contact he means rolling over a leaf or a twig… You'll get caster flutter. That would've been helpful information in the beginning. What's the point in being able to go 7.5 mph if you can only do it in a perfectly flat hallway or in 100 yards spurts until you rollover a pebble.
      The demo chair didn't have this problem. And mine didn't do this for the 1st month and a half or so either.
      a ZX-1 for years. On my second one with lithium batteries; never a flutter. Glad to hear they're doing something about it. These new chairs and modified vehicles a a pain in the ass. Give me the old simple designed anyday.

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      • wchair
        wchair commented
        Editing a comment
        Thanks. My 1st chair 25 years ago was a quickie P210. It had a top speed of close to 9 mph (seems like in the late 90s, Medicare reduced the top speed that it would cover, so all the chairs now have slower max top speeds). But that thing never fluttered.

    • #19
      Originally posted by wchair View Post
      Now he's explained that any time you get up around 7 and one of the casters loses contact you'll get caster flutter.
      Like I was saying earlier just a little misalignment can be worse than a lot of it. Because with a little misalignment the caster may lose and regain contact more frequently than with more misalignment. There is always some degree of flutter. When it's low frequency it may be too little to notice. When it's high frequency there's more of it so it's noticeable. Seems like your guy is making mountains out of mole hills. It is a pain and requires patience but it's not complicated.

      Originally posted by wchair View Post
      The demo chair didn't have this problem. And mine didn't do this for the 1st month and a half or so either.
      Good news right? It's typical that new chairs work well initially, loosen up a bit and need some adjustment a short time later, then stabilize.

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      • wchair
        wchair commented
        Editing a comment
        Yeah, he's trying. He says this set is as tight as possible and they are aligned right, so I think that is why he is planning starting with an entirely new set.

    • #20
      Caster flutter can be tricky to fix. I had this issue many years ago with a different model Permobil and I remember looking at Permobil's service manual instructions. They were extremely finicky, requiring exactly the correct amount of torque to be applied (to be measured with a specific type of tool); and specific type of lubricant among other things. It is probably easiest just to replace the whole caster assembly - both casters, not just one.

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      • #21
        Simple test: If the problem is the caster assembly then switching sides should result in the flutter switching sides.
        If flutter doesn’t follow the caster then it’s something else. I don’t know your chair. But in a rigid frame manual chair the footplate holds the frame together. If the footplate is misaligned then the frame is misaligned and you’ll get flutter. What holds the front end together from left to right on your chair?

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        • #22
          The trouble (?) with bearings is that they are smooth and responsive like they should be. Unless they are knackered or jammed full of crud.
          Bushes are a better option for castor spindles but have their own drawbacks, like regular maintenance. correct fitment (reaming etc) and on.

          I recall my old 50's Triumphs steering head bearings with the disc friction damper adjustment - star tension washer, friction washers and discs etc.
          Then Triumph did away with this. IMO it was an expedient, retrograde step. Then we had to initiate our own remedy to stabilise the steering because it was too bloody responsive. Which we did.
          Then came aftermarket and OE steering dampers

          If you can direct preload on the spindle inner bearing shell only, that may go some way to reducing flutter.

          Me? I would pack those bearings with heavy cable grease, the tar like stuff that sticks like the proverbial. This will go a way to reducing the response of your bearings (and caster spindle) and the inclination to flutter.

          If that was not fully successful or only partially, I would get some good quality heavy leather and fashion a ring that could be compressed directly on the balls.
          If it chews up over time, so what, it is only leather and will not screw up the bearing races or balls.

          Ensure that the bearings are protected from ingress by dust and such.

          The thing is, you want a smooth ride. Engineering design geometry, fixed frame go a long way to achieving that end; but will not always give you a total solution because you are not always running on ideal terrain.
          Try it, what can you lose? A bit of time and effort is all.
          Last edited by slow_runner; 06-28-2020, 01:25 AM.

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          • #23
            What is with marking my post #23 as spam??
            Never mind. Thank you Mods for sorting that.
            Last edited by slow_runner; 06-24-2020, 10:40 AM.

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            • Oddity
              Oddity commented
              Editing a comment
              It's automated. Not sure why this tripped the software. Might be that thing next to the smiley that doesn't load right. What was that? It false positives from time to time but also saves us a ton of work behind the scenes.

          • #24
            Oddity commented Today, 09:59 AM It's automated. Not sure why this tripped the software. Might be that thing next to the smiley that doesn't load right. What was that? It false positives from time to time but also saves us a ton of work behind the scenes.
            It was interesting and a first for me.
            Perhaps it was the editing. I edited my post 3(?) times in succession.
            Last edited by slow_runner; 06-26-2020, 05:24 PM.

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            • #25
              I've been watching this thread and guess it's time I put my 2 cents in. First, the bearings are not preload adjustable. Yes you can make mods to add tension to them but that would grossly increase the jerking when casters swivel when making directional changes at slow speed.
              I had a new 2014 M300, 8 MPH chair. It jerked horribly. So much that it damaged doorways and doors. Permobil attempted to address my complaint by installing an updated spacer to allow casters to swivel freely (they had a slight drag before update). That reduced the jerking but not to an acceptable level. Up to that point I had a small intermittent flutter from rear casters at high speed. Shifting my weight to rear helped reduce it.
              Rough riding as mid drive chairs are, I softened up the suspension. This made the flutter worse. Since these are considered an indoor chair, I accepted the high speed flutter outdoors as typical.
              Attack life, it's going to kill you anyway
              Steve Mcqueen (Mr Cool)

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              • wchair
                wchair commented
                Editing a comment
                This makes sense, when I 1st got chair, anytime the casters would spin at slow speed there was a very small jerk. Not enough to throw me off, but noticeable compared to my other chair. That was prior to the flutter starting… Now, either I've adjusted or they are spinning more smoothly. I'm not sure which.

            • #26
              Originally posted by slow_runner View Post
              What is with marking my post #23 as spam??
              Never mind. Thank you Mods for sorting that.
              The honest answer to your question is I don't know. I didn't realize I did it. I'm really sorry if it created problems for you. Let me know if I need to do anything to correct. Apologies again.

              Comment


              • #27
                Originally posted by wchair View Post
                The honest answer to your question is I don't know. I didn't realize I did it. I'm really sorry if it created problems for you. Let me know if I need to do anything to correct. Apologies again.
                Did I suggest that you were responsible for the spam lock wchair? No.
                My query was an open one.

                Importantly, is your chair sorted now ?
                Last edited by slow_runner; 06-26-2020, 05:48 PM.

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                • #28
                  Originally posted by slow_runner View Post

                  Did I suggest that you were responsible for the spam lock wchair? No.
                  My query was an open one.

                  Importantly, is your chair sorted now ?
                  I just assumed it was me. Anyway, not yet. Permobil rep wants to do all new casters, so I'm going to go with that and see what happens.

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                  • #29
                    Originally posted by wchair View Post
                    Now he's explained that any time you get up around 7 and one of the casters loses contact… And by losing contact he means rolling over a leaf or a twig… You'll get caster flutter.
                    Your tech is telling you what he believes to be the cause. He hasn't explained the why of the matter- possibly he doesn't know himself?
                    The reason has been explained in previous posts, most clearly by Phil, supported by Patrick and Augusts experience.


                    Originally posted by wchair View Post
                    I just assumed it was me. Anyway, not yet. Permobil rep wants to do all new casters, so I'm going to go with that and see what happens.
                    I hope that works for you but I wont be surprised if it doesn't.
                    Good luck with that Wchair; a smooth running chair is crucial and the next best thing to functioning legs.
                    BTW, if my earlier response appeared terse, that was not my intent.
                    Last edited by slow_runner; 06-28-2020, 05:41 AM.

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                    • wchair
                      wchair commented
                      Editing a comment
                      Yeah, with the new casters, I'm going to have him double check the alignment, and check the frame. He has also tightened up the suspension, which I believe will help maintain contact unless I am thinking backwards. I understand what they are saying, and I believe he has said as much, at least in a more simplistic way. Still think he should have said something when marketing the speed of the chair. In any case, it's been properly explained to me by you guys. How have him run through everything when he puts the new hardware on. Thanks for all the explanations.
                      I'm also having some problems with the back… The recline which I'll save for another thread.
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