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  • Slide lag

    2020 Grand design 390 rk-r. I noticed when pulling in, and extending the 2 main room slides, they both start out together, then one side stops, and when the other side has completed, then the slide that stops starts again. Is this normal operation? Being that they are on the same switch? Thanks.
    2020 GD 390 RK. 2020 Ford F350.

  • #2
    Originally posted by RvPete View Post
    2020 Grand design 390 rk-r. I noticed when pulling in, and extending the 2 main room slides, they both start out together, then one side stops, and when the other side has completed, then the slide that stops starts again. Is this normal operation? Being that they are on the same switch? Thanks.
    Yes this is normal. The hydraulic system will run through the path of least resistance first. When operating the switch for the 2 slides and the both start with one stopping means the one that continues to move is either the first or second in the line plumbing schematic ( not sure which one , I am sure an engineer of some kind will straighten that out for you , might even be a civil engineer).

    Brian
    Brian & Michelle
    2018 Reflection 29RS
    2022 Chevy 3500HD

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    • #3
      Yes, since the hydraulic cylinders are on the same line the one with the least resistance will always operate first.
      2018 F450 Lariat Ultimate 4x4, magnetic grey
      2019 Momentum 381M w/Reese Goosebox 2.0, no FBP :(

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      • #4
        RvPete
        It sounds like the first slide is binding so the hydraulic fluid takes the path of least resistance and continues to move the other slide. When the second slide reaches full travel, the hydraulic pressure builds and pushes the first slide past its resistance. It would be worth investigating why the first slide is binding.

        Edited to remove my comment “this is not normal”. Apparently this is “normal”. (Still something that I would investigate further for root cause)

        Rob
        Last edited by Cate&Rob; 04-20-2020, 06:43 PM.
        Cate & Rob
        (with Border Collies Molly & Angel + Kitties Hazel & Elsie)
        2015 Reflection 303RLS
        2022 F350 Diesel CC SB SRW Lariat
        Bayham, Ontario, Canada

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        • #5
          Originally posted by Cate&Rob View Post
          RvPete
          It sounds like the first slide is binding so the hydraulic fluid takes the path of least resistance and continues to move the other slide. When the second slide reaches full travel, the hydraulic pressure builds and pushes the first slide past its resistance. So . . . no, this is not “normal”. It would be worth investigating why the first slide is binding.

          Rob
          I disagree. There's nothing wrong with my slides. My Momentum has done this since day one.

          I also build hydraulic powered skid steer attachments. Anytime you tie 2 cylinders into a common line this is normal. Each slide weighs a different amount and has a different amount of drag due to surface area of the seals and floor. The easier one will always finish first.
          2018 F450 Lariat Ultimate 4x4, magnetic grey
          2019 Momentum 381M w/Reese Goosebox 2.0, no FBP :(

          Comment


          • #6
            Originally posted by Cate&Rob View Post
            RvPete
            It sounds like the first slide is binding so the hydraulic fluid takes the path of least resistance and continues to move the other slide. When the second slide reaches full travel, the hydraulic pressure builds and pushes the first slide past its resistance. So . . . no, this is not “normal”. It would be worth investigating why the first slide is binding.

            Rob
            I agree there is increased friction on one side OR there may be air in the system that can also operate in this manner.

            Jim

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            • #7
              Originally posted by motocamper View Post

              I disagree. There's nothing wrong with my slides. My Momentum has done this since day one.

              I also build hydraulic powered skid steer attachments. Anytime you tie 2 cylinders into a common line this is normal. Each slide weighs a different amount and has a different amount of drag due to surface area of the seals and floor. The easier one will always finish first.
              No disagreement here. My observation is that the first slide moves easily and then binds until the second slide is all the way out. My comment is that I would investigate why the first slide starts to move easily and then hangs up. May quite likely be nothing significant, as you say . . . or might be an indication of the start of a problem.

              Rob

              Cate & Rob
              (with Border Collies Molly & Angel + Kitties Hazel & Elsie)
              2015 Reflection 303RLS
              2022 F350 Diesel CC SB SRW Lariat
              Bayham, Ontario, Canada

              Comment


              • #8
                Originally posted by motocamper View Post
                Each slide weighs a different amount and has a different amount of drag due to surface area of the seals and floor. The easier one will always finish first.
                Both of my Solitudes with hydraulic slides operate as the OP describes and I always figured it was due to differences in the weight and friction of the slides as they move through their range of motion.
                Brian & Kellie
                2020 Grand Design Solitude 310GK-R, FBP, MORryde IS, 1,460w solar and 540ah BBGC3
                2020 Ford F-350 Platinum SRW PSD Tremor, 60g TF fuel tank, Hensley BD3-F air bag hitch

                Previous setups:
                2019 Grand Design Solitude 373FB-R, 2019 Ford F-350 Platinum DRW Powerstroke, Hensley BD5 air bag hitch
                2016 Grand Design Reflection 318RST, 2016 GMC 3500 Denali SRW Duramax, Hensley BD3 air bag hitch

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                • #9
                  I certainly would not argue since I do not have this system but do have that wonderful schwintek system which is completely trouble free. But there can be only so much uneven travel or folks could get into serious trouble with a binding hydraulic system controlling a box of plywood. If both cylinders are on the same hydraulic circuit and connected to a common manifold, they would operate independently based on the friction encountered from side to side. A well designed system should have that friction managed as close as possible on both sides to allow for smooth and even motion. I also pulled up the LCI manual where there are many adjustments to help with this and also there are statements about air in the system which can cause this issue. It does not take much air to cause uneven operation since the air can compress and can give back this compressive energy when friction is reduced at different points during travel.

                  If the uneven travel is minor and the system is not leaking, I would not worry about it.

                  PS. I think one of my Schwintek motors is going bad....again.

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                  • #10
                    Well I will argue then if nobody else wants to.

                    The way I understand this system is there is a valve that can be closed so only one slide operates. This tells me that when the valve is open fluid will be flowing thru the valve and into 2 sets of cylinders. The fluid at this time will want to fill the cylinder the furthest away from the valve first. When this cylinder is full then it will fill the next furthest cylinder and so on. The reason it starts both is the fluid has to find that furthest point. If you would think about a loader on a tractor and you are lifting the loader it rises at a speed , if you curl the bucket at the same time they both will move slower.

                    On this RV hydraulic system they would need to put a restrictor type orifice in the line of least resistance to make all move at the same time.

                    Simple fluid dynamics that was taught in the 2nd grade.(That was fun)

                    Brian
                    Brian & Michelle
                    2018 Reflection 29RS
                    2022 Chevy 3500HD

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                    • #11
                      Thanks to all that replied. I appreciate it.
                      2020 GD 390 RK. 2020 Ford F350.

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                      • #12
                        My Solitude's hydraulic slides have also operated this way from day one, the dinette and kitchen slide start out together then the kitchen slide stops until the dinette is all the way out. It's the same process when retracting them also, dinette first then street side last. I see no issues with it.
                        Jeff
                        2019 Solitude 375 RES
                        2020 Ford F450 Platinum

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