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Ever see a screw scissor jack let itself down?

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  • #31
    They are not supposed to be oiled. Just like the old drum brake expanders - the maintenance of them specifically states to "Use no lubricant" on them.

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    • #32
      The "jacks" on a camper like those pictures are only meant to be stabilizers.
      They are not meant to take the weight of the camper, even to help change a tire.
      They are there only to keep the camper from rocking as you walk around the inside.
      SE MI, USA

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      • #33
        Originally posted by PStechPaul View Post
        Crush a couple Viagra pills and mix the powder with some K-Y jelly to lubricate the screwing shaft. That'll make it stay up all night!
        Best suggestion yet.

        Nev.

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        • #34
          Trust no jack period. Jack stands must be used whenever you want to go under something being held up with a jack, no exceptions. There are always a few deaths each year from a failed jack and I never here of any deaths from a jack stand failing to hold a load up. Personally I always use a pair rated at twice the load I am trying to hold up. Then lower the load so the stands are holding the load and then I will leave the jack in place just because I can.

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          • #35
            [QUOTE=Tundra Twin Track;n1954760][QUOTE=vpt;n1954662]

            I’ve never seen that ever,I have a Heavy Duty Version of that with a 3.7 to 1 Planetary Reduction that is a first for me also.No clue what truck it’s from but guessing a 1 ton maybe someone can ID the maker.
            Click image for larger version

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            Originally posted by vpt View Post
            Wow that things pretty serious,,, took some effort to build too, with all that reduction it's most likely eliminated the "auto - rotation" problemo... cool jack...

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            • #36
              We used to build checking fixtures for automotive jacks, and I always wondered just how many ended up in the trunk of junked cars that had never been used or even left their homes. Probably about 75% I'd guess.

              I'd bet you'd be able to walk out of a junkyard with brand new ones for all 4 corners for under $20.

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              • #37
                Originally posted by Mike279 View Post
                Trust no jack period. Jack stands must be used whenever you want to go under something being held up with a jack, no exceptions. There are always a few deaths each year from a failed jack and I never here of any deaths from a jack stand failing to hold a load up. Personally I always use a pair rated at twice the load I am trying to hold up. Then lower the load so the stands are holding the load and then I will leave the jack in place just because I can.
                You are a wise man...

                one of the biggest F-up's I see out here in redneck ally is dim bulbs using cinder blocks!!! and they use them with the holes going horizontal!!! not that placing them the other way is much better, I don't care if their solid it's not the place for them... they are not designed to take "pinpoint unit pressures" they can fail in a split second and you will be MUSH...

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                • #38
                  TTT, that reminds me of something I saw years ago during work hours when a buddy and I were headed out of town in a tandem digger truck with a pole trailer behind with a full load of power poles. We were bombing down the highway when we saw a half-ton pulled over onto the paved shoulder and the driver must have had a flat right rear tire because he had a Jack-All under the right side of the step bumper and had the truck high enough to remove the tire. As we neared him we saw the truck start to go sideways because he had so little weight on the left rear tire and he jumped up and went to push the jack over to the left to try stop it from falling down but just as soon as he got level with the back of the truck, the Jack-All slide sideways under the step bumper and the top end of it slammed down into his thigh! It didn't break his thigh bone apparently because he was hopping around in obvious great pain and as we passed we could literally see him screaming in pain. We were going to stop to help him but we saw in the rear view mirrors that at least one car had pulled over so we kept on going.

                  A few years before that I a flat rear tire on a 3/4 ton work truck with a load of pole mount transformers in the back and the only jack there was, was a Jack-All but I was a farm kid and I knew the pitfalls of those jacks. As it happened, I was alongside a farmer's summerfallow field and since it was the middle of December, the ground was frozen so I pulled into the field and parked 90o to the direction of the deep tillage furrows and used the furrows as wheel chocks. Worked like a charm, although I had to really lean the jack over so when it was at height, it was more or less vertical with a very, very low chance of it sliding sideways along the step bumper.

                  Mike279, years ago there was a fellow employee in another town who was working under his car with just a bumper jack holding it up. Apparently his neighbour saw this and told the guy not once but twice to not do that because it was so dangerous. He didn't have to warn him a third time because by then the bumper jack had failed to support the car and the guy was squished to death.
                  Location: Saskatoon, Saskatchewan, Canada

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                  • #39
                    Originally posted by vpt View Post
                    I was working on the camper yesterday and this happened to me. I never thought this was possible and I have never ever seen this before in my life.

                    https://youtube.com/shorts/8RKrmuGkdrc?feature=share
                    That was kinda fun to watch, like watching a metal shaper

                    I wouldnt chit can it. Just maybe check into de-lubing it and as others said. Its only a jack, not a jack stand. JR

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                    • #40
                      The handle is bent wire. It is designed to be moved round to 90 degrees to the thread so that it braces against the ground and locks the thread solid. No problem.

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                      • #41
                        Originally posted by Mike279 View Post
                        Trust no jack period. Jack stands must be used whenever you want to go under something being held up with a jack, no exceptions. There are always a few deaths each year from a failed jack and I never here of any deaths from a jack stand failing to hold a load up. Personally I always use a pair rated at twice the load I am trying to hold up. Then lower the load so the stands are holding the load and then I will leave the jack in place just because I can.
                        The video was of a camper and the jack is a stabilizer jack. The jack isn't meant to support anything beyond keeping it from rocking around when you are walking around it it or doing the nasty. No worries at all of anyone getting hurt as a result of the jack lowering itself.

                        I sure wonder what kind of lubricant they used on it though. I've spent literally years camping in a 5th wheel RV and used those types of stabilizer jacks on four different RV's and never had any of them move at all.
                        OPEN EYES, OPEN EARS, OPEN MIND

                        THINK HARDER

                        BETTER TO HAVE TOOLS YOU DON'T NEED THAN TO NEED TOOLS YOU DON'T HAVE

                        MY NAME IS BRIAN AND I AM A TOOLOHOLIC

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                        • #42
                          Originally posted by Baz View Post
                          The handle is bent wire. It is designed to be moved round to 90 degrees to the thread so that it braces against the ground and locks the thread solid. No problem.
                          Nope. It's an RV stabilizer and they just have either a hex or a hole to put the crank too into but I've never seen anyone leave the crank tool to keep it from turning. How many cranks do you think RV'ers carry with them?
                          OPEN EYES, OPEN EARS, OPEN MIND

                          THINK HARDER

                          BETTER TO HAVE TOOLS YOU DON'T NEED THAN TO NEED TOOLS YOU DON'T HAVE

                          MY NAME IS BRIAN AND I AM A TOOLOHOLIC

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                          • #43
                            I have found my RV stabilizers need to readjusted every couple of days to keep the trailer steady.

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                            • #44
                              Originally posted by bborr01 View Post
                              I've spent literally years camping in a 5th wheel RV and used those types of stabilizer jacks on four different RV's and never had any of them move at all.
                              Only 30 years for my Family. Dad , Uncle and everyone else had some sort of 5th wheel.

                              Those are stabalizing jacks like he said. When the rig is up on its posts they are to support the massive overhang the Americans like! LOL.

                              My uncles rig was 30+, stupid. My parents 5th wheel rig, 28ft. lol. Hualed that thing across america many, many times for its 27yr life. Good trailer. Two trucks with it LoL. It used two trucks, good trucks, F350.

                              I miss traveling. JR

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                              • #45
                                I will echo the stabilizer vs jack comments. The reason that it went down on it's own is called backdrive. The lead angle of the thread needs to be shallow enough to be self locking against the pressure of the load on the lead screw. Selecting the lead angle (pitch) of the screw to prevent backdrive is part of the design process. A stabilizer, vs a jack, is not expected to carry a heavy load so the screw pitch (in this case a steeper lead angle) was probably selected with fast travel in mind.

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