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Ever see a screw scissor jack let itself down?

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  • Ever see a screw scissor jack let itself down?

    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
    Andy

  • #2
    That is furking scary, cut the bloody thing up for scrap, jacks do no lower themselves, no buts that is dangerous imho, seen a catastrophic fail where the cheap nylon nut stripped but never demonic possession.
    mark

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    • #3
      Nothing that a little pine sap or tar on the lead screw won't take care of....

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      • #4
        That is not normal. I would immediately take that jack out of service, turn it into a pile of parts.
        25 miles north of Buffalo NY, USA

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        • #5
          It's just super free and been treated with good lube, you can "thicken" things up a bit to create the extra drag needed, that jack as is takes minimal effort to raise a vehicle (or whatever) which is great in that respect --- I rather deal with that and know the lead's not all butchered up and about to strip the nut and the whole kit and kaboodle fall in an instant...

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          • #6
            The only remedy is a less slippery lubricant on the parts. Please tell us what the lubricant was as there are times when the best qualities are appreciated.

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            • #7
              Did you clean off all that nasty grease and replace it with some quality oil?
              Many a scissor jack has been ruined with WD-40 or spray silicone lube.
              SE MI, USA

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              • #8
                I bet the crank's handle has just enough counter weight to keep the screw turning under pressure. But, it also has to be lifted on the other side by the jack's screw design. I wouldn't trust it even without the handle attached. I've seen some trailers with trailer tongue type "leg" jacks using one vertical screw that swing down from the frame, and lock in place. They are then cranked into desired position. Would that type of screw jack be less prone to self actuation?

                Must be interesting to be rolled out of bed by the camper, rather than you rolling out of bed...
                S E Michigan

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                • #9
                  My go to lubricant especially for things like this is chain lube. I will have to look when I get out to the shop what brand it is.
                  Andy

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                  • #10
                    If it's not used but once in a great while fine sawdust will take care of things also - just a quick dusting and your good to go...

                    a long term honorable mention would be to clean it all up and then melt paraffin onto it - great lube, thick stuff and repels dirt, last forever...


                    My mills table actually does this lol it will not keep going but I cannot "park it" with the handle hanging off to one side or it will migrate to the bottom so have to "unplug it" every time... no big whoop she's free as a bird....
                    Last edited by A.K. Boomer; 08-03-2021, 12:15 PM.

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                    • #11
                      Is the lead of the screw a double lead or at least a fast pitch? Is it a vee thread? Most good screws are a Acme thread. the faster the lead, the more likely this would happen. To visualize a self actuating thread, think Yankee Driver. Most old timers remember them.

                      Sarge41
                      Last edited by sarge41; 08-03-2021, 12:06 PM.

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                      • #12
                        Ok, who remembers the old bumper jacks that you could let the handle recoil and it'd keep bouncing and lower the car all by itself.

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                        • #13
                          Originally posted by paul463 View Post
                          Ok, who remembers the old bumper jacks that you could let the handle recoil and it'd keep bouncing and lower the car all by itself.
                          I do I do lol

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                          • #14
                            A "hi-jack"? Ever have it not latch and gave the handle come back and nail you in the chest? Good times!


                            Here is the lube I use on everything. I usually go for the cheap stuff.
                            Click image for larger version

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                            Andy

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                            • #15
                              Perhaps not exceeding the design weight would be a good idea

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