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  • #16
    Can you back up to it set it on the tailgate, lift then back up some more till straight WITH A GUY WIRE ON THE TOP TO CONTROL THE AND SLOW THE
    MOVEMENT TO VERTCALE.
    Ed
    Agua Dulce, So.California
    1950 F1 street rod
    1949 F1 stock V8 flathead
    1948 F6 350 chevy/rest stock, no dump bed
    1953 chevy 3100 AD for 85 S10 frame have a 4BT cummins motor, NV4500
    1968 Baha Bug with 2.2 ecotec motor, king coil-overs,P/S

    Comment


    • #17
      I will show you my SNATCH block if you show me yours.. Click image for larger version

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      • #18
        Those photos that were referenced in an earlier post show a variety of ways to do this. And, unfortunately, the vector diagrams and therefore the forces for them will differ. They will differ either by the details or by the basic method. The devil here really is in the details.

        You said, "...bolted the two ears to the base section." Just what are these ears? Are they pivot points which will keep the bottom end of the tower aligned to that base? Are something else? You make reference to the base section. Is that firmly mounted on whatever foundation that will support this tower? And how high off the ground is it? Is the bottom end of the tower section to be raised ON the ground or above it? By how much?

        You talk about using an electric winch. Where will that be mounted? Will it be on ground level or above it? Will there be any supports to keep the winch from moving toward the tower base?

        In order to raise the tower section, one component of the force vector must be in a direction that is normal to that tower section. Initially, that would be in a vertical (up) direction. And it will change as the tower section is raised. If the tower section is flat on the ground and the winch is also on the ground, then ALL of the force will be horizontal and the vertical component of that force vector will be ZERO. That won't work. So some means must be used to redirect that force vector into a more vertical direction. Those photos that are referenced above show various ways for doing this. But again, the devil IS in the details. And that 800 pounds that you estimate the tower section weighs can EASILY be multiplied by a factor of 2, 4, 10 or more depending on the angle of the lift cable. So a winch rated at 2500 pounds can EASILY be overpowered by the 800 pound weight of the tower section.

        Some photos of the tower and the site may be useful here. I can do some diagrams, but I am not going to waste my time until I know more real details.

        A word of warning here. Besides the obvious danger if the tower falls back, like if the cable breaks, there is another potential danger. That is, at some point in raising it, the center of mass of the tower section will pass over the pivot axis. When that happens, the forces reverse themselves and that tower section will start to fall in the opposite direction (toward the winch and cable) The cable will go slack and the tower will continue moving until it is seated on the base. But that alone will not stop it and it will continue to move until something does stop it. This can be the combination of the matching flanges on the legs of the tower AND the pins/bolts that are used as the pivot hinge. But if that will not stop it, then you MUST have something there to do so or the tower will continue until it is on the ground on the opposite side, probably on top of the winch and possible on the person operating the winch. Please think about this before you start to raise it.

        What I would do? You said you raised the top end a few inches so 2x4s could be placed under it. To me that says that three or four people could probably lift it up and onto the base. They would probably need some lumber placed crosswise at the top so that all of them could get a grip. And additional lengths of lumber should be placed at lower levels for when the top is no longer reachable by a person at ground level. NO ONE should ever be under the tower section. An extra safety man may be needed on a rope to prevent the tower section from going too far and falling to the opposite side. You will need a few friends and probably a couple of six packs for after the lift. That's one way but it is probably only good for one or two raise/lower cycles.

        If it will need to be raised and taken down on future occasions, then you probably will want some kind of permanent, winch operated mechanism. And that should have some math behind it. BTW, many of the winches for this size tower are manually operated. If there is already a manual winch in the tower base for raising and lowering the sections, that may also be used to raise/lower the whole thing on the base. A pulley attached to a hard point at some distance from the tower base would be needed.

        Oh, one more question, how many legs, 3 or 4?
        Last edited by Paul Alciatore; 07-11-2020, 05:52 PM.
        Paul A.
        SE Texas

        Make it fit.
        You can't win and there IS a penalty for trying!

        Comment


        • #19
          Originally posted by Ed ke6bnl View Post
          Can you back up to it set it on the tailgate, lift then back up some more till straight WITH A GUY WIRE ON THE TOP TO CONTROL THE AND SLOW THE
          MOVEMENT TO VERTCALE.
          Wouldn't attempt it that way. The closer you are to the bottom the harder is it to lift.
          It's going to be either the raising fixture like shown in some of the pictures or the winch bolted to the trucks hitch.

          JL...............

          Comment


          • #20
            Originally posted by Paul Alciatore View Post
            Those photos that were referenced in an earlier post show a variety of ways to do this. And, unfortunately, the vector diagrams and therefore the forces for them will differ. They will differ either by the details or by the basic method. The devil here really is in the details.

            You said, "...bolted the two ears to the base section." Just what are these ears? Are they pivot points which will keep the bottom end of the tower aligned to that base? Are something else? You make reference to the base section. Is that firmly mounted on whatever foundation that will support this tower? And how high off the ground is it? Is the bottom end of the tower section to be raised ON the ground or above it? By how much?

            You talk about using an electric winch. Where will that be mounted? Will it be on ground level or above it? Will there be any supports to keep the winch from moving toward the tower base?

            In order to raise the tower section, one component of the force vector must be in a direction that is normal to that tower section. Initially, that would be in a vertical (up) direction. And it will change as the tower section is raised. If the tower section is flat on the ground and the winch is also on the ground, then ALL of the force will be horizontal and the vertical component of that force vector will be ZERO. That won't work. So some means must be used to redirect that force vector into a more vertical direction. Those photos that are referenced above show various ways for doing this. But again, the devil IS in the details. And that 800 pounds that you estimate the tower section weighs can EASILY be multiplied by a factor of 2, 4, 10 or more depending on the angle of the lift cable. So a winch rated at 2500 pounds can EASILY be overpowered by the 800 pound weight of the tower section.

            Some photos of the tower and the site may be useful here. I can do some diagrams, but I am not going to waste my time until I know more real details.

            A word of warning here. Besides the obvious danger if the tower falls back, like if the cable breaks, there is another potential danger. That is, at some point in raising it, the center of mass of the tower section will pass over the pivot axis. When that happens, the forces reverse themselves and that tower section will start to fall in the opposite direction (toward the winch and cable) The cable will go slack and the tower will continue moving until it is seated on the base. But that alone will not stop it and it will continue to move until something does stop it. This can be the combination of the matching flanges on the legs of the tower AND the pins/bolts that are used as the pivot hinge. But if that will not stop it, then you MUST have something there to do so or the tower will continue until it is on the ground on the opposite side, probably on top of the winch and possible on the person operating the winch. Please think about this before you start to raise it.

            What I would do? You said you raised the top end a few inches so 2x4s could be placed under it. To me that says that three or four people could probably lift it up and onto the base. They would probably need some lumber placed crosswise at the top so that all of them could get a grip. And additional lengths of lumber should be placed at lower levels for when the top is no longer reachable by a person at ground level. NO ONE should ever be under the tower section. An extra safety man may be needed on a rope to prevent the tower section from going too far and falling to the opposite side. You will need a few friends and probably a couple of six packs for after the lift. That's one way but it is probably only good for one or two raise/lower cycles.

            If it will need to be raised and taken down on future occasions, then you probably will want some kind of permanent, winch operated mechanism. And that should have some math behind it. BTW, many of the winches for this size tower are manually operated. If there is already a manual winch in the tower base for raising and lowering the sections, that may also be used to raise/lower the whole thing on the base. A pulley attached to a hard point at some distance from the tower base would be needed.

            Oh, one more question, how many legs, 3 or 4?
            Paul, to answer some of your questions. The ears or I should have said the uprights of the base are bolted to the two legs of the tower. The tower pivots up at that point. This tower has three legs. The T base is bolted to the anchor bolts that are set in the concrete base. All that is left to do is to stand this thing up.

            My friend sent me this link. This isn't his set up but one that is similar. There are a lot of pics here and you can easily see how this is done with the lift frame bolted to the base. This guy has all the pics you need to see every step of setting one of these towers up.

            http://www.w9gr.com/tower/tower.html

            I understand that the forces change as the tower is being tilted up and all this varies depending of where the cable is attached (height wise) on the tower and the height of the winch.

            Hope the pics he sent me will help explain what were doing.

            JL...................

            Comment


            • #21
              you can do all the vectoring you want but in the end you have to do it with what You have. I have done it and it worked safely and my 15 year old boy was my helper at the time.
              Ed
              Agua Dulce, So.California
              1950 F1 street rod
              1949 F1 stock V8 flathead
              1948 F6 350 chevy/rest stock, no dump bed
              1953 chevy 3100 AD for 85 S10 frame have a 4BT cummins motor, NV4500
              1968 Baha Bug with 2.2 ecotec motor, king coil-overs,P/S

              Comment


              • #22
                Originally posted by Ed ke6bnl View Post
                you can do all the vectoring you want but in the end you have to do it with what You have. I have done it and it worked safely and my 15 year old boy was my helper at the time.
                That's pretty much it. I inquired because I wanted an "idea" of the forces I was dealing with.

                JL................

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                • #23
                  Don't do it on a Windy day..

                  Comment


                  • #24
                    Originally posted by 754 View Post
                    I will show you my SNATCH block if you show me yours.. Click image for larger version

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                    How does it open to insert the line?

                    -D
                    DZER

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                    • #25
                      Pull the pin and swing the shackle thing about 180 degrees... insert line, then close up
                      found it while logging one day about a mile or two from YLW airport here...

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                      • #26
                        You tie a rope to the top so that one man can control it as it nears vertical. He plans a run path so if it accidently comes down, he can clear. Make an A frame from a pair of 2x4s that will stand on the base and act as a gin pole. Two screws put in the top gives a channel to lay the cable across. I would move the cable attachment point up to about 12 ft or maybe 14 ft That will give you better control of the tower as you pull it up. You'll get up to about 30 degrees or so before the cable lifts out of the A frame. One man pulIs the frame out of the way as soon as this happens, or you can just let it fall. I would pull it with a winch mounted to a vehicle, as that way you have decent control over the lift. I would not pull it with a vehicle, although you probably could. It's too easy for something bad to happen- but with the right guy at the wheel it could be safe enough. The man with the rope can work against the winch cable to tilt the tower precisely to align bolt holes in the base, once the tower is near vertical. With the angles laid out, and with the pull point (the winch) about 15 ft from the base, you should be able to pull the tower up with about 2000 lbs of tension.

                        Obviously somebody has to climb the tower at this point to remove the rope and cable. Not clear to me how you need to raise the inner sections- perhaps the winch can help you there too. Run the cable up and over a pulley temporarily bolted to the top of the first section.

                        Oh, now I see you said it was a crank up tower. No need for the winch to extend it.
                        Last edited by darryl; 07-12-2020, 01:18 AM.
                        I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

                        Comment


                        • #27
                          Originally posted by 754 View Post
                          Pull the pin and swing the shackle thing about 180 degrees... insert line, then close up
                          found it while logging one day about a mile or two from YLW airport here...
                          That's real heavy duty. isn't that the one that the loggers use when they run those skylines ?

                          JL....

                          Comment


                          • #28
                            Be careful of that 2,500lbs rating. Auto-type winches are often (usually/always???) rated as the mass of the vehicle the winch can pull out of the mud. It is (probably) NOT the pull the thing can exert on the cable.

                            But if you can manually lift one end of it while the other end is in the pivots (i.e., lift half the weight), then unless you are an Olympic weight-lifter I doubt very much that it weighs 800lbs.

                            Be aware also that those 4WD winches cannot pay out under control, so if for any reason you need to let the tower down again, you're screwed.

                            Your friend seems to be under the impression that once up the tower will never need to come down again. I wish him luck with that—it certainly does not accord with my own experience.

                            Next time he might want to build a tabernacle to pivot the thing on. This puts the pivot point some useful distance up the tower, nearer to its Centre of Gravity, thereby making the whole operation very much easier. FWIW, the tabernacle for my 50' tower (fixed length, not crank-up) is two parallel 4m (13') lengths of 100x50 (4x2)RHS steel, with the bottom metre buried in five tons of concrete. So the pivot is about ten feet above the ground. The winch cable goes from the tabernacle (just above ground), around a sheave at the bottom of the tower, back to a sheave on the tabernacle, and thence up the tabernacle to the winch. That way the pull on the cable is only half what it would be if its end was fixed directly to the bottom of the tower. I recently converted the manual winch to power, using a 1/8HP motor with a reduction box that gives me 24RPM with loads of torque. It's slow but steady, and takes me precisely no effort at all.
                            Last edited by Mike Burch; 07-11-2020, 11:57 PM.

                            Comment


                            • #29
                              "Auto-type winches are often (usually/always???) rated as the mass of the vehicle the winch can pull out of the mud. It is (probably) NOT the pull the thing can exert on the cable."

                              Now, there's another scare factor. So what force can a 2500 pound auto winch actually produce? 2000 lbs? 1250 lbs? 800 lbs? Or what? He says that things weighs around 800 lbs. and this may just about account for that in a straight, no angle pull. It only gets worse from there.



                              Originally posted by Mike Burch View Post
                              Be careful of that 2,500lbs rating. Auto-type winches are often (usually/always???) rated as the mass of the vehicle the winch can pull out of the mud. It is (probably) NOT the pull the thing can exert on the cable.

                              But if you can manually lift one end of it while the other end is in the pivots (i.e., lift half the weight), then unless you are an Olympic weight-lifter I doubt very much that it weighs 800lbs.

                              Be aware also that those 4WD winches cannot pay out under control, so if for any reason you need to let the tower down again, you're screwed.

                              Your friend seems to be under the impression that once up the tower will never need to come down again. I wish him luck with that—it certainly does not accord with my own experience.

                              Next time he might want to build a tabernacle to pivot the thing on. This puts the pivot point some useful distance up the tower, nearer to its Centre of Gravity, thereby making the whole operation very much easier. FWIW, the tabernacle for my 50' tower (fixed length, not crank-up) is two parallel 4m (13') lengths of 100x50 (4x2)RHS steel, with the bottom metre buried in five tons of concrete. So the pivot is about ten feet above the ground. The winch cable goes from the tabernacle (just above ground), around a sheave at the bottom of the tower, back to a sheave on the tabernacle, and thence up the tabernacle to the winch. That way the pull on the cable is only half what it would be if its end was fixed directly to the bottom of the tower. I recently converted the manual winch to power, using a 1/8HP motor with a reduction box that gives me 24RPM with loads of torque. It's slow but steady, and takes me precisely no effort at all.
                              Paul A.
                              SE Texas

                              Make it fit.
                              You can't win and there IS a penalty for trying!

                              Comment


                              • #30
                                OK, ASSUMING that you are going to have something like shown in the photo labeled as Sept09 01.img, here is a spit ball analysis.

                                The triangle formed by the cable in the down/ground position looks like about a 30-60-90 degree one. The most important angle there is the 30 degree which the cable meets the mid point of the tower at. The vertical component of the lift force there would be your 800 pounds and, using trig I get the needed force parallel to the cable as about 1600 pounds. Now, the photo also shows a pulley being used at the connection point to the tower and the cable doubles back to the top of the rigging pole where I assume it's end if fixed. So there is a 2::1 mechanical advantage there and the tension in the cable drops back down to the value of 800 pounds. But please understand that this is ONLY if a pulley is used in the same manner as shown in the photo.

                                The cable appears to go across another pulley at the top of that vertical rigging pole and then down to the winch. This second pulley only changes the angle of the cable: it does not add any additional mechanical advantage. So that 800 pounds would be what the winch needs to apply.

                                There are other elements in that photo. First, there is that vertical rigging pole and it will also see that 800 pound vertical force and must be stout enough to withstand it.

                                There are two diagonal braces on that vertical pole. They serve two purposes: one to act against the horizontal force at the top of the pole and second to prevent the vertical pole from twisting to one side or the other. The second purpose is why there are two of them and why they are fastened somewhat outboard of the main horizontal axis of this set up. That second purpose will probably be taken care of if they are capable of meeting their first purpose. OK for their first purpose: they also appear to form about a 30-60-90 triangle as viewed from the side. Working with trig again, I calculate the horizontal force at the top of the vertical pole to be about 1385 pounds. Why so much? Well, there are TWO cables at the top of the pole and EACH one has about 800 pounds of tension. That's 1600 pounds. When multiplied by the cosine of 30 degrees I get 1385 pounds. But that is at the top of the vertical pole and the diagonal braces are attached at about the middle point so we need to multiply that by a 2X mechanical advantage for about 2770 pounds. That is the horizontal force at that mid point.

                                But it still gets worse again. The 30 degree angle of attachment for those diagonals again doubles that force to about 5540 pounds that is acting along their length. Now for a favorable factor; there are two of them so we divide by 2 and are back to about 2770 pounds. These are loaded in compression and almost any steel will be OK for that. BUT, they will also need to resist bucklling with that much of a compressive load and that is what is needed for the calculation.

                                All of my above estimates are just that, ESTIMATES. I am working from what you said and I can not know what you may have left out. Also, it is generally accepted to use a safety factor whenever any mechanical device is designed. It is DOUBLY important to have a generous safety factor when there is any possibility of injury or loss of life. I would, at the very least, double all of the numbers that I came to above and if I were going to be involved in the erection, I would multiply by a factor of four or five, if not even more.

                                If you alter the details of the design shown in that photo, then all bets are off.

                                Machinery's Handbook gives the equations for calculating the strengths of various materials with the various types of loading that are possible. It would be a good reference to use at this point.

                                I would greatly appreciate it if some others here would double check me on the above calculations.



                                Originally posted by JoeLee View Post
                                Paul, to answer some of your questions. The ears or I should have said the uprights of the base are bolted to the two legs of the tower. The tower pivots up at that point. This tower has three legs. The T base is bolted to the anchor bolts that are set in the concrete base. All that is left to do is to stand this thing up.

                                My friend sent me this link. This isn't his set up but one that is similar. There are a lot of pics here and you can easily see how this is done with the lift frame bolted to the base. This guy has all the pics you need to see every step of setting one of these towers up.

                                http://www.w9gr.com/tower/tower.html

                                I understand that the forces change as the tower is being tilted up and all this varies depending of where the cable is attached (height wise) on the tower and the height of the winch.

                                Hope the pics he sent me will help explain what were doing.

                                JL...................
                                Paul A.
                                SE Texas

                                Make it fit.
                                You can't win and there IS a penalty for trying!

                                Comment

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