Telescoping Boom Question

Pull on one end to extend.
Pull on other end to retract.

Just like a cord on a pair of curtains...pull yourself together man!

What do you hook the ends to? Do you need need a pulley in the right place? The real question is, how do you push a rope without freezing it?

Sorry for the facetious reply ...I shall draw a pic when I get home...you need 'n-1' ropes to extend 'n' sections as I see it.... (Retracting the sections is easy enough).

watch this space

Del

Voilá!

Del

Regards JD.

If the 'extend 2' cable is attached to the bottom (red) section (at any convenient point), then it will automatically extend the black section as the blue section is extended... So now its just 2 cables .

(I shall have a nice cup of tea for that brain wave)

Del

Yes just the two ropes to operate.

Regards JD.

Del: But you neglected to tell the man where to attach the rope! To the bottom of the upper-most segment in the telescope, and run the rope up thru the segments and back down the outside? Would that work? Remember, you're talking to an engineer!

look at a block and tackle. Affix the individual sheaves to the separate stages of your boom to pull the bottom of one end closer to the top of the other to extend. To retract pulling the tops of the stages together.

Pull up or down on one rope and get a synchronized movement of all segments.

can be extended to more segments if needed. No need to "push" the rope.

1. Assume that the retract is by gravity (bi-directional can be done also).

2. Have only one rope going to the operator. Run it from the operator around a pulley at the upper end of the base section and terminate it on the base of the first extension section.

3. Run a second rope from near the top of the base section around a pulley at the upper end of the first extension section and terminate it at the base of the second extension section.

4. Additional extension sections can be done by duplicating step 3. (Run another rope from near the top of the extension section second below the newest around a pulley at the upper end of the extension section below the newest and terminate it at the bottom of the newest extension section.)

When you pull on the operator's rope, it lifts the first extension section up, which lifts the second extension section up simultaneously. All sections raise and lower at the same time, subject to real world limits such as elastic stretching of the ropes.

Simple--JMM

1st assumption does not work in all situations it can stuck

Yes, it can get stuck. By making that assumption obvious, instead of leaving it unstated, I can answer your objection: Use rope loops with an upper and lower pulley, and anchor the loops in two places where stated. The lower pulley would go on the bottom end of the same section the upper pulley was on. The operator's rope would have both its ends tied to the rope loop on the lowest section, so that pulling on one side will raise the second section by pulling that loop one way and pulling on the other side of the operator's rope will lower the second section by pulling that loop the other way.

When I was a child, I had a toy fire truck with a multiple section extension ladder. It was operated in a way similar to the way I first described.

--JMM