Seems to be 'self-reversing screw

EXACTLY!

But it needs to be driven at the correct speed in accordance to the rotation of the bobbin. As the hose is pulled out the reversing screw needs to follow the hose so that when it's rewound it continues to maintain its relationship with the bobbin and hose.

 

Seems to be 'self-reversing screw'. Something like this?

Exactly.

ak

 

Just had another thought.

4x4 usually gave a winch on the front, many winches gave a guide that spools the wire back onto the reel.
Maybe you could look into something like this?
https://alexnld.com/product/100mm-l...-linear-slide-stroke-with-42mm-stepper-motor/

 

@Jonlate That's a reasonable approach. However, when the hose is unwound anything other than fully unwound it can't be known where to start guiding the hose or which direction to start it in. The only solution is going to be that it has to KNOW where the hose is and how much has been extended so it can competently wind the hose back onto the bobbin without doubling over some of the already wound hose. I don't know how wenches do it; so your idea may have some merit.

 

All the wiper motors I've seen had a bell-crank/crankshaft arrangement to produce reciprocating movement.

How you reverse a motor depends on which type. With PM brush motors you simply reverse the current - with wound field brush motors, you have to reverse connections to the brushes.

A simple crank will produce the varying velocity, which is why I have mentioned using a constant velocity cam twice. A CV cam is sort of heart shaped and thus gives the same motion per degree of rotation as it turns. Am I the only one listening to my suggestions?
The reversing lead-screw approach would be a very good one, with the added advantage that with a bit of effort it could be driven by the same motor that winds and unwinds, which would keep things in step very well. But I am not certain where you could find such an item in the size that this project requires. Actually, driving a standard lead-screw with the variable speed gear motor could be made to work fairly well, and it could include the half-turn of the drum as a resting period

 

Am I the only one listening to my suggestions?

No, I heard (read) you. Not a bad approach, but the cam has to drive an arm. Without any way of synchronizing it to the bobbin, it may give good results one time and not so good results the next, and some rather less than desirable results, all depending on where the hose is on the bobbin to start with.

Commercial garden hose reels that have the reversing screw are geared directly to the hose bobbin. When you pull hose out the screw follows along. I also hear you suggesting the user may have to synchronize the screw with the bobbin. I believe I said that already. So, aren't you listening?

I don't mean to be an arse. Sometimes I miss points others have made as well. So sometimes it may appear like I'm not listening either. Sometimes I jump to the end and open my mouth before having read all comments, and I look like an arse.

The success of the project the TS wants is dependent on where the hose is on the bobbin and exactly how that is determined. Mechanical approach as opposed to an electronic approach is likely preferred. However, finding an industrial strength reversible screw may be cost prohibitive to this project. Which is why at one point I said that this project might not be worth pursuing. However, discussion on just how to do so is often stimulating. And makes us think of creative ways to solve problems.

 

I don't know how wenches do it

Seductively?

 

This link http://www.legacymfg.com/instruction-manuals/
will take you to a manufacturer's listing of stuff they make. Scroll down to the "reels" section, then scroll down to the "Levelwind" section. There, you will find manuals with parts breakdowns to show how commercial products do it. It appears that they use the self-reversing-screw. The self-reversing-screw is coupled to the bobbin by a belt. Since part numbers are listed, the self-reversing-screw assembly should be available.

 

I had the same problem back around 1956 with a reel of 1/4 in cable X 2500 ft. Finally milled a level wind screw using a drill press. Rod was 5/8 in. bronze X 15 in. with a steel follower. Rod was driven by reel motor.
What surprised me was that it worked & I logged many holes. Now you can buy a set-up.