Winch with continous variable gear?

[pa36651]

Does it exist any manual sailing winch with continuously variable gear where the torque at the handle is kept constant and the speed of the drum is varying?

[cal40john]

Originally Posted by pa36651

Does it exist any manual sailing winch with continuously variable gear where the torque at the handle is kept constant and the speed of the drum is varying?

Reel winch, used to be common as halyard winches. As the wire wraps on the drum the diameter increases, reducing the gain and increasing the speed of takeup.

Probably not what you were looking for!

John

[tager]

This would require some seriously complicated planetary gears. Unless I am missing some simple idea that would make this possible.

[Blue Stocking]

In what application would you use this winch. 2 and 3 speed geared winches already exist, which shift their ratios by reversing cranking direction.

[Adelie]

CVT is pretty complicated, it's taken decades to work its way into the automotive industry. Putting it in a winch would be expensive and probably less reliable than current versions. Maybe in another decade.

[pa36651]

I would like a winch where the input torque was constant by adjusting the winch speed in a larger range then a 2 or 3 speed winch. Ideally the gear ratio should be something like 5:1 when hauling a slack genoa. When the tension increases the gear ratio shall adjust to 1:10 so the hauling can be made with less effort.

[Blue Stocking]

Interesting concept. I could see the advantage when tacking headsails not bigger than 110%, but for bigger sails, you need to haul in a lot of sheet very quickly. I doubt if it can be done more efficiently than by manual "tailing".
What circumstances can you foresee requiring this winch?

[Pblais]

Ideally the gear ratio should be something like 5:1 when hauling a slack genoa. When the tension increases the gear ratio shall adjust to 1:10 so the hauling can be made with less effort.

An automatic transmission would get a bit bulky. You would want it to be reversed from an automobile so you are in high gear to start and then go to the lower gets. You might want to just go with a powered winch handle and just push the button

Three speeds is all they go and two on most mid sized boats is enough though many boats are using winches that are too small. They are expensive. If the winch is dirty it does work as well. It gets a lot easier if they are clean and properly sized. For a tack I pull by hand, then winch in high and reverse to low. If it is too hard in low your winch is under sized. Three speeds is mostly for the last little bit of sheeting in.

[Blue Stocking]

Paul,

1 way would be with a conical winch drum, and a sheet alignment guide controlled by load sensor.
I haven't had my 2nd coffee yet, so I'm on the fringe mentally

[Pblais]

1 way would be with a conical winch drum, and a sheet alignment guide controlled by load sensor.

I suppose it might work but shifting the wraps down an inverted cylinder is going to rob from the efficiency. The sensor might be done mechanically but I'm not clear how. As this contraption grows the efficiency has to suffer. Arm force increase a little as the penalty. Even a good two speed winch uses precision cut gears and the resistance in the gears when dirty points to the problem of over gearing the device. The changing of the gearing becomes the sticky part. The winch has to hold when you release the handle. A reverse ratchet like the current winches use does that exceptionally easy. It's going to be hard to beat it. If each reversed motion changed another ratio I suppose the process could go to 5 speeds. Skipping between the speeds would be hard. Fitting the larger gears and adding more gears starts to get in each others way. Working in bronze sets the cross section area of the teeth. Some high tech super stainless might do better with smaller gears.

If you take a good two speed winch apart it's hard to imagine something much better. The simplicity and durability combined with the precision make it quite the work of art. Mine are 20 years old and aside from some slight discoloring look as good as new.

Powered winch handle still wins

[malovich]

Input would be a shaft connected to where the sprocket is, the hub would be the drum.

http://www.youtube.com/watch?v=VpjKa...eature=related