Gear Ratios and Progressive slowing?

[HUGETOOL]

I would like to take a line of rope and slow it down to a stop in a relative short period of time using a gear mechanism that would activate when touched to the reel wheel. Any suggestions on something that may already be out there or perhaps the easiest way to go about doing this? Thank you for any help in advance.

 

[Danger]

Welcome to PF, Hugetool. (Although I suspect some exaggeration there...)
You haven't mentioned the scale of this rig, or how strong it has to be. Moreover, why does it have to be a gear mechanism? A simple brake shoe would do just fine.

 

[HUGETOOL]

I wanted this to be automatic; I don’t want anyone to have to apply the brake. I assumed that it would have to wind down to a stop. I prefer to keep it mechanical rather than use a computer to regulate a brake. The device would have to be able to stop a few humans from pulling away from the reel.

 

[pantaz]

You still need to answer the questions in post #2.
Are you looking at 4mm nylon rope with a 2kg sandbag, or 3 inch lines on a tugboat?
Is the wheel (winch drum?) spinning 5 rpm, 500 rpm, 5000 rpm?
Does it need to stop in 6 inches or 6 feet?
What are the consequences if it stops too short, or too long?

 

[mgb_phys]

Isn't a centrifugal brake the normal way to do this?
You can buy them off the shelf to attach to the winch, or you could just use a self retracting lifeline that includes the cable, winch and brake.

 

[HUGETOOL]

The line is thin just a few MM thick nylon with btwn 20-100lbs pulling on it. The wheel has a RPM of around 20-100. I would like to slow down within 2-3 feet.

Thanks for the help so far!

 

[TVP45]

You might look at Ziplines for ideas.

 

[HUGETOOL]

That is very similar and kind of where I’m coming from; only the line in this case would be between the unit and the moving weight. On most long zip lines they have a mechanism to catch the traveler at the end of the line using dampers and springs.

 

[pantaz]

How is the brake going to be activated? (Will the operator initiate braking, or will the moving load trip a switch/lever?)

Can you post a drawing or photo of the machine? It's very difficult to figure out what we're deaing with from your cryptic descriptions.

 

[HUGETOOL]

The user will activate the mechanism by pushing down on a button manually; although I would also like to look into activation based on speed. I have no pictures as this is something I would like to design. Imagine an adult running from a stationary object and instead of getting hurt by a quick stop. The adult comes to a slow stop from resistance on the line. The retractable line becomes free after the user releases the button.

 

[Danger]

I thought of this about 8 hours ago, but couldn't get on line.
How about you just use a grab-by-the-nuts-stop-right-now ratchet brake on the reel, and connect the passenger to the line with a bungie cord?

 

[Bob S]

I suggest you look at electric brakes for trailers. See
http://shop.easternmarine.com/index.cfm?fuseaction=catalog.catalog&categoryID=149