Worm Gear Self Braking 3

[Cevennes]

I have been finding the anti-backdriving ratios for worm gears posted to be anywhere from 30:1 to 50:1. I want to use a worm gear for a winch but I want a ratio between the input and output to be much lower. Is it possible to have the gearing to be, say, 40:1 and then attach the gear to a larger ouput pulley thus reducing the output ratio and still maintain the anti-backdriving characteristics?

I am trying to come up with an economincal winch design that will be used to manually raise and lower 2-300lbs without having to add clutches or brakes and without having to crank forever on a worm gear.

 

[israelkk]

You should check safety regulations they may force you to use brakes and not rely on the self locking property of the worm gear alone. One issue to remember is that self lock worm gear has an efficiency rate of 0.37 (37%) meaning that you will need to apply more than double the torque manually or mechanically.

 

[Cevennes]

As an alternative to relying on the worm gear for braking, is there a simple bi-directional shaft brake on the market. I have found sprag clutches, uni-directional bearings and very expensive disk brake assemblies but I was hoping for something more elegant and cost effective.

 

[ccw]

Hi Cevennes,

Have a look at

http://www.jeamar.com.

(Canada?)

We have put four of their hand operated marine CMA1100 (approx $1000 US) winches to work in the field, some modified here with tow line elec. instrument cable and slip ring commutator. The riggers like the auto-bi-directional brake. The unit is sprocket chain drive about 16:1. These units are not beautiful but keep on ticking.

I noticed they also have another line with a worm drive with brake winch.

 

[Cevennes]

Thanks Nuclear,

I have actually spoken with Jeamar on the phone. I am trying to create a custom product and they were not interested in anything except their established product line. I approached them because I liked their apparent quality but I need a custom piece and their winches cost too much for me to use and modify.

 

[unclesyd]

Take a look at these winches. I have used several different types and all gave very good service.

Look at their design a winch.

http://www.thern.com/products.php?loc=wghw4k