On Monday, February 10, 2020 at 12:53:44 PM UTC, Tim+ wrote:
fred wrote:
For various reasons I wish to run a thinnish pull cord via 4-5 pulley
wheels. Does anyone know if smaller pulley wheels offer more resistance than big ones?


If you imagine reducing your pulley diameter to zero, then it becomes
obvious that smaller pulleys will offer more resistance. There will be
fairly rapidly diminishing returns for enlarging them beyond a certain
point though.

Tim

--
Please don't feed the trolls

Thanks for all the input. The pulley wheels would be used to change the direction of travel of the cord by 90 degrees. A total of 4 pulleys would be involved. I'm looking at some 40mm diam. closed pulley wheels on ebay which should suit me.
An explanation. THe electric roller shutter door has a corded release in case of a power failure. The garage has a side door adjacent to the motor but at a right angle. This door opens inwards, is rarely used and consequently is always blocked. I want to extend the cord pull to have it drop down alonG the side of the side door so that it could be accessed with minimal opening of the door.

The real answer would be an U.P.S with a fail safe to open the door in the event of power failure.

If only!