In this context, when it suddenly stops, it will jump off one of the pulleys
due to the elasticity of the cord, in my view, so make sure this cannot
happen if the tension reduces.
Brian

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"charles" wrote in message
...
In article , fred
wrote:
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

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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.

Have you worked out how much force you'd need to go manual?

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