Do Extra Pulleys Make It Harder To Open A Curtain ?

[Don Allen]

I am doing the lighting at a community theatre that has shifted the adjustable floor pulley of their middle stage traveller curtain, from directly underneath the two pulleys at the end of the old theatre track open truss track, to against the wall, aproximately 3 metres away.

 

They have run the cord through ring guides as the cords now go off at about 30 degrees horizontal from the end of the curtain to the wall, so no longer uses the two pulleys fitted to the end of the track, then through a horizontal nylon pulley into a vertical nylon pulley, to go verticaly down the wall to the adjustable floor pulley.

 

Have they introduced unnecessary effort into opening the curtain by having the horizontal, then vertical pulley doing the job of one angled vertical pulley, if so is there a formula or guidelines to convince them of the best way of rigging this manual cord ?

 

They did not think there was a problem with what the had done, as it was a temporary change that has been in place for a while, even though the curtain jams.

 

I have replaced the ring bolts with pulleys, so the curtain no longer jams and replaced the frayed 6mm cord, but would like to replace two pulleys with one, to make it easier to open the curtain. Or is it not necessary ?

[bigclive]

The pulleys won't add much resistance. Biggest causes of jamming tend to be misuse of grease on tracks which can make them really drag or slight misalignment between sections of track that snag a roller every so often.