I’ve been working on windows for over 7 years at this point and hadn’t seen hidden pulleys until this summer….when I had three separate projects with this pulley situation. And they were all different from each other!

So this week I installed two double hung windows with hidden pulleys. I was so unsure of how I was going to get new cords installed but knew I’d figure it out eventually. But, I was honestly dreading it. Turns out, the simplest method was correct and I was overthinking it.

I didn’t take any pictures as I was removing the sashes because I was trying to figure out what was going on but I did take a number of pictures and videos when I put the sashes back. I’ll outline the removal process and then outline and add pics for the installation process.

Here’s the pulley situation. You can see where the cord is exposed but here is not visual of the pulley. The cords have a metal cuff of sorts that fits into the plow on the sash stiles. These are new to me.

Steps for removal:

Remove interior stops, label and set aside. Raise bottom sash as high as possible. Remove wooden weather stripping. I was able to do this with just my hands as they were friction fit and not too tight. This is for the best or these would surely have broken. Unhook sash cords from sash if necessary. I was able to pull the cord away from the sash with the cuff and cord intact. Save the cuffs. Set bottom sash aside. If at all possible, lower the top sash as much as you can. I was not able to do this because they were heavily painted shut. This means I had to destroy the parting stops to get the top sashes out. I finally got them lowered and was able to remove the wood weatherstrip as I had with the bottom sashes. Label all pieces and set aside. Remove top sash in the same way as the bottom sash.

To install:

This is a reverse of the steps above, for the most part.

Open the weight pockets by removing the weight pocket cover.

Remove the weights from the weight pocket.

Starting with the top sash pulleys, install new sash cord by pushing the cord through the small hole at the top of the jamb. This video shows what’s happening because the trim for the center mullion has been removed. I could not see the cord moving into the jamb on the far left and right of this two double hung set up.

This is the part that surprised me. I was expecting to have to remove all the trim and cut a whole through the plaster and lathe because I just couldn’t imagine how this was going to work. It seems the pulleys are closed in a way that allows the cord to move through them in a way that typical pulleys are not. It’s pretty slick and very quick. I found it worked even better if I sprayed some dry lube into where I thought the pulley was inside the casing.

Tie the cord to the weight. Remove the cuff from the original cords by opening them enough to allow the new cord to fit. Close tightly over the sash cord. Make sure the small tab on the cuff is installed away from the end of the cord. The length of the cord should be long enough just so the cuff hangs about an inch or two out of the hole in the jamb.

Connect sash cords to top sash and lower the sash as much as possible. Install the wood weatherstrip into the slot on the jamb from the top of the sash.

While the sash is lowered, install two parting stops. Raise sash.

Install the bottom sash cords in the same manner. Lift the bottom sash all way way up to install weatherstrip.

Lower sash into place and install interior stops.