What is this part in my window frame

[SteveF]

I'm trying to repair a wooden window and cannot work out how it should work.

The window is one of those that lifts up - like a sash window - but the part that keeps the window raised seems to be broken and the window won't stay up. At the side of the window frame is a hollow metal tube containing some sort of spiral device. On the window itself are two sping-loaded plastic rods that press against the metal tubes.

My questions:
What is this type of window called?
How does the spiral/tube device work?
How easy is it to fix?

TIA

Steve

 

[masona]

Spiral Sash Window

See this.

 

[SteveF]

Thanks. Spot on. That's enought for me to get it sorted.