The warp was taken off the reel and rolled onto the drum. You can see the ties for the raddle (group) cross dangling at the end of the warp. Then the raddle was loaded. See the rubberbands on top so the threads don’t come out of the teeth.
The raddle was then clamped onto the loom so beaming could begin. The warp comes off the drum under tension, goes through the raddle and onto the warp beam. The drum is essential to keep all the threads under tension while I crank the beam. Directions for building a warping drum are in my book no. two “Warping your Loom and Tying On New Warps”.