This one had me scratching my head for awhile too. The area where there are four crates, and a large doorway. What you do is as soon as you drop down from the lava area, head down a short pathway that is to the left of you. Turn around and pull the first crate as far back as you can go. Climb over the crate and do the same with the next crate. You will probably have to climb over the second crate, turn around and push it the rest of the way. I believe there is a third crate you have to push/pull as far as it can go. Once this is done, the door to the fourth crate will simply fall open. The wheel will be inside. You have to crawl in and get it. Grab the pully and make your way back to the basket that needs the pully. Push the small crate into position just behind the carrage and quickly put the pully into place (Russians will be shooting at you from across the lava) Once the pully is in place, the Russians will break through a wall and run at you in a large group. Quickly get into the carrage and push the button. Indy will then make his escape across the lava.