In the Research Lab, Lara will need to get down to the tomb in the lower levels of the building. However, the door to the bottom level (1) is locked and can only be opened from the other side. To create an opening to level 1 she needs to make an elevator fall down it's shaft. It is done by breaking the four gears on the bottom corners of the elevator.

1.
You enter the shaft at the 2nd level by activating a door. Go to the elevator panel here and activate it. The elevator moves down to the 2nd level, but jams.











2.
Climb onto the crates to the right of the elevator doorway and pry the gear (in the right-hand front corner), that is now accessible, with the axe. The gear gives way and the elevator sinks a bit lower in the shaft.











3.
Climb onto the (somewhat) lowered floor of the elevator at this level and climb through the square opening in the back so that Lara drops onto the staircase. Go the short distance down to the locked door on level 2 and pry it open with the axe so Lara has stairway access to levels 3 and 4.

1.
Climb the stairs to level 3. (You may find a document here.) Activate the elevator on the console here. It moves up and stops at the 3rd level.











2.
Now take the stairs back down, but stop halfway between levels 2 and 3. Jump onto the platform there, where a second gear (right-hand side, at the back, as one entered this area) is now accessible through a small square opening in the shaft.











3.
Pry it loose using the axe and get down from the platform.

1.
Go up to level 4 - jump the gap in the stairwell on your way. Activate the console there so the elevator moves up to the 4th level.











2.
With the elevator on the 4th level, go down to level 3. Jump to grab the ladder and climb to the top.











3.
Pry the gear (left-hand side, front, as you entered the area) that is now accessible through another small square opening in the shaft's side. "OK! Just one more to go!"

1.
Climb down the ladder and activate the console at level 3*.











2.
Go up to level 4. If you haven't done so already, use the shotgun to shoot out the planks in the shaft's side just below the 4th level (you can shoot it out from the 3rd level as well). You are going to use the resulting opening to get to the last gear. How? You are going to jump through that opening while the elevator is moving upwards and hit the climbable wall on the other side with your axe so you don't fall all the way to the bottom of the shaft. The right time to jump is when the bottom of the elevator reaches the top half of the 3rd level.
*If you feel that you need more time to get ready for the jump, activate the console at level 2 rather than at level 3 (point 1 above). This gives you more time before the elevator reaches the "jump spot".











3.
Take a deep breath. Activate the console at level 4. Quickly hang from the side of the shaft and drop down to the floor of the elevator as it moves upwards. Face the side the square opening is on. When the elevator reaches the proper height, run and jump at the opening, hitting out with the axe as you reach the wall.




















4.
Once you are safely clinging to the climbable wall, climb up and to your left until Lara reaches out to the next patch of climbable wall. Jump in that direction and again hit the wall with the axe. Climb to the far left and get down from the wall.




















5.
You have reached the last gear. Lara can reach it through the small square opening in the shaft construction. Pry it loose with the axe and watch as the elevator falls to the bottom of the shaft, making an opening for Lara to continue the game.




















6.
Go down to level 2 and jump down to the top of the fallen elevator, which has now smashed a way into level 1.











If you like, you can open the level 1 door from the inside. Continue your quest on level 1.


*** The puzzle has now been solved. ***