Task: Sentence Ordering
Input (English): Steps: (1) Coal is loaded into the firebox (2) The boiler produces steam under high pressure (3) The steam generated in the boiler flows down into a cylinder (4) Just ahead of the wheels, pushing a tight-fitting plunger, the piston (5) As the piston pushes, the crank and connecting rod turn the locomotive&#x27;s wheels and power the train along (6) An outlet valve opens and the piston pushes the steam back through the cylinder and out up the locomotive&#x27;s chimney  
Where does the following step fit into the given list of steps: The piston is connected to one or more of the locomotive&#x27;s wheels through a kind of arm-elbow-shoulder joint called a crank and connecting rod 
Output (English):  After step 4.