Simple tools that have been a mystery

1. The mechanism through which is secured a second hand ratcheting

2. Radial engine 

3. Reciprocating 

4. That's working a sewing machine

5. Internal combustion engine

6. External combustion engine

7. Rotary-piston engine

8. Gun

9. Steam-engine

10. Autococker Paintball Gun 

 

11. Stirling engine

12. Steam-engine double-acting