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Across 3. the first stroke in a four-stroke internal combustion engine cycle. It involves the downward movement of the piston, creating a partial vacuum that draws (allows atmospheric pressure to push) a fuel/air mixture into the combustion chamber. 6. the fourth of four stages in a four stroke internal combustion engine cycle 8. a split ring that fits into a groove on the outer diameter of a piston in a reciprocating engine such as an internal combustion engine or steam engine. 10. intake lets fuel and mixture in, exhaust lets exhaust fumes out 11. converts up and down motion of piston into rotary motion 17. contains the piston, capped with a thick plate called a head 18. combustion engines derived heat from fuel consumption outside the engine 19. the tendency of a force to rotate an object about an axis, fulcrum, or pivot. 21. controls the speed of an engine by regulating the amount of fuel (or working fluid) admitted, so as to maintain a near-constant speed, irrespective of the load or fuel-supply conditions. It uses the principle of proportional control 22. a type of internal combustion engine which completes a power cycle in only one crankshaft revolution and with two strokes, or up and down movements, of the piston 23. a U.S.-based, globally active professional association and standards organization for engineering professionals in various industries. Principal emphasis is placed on transport industries such as automotive, aerospace, and commercial vehicles.

Down 1. a standard measure of the performance of a motor or aviation fuel. The higher the number, the more compression the fuel can withstand 2. the second of four stages in an otto cycle or diesel cycle internal combustion engine. In this stage, the mixture (in the case of an Otto engine) or air (in the case of a Diesel engine) is compressed to the top of the cylinder by the piston until it is either ignited by a spark plug in an Otto engine or, in the case of a Diesel engine, reaches the point at which the injected fuel spontaneously combusts, forcing the piston back down. 4. a measure of its resistance to gradual deformation by shear stress or tensile stress. For liquids, it corresponds to the informal notion of "thickness". For example, honey has a higher viscosity than water. Is due to the friction between neighboring particles in a fluid that are moving at different velocities. 5. a device that blends air and fuel for an internal combustion engine. It is sometimes colloquially shortened to carb 7. a device composed of fibrous materials which removes solid particulates such as dust, pollen, mold, and bacteria from the air 8. the stroke or movement of a cyclic motor while generating force and thus power. It is used in describing mechanical engines. This force is the result of the spark plug igniting the compressed fuel-air mixture. 9. a shaft to which a cam is fastened or of which a cam forms an integral part 12. engine operates on four series of four strokes to a cycle 13. rotating mechanical device that is used to store rotational energy 14. complete disassembly with cleansing and reconditioning/replacing of most moving parts 15. a component of reciprocating engines, reciprocating pumps, gas compressors and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. 16. combustion engines provides power for machines 20. mass of metal containing the cylinder