Simple Machines

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Across
  1. 2. Two wheels of different sizes that rotate together (doorknob).
  2. 3. Groved wheel with a rope or chain running along the groove (flagpole).
  3. 5. Moving inclined plane with 1 or 2 sloping sides (axe).
  4. 6. Inclined plane wrapped in a spiral around a cylinder.
Down
  1. 1. Sloping surfaces used to raise objects (ramp).
  2. 4. a bar, free to pivot about a fixed point (wheel barrow).