Might be able to get buy with a less powerful motor with a gear reduction ...or stick with the tried and true washing machine motor.

Google Image Result for http://swotti.starmedia.com/tmp/swotti/cacheC2FYDG9YAXVZIG11C2NSZQ%3D%3DT3ROZXJZLU90AGVYCW%3D%3D/imgsartorius%2520muscle1.jpg

Illustrations. Fig. 433. Gray, Henry. 1918. Anatomy of the Human Body.

Upperleg

Basket swings are great for groups of children, toddlers and less able children.

Creative Swing @Craig Lopez

Double Cacoon - for 2 persons

Arbor Swing Plans - Outdoor Furniture Plans & Projects | WoodArchivist.com

DIY Farmhouse Table with 2 style options for legs!

DIY X-Brace Bench | Step 4