Page 324 - Robots Androids and Animatrons : 12 Incredible Projects You Can Build

To muscle

Fill air Hold Empty air
To muscle from muscle
foot pump

16.3 Three-way air valve for air muscle operation
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Item 4, the PET soda bottle, is used for air storage. A plastic soda
bottle can hold 50 psi easily. I have static-tested plastic PET bottles
to 100 psi. Caution: Never use any type of glass bottle for air
storage. A slight fracture in a glass bottle or dropping it accidentally
may cause the bottle to explode, sending tiny glass fragments all
over. Plastic PET bottles elongate when overpressurized.
Item 5 is the foot-pump adapter and item 6 is the foot pump. A sim-
ple foot pump with an air pressure gauge can charge air storage up
to 100 psi. Because of the low volume of the PET bottles, air storage
is brought to 50 psi with three or four strokes of the air pump. The
air muscle uses so little air that a small PET bottle holds enough air
for four to five complete cycles of the air muscle. Item 7 is nylon
cable ties, used to quickly connect the air muscle to a mechanical
device.

Figure 16.4 illustrates a general overview of how the parts are put
together. In some cases you may want to epoxy glue some compo-
nents together to prevent them from popping off. For instance, if
you will just be using the three-way air valve on one bottle adapter
for air muscle experiments, you may want to glue the three-way
valve to the adapter permanently.
Team LRN Android hand