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First, it is necessary to determine an appropriate COTS solution for the piston. Due to timeline constraints associated with the difficult task of engineering base plates (most notably, all of the required seals), it is logical to take an existing piston and modify it to meet our needs (i.e. changing the throw on the piston, making mass saving cuts, etc). We recognized from the outset that we might not be able to find a piston that meets the previously selected 0.5 in bore diameter.
Solution No. 1: 1691T104
The first solution is a 0.5 in diameter compact tie rod air cylinder with a 4" stroke. Because the coupling section is 4.5", we need a much larger throw than that to achieve an appropriate factor of safety. Thus, it is necessary to replace the bore with a longer one (and also the tie rods). This is also necessary because the 1691T104 piston has a composite bore, which adds safety complications.
Some notable challenges with this option are:
- Rod end is internally threaded. We'd be making a new rod anyways, but there's always a question of compatibility...
- Different port size than our current piston. Not a huge issue because we'd probably redesign our actuation system anyways.
- Only two holes for mounting on each base plate–poor load distribution
This piston has 4 inches of throw... Assuming that everything but the bore and the tie rods are identical, it may make most sense to actually purchase a piston with much less throw, such as the 1691T69.
Solution No. 2: 4211K121
Resources:
The following resources are useful materials for learning about pressure vessel and piston theory:
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