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====== Pneumatic Cylinder With Two Switches ======

**Keywords:** Lego, Pneumatic, Sequencing, Circuit, Cylinder
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==== Motivation and Audience ====
This expands on the switch built in tutorial one. Using two switches linked to a single cylinder, students will be able to control the flow of multiple currents through only one control process.
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==== Parts List ====
^ Part Description                       ^ Part #    ^ Qty|
| Technic Axle Pin                       | 3749      | 6 |
| Technic Pin With Friction              | 4459      | 8 |
| Technic Cross Block 1 x 2 (axle/pin)   | 6536      | 2 |
| Technic Brick 1 x 14 with holes        | 32018     | 2 |
| Technic Beam 3 x 3 x 0.5               | 32056     | 4 |
| Technic Axle 2 Notched                 | 32062     | 2 |
| Technic Pin Long                       | 32556     | 1 |
| Technic Pneumatic Valve with Pegholes  | 47223b    | 2 |
| Technic Pneumatic Cylinder             | 47224c01  | 1 |
| Technic Axle Joiner Inline Smooth      | 59443     | 2 |
| Pneumatic Hose - Various Length        | 5102      | 1 |
| Technic Pin Long with Stop Bush        | 32054     | 1 |
| Technic Beam 5 x 0.5                   | 32017     | 1 |

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==== Construction ====
**Step 1:**\\
Repeat tutorial I through step 3.\\
{{:screen_shot_2016-02-24_at_11.54.22_pm.png?nolink&200|}}

**Step 2:**\\
Add a second pneumatic valve to the block. Use another axle joiner, notched axle 2, and a cross block to extend the lever of the second valve.\\
{{:screen_shot_2016-02-25_at_10.12.05_am.png?nolink&200|}}
{{:screen_shot_2016-02-25_at_10.12.14_am.png?nolink&200|}}

**Step 3:**\\
Use two 5x0.5 beams to connect the two levers to the pneumatic cylinder. A long pin can be used for both valves, however it is recommended a long pin with a stop bush is used for the valve that is not directly linked to the cylinder.\\
{{:screen_shot_2016-02-25_at_10.12.23_am.png?nolink&200|}}
{{:screen_shot_2016-02-25_at_10.12.29_am.png?nolink&200|}}
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==== Final Words ====
When building electronic circuits, it is very common to have multiple voltages inverting at the same time. In the same regard, when building pneumatic circuits sometimes it is necessary to have two or currents of air change direction at the same time. For large arrays of synchronized switches, building an individual piston for each valve can be large and take up a lot of space. Linking two or more valves to the same cylinder can cut back on space used in further installations. It is important to note however, that adding more valves onto a single cylinder adds more resistance and thus the cylinder requires more pressure to work.