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Official Q&A: VRC 2022-2023: Spin Up

Usage Guidelines All Questions

Using pneumatic cylinders as gas shocks

John Holbrook (Event Partner)


<R17> Pneumatics are limited. A Robot’s pneumatic sub-system must satisfy the following criteria:

a. Teams may use a maximum of two (2) legal VEX pneumatic air reservoirs on a Robot.

b. Pneumatic devices may be charged to a maximum of 100 psi.

c. The compressed air contained inside a pneumatic sub-system can only be used to actuate legal pneumatic devices (e.g., cylinders).

The intent of R17a and R17b is to limit Robots to the air pressure stored in two reservoir tanks, as well as the normal working air pressure contained in their pneumatic cylinders and tubing on the Robot. Teams may not use other elements for the purposes of storing or generating air pressure. Using cylinders or additional pneumatic tubing solely for additional storage is in Violation of the spirit of this rule.

The intent of R17c is to ensure that pneumatics are being used safely. Pressurized systems, such as a Robot’s pneumatic sub-system, have the potential to be dangerous if used incorrectly. This rule ensures the safety of participants, and prevents potentially unsafe uses in the future.

Another way of thinking of R17c is that pneumatics should only be used with pneumatics. Teams should not use compressed air as a means of actuating non-pneumatic devices such as screws, nuts, etc. For example, pulling a pin with a pneumatic cylinder is okay, but using air to actuate the pin itself is not.

The attached image shows two configurations of pneumatic components with no solenoid. When the shutoff valves are closed, the cylinders essentially behave as gas shocks. The force of the gas shock can be great enough to replace rubber bands in some robot applications, particularly if configuration "B" is used and the system is first charged to grater-than-atmospheric pressure.


  1. If the system is charged to 100psi or below with the cylinder fully extended before a match, but exceeds 100psi when the cylinder is compressed, would that be a violation of R17b? If so, how should inspectors/referees determine whether the pressure exceeds 100psi when the cylinder is compressed?

  2. If the cylinder is compressed using power from a V5 motor (e.g. when pulling back a catapult), would this be considered an element "generating air pressure" as prohibited by the R17 red box?

  3. Would configuration "B" in the attached image (where the cylinder is connected directly to a shutoff valve with no reservior) be legal? Q&A 1209 concerns using pneumatic components without a reservoir, however this configuration is somewhat different to the use case described in that question.

  4. If configuration "B" is used on a robot, but there is also a reservoir elsewhere on the robot connected to different cylinders, is the answer any different? In other words, do all of the cylinders used on a robot need to be connected to a reservoir?


Answered by committee

As noted in Q&A 1209, the use of pneumatic tubing and/or cylinders solely for the purposes of storing air without pneumatic tanks is not permitted. Therefore, example "B" would not be legal.

Example "A" satisfies this requirement and would therefore be legal.