Gas charged hood lifts: are they legal in 2016

[paul.dornfeld]

We want to go to the local auto parts store and purchase gas-charged hood lifts to use on our bot for lifting our tower-scaling hook. We will be using two in series to be able to achieve the needed height. If constructed "safely", is this stored energy source legal in 2016? We are not recharging or discharging any gasses in this scenario.

[EricH]

You may be interested in R35D.

You're also going to want to make sure that all other rules are followed, of course.

[paul.dornfeld]

Awesome!
Thank you so much. That helps greatly.

[GeeTwo]

Also, read the directions on the shocks. Most air springs are intended to be installed in a particular orientation (vertical, with shaft down) for best lifespan.

[MrForbes]

If you want a nice variety of sizes and forces, try a source such as McMaster-Carr. for gas springs. The ones used in cars are a small subset of the ones that are available. We've used McM gas springs for several things over the years on our robots, they're very helpful to reduce the load on arm drive motors, for example.

[Chris is me]

Originally Posted by GeeTwo

Also, read the directions on the shocks. Most air springs are intended to be installed in a particular orientation (vertical, with shaft down) for best lifespan.

This is basically totally irrelevant for FRC, where a gas spring might see 500 cycles on a very thoroughly driven competition robot depending on the application. You generally don't have to worry about wear on a gas spring in an FRC context, which is nice.

[GeeTwo]

Originally Posted by paul.dornfeld

We will be using two in series to be able to achieve the needed height.

Your build would almost certainly be more robust if you used two in parallel with a shorter moment arm. (Or getting a shock of the correct length as suggested above).

[GeeTwo]

Originally Posted by Chris is me

This is basically totally irrelevant for FRC, where a gas spring might see 500 cycles on a very thoroughly driven competition robot depending on the application. You generally don't have to worry about wear on a gas spring in an FRC context, which is nice.

We like to demo our robot for at least the next year, sometimes longer. That said, I agree that we would not weaken a competition design to accommodate this orientation.

[paul.dornfeld]

Originally Posted by MrForbes

If you want a nice variety of sizes and forces, try a source such as McMaster-Carr. for gas springs. The ones used in cars are a small subset of the ones that are available. We've used McM gas springs for several things over the years on our robots, they're very helpful to reduce the load on arm drive motors, for example.

Great idea to reduce the arm-drive motor load. Thank you. We will be keeping that in mind for future reference. For this season, we will be using bungee cords from Menard's.

[MrForbes]

We've also use latex tubing to support arms...works well, comes in the KOP

[Ken5736]

We are lifting with gas shocks. (Gas springs)

http://youtu.be/gdfB82rSGrM

[Chris Fultz]

Originally Posted by Chris is me

This is basically totally irrelevant for FRC, where a gas spring might see 500 cycles on a very thoroughly driven competition robot depending on the application. You generally don't have to worry about wear on a gas spring in an FRC context, which is nice.

The reason for the rod-down orientation is to keep the seal lubricated. Gas shocks have a small level of oil inside to keep the seal between the rod and case lubricated so it will not leak, and lose force.

[MrForbes]

I wonder why folks keep calling the gas springs we are talking about, by the name "gas shocks"?

strange.

[orangemoore]

Is possible to exceed the recommended Cycle per minute value? Would this damage the them or would the life span be shortened?

[GeeTwo]

I don't know for sure, but given the general behavior of gas springs, it doesn't seem likely you'll be able to run them much faster than a few cycles per minute without using greater forces than they're designed to handle. All of the ones I'm familiar with have internal flow control valves that limit the rate of motion, especially in the extension direction.

If you want to be able to extend/contract quickly, you should consider switching to regular (steel helical) springs, probably compressional. Perhaps a storm door spring could work (wrong direction).