Bungy and Surgical tubing

[Ether]

Originally Posted by Daniel_LaFleur

Mike,

I'm not sure that that 'spec' is actually a spec, but instead is a 'recommendation' from Bimba.

Additionally, the speed of the cylinder is not an issue. What is an issue is the impact on the endcap of the cylinder. Consider that some teams are using upwards of a 2 pound mass on the end of a 8-10" lever and accellerating that to 50 ips and you have some serious forces trying to unseat the endcap of the cylinder.

My suggestion to all teams that are using this type of system (including elastomer assist) is to have a hard stop on your robot so that the cylinder does not 'bottom out' against the endcap.

Hi Daniel,

I think you are correct about the high impact force on the cylinder endcap being the primary safety issue, especially with the large inertial forces arising from the sudden deceleration of the additional mass attached to the shaft.

It is possible that the piston speed recommendation (if indeed it is a valid recommendation - still TBD) was more related to piston seal wear. BUT it could also be a recommended max impact speed with NO inertial mass loading.

In either case, it seems most prudent to provide a robust mechanical stop to prevent the piston from smashing into the cylinder endcap. I wouldn't mind seeing a hard and fast rule about this, to make the inspector's job easier.


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