Quote:
Our gas springs are restrained by two steel hooks per side that mechanically link the upper part of the lift's four bar linkage with the lower part, holding them shut. On the bottom side of each lift is a Fisher Price motor passing through a Banebots 256:1 gearbox with a custom clutch and bellcrank assembly on the output. The bell crank is fixed to the hooks by some threaded rod and translates the rotary motion of the motor to linear motion required to release the hooks. It takes a fraction of a second long pulse of power to the FP motors to rotate them enough to pull the hooks and the clutch helps to avoid damaging the bell crank if the system is overrevved.
In effect, we're using the force of the gas springs -- 125 lbs. ea., 250 lbs. per side -- to create sufficient friction between the hooks and the lower part of the four bar linkage. When the lifts do not have a robot on them, it's very difficult to overcome that friction and release the lifts and is intentional. The added weight of a robot on the lifts reduce the force of friction and makes it far easier to release the hooks. It's as much of a failsafe as we could afford and works very well. The lifts have only deployed unintentionally twice and both resulted from very high shock loads.
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I agree. It took me, 170 lbs, and two really big guys, 220+ to put them down. Although, the trip down was pretty fast.
That's it, I hope no one was expecting anything brilliant.
Oh yeah, Madison...
HAPPY BIRTHDAYYYYY!!!!!