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Unread 14-12-2012, 19:17
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FRC #1197 (Torbots)
Team Role: Engineer
 
Join Date: Jan 2005
Rookie Year: 2003
Location: SoCal
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Re: Elevators: Cascaded vs Continuous

Quote:
Originally Posted by Wayne TenBrink View Post
Each moving stage acts as a closed loop, but the linkage involves the two stages before it. For example, the cable (belt, chain, etc.) would be anchored to stage 3, run over pulleys at each end of stage 2, and be anchored to stage 1. The stage 2 cable would be anchored to stage 2, run over pulleys on stage 1, and be anchored to the non-moving chassis/frame. The stage 1 cable would be anchored on stage 1, run over pulleys on the chassis/frame, and be anchored/attached to the drive drum. The ends of each cable terminate at one anchor point which includes the tensioning adjustment. The other anchor point for each cable is normally a clamp restraint on a continuous section of the cable. When loosened, it allows for adjustment of the location of that stage relative to the other stages. It doesn't matter which of the stages the different anchor points are on.
330 did that for multiple years (1999, 2000, 2001, 2004, with a single-stage moving piece in 2002). No variation in drum diameter between up and down cables; the return cable simply attached at the top and fed back to the drum. The main issues with those lifts (all blue, all cable-driven) were when cable needed restringing--break out the aircraft cable crimpers and sneak them in somehow to make the crimp. I can't recall tensioners being used at all.

The other issue I can recall was a direct result of two FPs trying to drive the lift down past its hard stop in 2004. I think we were able to bend the C-channel back to normal; I do know that it held up through the rest of the regional and the Championship and offseasons, and if we powered it today it'd probably still function.
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Past teams:
2003-2007: FRC0330 BeachBots
2008: FRC1135 Shmoebotics
2012: FRC4046 Schroedinger's Dragons

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