Pushing down the bridge

[seg9585]

In San Diego, we were originally having issues with our ramp lowerer -- which was van door motor direct drive. After adding a combination of weight, angle, and robot velocity during the match we were able to force the ramp down. When hitting the ramp, the appendage would get pushed up by the ramp typically.

If I were to rebuild it, I would probably go with the FP+gearbox or window motor to take advantage of the (locking) worm gear in combination with the angle on the appendage to slide the ramp down as the robot moves forward into it.

[MysterE]

We are using an extendable arm that locks into a angular horn on our frame when extended. Essentially we are using the weight of our robot to push down the ramp.

[Sh1ine]

Originally Posted by Greg Shaw

We were fortunate enough to travel to another teams location to practice on a competition replica bridge before the kettering event. Our original bridge arm was not strong enough. We eventually lowered the bridge by combining an andy mark PG67 gear and motor combo with a andymark tough box gearbox. the actual bridges are much harder to lower than the plywood version.

How did you do this? Did you just bore a CIM pinion out with a 10mm drill bit and press it onto the shaft?

[rcmolloy]

Originally Posted by AlexH

The funny thing is we wheelied onto the bridge...

I saw that and thought it was the greatest thing ever haha. You guys always have a beastly drive every year.

[yclee31]

I came up with pneumatic based bridge lower where piston will deploy the straight bars which will slide over the bridge to push it down with robot itself's torque.

[Josh Drake]

We have no motor, no pneumatics, no arm. We just drive up under the bridge and lower the other side. Then our partners can climp up, or we can back out and when the bridge on our side comes down, we drive up. K.I.S.S. We got 110 bridge points in week one. Funny thing is we had joked about doing it this way before we bagged, and then realized it was the best way for us when we got to the competition.

[Anupam Goli]

Are people running their motors at full power when they attempt to lower the bridge, and is any motor doing it ungeared?

[Bruceb]

From watching several competitions now I have to say that those of you trying to use the drivers depth perception and an arm to lower the bridge have 2 problems. 1. getting the bot at just the right distance from the opposite side of the bridge to allow your arm to lower the bridge is difficult at best.
2. developing enough torque with a motor and coordinating its lowering with your forward motion is a trick in itself.
Solution. just lower a wedge shaped arm at the front of your bot using an over center link(motor or pneumatic) and just drive up the bridge to lower it. see our bot here.

http://i1121.photobucket.com/albums/...2/100_0011.jpg

[rag82557]

Van door motor straight out of box worked great for us.

[GDG 2337]

In a previous thread from 3601. An adapter was made by the NerdWorks to use a PG71 as an input motor into a toughbox nano. Pictures are attached. Combination worked so well lowering the bridge, they were picked by 3322 at Kettering to be part of the #3 alliance

[Coach Norm]

Team 2468 used a PG71 motor with Tetrix 120 tooth and 40 tooth gears for a 3 to 1 reduction. We have an arm that has a 4" Vex wheel mounted on the end of it. From the edge of the wheel to the frame is 14". The arm is made 3/4" aluminum angle x 1/8" thick. It proved strong enough to push the bridge down or pick it up.



Edit:

See picture below.

You can see the tipper in action at the 16:07 mark of the following video on Ustream: http://www.ustream.tv/recorded/20856729

[Peter Matteson]

We just push straight down on it with a 1.5" pnuematic. Worked great at the Suffield scrimmage with the real field during week 0 so we assume it will work fine when we compete at our first regional this week.

[dellagd]

Originally Posted by Bruceb

From watching several competitions now I have to say that those of you trying to use the drivers depth perception and an arm to lower the bridge have 2 problems. 1. getting the bot at just the right distance from the opposite side of the bridge to allow your arm to lower the bridge is difficult at best.
2. developing enough torque with a motor and coordinating its lowering with your forward motion is a trick in itself.
Solution. just lower a wedge shaped arm at the front of your bot using an over center link(motor or pneumatic) and just drive up the bridge to lower it. see our bot here.

http://i1121.photobucket.com/albums/...2/100_0011.jpg

As for getting the right depth, you are right. That is why we have our turret servo mounter on the tilt assembly. We can look down to lower the bridge or up to camera track

[davidthefat]

We are using pneumatic pistons.

[Gray Adams]

We have 2 devices which can lower the ramp. One is an aluminum wedge with a linkage that locks, driven by a window motor. Works great, moves the bridge super smoothly. The other is a ball gatherer on the other side, also lowered by a window motor. It's harder to use because you have to be positioned properly for it to work, but it has no trouble when done from the right position.

Unrelated, but I've been trying to do a wheelie onto the bridge, but I can never get both the right height and be in the right position at the same time.