# Weight needed to tilt bridge...

Posted by Angelique at 1/26/2001 5:27 PM EST

Student on team #49, Delphi Knights, from Buena Vista High School.

How much weight is needed to tilt the bridge from a level postion and from the tilted position? Our bridge requires about two lbs. from the tilted position and about twelve lbs. to tilt from the level position. Does anyone have any information that could help me out? Thanx.

Posted by Ken Leung at 1/26/2001 7:31 PM EST

Student on team #192, Gunn Robotics Team, from Henry M. Gunn Senior High School.

In Reply to: Weight needed to tilt bridge…
Posted by Angelique on 1/26/2001 5:27 PM EST:

Here is what our team’s field expert Andy lee found out about manipulating the ramp:

(the -'s are just for spacing)
Data set one: An unloaded ramp.

Inches froms pivot point----Static mass required to ----------------------------change posistion(lbs).
----------------------------Slanted--------Balanced

12--------------------------30--------------80
24--------------------------15--------------30
36--------------------------10--------------15
48--------------------------5---------------10

Data set two: Loaded with 260Lbs of robot(105bls), goals(70lbsx2), and balls(black 1lbsx10 each & one big 5lbs)

Inches froms pivot point----Static mass required to ----------------------------change posistion(lbs).
----------------------------Slanted--------Balanced

12--------------------------170--------------80
24--------------------------50---------------30
36--------------------------30---------------15
48--------------------------25---------------10

Force to hold a goal on the ramp while tilted = 10 Lbs
Constant force required to pull the goal up the ramp = 20 lbs
Force to pull the strecher up the ramp = 30lbs

These are all approximate values due to the dynamic nature of the system.

Posted by Anton Abaya at 1/27/2001 1:08 AM EST

Coach on team #419, Rambots, from UMass Boston / BC High and NONE AT THE MOMENT! :(.

In Reply to: Bridge force chart
Posted by Ken Leung on 1/26/2001 7:31 PM EST:

: Here is what our team’s field expert Andy lee found out about manipulating the ramp:

: (the -'s are just for spacing)
: Data set one: An unloaded ramp.

: Inches froms pivot point----Static mass required to ----------------------------change posistion(lbs).
: ----------------------------Slanted--------Balanced

: 12--------------------------30--------------80
: 24--------------------------15--------------30
: 36--------------------------10--------------15
: 48--------------------------5---------------10

: Data set two: Loaded with 260Lbs of robot(105bls), goals(70lbsx2), and balls(black 1lbsx10 each & one big 5lbs)

:
: Inches froms pivot point----Static mass required to ----------------------------change posistion(lbs).
: ----------------------------Slanted--------Balanced

: 12--------------------------170--------------80
: 24--------------------------50---------------30
: 36--------------------------30---------------15
: 48--------------------------25---------------10
:

: Force to hold a goal on the ramp while tilted = 10 Lbs
: Constant force required to pull the goal up the ramp = 20 lbs
: Force to pull the strecher up the ramp = 30lbs

: These are all approximate values due to the dynamic nature of the system.

thanks ken.

Posted by Brian at 1/30/2001 8:40 PM EST

Student on team #670, HHSRC, from Homestead High School.

In Reply to: Bridge force chart
Posted by Ken Leung on 1/26/2001 7:31 PM EST:

: Here is what our team’s field expert Andy lee found out about manipulating the ramp:

: (the -'s are just for spacing)
: Data set one: An unloaded ramp.

: Inches froms pivot point----Static mass required to ----------------------------change posistion(lbs).
: ----------------------------Slanted--------Balanced

: 12--------------------------30--------------80
: 24--------------------------15--------------30
: 36--------------------------10--------------15
: 48--------------------------5---------------10

: Data set two: Loaded with 260Lbs of robot(105bls), goals(70lbsx2), and balls(black 1lbsx10 each & one big 5lbs)

:
: Inches froms pivot point----Static mass required to ----------------------------change posistion(lbs).
: ----------------------------Slanted--------Balanced

: 12--------------------------170--------------80
: 24--------------------------50---------------30
: 36--------------------------30---------------15
: 48--------------------------25---------------10
:

: Force to hold a goal on the ramp while tilted = 10 Lbs
: Constant force required to pull the goal up the ramp = 20 lbs
: Force to pull the strecher up the ramp = 30lbs

: These are all approximate values due to the dynamic nature of the system.

Is there some reason that the measured torque required to manipulate the bridge changes from the recorded measurement at 1 ft, 2 ft, and 3 ft to 4 ft by 33%?
(drops from 30 ft-lbs to 20 ft-lbs) Unless I overlooked some glaringly obvious fact, the force required should be approximately 7.5 lbs – similarly so with the data for the loaded ramp. Can anyone give a reason for the discrepancy please?

Posted by Dodd Stacy at 1/30/2001 8:58 PM EST

Engineer on team #95, Lebanon Robotics Team, from Lebanon High School and CRREL/CREARE.

In Reply to: Bridge force chart
Posted by Ken Leung on 1/26/2001 7:31 PM EST:

: Here is what our team’s field expert Andy lee found out about manipulating the ramp:

: (the -'s are just for spacing)
: Data set one: An unloaded ramp.

: Inches froms pivot point----Static mass required to ----------------------------change posistion(lbs).
: ----------------------------Slanted--------Balanced

: 12--------------------------30--------------80
: 24--------------------------15--------------30
: 36--------------------------10--------------15
: 48--------------------------5---------------10

: Data set two: Loaded with 260Lbs of robot(105bls), goals(70lbsx2), and balls(black 1lbsx10 each & one big 5lbs)

:
: Inches froms pivot point----Static mass required to ----------------------------change posistion(lbs).
: ----------------------------Slanted--------Balanced

: 12--------------------------170--------------80
: 24--------------------------50---------------30
: 36--------------------------30---------------15
: 48--------------------------25---------------10
:

: Force to hold a goal on the ramp while tilted = 10 Lbs
: Constant force required to pull the goal up the ramp = 20 lbs
: Force to pull the strecher up the ramp = 30lbs

: These are all approximate values due to the dynamic nature of the system.

Ken,

Thank you and your team for generating and posting the bridge force data set. What I find quite interesting is that the force at each point to tip a balanced bridge is the same whether the bridge is empty or loaded with a robot and two full goals.

It doesn’t look like dragging a couple of goals up with the bot is going to make it any less twitchy to balance!

Dodd