|
|
|
![]() |
|
|||||||
|
||||||||
This is a drivetrain we are currently building. It has a custom 3 CIM 2 speed gearbox designed for lots of acceleration with a reasonable top speed. It uses a pneumatic cylinder to shift one of the outside wheels, lifting the robot enough to only be on the shifted wheel and the other outside wheel, any of the wheels can be either traction wheels or omni wheels. We plan on first testing it with omni wheels on the outside and traction on the inside, however we have been warned that we may not be able to push anything in this configuration and have left omnis on the inside and tractions on the outside as an option. Overall, the entire thing only weighs 32 pounds, only slightly more than our 2014 robot's 4 CIM standard tank drive. The cad is available at http://frcdesigns.com/designs-drive/
This has been strongly influenced by 624's grasshopper drivetrain as well as other sheet metal robots like 67, 148 and 33, I'd like to thank those teams (and others) for making their CAD and/or help public. I don't think this could exist without this.
Future improvements and tests: (I already have a list and it isn't even built...)
27-06-2014 08:04
z_beeblebrox
Very nice.
How do you maintain chain tension when raising or lowering the outside wheel?
27-06-2014 10:36
cad321|
Very nice.
How do you maintain chain tension when raising or lowering the outside wheel? |
27-06-2014 14:48
Greg WoelkiCould we have a closer look at the gearboxes?
27-06-2014 18:52
Aren Siekmeier|
Assuming that the chain shares the same axle that the module pivots on, In theory it should have the same tension in both positions. This is because it's moving on an arc with a constant radius so the distance between the wheel and the pivot point never change.
Thats my understanding of it anyways. Please do correct me if I'm wrong. |
28-06-2014 08:11
Bryce PaputaThe chain run will lose .07 inches of length when in the up position, if this becomes an issue, we will add a spring tensioner to it. The gearboxes are a slightly modified version of the earlier posted one, the final version is at http://frcdesigns.com/designs-gearbox/
30-06-2014 17:57
apalrd
Way back when we ran an articulating drivetrain in 2011, we designed it so that the chain length was identical in the up and down position but it got a bit of slack while moving. We deemed this to be acceptable and never had any issues.
30-06-2014 20:57
Electronica1|
Way back when we ran an articulating drivetrain in 2011, we designed it so that the chain length was identical in the up and down position but it got a bit of slack while moving. We deemed this to be acceptable and never had any issues.
|