Help adding motors to direct drive

lathashivakumar · January 25, 2018, 7:05am

Hi,
We are a small team, and this is our first year in Vex. We used to have a full sized robot with a DR4B, using 4 motors on the DR4B, and 2 on the drive. Our lift was very problematic, and we decided to scrap it and mount our chainbar directly on the chassis, just like ALBA. However, now we have an extra 4 motors that we would like to add to the drive.

Our motors were direct torque to our back wheels. Now we are trying to add a second motor, but we don’t know how to link them. I am attaching a sketch of our setup. The left motor was already there, the right motor is new and is not connected to the wheel. Our first idea was to use pinions to connect them, but as there is one hole in between the two motors’ shafts (That is when attaching the motors as close together as they could get, the casing makes them fat) we could not fit an idler gear as there is no where to mount the axle on the other side. Any ideas?

steven1233f · January 25, 2018, 7:15am

Chain them together. Using the same size sprockets will still give you a 1:1 ratio. You could also probably change the internal gearing to high speed

robotguy · January 25, 2018, 7:15am

put the next motor in front of it and chain it back

lathashivakumar · January 25, 2018, 7:18am

We only have low-strength chain, is that fine? Also, is it fine to make a 4-motor rear wheel drive into HS?

robotguy · January 25, 2018, 7:21am

in that case, i would recommend doing HS direct on back wheels. then chain your other motor on each side up to your front wheels, so you have 4 wheel drive this way it will push and pull for getting over the 10. pt bar to do mogos. be sure to use at least 2 lengths on the low strength on each side. if room permits use three lengths. that stuff is pretty weak and if you only use one length per side it will probably break and leave you stranded.

robotguy · January 25, 2018, 7:27am

is that possible with your design

lathashivakumar · January 25, 2018, 7:30am

Our robot w/ 2w torque already crosses the starting bar with ease. But either way, it is probably a good idea to use those two extra motors and chain them to the front. Once we do that, we will still have two extra motors. I guess we should use those on the rear wheels if we can, making it a 6 wheel drive. But is it fine to use low strength chain on both parts?

Easton · January 25, 2018, 7:32am

As long as you use 2 or three lengths of low strength chain next to each other it should be fine, but it is really weak so if another robot hit the chain it may break. Use LS chain at your own risk

lathashivakumar · January 25, 2018, 7:33am

We don’t have much space to run two lengths. Especially not in the first case, where we are connecting the two motors on the rear wheels

robotguy · January 25, 2018, 7:33am

as i said you two lengths minimum and three of you have the space

lathashivakumar · January 25, 2018, 7:39am

Would it be worthwhile to buy HS chain now? Is HS any wider than LS? Because we left very few holes in between the two rails on our chasis that there is not much gap. Add that to the fact that we use the big 4inch omnis, and there is hardly any room. Our spacing is done as follows:

Rail
8mm spacer
Shaft Collar
4-inch Omni
Shaft collar
8mm spacer
Rail
Motor

From outside to inside. Can the HS gears replace the 8mm spacer? Also, can they fit between a motor and the C-Channel it is mounted on?

Thanks for the help

Gameon2546 · January 25, 2018, 7:43am

LS chain may be smaller but it will not sustain the torque of a drivetrain. HS is bigger but allows for much better motor placement on any systems.

DougMoyers · January 25, 2018, 7:56am

You can gear them together with 60 tooth gears.

Inventor_Inventor · January 25, 2018, 9:47am

We have a four wheel drive on our base, one motor per wheel and we chained the sides together