DR4B Question

VEX V5 Technical Support
#1

Hi,

So I’m currently making a Double Reverse 4 Bar Lift on my robot for In The Zone, and I’m just wondering, is it necessary to have gears at the base of the DR4B?

I’ve seen some images where there are no gears on the bottom supporting it. I know it can handle that due to how the motors on the reversing part are supposed to function, but as a precaution should I put gears and/or motors there?

Is it even necessary?
dr4b.jpg
liftphoto.jpg

#2

From what I understand the gear placement on the bottom tower are only used if you use it as a mounting point for the arm or are driving the arm from the lower tower. If you are driving from the middle elbow joint I doubt you will need to put gears on the lower tower.

#3

Well to start, your first image is actually a Danny lift and not a dr4b. You only need gears at the bottom if you wish to have motors powering your lift from the bottom, If you wish to have all you motors on the middle section, then you don’t need gears on the bottom. If you have good build quality, it be fine just on the middle section, but if your worried, then you can just place gears there and motors if your really worried.

#4

I like powering from both the middle and the bottom, but it’s not necessary. There are some good examples in this thread: https://vexforum.com/t/best-double-reverse-four-bar-examples/41193/1

#5

Yes I know, I just wanted to provide a relevant example because I was having a hard time finding a picture of a DR4B base. I think I’ll just make the lift without the gears on the base. Thanks for the suggestion.

#6

Thanks, I’ll check it out soon.

#7

@TheGee_ the second picture Is a double reverse 6 bar

#8

Considering that the bases weigh 3.7 pounds plus the weight of the arm, I would put motors at the bottom to help with all that weight.

#9

Like I said earlier, I just wanted to provide a relevant example about the base having gears/motors or not.

#10

@TheGee_ ok, it does really matter, as the gearbox on the middle of the lift only serves to remove slop, and if you have the wire extenders to do it go ahead, it works wonders to remove slop

#11

All right, thanks.

#12