Using L-motor to power crawler

[Rooneypower]

Hello all, I have a few questions regarding the use of 2 L-motors for powering a crawler. 

I have done some research and have not been able to find many MOCs that use L-motors for drive, does anyone have any advice on using them instead of 2 XL motors for drive. I know the torque output will be less with the L-motors but the overall speed will be quicker. If geared properly couldn't a L-motor be able to closely match an XL motor, but spin faster? Netting me more of a buggy type of crawler instead of a pure crawler? Also if I were to use L-motors I can keep the overall size of my axles smaller. 

 

One of the downsides is the power draw from the 2 L-motors will be too much for a Lipo battery setup, correct? I'm building some custom axles in LDD and cannot make up my mind which way I should go with my PF, XL drive or L drive motors. I have designs for both size motors, any advice or experience would be welcome, thank you!

[TechnicRCRacer]

This may help:

https://rebrickable.com/mocs/MOC-2964/Madoca1977/compact-cuv/

[Rooneypower]

Thank you for that source. I'm trying to gauge which would be best for my current plans, XL motor for torque and weight at the cost of size, or attempt to gear a L-motor that will be capable of pushing my crawler while giving me bursts of speed if needed. Also the bonus of a minimal design is a bonus too. 

These are my rough plans so far for a rear axle. Any suggestions are welcome. I'm thinking of using 1x11 length long arms for the bottom 2 links in the 4-link setup.

Edited May 1, 2017 by Rooneypower

[mocbuild101]

3 hours ago, Rooneypower said:

One of the downsides is the power draw from the 2 L-motors will be too much for a Lipo battery setup, correct?

If you mean the Lego Lipo, no it is fine. XL-motors draw more power than L-motors.

It is 2x buggy motors that cant be used with the Lego Lipo.

[Rooneypower]

26 minutes ago, mocbuild101 said:

If you mean the Lego Lipo, no it is fine. XL-motors draw more power than L-motors.

It is 2x buggy motors that cant be used with the Lego Lipo.

It will be powered by a BuWizz...one thing i noticed with 2 Lmotors is when they are on the same channel and being operated via a slider control, when engaged slightly (open) one motor will start to turn before the other. Then yhey will turn in unison. Im playing with a crawler that is operated by 2 XL motors and have not noticed this. Maybe i need to do more testing. 

[BusterHaus]

11 minutes ago, Rooneypower said:

It will be powered by a BuWizz...one thing i noticed with 2 Lmotors is when they are on the same channel and being operated via a slider control, when engaged slightly (open) one motor will start to turn before the other. Then yhey will turn in unison. Im playing with a crawler that is operated by 2 XL motors and have not noticed this. Maybe i need to do more testing. 

All regular motors do this.  It's due to differences in build, wear and coupling.  The only Lego motors that turn at identical speeds are servo motors from Mindstorms because they have a position sensor that sends feedback to the controller.

[mocbuild101]

9 hours ago, Rooneypower said:

It will be powered by a BuWizz...one thing i noticed with 2 Lmotors is when they are on the same channel and being operated via a slider control, when engaged slightly (open) one motor will start to turn before the other. Then yhey will turn in unison. Im playing with a crawler that is operated by 2 XL motors and have not noticed this. Maybe i need to do more testing. 

I don't have any experience with BuWizz, but all motors will start turning at slightly different voltages.

 

9 hours ago, BusterHaus said:

The only Lego motors that turn at identical speeds are servo motors from Mindstorms because they have a position sensor that sends feedback to the controller.

Except those .

Edited May 1, 2017 by mocbuild101

[JJ2]

My crawler uses 2 L motors for drive

 

[andythenorth]

Keep it simple eh?  1 L-Motor per wheel, one gear pair.  Very strong, very robust, very easy to repair.  

Performance (click picture for video)

Untitled

Gallery of axle construction:

https://www.flickr.com/photos/andythenorth/albums/72157649987860696

Easy to regear also.

Version with Power Puller wheels (click picture for video)

Edited May 1, 2017 by andythenorth

[Rooneypower]

Great ideas, thank you for all the input and advice. I think I will actually go the route of L-motors and see what I can do. I have a prototype crawler already built but there is a lot of flex in the body and I need to correct my shock towers, linkage points and I might change up the steering. 

Edited May 1, 2017 by Rooneypower