Need advice: is this construction possible?

[Lauris]

Hello,

I got out of my dark ages few months ago and now I have 9395, 8081, 8070, 9392 and 8043 in my collection. As with 8043 comes PF IR receivers and 4 motors, I am thinking that at this point I might be able to do some nice MOC's as you all have doing here for long time, while I was living without LEGO (don't understand how it was possible )

so my question is to more experienced people than I am, if is this combination possible - putting two M motors aside to run one axle that powers the driving axle of some vehicle. Sorry for poor LDD pic, I haven't studied LDD a lot, so I don't understand how to connect parts that are not in the LDD floor level, so making this pic, took some time and the middle gear sticks out... hope you understand the idea... here's the pic: http://www.brickshelf.com/cgi-bin/gallery.cgi?i=5612690 (I uploaded the file to brickshelf few miutes ago, so it might not be visible - alternate link to my blog: http://laurisklavins.blogspot.com/ )

I have all the parts to make such construction, but I don't want to break my motors if this is not a good idea (as the motors might run against each other and stall), so I wanted to ask - maybe someone has done this before? I think this construction would be somewhat more powerful than puting one motor to run the axle, as well it allows to keep differential benefits, as I would like to keep the original diff to keep the possible MOC small. Also, I think that I have seen the construction like this somwhere here in forum, but I can't find it anymore...

Hoping for your advice and thanks for your time!

Edited September 17, 2012 by Lauris

[Nazgarot]

Welcome back to a great hobby!

Yes, this i possible although you will need to use some different gears. The black and grey gears form you pic wouldn't connect. I would how ever recommend putting a differential between the motors, as any difference in speed will result in the faster motor wasting energy to speed up the slower one. That said I have used this setup myself to get more power, and lacking the room to include a differential.

Right now I'm working on a model of the Howe and Howe "RipSaw" where I connect two XL motors in this way to get sufficient power. It's a bit harder on the batteries, and the motors develop a little bit more heat, but i have 6 XL motors and have been matching their speed against each other, and have picked out the two that are closest in speed. This can easily be done by connecting two motor running in opposite direction through a differential and measure how much/fast the differential spins.

Good luck with your project, and keep us updated! A WIP (Work in progress) blog as a topic here is a good way to get help with your construction.

See you around

-ED-

[Lauris]

Yes, this i possible although you will need to use some different gears. The black and grey gears form you pic wouldn't connect. I would how ever recommend putting a differential between the motors,

Thanks for advice Yes, the gears might be different, I didn't pay much attention to them, the point was to show the idea, as truth will come with practice In few days I might try putting diferential between motors, although I can't imagine how it would look, so pictures are welcome

And I will definetly make WIP/MOC topic, I already created a list of "must do" stuff, gotta pick up my last bricklink order and see what I can do

[Alasdair Ryan]

I hope I have understood right,you would like to power one axle with two motors?

If so you will need to build a adder as both motors turn at different speeds (with out one it creates strain to both motors).

Here is a picture of a adder.You should replace to two buggy motors with two PF ones.You will need to have one motor going in reverse using a switch.

Edited September 17, 2012 by Alasdair Ryan

[Lauris]

I hope I have understood right,you would like to power one axle with two motors?

Yes correct two motors to one axle.

Ok, I think I got this visualised as well. Puting PF motors perpendiculary the diff will require two bevel gear connections to axis that will turn the diff.

Thanks for pic!

[allanp]

Yes it's possible and you don't need a differencial gear. Using a differencial may give you some minor efficiency benefits (or losses) but hardly noticeable if at all. Just make sure the motors are geared so they spin the same direction and speed, that way you will be sure to not harm your motors. The stress from the motors running at very slightly different speeds is nothing compared to the stress on the motors when in normal use. For an example of where this is done in an official set, look at the power puller. It comes with a motor and gives instructions for adding a second motor. A more recent example is the crawler. When it's driving on the ground the motors are technicly linked directly to each other without differencial via a huge "gear" known as the earth!

Edited September 17, 2012 by allanp

[DLuders]

@ Lauris: Mahjqa recently posted pictures of his Lego Technic Batman Tumbler (named "Tumbly") on his Flickr photoset. As you can see on the third image below, two Lego Power Functions L-Motors are driving the rear axle. Click on the image below to study it closer (at FULL SIZE), or you can study the "Camo Tumbly's Lego Digital Designer (LDD) .lxf file on this webpage.

[DLuders]

For his Lego Technic Racing Truck, Sariel posted these pictures of his "Adder" mechanism (using two Lego Power Functions XL motors as his "input"):

Edited September 17, 2012 by DLuders

[hoeij]

putting two M motors aside to run one axle that powers the driving axle of some vehicle.

One L motor produces roughly the same speed and torque as two M motors. So if you have an L

motor, that'd make things a whole lot easier...

[Lauris]

One L motor produces roughly the same speed and torque as two M motors. So if you have an L

motor, that'd make things a whole lot easier...

Ofc, if I had unlimited budget... but the choice was between Crawler and 8043... and knowing that 8043 probably will be discontinued in few months and then purchasing it via Bricklink should be a lot more expensive... I choosed the 8043. It took me ~6 hours together with sorting parts and some looking through eurobricks forum to fix some of the design issues of 8043, but I feel that it might have improven my technic understanding a lot more than crawler. And definetly it is fun! And I might get the crawler in some time later ;)

So thanks for your advices and pics they are appreciated and I will put them to good use

Edited September 17, 2012 by Lauris

[Hopey]

This is possible. I made a pseudo-9398, using the actual instructions and the parts that I had (8043, 8110 and 8109), and used 2 M motors in place of each L motor:

Apparently you're not supposed to do it like this, but I've not had any issues with it. You can even take it to extremes

(That's 6 M motors driving a single axle, by the way).

[hoeij]

Apparently you're not supposed to do it like this, but I've not had any issues with it.

I don't think that this would cause any problems, as long as the motors are electrically connected.

[allanp]

The most I have had was 8 m-motors in a v8 configuration running a single axle (also in a dragster) and had no problems.

[GuiliuG]

@ Lauris: Mahjqa recently posted pictures of his Lego Technic Batman Tumbler (named "Tumbly") on his . As you can see on the third image below, two Lego Power Functions L-Motors are driving the rear axle.

Your example is not correct as both L motors are not linked together. One drives left wheel and the other the right one.