Torque vs RPM

If you have a tank query and you can't find the answer anywhere else, post here. (TIP - Check for answers in FAQ, use the 'search' facility or even check this board before posting here).
Forum rules
If your question is electronics related please post it in one of the relevant boards here: viewforum.php?f=31
User avatar
MichaelC
2nd Lieutenant
Posts: 2448
Joined: Tue Oct 16, 2012 4:03 pm
Location: Toronto, Canada

Torque vs RPM

Post by MichaelC »

Hi all,

Just curious to see if anyone knows some of the so called hi torque motors generate their higher torque by revving at higher RPM which could be off set by whatever gear sets you are using. For example, what is the real difference between standard HL (320/380s ?) vs 400s vs 480s in terms of torque output at same RPM and the max RPM ?

The real life application is that it appears my Maus is revving too fast and not generating enough torque to actually move much once it has resistance (i.e. on the ground vs on a brick) and I am wondering changing motors that would have a lower RPM and higher torque would help. Unfortunately I am bounded by the gear sets (i.e. Mato Brass 3 to 1s I believe) but I do have the option of changing the motors. I have a set of 480s, a set of black motors from Tank Army that was advertise as 3 times the torque as standard HLs, and a set of red motors also from Tank Army that was advertise as 5 times the torque as standard HLs, obviously bucket loads of HL standard ones, and the ones that came with the Mata brass gears 3:1 that is suppose to be 380s.

MichaelC.
ALPHA
Major-General
Posts: 10963
Joined: Thu Oct 03, 2013 1:06 am

Re: Torque vs RPM

Post by ALPHA »

You would be surprised at the speed a torque motor can hit michael :haha: ...from dealing with airsoft rifles ... it was pretty surprising to me that a torque motor turns faster than a speed motor :D
The biggest difference is the windings ..... torque motors have thicker windings...less ...but the gauge of wire is thicker...also the magnets are stronger...I remember having to prove to some "experts"...just how fast and how powerful the High Torque motors were...Took a mid priced High Torque motor made by a Chinese company (JING GONG)and put it up against a Top of the line SYSTEMA high speed motor.(which they pimped a lot lol)...So a 35 to 45 dollar motor compared to a 100...150 dollar motor ....hooked them both direct to an 11.1 lipo ...just from the sound...you could tell the Jing Gong was revving higher...the scream the motor put out was impressive...drown out the Systema easily :D

To me it boils down to the nature of the beast...... High Torques are build heavier ...for heavier duty...as well as performance...Speed motors are the opposite...the windings are thinner...magnets about the same as the HTs ...but it's the way current runs through the windings that make the difference...bigger wire... more current flow...stronger magnets...power :haha:

Stock motors are built much in the line of speed motors....you could improve them by just changing the magnets ...which is probably what companies do when they market the 400s...the 480s they did the works...windings and magnets

I have played with the idea of using Airsoft motors in my tanks....thing is most operate at a higher voltage... which might blow out the RXs I use ;)

ALPHA

PS. Interesting note on the High torque airsoft motors....you can barely turn the pinion with your hands :haha: :haha: :haha:
User avatar
dgsselkirk
Warrant Officer 2nd Class
Posts: 1484
Joined: Tue Oct 16, 2012 1:57 am
Location: Kitchener, Ontario, Canada
Contact:

Re: Torque vs RPM

Post by dgsselkirk »

So how does brushless fit into this equation. I know nothing about motors but like Michael looking for torque not speed. I hate seeing tanks running around like Ferrari's doing 100MPH at scale speed.
"There are things in Russia which are not as they seem..."
Georgy Konstantinovich Zhukov
User avatar
dgsselkirk
Warrant Officer 2nd Class
Posts: 1484
Joined: Tue Oct 16, 2012 1:57 am
Location: Kitchener, Ontario, Canada
Contact:

Re: Torque vs RPM

Post by dgsselkirk »

The reason I mention brushless is because I see how short they are in comparison to the standard motors and wonder if you can get a high torque that would somehow work with our gearboxes...
"There are things in Russia which are not as they seem..."
Georgy Konstantinovich Zhukov
User avatar
MichaelC
2nd Lieutenant
Posts: 2448
Joined: Tue Oct 16, 2012 4:03 pm
Location: Toronto, Canada

Re: Torque vs RPM

Post by MichaelC »

Okay just found out that the motors I am using are 380s (?!?!) and 15,000 RPM. No torque numbers of any kind. The Brass gears are Mato 5 to 1 (?!?!?). So the question is, would I get better torque at a lower RPM if I swap out the 380s with HL stock, 400s or 480s ? (I am pretty sure the black ones I got are 400s knock offs and the red ones are 480 knock-offs).
User avatar
tomhugill
Captain
Posts: 4745
Joined: Thu Apr 15, 2010 11:21 am

Re: Torque vs RPM

Post by tomhugill »

Dg, I think a good option might be a brushless outrunner (these tend to have a shorter can which rotates), inrunners look more like standard brushed motors. Usually the lower the KV rating for a set size motor the higher the torque, (and higher the speed) the opposite is also true. Michael have you tried the super strong hl replacements yet? Dan ( YHR) said good things about them in his leopard.

I'm not sure what alphas talking about; more turns usually equates to higher torque. Crawler motors tend to have a large number of turns (windings).

http://www.amain.com/rc4wd-540-crawler- ... 0t/p260759

Have a look at this 80t 540 motor. Max rpm is 5500 odd between three and four times less than a standard tank motor. I'm not sure if you can get 400/480 sized crawler motors but might be worth a try. However always check max current draw so you don't pop an esc!

I've always wondered what if it was possible to mix up the motors in the tamiya leopard and use a pair of crawler motors on high power setting.
ALPHA
Major-General
Posts: 10963
Joined: Thu Oct 03, 2013 1:06 am

Re: Torque vs RPM

Post by ALPHA »

dgsselkirk wrote:So how does brushless fit into this equation. I know nothing about motors but like Michael looking for torque not speed. I hate seeing tanks running around like Ferrari's doing 100MPH at scale speed.
BRUSHLESS... the rotation is from pure magnetic pulse...meaning there is a constant flow of one polarity through the stator and the other polarity flowing through what would be the magnets in a normal brushed motor....on a brushed motor the polarities break and switch...if you look and the commutator there are thin gaps between the copper contacts this is what creates the "pulse" from the flow of current... try joining them and the motor won't rotate at all ;)

ALPHAB
ALPHA
Major-General
Posts: 10963
Joined: Thu Oct 03, 2013 1:06 am

Re: Torque vs RPM

Post by ALPHA »

tomhugill wrote:Dg, I think a good option might be a brushless outrunner (these tend to have a shorter can which rotates), inrunners look more like standard brushed motors. Usually the lower the KV rating for a set size motor the higher the torque, (and higher the speed) the opposite is also true. Michael have you tried the super strong hl replacements yet? Dan ( YHR) said good things about them in his leopard.

I'm not sure what alphas talking about; more turns usually equates to higher torque. Crawler motors tend to have a large number of turns (windings).

http://www.amain.com/rc4wd-540-crawler- ... 0t/p260759

Have a look at this 80t 540 motor. Max rpm is 5500 odd between three and four times less than a standard tank motor. I'm not sure if you can get 400/480 sized crawler motors but might be worth a try. However always check max current draw so you don't pop an esc!

I've always wondered what if it was possible to mix up the motors in the tamiya leopard and use a pair of crawler motors on high power setting.
I'm not referring to the no. of turns of wire...but the gauge of the wire to make the turn or winding...thicker you get a freer flow of current...thus creating a wider magnetic field ...coupled with stronger magnets...you get more torque as well as as speed ....Crawlers crawl because of added gadgets...speed controllers (basically a reostat or a no. of resistors linked in tandem to cut the current flow ) and gearing to mention a few :D

ALPHA
Last edited by ALPHA on Fri Nov 21, 2014 7:50 pm, edited 1 time in total.
User avatar
Tankbear
Lieutenant
Posts: 3002
Joined: Sun May 22, 2011 12:00 pm
Contact:

Re: Torque vs RPM

Post by Tankbear »

Sorry Alpha more turns is higher torque and slower speed.

Here's rock crawler motor if you scroll down it gives details for each motor

http://www.ebay.co.uk/itm/540-Crawler-B ... 4897.l4275

Also look in the download section

downloads/

There is a gearbox calculator in excel. As you can the stock HL motors are slow any branded speed 400 motor would be easily 50% faster. Torque will also improve simply because of better quality of the motor.

Another thought for Michael is have you got too small cable causing too much resistance or your battery not up to the job?

Ian.
www.mad-tanks.weebly.com
www.rctankelectronics.com
www.rc-truck.weebly.com
www.rc-boat.weebly.com
ALPHA
Major-General
Posts: 10963
Joined: Thu Oct 03, 2013 1:06 am

Re: Torque vs RPM

Post by ALPHA »

Tankbear wrote:Sorry Alpha more turns is higher torque and slower speed.


Ian.
Not at 12 volts lol...proved it many times...with airsoft motors...there are HT motors that did do what you say....but in those cases the windings weren't as thick and the magnets of lower quality....there is a motor made by a company SR...really lousy...the magnets no where near as strong as the JG ...and the windings poorly done...didn't reach near the rpm that the JG did

I suspect the same goes for RC cars... who's can motors aren't made half as well as an airsoft motor... ;)

like I said... I've had this convo with a lot of "experts"...who's minds I've changed once I demoed for them :D

ALPHA

Ps...Explain to me why the SYSTEMA high speed motor has thinner windings ..more of them... and is not as powerful as the JG HT motor with thicker windings and less of them :D ....I can literally spin the SYSTEMA with my fingers... where the JG you barely can ...it's all about Magnetism...and how that is created and how that is generated into a pulse ;)
And as I stated...in a rock crawler STOCK... the gear ratios is what affects the speed...add a speed controller and as far as slow goes...sky's the limit....airsoft guns have speed controllers too...never used them ...totally impractical :D
Post Reply

Return to “General Questions”