Relative power of different drive trains in comparison to each other

**daveimi** · 28th June 2014, 20:11

As in the title, I was wondering if a few of you would be able to put up some fractions or something with regards to how powerful the common drive trains are to each other. This would be for a 2wd pusher along the lines of Endevour, Tiny Toon etc. So my holy grail drive train is Speed 900 on a single stage reduction. How powerful in comparison to this in the real world are (i.e. 1/4 as powerful, half as powerful, twice etc.):

£10 drill motors
Speed 600's
Gimson 18v
Torpedo 800's
Dewalt 18v
Makita's
Torpedo 850's

and so on.

**plargen** · 28th June 2014, 21:29

you want reliability as well, the cheap argos don't seem to last long, endevour uses 2 speed makita's on 14.4v i believe which are the same version as im going to use in Night fury 2, so on a 4s lipo with 100mm wheels should be able to do 15mph and have twice the power of the old drills, its predecessor used 12v ryobi drill which are still intact after 2 years of abuse and no maintenance but the motors did start to come loose from the gearboxes but they were easily tightened as far as the other motors i will have to leave that to others as i haven't used them

**overkill** · 28th June 2014, 23:12

Perhaps the title should be 'How effective are these motors'. Just knowing what their power output is, is only part of a much more complicated equation: you will also need to factor in the voltage, gearing, tire coefficient of friction, speed and more. All that stuff is hard to work out, so I use these two resources:

http://architeuthis-dux.org/torquecalc.asp

http://www.enigmaindustries.com/EDTSim.htm

You can find extra motor specifications via Google or substitute generic motors from Johnson or Mabuchi for various drills. Past a certain point, it doesn't matter how powerful the motors are. Once the wheels break traction and spin, any extra power the motor might be able to produce is mostly (see below) irrelevant.

When looking at motor power output, most manufacturers quote the peak output in watts but fail to mention how long the motor can sustain that before overheating and failing. A larger motor with more power than you need provides a safety factor that makes it more reliable.

Out of that list, the Dewalt 18V is easily the most most powerful at 1,100 watts and the heavy construction and efficient fan means it can put out that peak power for longer than other motors. If I was going to design a pushy bot, I'd go with 18V new series Dewalts and the Dewut mounting kit; its a good balance of power, weight and reliability. Add some really grippy wheels and you have a a contender

**daveimi** · 29th June 2014, 08:32

That's cool, thanks for the guidance

Is it true that the DeWalt motors fall apart if you take them out of the casings, and if so do you know a way round this? I've always known that Wattage is the power rating of the motor but I always wondered is this was literally an accurate guide of a motors power in the real world, after efficiency comes into it and so on.

I will have a look at those links

**shakesc** · 29th June 2014, 08:36

As Nick said if you have enough torque to break traction then next for me is reliability. I've got through endless drill motors and dont want to spend half the time at an event replacing motors.
I have a speed 900 powered pusher lifter. Apart from its appetite for batteries I don't have too many worries with that. No chance of replacement motors though.
I have some Dewuts for lifters and they are nice but heavy units.
I'm watching how the Aussies get on with brushless http://robowars.org/forum/viewtopic....asc&start=5565

**typhoon_driver** · 29th June 2014, 08:41

robot market place have some nice dewalt kits. The US have been modding and using those motors for years.

**overkill** · 29th June 2014, 09:10

Originally Posted by daveimi

Is it true that the DeWalt motors fall apart if you take them out of the casings, and if so do you know a way round this?

I am not sure what you mean by that - do you mean taking them out of the plastic drill shells? I wouldn't be surprised if the motor and gearbox separated when the drill is taken apart, but the motors are one self-contained unit and definitely don't come apart. There are some other DeWalt drills that have 'frameless' motors, which would probably fall apart when the drill is disassembled; these aren't the droids you're looking for

. I would recommend getting the motors & gearboxes on-line from the RMP or somewhere similar.

**overkill** · 29th June 2014, 09:12

@ Chris: not long to go for the testing - I just took a break from mounting the gearboxes and electronics.

**daveimi** · 29th June 2014, 21:04

Yeah I mean do you know if anyone sells a kit or something. I suppose you could just leave them in the casings and pull the chuck off to mount your wheels.