Nice little device (provided it can be found at a reasonable price) that
eliminates a couple of hassles associated with mounting sprockets on shafts.
On 8/10/2013 10:25 PM, Derek Engelhaupt wrote:
Isaac,
When I had a set of EV Warrior motors, I bought some Fenner Trantorque
keyless bushings to mount my drive sprockets to the 8mm shaft. The
5/16" version actually is well within tolerance for use with an 8mm
shaft. The keyless bushings don't mar the shaft at all or require any
thing going through the shaft. I found mine on Ebay for like $5/per
bushing, but they are normally like $20/per if bought at retail price.
I do have some left over that are still in the factory packaging if
you want to give them a shot. I'd let them go for what I paid plus
shipping.
The issue of using the 8mm bushing from Fenner as opposed the the 5/16"
bushing is that you would then need metric sprockets which are hard to
find to fit over the 8mm keyless bushing. The keyless bushings cinch
down on the shaft while pushing out on the sprocket mounted over them.
No keyway or set screws are used. Using the standard 5/16" size on
the 8mm shaft means that normal standard bore sprockets can be used (in
this case 3/4"). I got lucky and found some small 3/4" bore sprockets
(like 10 tooth and no hub) in standard 35 pitch that fit right over
them. I sold the motors, connector pigtails, EV mounts, sprockets, a
set of bushings, and the sprockets to someone here on the list a while
back because I didn't want to deal with creating a reduction for them.
Here's what the keyless bushings look like:
http://www.fennerdrives.com/trantorque/?s=ZnwyMzE4
I use them for my drive sprockets to mount the 60 pitch sprockets to my
5/8" main drive shafts. You can see the gold colored keyless bushings
on the rear drive axles (of course those are much larger than the ones I
used on my EV Warrior motors):
On Sat, Aug 10, 2013 at 8:02 AM, isaac goldman <[email protected]
<mailto:[email protected]>> wrote:
Thanks for the advice; I really appreciate that you took the time to
type all that up.
Much of it confirms what i already thought or had read on-line, or
that i already learned the hard way in various other robotics
competitions. Good to know im on the right track.
On Sat, Aug 10, 2013 at 8:47 AM, TyngTech <[email protected]
<mailto:[email protected]>> wrote:
As the first and only current operator of a 24v EVW drive system
in the hobby, I say welcome to the family but be warned! EVW's
at 24 volts are special beasts that will require a resolute
nature and unfailing faith in your technical prowess to tame!
Steve Tyng
Advice in no particular order:
* These motors are timed CW or CCW. Have a matched set or
re-time as required: http://redneckrobots.com/ev/mod.htm
* Remove the internal case grounding and add suppression
caps:
http://www.robot-village.net/images/vi/build/debil.jpg
http://www.robot-village.net/images/vi/build/dremeltab.jpg
* Review the T040 Cromwell build log:
http://rctankcombat.com/tanks/T040/index.cgi
* If you can get them, use the OEM harnesses to wire to your
controller.
* Use the same gauge as the OEM for battery to controller.
* Build STRONG motor mounts
* Build a STRONGER transmission
* You will need a PWM controller. Don't even think of using
the old style on/off TriPact controllers
* A single 80A fuse before the controller has worked well
for me going on 8 years
* Motor shafts are 8mm, buy an 8mm bit to bore your motor
sprockets. Use a lathe for boring if you can
* You will need effective air flow over the motors for cooling
* A 9:1 reduction will get you over 8MPH but limited run
time on a set of 18AH SLA's.
* A 11:1 reduction gets you 6 to 7MPH with an hours run time
on fresh SLA's
* Using only setscrews on a round (or slightly flattened
shaft) will fail. Keyed shafts, cross pins, etc. highly
recommended in your drive-train design
* At workable reductions, these motors will shred your
drive-train before they stall
Good luck!
On Thursday, August 8, 2013 7:50:57 PM UTC-4, True North
Armouries wrote:
Update; I just received a set of EV motors, and am almost at
the stage of mounting them in the tank. I have a few
questions concerning EV motors though for people who know
about them. Im planning to run them off 24 volts.
Id like to know what rating on the fuse and relays people
use, as the datasheet claims a stall current of over 100
amps. Id like to know how many Ah the batteries should be.
Lastly, do i need the ev wiring harness or do the tabs
accept standard sized crimp connectors?
On Sunday, July 7, 2013 8:46:19 PM UTC-4, True North
Armouries wrote:
Hi all,
I started working on my t34-85 this past Canada Day,
though ive been doing research and electronics work
since Easter. I'd like to take a moment to thank Steve
for the T34 plans; for my first tank im really grateful
to not have to scale any drawings before I can start sawing.
Ive been looking at motors, and I need some advice; most
of you seem to have EV motors, which are increasingly
hard to find. I have done a fair bit of looking on-line,
and have come to the conclusion I have no idea how many
watts my motors should be. I found someone selling 350
watt 24 volt scooter motors for a good price, but I
wanted to know what you guys think, seeing as some of
you have far more experience. Is 350 watts per track
enough power, or is it going to be sluggish and i should
look for at least 500-600 watts?
Thanks in advance,
Isaac
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