Source of gear boxes for Speed gems (team trinity) motors

[George Williams]

I think I can use some of their motors for a custom vehicle,
but I'd like some gearboxes to slow them down from 17,000
rpm to about 200-400 rpm.

[Paul - xxx]

George Williams vaguely muttered something like ...
> I think I can use some of their motors for a custom vehicle,
> but I'd like some gearboxes to slow them down from 17,000
> rpm to about 200-400 rpm.

http://www.hpc-gears.co.uk/

--
Paul ...

(8(|) ... Homer Rocks

[Alan]

If you want to drop the drive RPMs to that range, you'll need a good
sized gear reduction set-up. For a final drive RPM of 200, you'll
need a 85:1 gear reduction and for 400 RPM, you'll need a 42.5:1 gear
reduction. That is just going by a motor that is actually putting out
17,000 RPMs. I'm not really sure that you are going to be using this
on, but you might want to look into the Clodbuster gearboxes and/or
the clodbuster gear reduction kits that were made by stormer and I
think are now being made again by Thunder Tech Racing. The clodbuster
gearbox has a gear ratio of 30.1:1, so if you throw on one of the
above gear reductions, you could get a final ratio of over 200:1
(great for truck pulling). Once again, I'm not really sure of what
this is going on and if you have size limitations, etc. If you give
some more info, someone could probably help a little more.

George Williams <nyar1ath0tep@mac.com> wrote in message news:<41131119.8926271C@mac.com>...
> I think I can use some of their motors for a custom vehicle,
> but I'd like some gearboxes to slow them down from 17,000
> rpm to about 200-400 rpm.

[George Williams]

Alan wrote:
>
> Once again, I'm not really sure of what
> this is going on and if you have size limitations, etc.

It's for a police robot - a crawler with pan/tilt video camera.
It has to be at least 12 inches wide by 18 inches long.
1/10 scale truck tyres (masher 2000, which are approx.5 inches
in diameter) work well in tests, but my motors
http://www.jameco.com part 161381
are rather weak, only 12 in-oz. (850 gm-cm) and too slow, at 145 rpm.
I would like a motor that can produce 100-200 in-oz at 200-300 rpm.
At the team-trinity website
http://www.teamtrinity.com/motors/motorspecs.asp
they have a table of motor specs (rpm and "power"), but the power
column has no units, so it could mean anything.

[Dean]

On Fri, 06 Aug 2004 18:58:39 GMT, George Williams <nyar1ath0tep@mac.com> wrote:

>Alan wrote:
>>
>> Once again, I'm not really sure of what
>> this is going on and if you have size limitations, etc.
>
>It's for a police robot - a crawler with pan/tilt video camera.
>It has to be at least 12 inches wide by 18 inches long.
>1/10 scale truck tyres (masher 2000, which are approx.5 inches
>in diameter) work well in tests, but my motors
>http://www.jameco.com part 161381
> are rather weak, only 12 in-oz. (850 gm-cm) and too slow, at 145 rpm.
> I would like a motor that can produce 100-200 in-oz at 200-300 rpm.
>At the team-trinity website
>http://www.teamtrinity.com/motors/motorspecs.asp
>they have a table of motor specs (rpm and "power"), but the power
>column has no units, so it could mean anything.

The power in that table is watts.

---
Proud owner of:
Associated RC10GT <the other basher>
Team Losi XX "CR" <the basher>
Team Losi XXX KE <the racer>
http://ripperd.com
email: dean (at) the above domain

[George Williams]

Dean wrote:

> >At the team-trinity website
> >http://www.teamtrinity.com/motors/motorspecs.asp
> >they have a table of motor specs

> The power in that table is watts.

Thanks. Then at 7.2 volts, 144 watts would use 20 amps. Man, would
that drain a battery quickly! But at 50% efficiency, there would be
72 watts converted to torque using my rule of thumb (6 gm-cm torque
per watt at 17000 rpm): 432 gm-cm. If I slowed it down to 340 rpm
with a 50:1 gearbox, then at 75% efficiency, it would be 16.2 kg-cm
at the wheel axle, or 225 in-oz.

[Justin Mahn]

An ESC is able to vary the RPM of the tires with more battery efficiency
than only a gear reduction. You should look into one.

--
Justin Mahn
remove Panties to e-mail


"George Williams" <nyar1ath0tep@mac.com> wrote in message
news:4113F2EB.B290FF4D@mac.com...
> Dean wrote:
>
> > >At the team-trinity website
> > >http://www.teamtrinity.com/motors/motorspecs.asp
> > >they have a table of motor specs
>
> > The power in that table is watts.
>
> Thanks. Then at 7.2 volts, 144 watts would use 20 amps. Man, would
> that drain a battery quickly! But at 50% efficiency, there would be
> 72 watts converted to torque using my rule of thumb (6 gm-cm torque
> per watt at 17000 rpm): 432 gm-cm. If I slowed it down to 340 rpm
> with a 50:1 gearbox, then at 75% efficiency, it would be 16.2 kg-cm
> at the wheel axle, or 225 in-oz.

[George Williams]

Justin Mahn wrote:
>
> An ESC is able to vary the RPM of the tires with more battery efficiency
> than only a gear reduction. You should look into one.

Those would be great if I could use them. I don't know much
about them. I'm looking at the pdf for a 12V motor, jameco part
232127, for example. The stall torque is 400 gm-cm at 7.7 amps
and the torque at max. efficiency is 73 gm-cm (17000 rpm). Does
this mean that the ESD can supply about 5 amps to the motor, while
limiting the speed to run it at approx. 350 rpm and 350 gm-cm torque?
I reckon I have alot to learn ;-)

[Jonathan Hodgson]

On Fri, 06 Aug 2004 21:06:51 GMT, George Williams wrote:

>> The power in that table is watts.
>
> Thanks. Then at 7.2 volts, 144 watts would use 20 amps. Man, would
> that drain a battery quickly! But at 50% efficiency, there would be
> 72 watts converted to torque using my rule of thumb (6 gm-cm torque
> per watt at 17000 rpm): 432 gm-cm. If I slowed it down to 340 rpm
> with a 50:1 gearbox, then at 75% efficiency, it would be 16.2 kg-cm
> at the wheel axle, or 225 in-oz.

I suspect that's mechanical output in watts, so the electrical drain
is going to be closer to 300 W at peak power. In our race cars, we
expect an *average* discharge current in excess of 20 A - and remember
that we have to come off the throttle for most corners! And the
current is higher at launch - about 60 amps seems normal for a serious
'modified' motor.

Also note that we get our motors pretty hot in a five minute run, and
rebuild them after a meeting or two at most - that's about an hour of
runtime. If you spec a 540 size motor, aim to run it well above its
peak power speed and hence at a lower torque and current - and cool it
well (like bolting it to a big metal plate).

HTH,
Jonny

[George Williams]

Jonathan Hodgson wrote:

> I suspect that's mechanical output in watts, so the electrical drain
> is going to be closer to 300 W at peak power. In our race cars, we
> expect an *average* discharge current in excess of 20 A - and remember
> that we have to come off the throttle for most corners! And the
> current is higher at launch - about 60 amps seems normal for a serious
> 'modified' motor.

That is a tremendous amount of current for those small wires.
ISTR from my electrics handbooks, one would use a copper conductor
with a diam. of about 5 mm. for that 60 A typical load, although
for only 20 A, a wire of 2 mm diam might be safe. I reckon the
heat must quickly melt the lacquer or thin insulation of the
wire in the coil.

[Jonathan Hodgson]

On Tue, 10 Aug 2004 18:46:02 GMT, George Williams wrote:

> Jonathan Hodgson wrote:
>
>> I suspect that's mechanical output in watts, so the electrical drain
>> is going to be closer to 300 W at peak power. In our race cars, we
>> expect an *average* discharge current in excess of 20 A - and remember
>> that we have to come off the throttle for most corners! And the
>> current is higher at launch - about 60 amps seems normal for a serious
>> 'modified' motor.
>
> That is a tremendous amount of current for those small wires.
> ISTR from my electrics handbooks, one would use a copper conductor
> with a diam. of about 5 mm. for that 60 A typical load, although
> for only 20 A, a wire of 2 mm diam might be safe. I reckon the
> heat must quickly melt the lacquer or thin insulation of the
> wire in the coil.

Well, they survive - insulation meltdown is a rare failure. Brushes
and commutators do take a hammering, and need regular replacement and
skimming, respectively.

I suspect your handbook is written for industrial installations, which
have to a) keep working and b) be guaranteed safe at high voltages!

The can of the motor comes off a run too hot to hold for more than a
few seconds, which I'd guess is about 55 or maybe 60°C. I've never
pulled the armature out straight after a race to check how hot that
is, though - mostly 'cos I can't hold the motor to take it apart!

Jonny

[George Williams]

Jonathan Hodgson wrote:

> The can of the motor comes off a run too hot to hold for more than a
> few seconds, which I'd guess is about 55 or maybe 60°C. I've never
> pulled the armature out straight after a race to check how hot that
> is, though - mostly 'cos I can't hold the motor to take it apart!

What I saw recently was a motor to which a guy attached heatsinks,
and then added a small blower. Analogous to what one would see
in an overclocked CPU, where they're trying to keep the heat down.
The blower seemed like a waste of battery capacity to me, but I
reckon it would be much easier to implement than a liquid-cooling
system with a pump and radiator ;-)

[Paul - xxx]

George Williams vaguely muttered something like ...
> Jonathan Hodgson wrote:
>
>> The can of the motor comes off a run too hot to hold for more than a
>> few seconds, which I'd guess is about 55 or maybe 60°C. I've never
>> pulled the armature out straight after a race to check how hot that
>> is, though - mostly 'cos I can't hold the motor to take it apart!
>
> What I saw recently was a motor to which a guy attached heatsinks,
> and then added a small blower. Analogous to what one would see
> in an overclocked CPU, where they're trying to keep the heat down.
> The blower seemed like a waste of battery capacity to me, but I
> reckon it would be much easier to implement than a liquid-cooling
> system with a pump and radiator ;-)

We've started to use small fans on 4wd motors now almost as a matter of
course at National level .. A decent PC fan of about 20 - 30mm diameter uses
little battery power, and with our batteries now coming off with loads of
power left (3300's) then we have a surplus .. unless we run 8 turn singles
maybe ... ;)

--
Paul ...

(8(|) ... Homer Rocks

"A tosser is a tosser, no matter what mode of transport they're using."