*gear reduction unit

[CustomRCmodels]

Originally Posted by Lil Giants

The big grippers I'm running are a bit taller than the stock tams of 83mm and I use the 12 tooth plastic pinion, that comes with wdc motors, on the output shaft from the twin motor coupler into the tam trans... the final drive output is somewheres around 50 rpm at the drive axle... and you're talking having ten times that with your wdc? That seems pretty quick for a heavy haul tractor.

The white tractor in my vids is usually running around in 2nd. I rarely ever use 1st. And flip into 3rd running empty, which is a bit faster than walking.

Joe ,
Don’t you use the 3:1 version of the Wedico double-motor coupler type I made up for Ric ?
I don’t remember if I had send you the gear to do that yourself , or if you did get it from Ric ?

[CustomRCmodels]

Originally Posted by fhhhstix

Joe we put 5 55turn motors on my dyno and they ranged from 4800-5900 rpm. Instead of running the dyno with a 12 power supply and regulating the dyno to 7.2v we ran the dyno with 2 of my good NiMH 7.2v batteries which give a better reading. We ran all 5 motors on one battery and then did it again with the other battery. The 12v power supply is fine to break in a motor but using a battery pack will give you a better reading of the motor this is how we used to do it for our race cars.

CAT-man
What dyno do you use ?
A typical 55 turn motor should have around 8000 rpm’s with zero timing .
Your readings look like readings you get on a dyno with a internal stabilized 5 volt supply , no matter what you connect to it .

Here are my test-results from 2002
Comparing my own WWR-Truckpuller vs the LRP Truckpuller ( 55 turn vs 80 turn )


and here my WWR-Truckpuller vs stock Mabuchi 540 ( 55 turn vs 27 turn )


here you can read my write up from back then :
http://www.customrcmodels.com/id442.htm

[CustomRCmodels]

Originally Posted by Espeefan

Argh! Joe, I know what I did wrong. After reading what you typed I realized it. I can't believe I didn't catch my mistake! Not more then a month ago I answered a question and wrote a 'how to' in the process on Scale 4x4, when a guy asked about ratios.

That completely slipped my mind. Can you guess what I didn't do? I feel stupid now!

Guess I need a different planetary drive now.

did you forget the ratio between motor and the transmission ?
since I wanted to asked you about that ….

[fhhhstix]

Willy it is a Phantom Facts Machine. The 55 we tested were cheap lathe motors. But using a power supply and setting the dyno voltage at 7.2 volts gave us higher rpms than the battery did. it takes a lot of power to spin up the fly wheel and a battery can't keep up like a power supply can. That is why we use the battery to simulate what will happen at the track. Yes Willy they will spin close to 8000 rpm on a free spin but just like your 55 in the read out above the max power is at 4168 rpm.

[Espeefan]

Originally Posted by CustomRCmodels

did you forget the ratio between motor and the transmission ?
since I wanted to asked you about that ….

I sure did! Sometimes it's the simplest things. You know, I looked up the ratios of the trans and the axles, but forgot about the pinion and spur gears! D'oh. The Wedico AWD 3 speed has a 24 tooth spur gear and it comes with a 14 tooth brass pinion gear. The motor however comes with a 13 and 12 tooth plastic pinion gear. The motor mount is not adjustable on the Wedico 3 speed, so I'm betting they want you to use the brass pinion that comes with the trans. That gives me a missing ratio, which I failed to factor into my calculations, of 1.71. I also have the belt drive reduction that I can't count, without pulling the plate off the trans. Gonna have to do that too!

[CustomRCmodels]

Originally Posted by fhhhstix

Willy it is a Phantom Facts Machine. The 55 we tested were cheap lathe motors. But using a power supply and setting the dyno voltage at 7.2 volts gave us higher rpms than the battery did. it takes a lot of power to spin up the fly wheel and a battery can't keep up like a power supply can. That is why we use the battery to simulate what will happen at the track. Yes Willy they will spin close to 8000 rpm on a free spin but just like your 55 in the read out above the max power is at 4168 rpm.

ok , cool Travis ,
I didn’t want to get in to this yet , load and no load , just was checking on your numbers ,
so we are on the same page here !

[Lil Giants]

Originally Posted by CustomRCmodels

Joe ,
Don’t you use the 3:1 version of the Wedico double-motor coupler type I made up for Ric ?
I don’t remember if I had send you the gear to do that yourself , or if you did get it from Ric ?

Yeah, that's part of the 6.2 additional reduction. 3:1 in the twin motor coupler and 2.1 in the t-case.

Nathan, with the 55 turn motor and 3:1 axles, I'd think you'd want 25 or 30:1 planetary box. Your wdc tires will be about 15mm smaller diameter.

[Espeefan]

Joe, thanks. I went back and re-did my calculations. I removed the trans cover and counted teeth on the spur gear as well as the belt drive reduction. Here are my findings, assuming I stick with the 3:1 axles.

1st gear final drive ratio is 66.87:1
2nd gear final drive ratio is 33.3:1
3rd gear final drive ratio is 16.65:1

Just for grins, I also calculated the actual mph in each gear. Had to see what kind of ground this truck would cover. One revolution of the tires covers 9" or .75 feet. Running a 6,000 RPM motor, 1st gear is good for .75 mph. 2nd, 1.5 mph. 3rd, 3 mph.

Hub speed is 89 RPM in 1st, 180 RPM in 2nd, and 360 RPM in 3rd.

Looks like a Novak on 12 volts would need a 16:1 planetary and 4:1 Rust axles to come out somewhere between the stock driveline's 2nd and 3rd gear speeds. About 1.8 mph.

Or with a 20:1 planetary and 4:1 axles, I'd be getting about 1.45 mph. A little under 2nd gear speeds.

If I stick with Wedico axles 3:1, a 20:1 planetary will give me about 1.9 mph.
16:1 planetary and 3:1 axles gives about 2.4 mph.

That looks much better!

[Rogue]

WOW..... You guys are way beyond my scope of intensity when it comes to figure gearing. Reading all these responses, I would think we're trying to decipher Einstein's theory of Realitivity

[Espeefan]

Rick...

So Rick, how much power do those little 385 motors have? I'm really curious if they struggle at all with a heavy load? Do they notice the load much, with the reduction? I'd be curious to see a video....

[Rogue]

I don't have any visual proof of it, but I have run my single axle and flatbed doubles around with a 12 pack on each trailer. At the time tho, the thought never crossed my mind to get a GVW on it.
Did it pull it? Yes...... Did it struggle doing it? It did, but not to anywhere near the degree that i was expecting. I was actually impressed with the capability of the 385 canned motor.
The biggest selling point for me on these gearmotors is the fact that there is ZERO backlash in them. Unlike a Tamiya 3 speed which has a ridiculous amount of slop in it.

[Espeefan]

You should do it again, Rick and get some video! I do believe you though. That's pretty strong for a little motor. A 12 pack is about ten pounds, I think. I hear you on the tranny slop. The Wedicos have that too. You'll get that anytime you have slots in a gear, so that the dogs can engage the gears better.

[Espeefan]

I ran into an interesting problem with Banebots today. I was going to place an order for the smaller planetary drives, which come with the 385 motor. It looks like they are discontinued now. The only one that is still available is the 36mm, 16:1 planetary drive with the the 385 motor. Seems Banebots is replacing them with the larger P60, 540/550 can motor boxes. The ratios are the same, but the smaller 385 sized boxes would fit better in some cases. I ended up going with a P60 20:1 instead. Just thought I'd give a heads up for the guys considering the smaller 36 and 28mm planetary drives.

[Rogue]

Another alternative is this. Scott (rcguy farms) turned me on to these years ago.

Look for the B series beetle motor halfway down the page
http://www.robotmarketplace.com/store_ant_motors.html

[SonoranWraith]

x2 on the beetle motors. Very nice size with good power and variety of gearheads in a small pkg.

[fhhhstix]

I have 2 of the beetle 104's in my tracked CAT tractor and they work great.

Travis

[Espeefan]

That looks like a great motor too. Maybe for a future project!

[oldboy]

I just reduce the size of the pinion gear from stock 13 or 15 to 10 or 8teeth and that slows them down real quick

John

[wolfws6]

So I have decided to run a 55t motor and 6 tooth pinion. I need to slow the truck down but I need a lot of extra torque over the stock motor to pull this massive 45lb toy hauler trailer around. BUT,,,,,,, Here is the magic question????? How much slower will it be vs 55t motor 6 tooth pinion and stock tires vs low pros? I'm running rc4wd low pro tires. They are 73mm tall vs stock Tamiya's 83mm. So theoretically it would be even slower maybe to slow. I want realistic speed more torque. Any suggestions Please help!!!!!

[Espeefan]

You won't loose much speed by decreasing the tire size 10mm. Only about a 1.123% decrease in speed overall. Not enough to worry about.

If you know what your motor's Kv rating is (RPM per volt), you could actually calculate the speeds of the truck in all three gears.