RC HEAVY industrial Dozer D11

Hi all, I’m looking at building an rc dozer 1:10 scale and am wondering if it’s better to go high voltage ie 48 or 60 volt versus 12 v. Only reason I can think of is higher the volts lower the amps and much cheaper to buy a speed controller for 40 amps or less. I’m trying to build a dozer with more torque than a d11 would have and pushing power for the same size machine but on a smaller scale.
Mine will weigh in at around 325 lbs and these two motors I can get will generate around 600 foot pounds of torque each. Any other thoughts on building this dozer?

For a second, I thought you might have been talking about a real D11. (For those that don't know, it's bigger than the biggest dozer you've ever seen. It's much too big to use on road construction projects.)

1:10 scale is still large and heavy. 325lbs sounds about right. 48V is probably about right too. You will find a tradeoff between high-current controlers and high-voltage controllers. One of the best sources is golf carts. Just use whatever they use.

It is still a big machine and can do a lot of damage if it looses control. A failsafe system would appear to be essential.

Weedpharma

Hi,
Look at electric forklift gear.

Tom.... :slight_smile:

Generally voltage scales as the square root of power, then the wiring doesn't have to get as thick as
an arm.

Something like 24V for 250W, 48V for a kW or so, 200+V for electric cars (20-50kW), etc. You
don't have to follow this, but parts like motors and contactors are easier to find if you stick to
industry standards/norms.

Stricter legal requirements kick in for high voltage (I think that's normally 50V or so), and there are
more options for electronics at 48V and below anyway.

Hi,

I'm trying to build a dozer with more torque than a d11 would have and pushing power for the same size machine but on a smaller scale.

With a smaller footprint, how do you envisage getting all that torque to the ground?

Tom..... :slight_smile:

Firstly torque doesn't go to the ground, it goes to the wheels. Force goes to the ground, the radius of the
wheels and number of driven wheels determines the ratio between ground force and driven wheel torque.

Lets use proper units then the calculations are nice and clear:

mass about 150kg, weight about 1.5kN. Suggested torque 807 Nm per wheel. The D11 seems from
photos to have wheels about 1m in diameter, so the model wheel radius would be about 0.05m, suggesting
a force per driven wheel of 16kN, or 32kN total for 2 driven wheels, making it stupidly overpowered.

To climb 33% slope with a load equal to its own mass would need 1kN per wheel, meaning 50Nm
per motor, not 807!!

Remember torque = force x radius, so force = torque / radius.

807Nm is a stupendous amount of torque, way beyond your everyday experience unless you race
formula 1 or fly jets.

Torque for traction scales as the square of size, not linearly.

To climb 33% slope with a load equal to its own mass would need 1kN per wheel, meaning 50Nm
per motor, not 807!!

Remember torque = force x radius, so force = torque / radius.

807Nm is a stupendous amount of torque, way beyond your everyday experience unless you race
formula 1 or fly jets.

Torque for traction scales as the square of size, not linearly.
[/quote]

Hi there thanks for helping me out with the calculations. This is based on final drive output speed of 60 rpm. The size of the elevated sprocket you see depicted often on D11s mine will be around 4 inch diameter or 2 inch radius if this helps. This unit can have more weight added to it if need be for more traction and less slippage and crazy pushing power.
Most dozers can push 30% to 60% of their own weight. Ive heard these united cd motors are cheap chinese motors that don’t last, not sure what other people experiences are but they are rated anywhere from 350w to 2000w. the one I was looking at was rated 48 w 1200 w 3200 rpm and 30 or so Neutons of force. Geared down I could probaby get 450 neutons. I thought would be a little light for my application. Ideally I’m looking for a brushless dc motor with controller geared down to 60 rpm but I could gear it down using sprockets say from 600 to 60 if need be.

http://www.alibaba.com/product-detail/48v-drive-brushless-motor-with-1200w_1705386801.html?spm=a2700.7724857.35.1.LlmMvM&s=p

thats the link for that possible candidate but this next one is sure to do the job and perhaps overkill but this is designed to really plow through the material.
Here is another option…

and finally … I like these because they are built stronger with 4 thicker planetary gears although it looks somewhat similar to the one above.

https://www.motiondynamics.com.au/brushless-gear-motor-60v-2000w-600-700-rpm-85nm-controller-accessories.html

Or I could simply go with these United cheap chinese dc brushless motors but I heard they burn out and not really for heavy duty applications. More for toy scooters and such, any thoughts?
Also this one only has an 8 mm output shaft and high rpm to have to deal with to get down to 60 rpm. I would think this would be my last choice.

and yet one more …

Who was this Isaac Neuton chappie? Newton is his name, newton is the unit, symbol N

You need to be careful about the difference between short term and continuous power ratings,
most electric motors are rated for intermittent use, not continuous, according to the application.
Bike hub motors are likely to be rated for continuous use in a plentiful flow of cooling air, for instance,
not the same as continuous indoors use. I think bike motors are a reasonable way to go, but
be prepared to install extra cooling if you are going for continuous full power use.

MarkT:
Who was this Isaac Neuton chappie? Newton is his name, newton is the unit, symbol N

You need to be careful about the difference between short term and continuous power ratings,
most electric motors are rated for intermittent use, not continuous, according to the application.
Bike hub motors are likely to be rated for continuous use in a plentiful flow of cooling air, for instance,
not the same as continuous indoors use. I think bike motors are a reasonable way to go, but
be prepared to install extra cooling if you are going for continuous full power use.

I would actually prefer to use a hub ebike motor but it doesnt fit well with the confined space I have in the hull. A scooter motor which looks something like your typical furnace motor shape would work well for my configuration. The thing I find most frustrating is on these chinese motor websites they list a motor for say 1200 watts then further down say 400 w then further down max output watts 1000 plus spelling mistakes etc and don't list dimensions to even see if it will fit. I would pay more and buy from US or canada but there's hardly any manufacturing anymore. I live in a city of a million people and no one seems to have a brain to even steer me to a supplier. If they don't have a part number, they are lost.

There are people that make large scale military tanks that might have useful info. The below is what google pulls up for making tracks.

https://www.google.com/search?as_q=diy+tank+tracks&as_epq=&as_oq=&as_eq=&as_nlo=&as_nhi=&lr=&cr=&as_qdr=all&as_sitesearch=&as_occt=any&safe=images&as_filetype=&as_rights=

UnoDozer:
I would actually prefer to use a hub ebike motor but it doesnt fit well with the confined space I have in the hull. A scooter motor which looks something like your typical furnace motor shape would work well for my configuration. The thing I find most frustrating is on these chinese motor websites they list a motor for say 1200 watts then further down say 400 w then further down max output watts 1000 plus spelling mistakes etc and don't list dimensions to even see if it will fit. I would pay more and buy from US or canada but there's hardly any manufacturing anymore. I live in a city of a million people and no one seems to have a brain to even steer me to a supplier. If they don't have a part number, they are lost.

For info on bike motors try an electric bike forum. For info on scooter motors try a scooter forum... I'm sure
people have used many of the bargain chinese motors and will have feedback on how good they are.

Some e bikes are driven from the chain. Look for those motors because they will even have a chain sprocket that might be useful to you. Unfortunately they will almost all have a clutch that allows the rider to pedal faster than the motor. This will be tightly integrated into the gear train and may be difficult to defeat.

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