What type of motor for a mini dozer?

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veloman   1 GW

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What type of motor for a mini dozer?

Post by veloman » Jan 25 2023 1:19am

I'm looking for expert opinions on what type of motor system would be suited for an application where the motor and controller will see high current near 0 rpm.
It will be geared for very low speed. This topic is not about gearing. Top speed is 3mph, but it will see speeds down to 0 at full load.
Do I want a brushed motor?
I've been testing with a bldc ultra low speed hub driving a chain reduction to the axle. I blew a cheap controller because it did not protect itself from high phase current as the rpms dropped from normal range to 0 (stall) under load.

The one option I see is just going with a high power system that will have vehicle traction loss occur as the yield mechanism. I also think a heavy flywheel on the motor may help with high current draw as the rpms drop.

Is there something particularly problematic with a very low kv hub motor (5.5kv) compared to inrunner bldc that spin at normal speeds? My converted tractor using a Motenergy motor and Kelly sinewave controller has no issue running at extremely low rpms (maybe 5%) of rated speed. Though it does have issues starting from 0 rpm with immediate load.
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Re: What type of motor for a mini dozer?

Post by DogDipstick » Jan 25 2023 5:20am

Forklift ( 10kW+) ( 500$+) or Genie scissor lift motor ( 4.5kW)( 150-700$). Curtis and a 24v system. Dead reliable.

I hear brushed motors love amps. Replaceable brushes.

I hear stall current can kill a strong BLDC hub motor really fast, too.

IF you use a flywheel you will still need the amps, to put into it, to get it up to speed,anyway... ... Seems like some kind of deficiency there since the load very well may be less than what is used in spinning the fly, and the amps drop when it spins up anyway... so in the med-high load motoring tork regions of operation you would be lugging and bogging unnecessarily...

.... and is this flywheel gonna have a one way bearing? To disengage upon stopping the electric motor? So it keeps its momentum? Or will you have to take the power to spin it down? Takes just as much power to spinup a flywheel as it does to slow it down. Horseypower. Put 5hp into a flywheel, in (X)time, takes same 5hp powerr to slow it down, in that same following (X)time. Do you plan to get this back though regen, or are you just gonna waste it to heat and brake the flywheel mechanically? Is it hydrolic prime mover? Will the electric motor have to come to a full stop?

I hear ( well, know) you can stall a blade easy.. backhoe, or dozer, snowplow. Dozers move stuff. Sometimes that which is to be moved.. doesnt move.. and your tires will just dig in with your weight ( if you have the chains, tracks, or tires for the traction) ... and dig.. and dig.. and dig.. until the load will stall the prime mover potentially...

I also know a broken bulldozer or traction engine.. is tough to get out of the field... where it broke down.

Lol.
84v of Ironhorse XC.. :) :bolt: by Chevy :bolt: :D You call .. that.. a "glitch:" ? :twisted: (...No Mom. The formula is Kaw > 1(Hr) = Impounded. The math checks out. I'll be fine. ).. :? Broke20Horsies! 17,830w !! :x 1 (pound / second) Hp = 338.24 M^2 Kg^2 / Sec^4 :twisted: ) :| isn't 13" x 27".. Oh nvrmnd :roll: 4+25% = 5 ; 5-20% = 4... 5(1-20%) = 4.. so, to correct the incorrect reading, of 4 ... 4(1+25%) = 5 :confused: Fabricator @BSECo. :( God. Damn. Slugs. :o

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Re: What type of motor for a mini dozer?

Post by ZeroEm » Jan 25 2023 8:43am

Industrial equipment with an ICE engine has one thing in common the engines are not directly connected to loads, they are linked with a hydraulic system. This allows the equipment to stall and not stop the motor. Flywheels are for ICE engines to balance the power between piston strokes. Can not think of a reason for a electric motor to have one. Not that i'm an expert, have run all the fore mentioned equipment.

Only way to replace hydraulic system would be to cut power to the motor before something burns up. May need to over spec the controller and have it cut out at stall or before. outside of gearing low volts and Kv motors seem to be the standard. Volts gives you speed. Amps gives the torque many need to up the amps until the desired power is achieved. As DogDipstick commented on 10kw motor at 24v should be in the range of 4-500a. They may have not changed the motors they were all brushed motors. the first ev's were build out of these motors.
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Re: What type of motor for a mini dozer?

Post by ZeroEm » Jan 25 2023 8:59am

Was looking over the latest offerings. It seems they are all over the place. Some still use brushed motors others have up to 240v BLDC and everything in between. On thing they have in common is two motors. One for the hydraulics and a second for the traction motor.
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Re: What type of motor for a mini dozer?

Post by veloman » Jan 25 2023 9:32am

Yes, hydraulic system for traction is the other option. Though I rather not go that route yet. Of course the drawback is efficiency loss. But it works for high force/torque.

The flywheel would put all it's energy into the drivetrain. That kinetic energy would balance the load requirements as I go from simple travel to ground engaging, where the machine WILL eventually be stopped (assuming the force at ground engagement isn't adjusted to allow continued travel, which is a good idea). The flywheel would put out huge peaks of wattage into the driveline as the tires are being forced to stopped by the ground engagement implement. ... or more likely the tires will loose traction when this happens.
Either way, the load will be lessened on the motor itself.
Higher wattage to get up to speed is expected and not a problem. The current 8) problem is the huge amp draw as the vehicle engages the ground.

A flywheel on a fixed drivetrain/motor setup will make the vehicle act heavier. So stopping will be something to consider. Since the motor rpms are so low to begin with, there won't be that much stored energy, even with a heavy flywheel. But you are right, being able to engage or disengage the flywheel would best.

I have a treadmill motor rated for 3hp, it has a flywheel on the shaft.

I'll probably pick up a walkie pallet truck for $500 and rebuild it into a dirt machine. Lots of good components and heavy steel.
Or go big with a 6000lb forklift for 1000-1500.

I converted a motorcycle in the past with a Perm132 brushed motor. It was plenty happy starting from 0mph with a load on a hill, compared to the bldc motors I've used. And that was with a top speed gearing of nearly 70mph. Geared to 3 or 4mph, a brushed motor should have little problem spinning the tires as the machine is stopped.
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Re: What type of motor for a mini dozer?

Post by ZeroEm » Jan 25 2023 10:51am

by veloman » Jan 25 2023 9:32am

Yes, hydraulic system for traction is the other option. Though I rather not go that route yet. Of course the drawback is efficiency loss. But it works for high force/torque.

The flywheel would put all it's energy into the drivetrain. That kinetic energy would balance the load requirements as I go from simple travel to ground engaging, where the machine WILL eventually be stopped (assuming the force at ground engagement isn't adjusted to allow continued travel, which is a good idea). The flywheel would put out huge peaks of wattage into the driveline as the tires are being forced to stopped by the ground engagement implement. ... or more likely the tires will loose traction when this happens.
Either way, the load will be lessened on the motor itself.
Higher wattage to get up to speed is expected and not a problem. The current 8) problem is the huge amp draw as the vehicle engages the ground.

A flywheel on a fixed drivetrain/motor setup will make the vehicle act heavier. So stopping will be something to consider. Since the motor rpms are so low to begin with, there won't be that much stored energy, even with a heavy flywheel. But you are right, being able to engage or disengage the flywheel would best.

I have a treadmill motor rated for 3hp, it has a flywheel on the shaft.

I'll probably pick up a walkie pallet truck for $500 and rebuild it into a dirt machine. Lots of good components and heavy steel.
Or go big with a 6000lb forklift for 1000-1500.

I converted a motorcycle in the past with a Perm132 brushed motor. It was plenty happy starting from 0mph with a load on a hill, compared to the bldc motors I've used. And that was with a top speed gearing of nearly 70mph. Geared to 3 or 4mph, a brushed motor should have little problem spinning the tires as the machine is stopped.
Don't think you need need hydraulic drive just take it easer on your controller. Limit the amps more or get a bigger controller.

Have a picture of your mini dozer that you can post?

All heavy equipment that I have been around was over built. Have not operated any really small stuff. Truck bed mounted back hole once. Dozers were D6 - D8 (getting big). Mostly D7' Dozer's never stalled the tracks, dozer would stop moving just pick the blade up a little. Run a track hoe for a short while, way to much work.

First wife was a farmers daughter so spent 10yrs around a farm, did not do any plowing, did work on the tractors and combines and drive trucks for them.
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Re: What type of motor for a mini dozer?

Post by veloman » Jan 25 2023 11:03am

ZeroEm wrote:
Jan 25 2023 10:51am

Have a picture of your mini dozer that you can post?

All heavy equipment that I have been around was over built. Have not operated any really small stuff. Truck bed mounted back hole once. Dozers were D6 - D8 (getting big). Mostly D7' Dozer's never stalled the tracks, dozer would stop moving just pick the blade up a little. Run a track hoe for a short while, way to much work.

First wife was a farmers daughter so spent 10yrs around a farm, did not do any plowing, did work on the tractors and combines and drive trucks for them.

The machine I built is not actually a dozer, but a mini wheeled loader/walk behind tractor. I still need it to dig into the ground a bit to load the bucket or do light grading. I made a rear plow for it, in addition to a front dozer grader blade. It's a wacky mess, really an experiment. Single axle with a small trailing caster. Walk behind style. It's purpose is for trail building.

I have an old Sears garden tractor that I converted. That can plow hard ground with a ripper. Much better weight and traction and torque with the transmission. Over 1200lbs drawbar pull. The drawback is that it sucks at maneuvering. The above single axle machine can zero turn with no rear implement (using the swivel caster wheel).

When I get a good piece of land I will convert an old dozer or similar to electric. Love watching heavy equipment videos.
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Re: What type of motor for a mini dozer?

Post by ZeroEm » Jan 25 2023 11:15am

:lol: Was thinking much bigger. I would shoot for enough power to keep the wheels turning even if the machine stalls, this should stop the motor from stalling. If that possible, may cost to much. Need like a locking third member or postrack to keep it from turning on you but may make it harder to turn.

Looks like fun! be safe.
which Motenergy motor do you have?
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Re: What type of motor for a mini dozer?

Post by veloman » Jan 25 2023 10:55pm

ZeroEm wrote:
Jan 25 2023 11:15am
:lol: Was thinking much bigger. I would shoot for enough power to keep the wheels turning even if the machine stalls, this should stop the motor from stalling. If that possible, may cost to much. Need like a locking third member or postrack to keep it from turning on you but may make it harder to turn.

Looks like fun! be safe.
which Motenergy motor do you have?
Technically it's a Mars ME0201013101.
Most of the conversion details for the tractor is here http://www.evalbum.com/5578

The walk behind has a solid axle, that's why I added the swivel caster to allow it to turn by applying weight on one side of the handlebar. I may have made a mistake with that setup. But I wanted the traction. It's also very hard to find a differential axle that is as narrow as I want - 32" vehicle width.

My next build will likely be a skid steer design. Two motors, driven separately. Though I think the wheelbase can't be much longer than the width for skid steering to work well.

I have a ton of crazy ideas. Love testing them out.
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Re: What type of motor for a mini dozer?

Post by ZeroEm » Jan 26 2023 7:52am

Don't think I can offer any advise you have not thought of. Looks like you are giving that motor enough. Want to stay in the continuous range if not you would need to stop and let it cool off that would not be any fun.

Was surprised when younger how little horse power tractors had, some 20hp. It's different now they are huge with high power. What they had was low gears. Remember the old International trucks with the granny gear, they were stump pullers.

Would look at gearing it down some how, don't know how much money you want to put into it.

Solid axel is what you want for maximum pulling. The old tractors had left and right brakes to make sharp turns. You would feel a jerk as it released torque on one wheel. Guiding it in the field was with steering wheel unless you were pulling hard then the front wheels would skid. You would tap one of the brakes to turn it. that is why all the weights on the front of tractors. To increase the weight or traction they would fill the tires with calcium or some solution to make the wheel heaver not discounting wheel weights.

Only thing I can think of it from stalling would be a bigger motor or lower gears. That motor is good size. maybe smaller implement that's the way farmers do it. They don't buy bigger plows than the tractor can pull at speed. They don't want to break anything or over heat the motor.
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