I am making an electric golf tow cart

[JoeFahey]

I have been wanting to start a project like this for some time. I am also considering an electric/remote control lawnmower like this:
http://evatech.net/images2/orange6e.jpg
For the golf cart I suppose I might want it to be something similar to this:
http://www.made-in-china.com/image/2f0j...l-Golf-Cart-Golf-Trolley-HB8868Y2-.jpg

I haven't done a lot of work with this type of stuff past working on RC cars and such. I saw an article in the DIY section of PopSci a month or two ago where they used PVC piping as the structure to support the contraption when they made an electric lawnmower.

As I said, I am new to this. This type of stuff reminds me of battlebots, and I found a parts site here:
http://www.robotmarketplace.com/store.html
Do you have any other suggestions for sites?
I am very handy, and I can learn on my own quickly. I just want to start getting into this fun type of hobby.

For powering something such as a lightweight golf bag tow cart, what kind of motor would you suggest? What would the specifications and requirements for such motors have?

Fabricating the chassis and other parts of these structures is not problem for me. It is just the electronics and motors that I am not entirely sure about.

All input and suggestions are welcomed! THANKS!

 

[JoeFahey]

 

[JoeFahey]

I know that you people are extremely intelligent and helpful when it comes to this kind of stuff.

 

[JoeFahey]

 

[us3rnotfound]

A remote controlled lawn mower? That doesn't sound too safe.

 

[LordMorpheus]

Originally posted by: us3rnotfound
A remote controlled lawn mower? That doesn't sound too safe.

He didn't say robotic.

THe golf cart will be fairly easy. PVC is a decent choice for the frame of the thing, but not the prettiest. You could use aluminum angle bracket (available at your local Lowes or Home Depot) as the structural element, either welded or bolted together. It's fairly easy to mount gear to, so that is a definate plus (careful, though, drilling holes reduces the strength so place your holes wisely).

That website you listed will have everything you need, but I don't know how prices compare. If it were my project, I'd use a motorcycle battery for power, I'd use motors from a powerful 12V cordless drill (these motors are very powerful. Go ahead and use the drill's transmission, too. It'll be compact, reliable, and specifically designed for the motor).

You'll need a couple motor controllers (which can be expensive) to drive the motors, and you'll need a 2-channel radio with the proper output interface to connect to the motor controllers (these should be easy to find, I think there is a pretty widespread standard for this kind of communication).

With a golf bag cart it will be tall and the center of gravity will be high - you'll need to give it a wide track to keep it stable. Look to use two independantly controlled drive wheels with either one or two free casters to allow it to turn.

Look to spend 40-50 per motor, 50-200 per motor controller, don't know radio prices, maybe 50 in raw material, and you'll probably need to gear the motors down farther than the drill motor transmission is setup for - you could probably drive the wheels with a chain-and-sprocket setup from the drill motors with that reduction built in (small sprocket on the tranmission output shaft, large on the wheel's shaft). These parts, the axels, and you're mounting hardware could set you back another couple hundred dollars. It won't be a cheap project.

Edit: I'm a rising senior student in mechanical engineering, I'm specializing in mechatronics (this kind of stuff).

PM me if you want help designing the thing, I'd be glad to throw in some time for you, I've got access to some software I can use to generate drawings, etc for you.

 

[JoeFahey]

Originally posted by: LordMorpheus

Originally posted by: us3rnotfound
A remote controlled lawn mower? That doesn't sound too safe.

He didn't say robotic.

THe golf cart will be fairly easy. PVC is a decent choice for the frame of the thing, but not the prettiest. You could use aluminum angle bracket (available at your local Lowes or Home Depot) as the structural element, either welded or bolted together. It's fairly easy to mount gear to, so that is a definate plus (careful, though, drilling holes reduces the strength so place your holes wisely).

That website you listed will have everything you need, but I don't know how prices compare. If it were my project, I'd use a motorcycle battery for power, I'd use motors from a powerful 12V cordless drill (these motors are very powerful. Go ahead and use the drill's transmission, too. It'll be compact, reliable, and specifically designed for the motor).

You'll need a couple motor controllers (which can be expensive) to drive the motors, and you'll need a 2-channel radio with the proper output interface to connect to the motor controllers (these should be easy to find, I think there is a pretty widespread standard for this kind of communication).

With a golf bag cart it will be tall and the center of gravity will be high - you'll need to give it a wide track to keep it stable. Look to use two independantly controlled drive wheels with either one or two free casters to allow it to turn.

Look to spend 40-50 per motor, 50-200 per motor controller, don't know radio prices, maybe 50 in raw material, and you'll probably need to gear the motors down farther than the drill motor transmission is setup for - you could probably drive the wheels with a chain-and-sprocket setup from the drill motors with that reduction built in (small sprocket on the tranmission output shaft, large on the wheel's shaft). These parts, the axels, and you're mounting hardware could set you back another couple hundred dollars. It won't be a cheap project.

Edit: I'm a rising senior student in mechanical engineering, I'm specializing in mechatronics (this kind of stuff).

PM me if you want help designing the thing, I'd be glad to throw in some time for you, I've got access to some software I can use to generate drawings, etc for you.

Thank you so much! With your major, this seems like something right up your alley.

For the cart, this I what I have and what I will probably end up using:
http://www.traileron.com/images/lt440.gif
It seems to have a somewhat wide base. I was thinking that the gears/motors and stuff could go in between the two wheels and underneath in a frame built by PVC. I also think I might want to add a swivel wheel onto the back end. For the basic design and frame for this cart I think I can figure it out. It's just getting the right electronics and motors that I am concerned about.

I weighed the cart with an average filled bag. The total weight was ~30.4 pounds. So do you think that 2 motors from a 12v drill would be enough for this? I found these Dewalt motors on the site I earlier linked:
http://www.robotmarketplace.com/marketplace_dewalt.html
I also saw all of these different categories of motors:
http://www.robotmarketplace.com/marketplace_motors.html
Is there a certain type that would work better in your opinion?

The other think that I am not entirely clean on is overall design of the motors, batteries, and motor controllers. Could the motors be hooked directly up to its respective wheel? If so, how would this be done?

For the motor controller, I found some on the site. There are more, but some of them include these:
http://www.robotmarketplace.com/marketplace_4QD.html
I believe that the one on the bottom would only be ~$100. It has different versions. One is a 12V model. Am I right in guessing that this means it is for a 12v motor?

Thanks again! And congrats on making it to your senior year! I have heard that engineering schools usually have the highest attrition rates.

EDIT: The motor controller, which is second from last on the page I linked, even says in its description that it could be used for something like a golf cart buggy. It said that it could be coupled with another controller to make the two motors act as one.

 

[Rage187]

my step father would modify 4 seater golf carts to 8 seaters. it was very lucrative.

He did this in SC for awhile than moved up to NC since he flooded the market down here.

 

[Kaido]

Someone hacked a Segway to carry luggage and follow them around, that would be a cool tow cart project

 

[JoeFahey]

 

[GuitarDaddy]

They've been around forever, I saw my first one over 25yrs ago. You might check out whats commercially available to get some design ideas

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Thats just a few of the ones I google up

 

[JoeFahey]

Originally posted by: GuitarDaddy
They've been around forever, I saw my first one over 25yrs ago. You might check out whats commercially available to get some design ideas

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Thats just a few of the ones I google up

Awesome! Some people at my golf course have these, but they aren't remote controlled. I am having trouble finding some of the more detailed specs on those though, such as the motor.

 

[Eli]

DO NOT use a motor from an electric drill to power this! It will NOT be powerful enough!

Well, I guess that's not entirely true. It depends on how fast you want to go, how much hill climbing power you need, etc. With enough gearing, they might be.. The one big advantage is they have a built in reduction.. But do not assume anything. Drilling is a lot different than imparting momentum on a static object. It better not be a China Special drill, is what I'm trying to say. Plastic gears and sleeve bearings will not stand up to such abuse for long.

I've been gathering parts to build a motorized hand truck/wagon for camping on the coast. The easiest solution for driving this that I could come up with, was motors and electronics from electric scooters. I have most of the parts for it, but haven't started putting it together yet. Such is the life of a tinkerer....

The biggest problem I've run into is the gearing, which is why a gearbox would be nice. Since the motors can spin ~2800RPM... with 13" tires, I need a ratio of like 7:1 to have a top speed of 4MPH...

Which isn't really a big deal, I have some 72 tooth sprockets that I will use.... But a gearbox and some smaller sprockets would be cleaner looking, probably.

 

[JoeFahey]

So far I have attached a piece of plywood to the base of the cart through 3 metal brackets with 2-4 bolts in each one. The whole thing is going to be completely detachable from the cart. I guess it will almost be like a little RC car when it is detached. So basically its going to be two sets of wheels attached to either the from of the back of the vehicle, and some other wheels to stabilize the thing on the other end.

For something like this, I have no idea on how to use the motors and the wheels. Do I buy to powerful motors and motor controllers, and attached them directly to the wheels? How would I just gears to make the wheels turn? These are newbie questions, but this is my first time building something like this.

I now need to figure out what to buy for parts. It has been suggested by the very intelligent LordMorpheus that I use a motor from a 12V drill. Are there any other suggestions? Besides a battery, motor controller, and motor, what else do I need? Again, what do I need to buy to use the motor on the wheels? Some kind of gearbox and chain?

The last thing I really need is a good site to buy from. Possibly I have already found one here:
http://www.robotmarketplace.com/store.html
Are there any other suggestions?

I am in need of a lot of help. Thanks guys!

 

[JoeFahey]

 

[Eli]

Whoa, that is an awesome site.

That site will have everything you need, but I bet it will be expensive.

Now you need to do some math. How fast do you want to go? How big are it's tires?

How many RPM do you want your motor to spin? How much current do you want it to draw? How big will your batteries be?

lol.. Lotta stuff to think about.

 

[JoeFahey]

Originally posted by: Eli
Whoa, that is an awesome site.

That site will have everything you need, but I bet it will be expensive.

Now you need to do some math. How fast do you want to go? How big are it's tires?

How many RPM do you want your motor to spin? How much current do you want it to draw? How big will your batteries be?

lol.. Lotta stuff to think about.

Well I don't know too many formulas. I don't have my engineering degree yet, lol. The wheels are ~10 inches. The total weight of the load will be ~30.4 pounds. It will be over the grass on the golf course, and there are a fair numbers of hills. It doesn't need to go too fast. I don't know, mabye around 3-5 MPH.

 

[Eli]

The formula for speed in MPH is:

RPM * tire diameter / gear ratio * 336.

The formula for gear ratio is:

RPM * tire diameter / MPH * 336.

It will weigh 30lbs fully equipped?... The motors, batteries, gears, etc?

Most lead acid automotive batteries weigh at least that.. What are you going to use to power this?

Will the batteries be level, or will they be subject to tipping? If so, you will need Sealed Lead Acid, or SLA(Also sometimes called AGM - Absorbtion Glass Mat) batteries.

You need to pick your motor(s) out before you can safely calculate your Amp Hour requirements.

 

[JoeFahey]

I used the formula and it has the result of ~8.8 MPH for this EV Warrior motor:
http://www.robotmarketplace.com/marketplace_ev.html
This is without calculating the weight though I am assuming. Right now from that site I am down to either the motor linked above, or this one:
http://www.robotmarketplace.com/marketplace_dewalt.html

Do you have any recommendations?

I also need a gearbox. The gearboxes for the Dewalt 24V are through the link at the top of the page for the Dewalt motor linked above.


In the description for the 24V Dewalt motor, there is a link for some "Dustin Motors." I think these are gear boxes. The one on the bottom is the cheapest. Would it work as a gearbox? The one on the bottom is in my price range, and it says it works with the DeWalt 24V. Do I just attached the motor to the the housing that is listed don the bottom of the linked page? Then do I attached one of their dirve shafts from this housing to the wheel?

All suggestions and comments are appreciated. Thanks!

 

[Eli]

Weight does not matter, really. The formula is a constant. If the motor is turning X RPM, you can figure out your speed.

Of course, if the motor is not powerful enough to spin at RPM in question, then you will move slower, or not at all.

BTW, your links all point to the same place.

Those gear boxes and motors look excellent.

How are you planning on driving the tire with the gearbox? Sprocket? Direct drive? How are the wheels setup? What kind've bearings do they have? Is it live axle(both wheels spin at the same time) or are they independent? If they are independent, do you want t drive both wheels, or just one? Both would be best, but would obviously require two motors, gear boxes, etc.. and would also use double the power.

I'm having a difficult time putting everything together in my head since this is not my original idea... That's usually the way I do things.

For my motorized wagon, the sprockets would be bolted directly to the hub of the tire, and then driven via chain from the motor.

However, after looking around on this site... I think I might just use those motors and gear boxes. It has the potential to be more reliable, I think.. Since it will be used on the coast, sand contamination is a big concern. I'm just iffy on the load support. I would probably have to add some pillow block bearing supports to the drive shafts if they are to carry the weight of the wagon and 150-200lbs in supplies, which will include a wind turbine.

Our goal is to more or less be self sufficient on the coast, and be able to stay for as long as we want. As it is, it is difficult to stay for more than a few days because it is a 2 mile hike in, and water, food and beverages are extremely heavy... you just can't bring enough.

 

[JoeFahey]

Originally posted by: Eli
Weight does not matter, really. The formula is a constant. If the motor is turning X RPM, you can figure out your speed.

Of course, if the motor is not powerful enough to spin at RPM in question, then you will move slower, or not at all.

BTW, your links all point to the same place.

Those gear boxes and motors look excellent.

How are you planning on driving the tire with the gearbox? Sprocket? Direct drive? How are the wheels setup? What kind've bearings do they have? Is it live axle(both wheels spin at the same time) or are they independent? If they are independent, do you want t drive both wheels, or just one? Both would be best, but would obviously require two motors, gear boxes, etc.. and would also use double the power.

I'm having a difficult time putting everything together in my head since this is not my original idea... That's usually the way I do things.

For my motorized wagon, the sprockets would be bolted directly to the hub of the tire, and then driven via chain from the motor.

However, after looking around on this site... I think I might just use those motors and gear boxes. It has the potential to be more reliable, I think.. Since it will be used on the coast, sand contamination is a big concern. I'm just iffy on the load support. I would probably have to add some pillow block bearing supports to the drive shafts if they are to carry the weight of the wagon and 150-200lbs in supplies, which will include a wind turbine.

Our goal is to more or less be self sufficient on the coast, and be able to stay for as long as we want. As it is, it is difficult to stay for more than a few days because it is a 2 mile hike in, and water, food and beverages are extremely heavy... you just can't bring enough.

Thanks for pointing out the problem with the links. They seem to have the same link for some of the pages.

I really have no preference for whichever of the ways to turn the wheels you suggested since I have never done this before. I was originally thinking I would have two separate motors. How would this work though? If I turn left, would the two separate speed controllers recognize that one motor would turn one direction while the other turned the other direction?

So basically, can I have the motor attached to the gearbox, and then the gearbox attached to the shaft, and the shaft attached to the wheels? Would you recommend this method?

Thanks again!

 

[Eli]

That would require pretty sophisticated controllers and other electronics. I don't think that is necessary for such a project.

If you are moving foward and make a turn, the wheel issue isn't a big deal - the tire that is turning slower will just slip. If you want it to be able to do zero-radius turns while not moving forward, you would need to be able to control each wheel as you stated above.

The drive method sounds good, but how exactly are you planning on attaching the shaft to the wheels?

 

[Homerboy]

yeah for bumping your own thread every 30 mins!

 

[JoeFahey]

Originally posted by: Eli
That would require pretty sophisticated controllers and other electronics. I don't think that is necessary for such a project.

If you are moving foward and make a turn, the wheel issue isn't a big deal - the tire that is turning slower will just slip. If you want it to be able to do zero-radius turns while not moving forward, you would need to be able to control each wheel as you stated above.

The drive method sounds good, but how exactly are you planning on attaching the shaft to the wheels?

I really do not know. the 10 inch wheels that came with it are hard plastic. I might want to upgrade these wheels, but I thing that the large wheels will make this thing handle the terrain better. I found these wheels on the site:
http://www.robotmarketplace.com/marketplace_wheels.html
I am assuming that some of these wheels have a simple way to attach the shafts they sell to the wheels. I still do not know though. Is there a simple way that is commonly done?
Thanks again!

EDIT: I found this Dustin 1 motor at the top of this page:
http://www.robotmarketplace.com/marketplace_dustin.html
Is this some sort of a gear box, or do IO need to buy a motor with it? Do you think that this would be powerful enough to power the two wheels for the cart?

 

[Eli]

Sprocket and chain is the easiest, most common way. It might be your best bet. Rigidly coupling the wheel to the drive shaft would probably be a mistake without considerable engineering thought. Stuff has a tendency to break under such conditions.... the gearbox bearings would be supporting the load. Maybe that would be okay with such a light load, though? Assuming it will be able to be kept light with the addition of batteries and such.

It does appear that those wheels can attach directly to the gearboxes, though. Neat!!

This is going to cause me to spend even more money on my project(s). DOH!