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Request for shove in the right direction: 12V motorized cart

Request for shove in the right direction: 12V motorized cart

Request for shove in the right direction: 12V motorized cart

(OP)
(It's been decades since my M.E. training, but I'll likely grasp your main points if you can remind me what I need to consider for the electric side of things.)

I am considering building a cart that can tote 100 lbs up a slight grade at walking speed.

PURPOSE:  aid me in carrying a barrel of WATER to a community gardening project I started: http://phoons.com/ger/

These components come to mind, but what do I need to pay attention to and find, etc?
- 12V motor (hp? diameter? rpm?)
- pulleys vs gears for reduction
- belt/drive to axle or to one wheel
- potentiometer for to ease to full speed?

[and the basic cart structure, wheels, steering--I can handle this]

Thanks!
oakisland

RE: Request for shove in the right direction: 12V motorized cart

Lots of good information on this site:
http://www.4qd.co.uk/

Benta.
 

RE: Request for shove in the right direction: 12V motorized cart

(OP)
Interesting. Thanks, benta.  

Something I see in that product site is reference to robots and remote control cars.

oakisland

RE: Request for shove in the right direction: 12V motorized cart

Find a clapped-out pallet jack and use everything but the forks.  You could probably use substantially smaller batteries with some gear reduction.  Then the user would operate it in the exact same manner.

Alternatively use a sit-on-it scooter (as seen on TV).  They move 200lb people up hill and have auto brakes on them too.  

Keith Cress
kcress - http://www.flaminsystems.com

RE: Request for shove in the right direction: 12V motorized cart

The rigorous way to approach this is a dynamic analysis of the torques required to accelerate & move that mass.  Size everything for "peak torque."  Websearch for the PDF document "Smart Motion Cheat Sheet" for a summary of the equations.  You may also browse through the engineering applications documents and web-based calculators of various gearmotor manufacturers (especially SEW-Eurodrive).  Going through that exercise will give you gearing/torque/RPM/horsepower values to help you infer what you will need.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering
www.bluetechnik.com

RE: Request for shove in the right direction: 12V motorized cart

(OP)
Thanks, itsmoked! Interesting ideas.

TygerDawg, that's exactly the kind of shove I needed--the reminder of "what do I need to focus on and calculate" etc.  There's an old parts place in town and I hope I can grab old parts of of shelves and put this together. Thanks!

oakisland

 

RE: Request for shove in the right direction: 12V motorized cart

(OP)
What I don't know yet (this side of starting to dig into product characteristics) is stuff like "what minimum HP motor would suffice".  Certainly the hobby/toy motor is out :) It's strong enough for lifting a marble up an archimedes screw...

oakisland

RE: Request for shove in the right direction: 12V motorized cart

I would guess 1 or 2 HP. If you need much more you may be better served by a small Honda gas engine.
As far as environmental friendliness, When you consider the emissions developed by the manufacture and disposal of a bank of lead acid batteries, a little exhaust may not seem so bad.
You can get a fairly reasonably priced hydrostatic transmission from surplus dealers.
Whoops! I just looked up some trans-axles and came across just what you need.
Take you pick!
https://www.surpluscenter.com/pages/Catalog284-127.pdf

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Request for shove in the right direction: 12V motorized cart

Why guess?  Calculate it.  There is a definitive relationship between RPM, torque, and horsepower (or Watts).  A 12VDC battery may be enough to do the job, but you might have to go very slow.  Or not.  The first step is to define your motion parameters:  accelerate to a determined speed, maintain, then decelerate to zero speed.  Your speed will determine torque requirements.  That will determine power requirements.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering
www.bluetechnik.com

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