Bringing the Smart Ass Fuel Mule Prototype from concept to drawing to life

Creating the World's Best Gas Caddy - Part 2

Author Jerry Hoffmann, Inventor of the Smart Ass Fuel Mule, and co-founder of Smart Ass Products, LLC shares how this idea came to life.  If you haven't yet-- you can check out Part 1 of this series here: Creating the World's Best Gas Caddy - Part 1


I was SO SICK of carrying gas cans to my dock!

So there I was, loving and living the lake life.  But NOT loving the gas jug lugging down to the dock on the regular.  Sure I could go to the marina, but the time involved, and the extra cost for marina fuel compared to street fuel, I knew there was a better way. 

So after failing hardcore, or more aptly-- finding the limits of a 2 wheeled platform, I set out to design a more capable solution.  A 4 wheeled off road fuel caddy solution, with a motor to do the hard work, and brakes to keep it all under control.  It had to be easy to load in and out of a truck.  Easy to get down to and out onto my dock, and able to navigate tight spaces well.  It should be able to handle fairly rough terrain, tracking over roots, rocks, ruts and anything else I was likely to encounter.  With a low center of gravity so it wouldn't be at risk of tipping over even on fairly steep ramps or hills.  Sure footed and capable.  Like a mule.   

Mules carrying jugs of fuel

Mules have 4 legs.  Surefooted and stable.  Powerful and capable.  Let's do this.


So just as mentioned as I ended Part 1 in this little series, I started to draw up what I had dreamt up.  Initially I drew up a proof of concept in a web based 3D CAD software I could easily use from my home PC.  And I came up with this rough idea of what I wanted to do:

Smart Ass Fuel Mule first 3D Concept Drawing in Tinkercad


I printed out a little 3D model of it on my 3D printer.   Now I wanted to make it lifesize! To prepare to do that I needed to take that drawing to the next level.  To fully dimension out what I was doing, and to be able to 'connect' the parts together with what's known as a constraint, allowing me to lock some parts together, but also allowing me to let some parts 'move' in the CAD software. 

I needed to work out the steering geometry to make sure that the steering arm, tie rods, spindles, and other parts could turn full range without hitting anything.  I had the right software, I used it at my business I operated at the time, a company I founded in 2004 and still operated at this point in 2020 when I was dreaming up the Fuel Mule.  I brought it home, and went to work.  Pretty soon, I came up with this:

Smart Ass Fuel Mule June 2020 Prototype Drawing Animation

Smart Ass Fuel Mule June 2020 Prototype Drawing


This was great.  It allowed me to work out all of the critical dimensions, and to plan for each and every part.   I could determine how much steel I was going to need.  How wide I needed my axle to be.  Where I would need bearings and what my tire clearance would be.  I designed the steel frame to be WAY tougher than it would ever need to be, I mean... why not use steel tubing that's twice the thickness of what would have done the job?  I figure any job that's worth doing, is worth overdoing.  That's just kindof how I roll. 

I spec'd out a brushed 500 watt motor and controller.  I calculated the gearing that I would need and determined what sprockets I would use for the chain drive to give me the torque and speed that were ideal.  The goal-- maximum torque so that it could climb hills and ramps easily, and a top speed just above walking speed.  At this stage I wasn't too concerned with it climbing up steep hills with a full load, so long as it carried a full load well on uneven terrain on slight inclines, level ground, and declines.  I found a brake that should do the job, this first of the 4-wheel prototypes would use a cable brake originally used on go-carts.

And then in June 2020, I started ordering parts. 

First Fuel Mule prototype parts to arrive in June 2020

And they started to come in.  I had them delivered to my home, working out of a small basement level garage.  

Some time passed as I refined my drawings a bit more.  And then I ordered steel.  That I took to my commercial shop where I have my welder and other fabrications tools.  

Welding up the very first Smart Ass Fuel Mule prototype frame on August 20th, 2020

And I began welding and grinding....  I fabbed up the very first Smart Ass Fuel Mule prototype frame on August 20th, 2020 at my shop off of Browns Bridge Rd in Gainesville, just down the street from my home on Lake Lanier.  

Smart Ass Fuel Mule Prototype P1 Frame nearly fully assembled on my shop floor

The frame was clearly overbuilt for the job, with heavy/thick walled tubing and a lot of it, but I wasn't worried about it being a bit heavy.  I wanted it to be strong.  Ridiculously strong.  


The moment when everything changed

And then it happened.  On August 27th, 2020, while coming home from having a cigar with a friend on the water.  I had a terrible accident that nearly brought an end to a lot more than just the Fuel Mule.  It almost brought an end to me.  

It was a dark night and I was coming home in my boat alone, after dropping my friend off at his dock.  I was passing a nearby marina on my ride home.  And unbeknownst to me- that marina had an 800' long breakwater sticking out in the middle of the channel.  The 120' that stuck out the furthest into my path, had zero functioning lights on it.  I was watching.  But I didn't see it.  And everything changed.

That's a story for another day perhaps.  But in short... I wasn't getting much done on this project for a while.  I was in ICU at Grady Hospital, the local Level 1 Trauma Center with 13 breaks in my jaw/face and a brain bleed.  I spent a total of 10 days and had two emergency surgeries there, and over the next year and half, had a total of 8 surgeries to repair the significant damage done to my face, jaw, teeth, and shoulder. I'll spare you from those pictures....

I'll never be the same, but I did survive that night.  I figure God must not be done with me yet.  Game on.   


Getting back at it

While living in my basement watching movies and healing from surgery to surgery for months.... I occasionally had moments where, whether in normal daylight hours or in the middle of the night not able to sleep due to the myriad of medications I was taking for pain... that I would slip out into my garage and work on the Fuel Mule.  Some of this early prototype assembly was done at 4am while the medicine wouldn't let me sleep.  

The very first Smart Ass Fuel Mule prototype nearing completion

Tank mocked up, ready for install of the pump, hose, and nozzle assembly.  Then completing those tasks by the Spring of 2021, the very first prototype of what I was then calling simply "The Fuel Mule" was complete.  

'Rusty' as it would later be called, as I was too excited to get it together to bother painting or powercoating the frame.  And as you can see, it's just beginning to earn it's name in this photo.

And we started to use it.  Regularly.  And we knew we were REALLY onto something here.  It made the job near effortless.  We saved time and money every time we filled up.  And as I used it, I thought about how I could make it even better.  And there were still some areas I knew I could improve on, but I had gotten pretty close.  Close enough that 4 seasons later, I'm still using Rusty myself.  

The first Fuel Mule Prototype aka 'Rusty' 4 seasons later

'Rusty' has served me well.  

In Part 3 of this series, I'll discuss more of that testing and refinement.   I already knew I had created the best fuel caddy solution for off road fuel transportation on the planet, but now it was time to put it to work, and to figure out how to make it even better.  




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