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Old 10-15-2009, 12:50 AM   #1 (permalink)
bennelson
EV test pilot
 
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Join Date: Jan 2008
Location: Oconomowoc, WI, USA
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I build a 4x4 Gas-Electric-Hydraulic Hybrid!

This is no joke!

But I am not talking about a car - rather, a riding lawn mower.

It all started because of my upcoming Annual Bonfire.
I hold a bonfire every year, as an excuse to meet up with old friends, and clear out brush and wood not useful for my wood stove.

The event is at my parent's property, which is large and wooded, with a big back area for the bonfire.

Also, my Dad runs a remodeling business, which is housed just down the street, so I usually grab extra wood out of the dumpster from down there. This year, one of the construction cargo trailers was filled with an entire torn-out cedar picket fence.

The idea was to pull the trailer already loaded up with all that cedar, from the shop over to the house, and then use the lawn tractor there to pull the trailer into the wayback, and unload it all for the bonfire.

It SEEMED like a good plan.

The problem is that it has been cloudy and rainy for the last two weeks solid, the ground has really softened up. The trailer is a BIG and HEAVY trailer and the jack is welded in place, it doesn't swing up.

I tried pulling the trailer across the lawn, but any time I got going even SLIGHTLY uphill, the tires would just start to slip on the grass.

I would back up just a little, to get a better running start, but every time I tried that the tires would just slip again, and I would end up further back than I started!

When I finally ended up in the lowest point of the side-yard, I decided it was time to give up. I unloaded most of the wood to the ground, and was then able to pull the trailer out to the road, up the driveway, and then into the back property.

It's a big hill going into the back. It's DOWNHILL out there, but UPHILL coming back. I thought that would be OK, because the trailer would be empty for the trip back.

Keep in mind that my father's lawn tractor is a Simplicity V-Twin with a Hydro-transmission. It is very powerful and has an variable speed transmission. However, I was NOT able to pull the trailer back up the hill with that gas tractor. It wasn't really a matter of power, more about where you put that power. The trailer is tail-heavy, and when not loaded, actually pulls UP just a bit on the ball hitch, instead of adding tongue-weight to press the tractor tires into the ground.

I just didn't have enough weight on the ball, and wide enough tires. The tires would just spin, no matter what angle I tried to tackle the hill at.
Of course, I couldn't just hop off and help push, because the tractor has a kill switch in the seat. Believe me, I TRIED to hold down the seat and push the tractor at the same time, it just really doesn't work.


[Similar tractor to my father's 16 HP V-Twin with Hydrostatic drive]

By this time, it was getting toward the end of the day, getting dark, and threatening rain. I had to get home, so I ended up un-hitching the tractor, parking that in the garage, and left the wood in the side-yard, and the trailer in the wayback.

I figured that maybe I could come back the next day bringing my Electrak ELECTRIC riding lawn mower. The tires are wider (and half-flat to boot!) and it's tough to get more torque than you can with an electric.


[My 30-some year old electric riding lawn mower with 1/2HP drive motor]

Soooo, today, I put MY tractor on my beater utility trailer (thanks Mr. Speed!) and drove over to my parent's house. I unloaded the tractor from the trailer, then hooked the trailer to the tractor, and in two runs had all the wood moved from the side-yard to the wayback.

The Electrak handled the big hill with no problems while towing my trailer back up it.

My Dad happened to be about while I was loading up the second load of wood. I explained to him about the night before how the gas tractor couldn't pull the empty trailer back up the big hill, and how I brought my tractor out to finish the job. He said something like "Aw, you just brought it out so later you could brag to your friends how your electric one works better than my gas one."

Um, yeah, I think he pegged me there.

Now that I actually moved all the firewood, the next job was to show off how great my Electrak worked by towing the construction trailer up the big hill.

I rode out back and went to hook up the trailer. That's when I remembered that the ball hitch on my tractor is really low. And the trailer isn't. The jack does NOT swing away, it can only be cranked up so far. I was actually able to hitch it up, but at the first little bump the trailer jack just dug into the ground.

Hmmm. So, that's not going to work. If only there was some way to skid the trailer jack OVER the ground. I grabbed a plastic sled from the garage and put that UNDER the jack. Instead of hitching the trailer to the ball hitch, I just hooked the safety chains to the ball instead. That way, the trailer could be up higher and NOT dig into the earth.
This actually worked. I started climbing the hill, and quickly got past the dug-in tire mark of last night's work with the gas tractor.

Still, it wasn't much further until the bad tail-weight of the tractor, and the increasing steepness of the hill meant that the Electrak's tires were now slipping as well.

Grrrrrr. Frustration.

I backed down the hill. I tried a couple other things, even hooking the BACK of the trailer to the tractor. None of them worked.

Oh, did I mention it was now raining? Not a downpour, but 40 degree rain is never fun, especially when you already have turf trouble.

So, my problem was that the tractor hitched up great to the gas tractor, but that didn't have enough traction, and the tractor wouldn't hook up decent at all to the Electrak, which had MUCH better traction, but still ended up slipping, just further up the hill.

If only I had four-wheel drive.

It occurred to me that not all four wheels had to be on the same vehicle.
One of the many little things I still need to fix on the Electrak is the seat safety switch. Since it doesn't work, it was simply bypassed, which simply means that if you fall off the tractor, it keeps driving without you.

That's also an advantage, because I now had at hand two tractors, but only one me.

I grabbed my tow rope and and moved both tractors to the trailer.

You can see where this is going, right?

I parked the Electrak just a bit up the hill, and hooked the tow rope to the ball hitch. I hooked the other end to the front bumper of the gas tractor. And hooked the trailer to the back of the gas tractor.

I now had an Electric-tow-rope-gasoline-hydraulic four wheel drive torque beast!

I put the Electrak in first gear - which is REDICULOUSLY slow - and then hopped on the gas rider and eased the hydro into its slowest speed. Because it's variable speed, I could speed up or slow down by tiny amounts to match the speed of the Electrak, mindlessly crawling away ahead of me, and keep tension on the tow rope.

Once or twice the wheels of one tractor or the other would start to slip, but all I had to do was speed up a tad to ease up on the Electrak, or slow down a bit and let the Electrak pull the gasser when its wheels were slipping.

I can't believe this actually worked.

I think it was like a Saturday Morning special.

I was all high big-headed thinking that my electric mower would out-torque the gasser and I could brag about it.

In the end, only by gasoline and electric getting along, could we all work together to get the job done.

Go Team Hybrid!

Maybe next year, I will go back to the old-fashioned way: stuffing firewood into the back of an electric car!


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