Electric tractor project

woodsmith · Jul 23, 2010

I made a parking brake lever.

Brake off:

Brake on:

It works well enough to stop the tractor from rolling away but while playing I forgot to let off the brake before applying drive. The brake broke. The bolt in the pulley spokes was ripped out and the steel strap twisted all out of shape. I have now 'beefed' it up a lot but I might remake it in my usual 6mm steel. It will be fine for parking up though.

I also made the gear lever from some 20x2mm box tube.

The link is a bit of 5mm rod that I had spare. I formed eyes into the ends to fit the M8 bolts.

Trying it out I found that the curved part of the lever was rubbing the back of my knee while sitting so I adjusted it.
I shortened the rod and put a twist into the lever so it is further back.

The next thing was to make the brake pedal. That was more my usual over the top and over engineered part. :laughing:

I still need to make a bracket for the master cylinder and also I will need to bend the crank lever over a bit as the cyclinder is a little close to the edge of the pedal.

This is how it all looks from the driver's seat (excuse the view between my legs! :ashamed: ).

You can see how the brake pedal fits in
The gear lever, to the right, is forward for low gear. High gear is only a 1 1/2" backwards.

I also have this master cylinder.

It will sit low between the chassis rails and have a conventional hand brake lever over it. It will be plumbed in line with the foot brake working on the same hydraulic line so I won't leave it on when parked over night, the bolt in the pulley spokes will surfice for that.

I also tried the MR2 throttle pot.

It works but, like the slider pot, seems to have a dead area over the first 1/4 to 1/3 of the action. I am begining to wonder if it is controller programming.
Reading the manual I can see that I can reprogramme it with a £450 programmer or by manual methods with the flashing LED. However, it doesn't say how.

woodsmith · Aug 2, 2010

Things have moved on a bit.

I had to remake the brake pedal to get twin masters for fiddle brakes.

I also managed to get some gauges. A big old retro 0-50V voltmeter and a couple of clip on ammeters, +-100A and +-600Amp.

I also managed to find a throttle pedal with built in pot. It is from a Land Rover Defender TD5. Compact, cheap and easy to fit so Ideal.

I then stripped the tractor back down to it's components for painting. I have opted for satin black on red oxide. Unfortunately, now that the tractor has been taken outside piece at a time I can see where the red still shows through the black and there are definate 'holes' in the black paint so it will need repainting to cover those and the chips and scrapes from building it up again.

So now it is outside and I have the brakes on it.
The pipes are stainless braided flexibles in red sleeve made up for me by David at Llama 4x4.

The red goes with the red calipers.

So here she is.

I added my retro voltmeter to the temporary dash.

I will need to try and find a 350A ammeter to match.

I also put some 'carrots' on the controller terminals.

It now lives in my carpeted furniture moving trailer. Looks made to measure.

The only snag is that the brake pedal is too hard to press. I will need to change the effective lever ratio on the pedal. It has worked out at around 2:1 and I need to change it to somewhere nearer 5:1 or better at 8:1.
Then I need to get on with making the wooden seat and body shell for it incorporating all the lighting.

Johndeere3720 · Aug 2, 2010

That looks so cool! :thumbsup: great job! :thumbsup:

brokenot · Aug 2, 2010

Reading the manual I can see that I can reprogramme it with a ｣450 programmer or by manual methods with the flashing LED. However, it doesn't say how.

That would be unusual.

Usually, the LEDs are just for quick diagnosing of fault conditions. Some Curtis controllers have trimpots hidden under screw covers for tiny adjustments of some functions like plug-braking, but controllers like the one you have *likely* need a hand-held calibrator for any programming adjustments. Alternatively, a laptop can be used in place of the hand-held programmer, but the software and interface cost more than the programmer itself does.

We've got two programmers at work for setting up MOS90 Sevcons like this, but they won't work on any other controllers:

Cool project by the way!

Mace Canute · Aug 3, 2010

woodsmith said:
I also managed to find a throttle pedal with built in pot. It is from a Land Rover Defender TD5. Compact, cheap and easy to fit so Ideal.

Just as long as it doesn't come out of a Toyota car!

woodsmith · Aug 3, 2010

Thanks for the support, it has been a great little project but now the hard work begins and I must build body work in my wood shop.

Brokenot, I think you are probably right and the controller only allows diagnostics and not programming. I may be confusing it with another 'black box' thing I worked on a while ago that allowed programming by counting the LED pulses and 'flashing' one of the switches at the appropriate time as it cycles around the parameters.

I don't know how reliable Defender throttle pedals are, they come up for sale every so often when owners change from the TD5 diesel to a V8 gas engine but I've not heard news reports of any runaways, yet.

woodsmith · Aug 4, 2010

Broken photo link in previous post.

To solve the brake problem I decided to combine shortening the lever at the cylinder end and then adding a second link as a multiplier.

You can see from the other side that the lever from the pedal pivot is now very short and that now works on an adjustable pull rod onto a 2:1 lever pivoted on a frame bolted above the master cylinders.

The return springs are a big snug but it shouldn't be too much of a problem.

I also decided to tackle the throttle pedal. A bit of loom and a plug arrived for it today. I tried it but nothing happened and the controller flashes throttle fault.

I removed the throttle and checked the readings again. After a few more trys and checks I discovered that my ｣1.99 multimeter that was Dad's left over stock wasn't reading right.
I had to set it to 20k and it quite happily read something low and flickery at one end and 5.6k at the other end. What I didn't realise was that it didn't read low ohms accurately unless I then switched it down to 200ohms and the 20ohms.
Testing with my quality DMM it told me that it was about 2k to 5.7k so no good.

I toyed with the idea of doing something else with the pedal and the MR2 throttle TPS but then decided that as the TD5 pot was scrap I might as well open it up and have a look inside.
It has 3 resistance tracks, three wiper tracks, three wipers and three resistances.
I found one track that was 5k, great. Unfortunately the only way it was connected to the pins was via a wiper track that had a 2k resistance in line.
I decided to 'hotwire' it and so I soldered a wire from the pin to the wiper.

I then checked it and found that the pedal at rest didn't allow the wiper to hit zero so I set about adding more range of movement both inside the pot and in the pedal.
I had to grind away a bit of the pedal so that it stopped higher when the pot read zero.

Great stuff. I now have a 5k throttle pot that goes from zero!
I put it back on the tractor and...

...Still no go.
Long story short, with a lot of messing about and fine tuning I discovered that I had rebuilt the pot to work from 0-5k and the controller wants 5k-0.

So I had another play with the insides of the pot and manage to get a set of connections that allows me to have 5k-0. Of course, now the pedal didn't have enough travel at the other end of the pot. It means that I now have 5k-0.7k so I can't get full throttle.

So the following morning, having finished working on it at midnight, I sorted out the throttle finally and fitted it.
It works great!

The snag now is that there is no activity from the controller for the first 20mm of pedal travel. So I reworked the pedal to remove the excess travel and measure the pot resistance. It was 4.7k so I have set the pedal to start from 4.75k.
I now have an almost instant throttle response.

The only thing left is to fit a hand brake lever and to make some ramps for the back of the trailer so I can get the tractor back out again! Then I can start on the body work.

woodsmith · Aug 6, 2010

Some good news and some bad news.

Good news:
I have video of me, and my Dad, driving the tractor about in first gear. second was a bit too fast and bouncy on the cobbles and there is no padding on the seat.

Me:

Dad:

Bad news:
While playing and falling about laughing with silly EV grins I managed to get a clunk from the transaxle. I think a tooth has broken off.
I will need to see if anything comes out with the oil and look for a stronger replacement one.

woodsmith · Mar 1, 2011

OK, its been a while, work, bad weather, more work...:confused2:

I finally got around to taking out the broken transaxle.:thumbsup:

Wheels off.

Transaxle out.

There was a distinct rattle inside the transaxle, something that says much bigger then just teeth.
I got it back onto the workshop and opened it up.

Now I'm sure I drained the oil when I put it away last year, I'm certain of it, (checks previous images) Yep, theres a bucket and a load of oil in it under the axle.

Anyway, there are some big bits in there.

The crown wheel is in six pieces, plus spider gears, broken teeth and other shrapnal.

I had gotten hold of one of an old Wheelhorse a while ago just in case.

I removed the transaxle from it.

When I drained the transaxle, and I did actually drain this one, I got two pints of water and a pint of mayo!

Still, I got it in the workshop and started to take stuff off it to open it up. It won't open yet as there is the hitch pin through the case that is rusted solid, I will deal with it later. It turns out to be a Unidrive 4 speed (3F-1R) with I think a LSD.:thumbsup: It will stop me having fiddle brakes though if it is a LSD.

I wanted to change to Land Rover rims to make it easier to get rims for different tyre use, road and agri, so I thought about using a couple of old Discovery hubs.
It turns out that the locating spigot on the Wheelhorse hub exactly fits in the oil seal rebate on the LR hub.

:thumbsup:

The five bolt holes don't quite match but I can slot the WH hub holes and then make a spacer so that the WH hub can bolt down to the LR hub and still secure the brake disc.

That will be another week's job though.

I will try to drill out and heat the stuck hitch pin so that I can remove it and open the box. Can't risk not checking it is ok on the inside with all that water.