Almost Finished...

It's been a while since I've photographed or documented anything - stuff has been done, the big items being re-doing the control panel to include a volt meter and joystick for the hydraulic lift, neatening up the wiring and mechanically, getting the bushes on the lift arms machined and/or replaced as the arm and operator basket was quite wobbly due to the un-lubricated and badly worn bushes. A visit to the neighbour and his machine shop soon had that sorted out.

So here's the machine, in the middle of doing work:

Note the housings over the motor (3mm steel sheet no less) and the cover over the batteries, which is also 3mm, but made of alupanel (aluminium polyethylene composite panel) which is much lighter, and after what the sheetmetal shop charged for the motor covers, I was a little put off that option.

This is the latest version of the control panel. Notable additions are the voltmeter and key and the joystick for the hydraulic lift. The little button next to the hydraulic joystick is an emergency drop switch which is separately wired back to the batteries and drop valves, so if the joystick, switching FETs or main breaker trip, the arm can still be lowered.

All the components are IP67except for the meter and little toggle switch - those two shouldn't be too hard to waterproof (I think you can get a little rubber boot for the switch) - then it should be safe to leave out in the rain.

One of the key safety features I added was a foot switch. This activates the main contactor, meaning the machine is essentially dead otherwise. The only niggle is that you have to wait 1/2 a second before operating the controls - I might add a beeper to indicate when the machine is "live".

The hydraulics are still exposed - it's a bit of an awkward thing to cover. The 48v charge port is just to the left of it:

The gaggle of electrics. Somehow I ended up with less room than I expected to have.

This is the common point for pretty much all the wiring. The bit of perfboard below the fuses is a couple of MOSFETs - they take the switching signal from the special hydraulics joystick (which is rather fancy - it has about 7 or 8 connections on it) and switch the hydraulic valves, either to open just the lift valve when the pump runs to lift the boom, or to open both the lift and drain valves to allow the boom to drop.

As mentioned, this drop switching is replicated by a switch on the control panel as an emergency backup.

The main 48v 400A contactor with precharge resistors sitting on top.

And the main breaker.

So what's left to do?

• Add some safety bars to the operator basket.
• Make it fully rain-proof.
• Add a 240v inverter to allow the use of electric tools such as chainsaws, hedge trimmers etc.
• Improve the braking system.
• Add a picking bag for harvest season.

Re-jigging Stuff

In converting the machine I had mounted everything kind of temporarily with a view of doing it properly once the machine was functional. Now it is, and it's time to do the final mounting and routing of wires.

First up, run the motor wires inside the wheel arms, starting with the ol' hole saw:

The a little editing of the hole and some steel inside the section with the welder:

Add a hole near the motor:

And a matching hole to the side of central chassis:

Next, find a nice way to mount the controllers, starting with a bit of angle-grinder action:

Controllers lined up with some sheet added above for mounting other stuff:

And a top and a bit of paint:

The middle controller is for the hydraulic lift - it's essentially there to allow the 24V unit to be run off 48v, but speed control is a nice benefit.

Putting the Brakes Back On

I had convinced myself along the way that because the wheel gearboxes used a worm drive, they couldn't be driven by the wheels.

Turns out that's a load of crap. If the machine is on a slope and in motion and the controllers drop out (so there's no motor braking) the machine will keep on rolling. That explains this thing on the other end of the input shaft of the wheel gearbox:

Which takes what I guess would be called a brake disk:

Then a friction disk thing goes on top:

And then a pressure plate:

A later pic with the gearbox back on the machine - there's a spring each side to apply pressure:

And the cover plate goes on over the whole lot:

This mild braking action improves manoeuvring as it stops an un-driven wheel from freewheeling, however at high speed it tends to get rather hot, and I'm not convinced it will apply complete braking action on a steep incline - it's certainly something to be improved down the track.

Protecting the Motors

So the machine works, but everything is exposed. First thing to sort out is protecting the motors and cabling.

So I shot some pics for the sheet metal shop to work from:

Back in one piece

Once the wheels were on, drive hooked up, batteries and controllers in place, it was time to re-install the lifitng ram, hydraulic pump, main boom and platform.

And here it is:

Still with temporary wiring.

Hydraulic power pack in place.

Temporary speaker cable seems to be holding up :)

Test control panel. The final unit will be more robust, waterproof and will have some guards around the outside to stop the joysticks from being accidentally knocked.

The slow/fast switch is meant to reduce the machine's speed by half. It doesn't. At best it drops maybe 10%. That's probably because once moving, the motors aren't having to exert much torque.

And finally, the view from the driver's seat.

The machine works well, the only niggle at the moment is speed. Running at 48v the machine is too fast and very difficult to manoeuvre precisely. At 36v the travelling speed is about right, but is still to fast and jerky for manoeuvring. 24v is much better for manoeuvring, particularly when the boom is up, but makes travelling tediously slow.

So I need to work out some way of switching between the 24v and 36v speeds...

Putting it back together

After a minor panic with the motors running like a pork chop on the test bench, the problem turned out to be mis-connected hall-effect position sensors that go between the motor and controller. Once hooked up correctly, the motors spin smoothly and quietly in both directions.

So it's time to put back together.

First the arms, wheels and the controllers.

Now with the 4 x 12v batts in place. All 240Kg worth.

Controller temporarily hooked up with speaker cable - I didn't want to go chopping up heavy-gauge wire until I was sure about how things would be routed and what lengths were needed.

Detail of the connection between the motor and wheel gearbox.

The motor mounts will get more paint and eventually a cowling to keep the weather off.

My test control box. The joysticks are 1-axis units made by Apem.

More temporary wiring...

And the main contactor with a pair of precharge resistors across the terminals to chanrge up the controller's capacitors so as not to incur a high current surge when the contactor is closed.

The contactor is rated at 400A. That looks to be possibly a little over-specced, as the unit looks to use about 10-40 amps when travelling, but I'll need to do more testing to find out what the range really is.

Again, this is a temporary install. Once everything is working properly I'll locate it in a more protected position and wire it up nicely.

Motor Problems

Well, I got everything hooked up on the bench, and it all works, kind of. It's *much* noisier in reverse, and seems to draw a lot more current than when going forward.

However the big problem I encountered was the motor randomly stalling. This most often happened when trying to reverse the motor. I swapped the controllers with the same result, then I tried the other motor - it wasn't as bad, but still often happened when engaging reverse. The motor simply won't move, despite the clamp meter showing 200A going in to the motor (I've got the controller limiting the motor current to 50%).

Usually engaging forwards will get the motor to spin, but with the first motor I tried, it was possible to have the motor stalled in both directions.

This is a serious concern, as at the moment there's virtually no load on the motor - just the gearbox - I'd hate to think how bad it'll be when it has to move the machine. This can't be normal...

Video below - the first part shows the setup, the stalling issue is at about 1:25