Convert 1975 Afron Cherrypicker?

Technical discussion on converting internal combustion to electric
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Convert 1975 Afron Cherrypicker?

Post by Electrocycle » Wed, 06 Jul 2011, 02:10

sounds good :)

It might be worth checking if the "turbo" function on the controller is configurable - to limit rpm (voltage) instead of current.

With the battery charging, I'd use 4 x 12v chargers or 2 x 24v chargers.
They're cheaper than buying a 48v charger - and it'll keep the batteries in balance a lot better.

What sort of charge time are you hoping for? (and budget for chargers?)
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Convert 1975 Afron Cherrypicker?

Post by Trogdor! » Wed, 06 Jul 2011, 02:35

Yeah, originally I didn't spot the fact that the "turbo" feature was current not voltage - no wonder it had almost no effect, except for low speed torque, which should have made me realise what it was actually doing.

I emailed Kelly Controllers, they weren't a whole pile of help, the pointed out that the turbo function wouldn't do what I was expecting, and supplied some suggested throttle pot mods (resistors on the wiper) which I haven't tested, but expect would not really work.

My default for chargers was a 48v 15A unit from Kelly at $199 plus freight, or a 48v 10A unit from Ev Works for $255 - I'm planning to order lugs and a crimping tool from them to do the proper wiring, so the freight component would probably be amortised a bit if I get it from them.

Charging would be an overnight affair, and a full day'ss work probably wouldn't take more than 50-75Ah out of the 150Ah at a guess, so I think either would be fine for the job.

I like the idea of the single charge connection, although I'd be inclined to do a 12v charge of each batt once in a while to make sure they're balanced.

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Convert 1975 Afron Cherrypicker?

Post by Electrocycle » Wed, 06 Jul 2011, 03:12

ah yes, I was thinking more along the lines of mounting the chargers onboard and permanently wired to the batteries - so you just plug in the power cable.

You could probably use 6 to 10A chargers for overnight charging, so they'd be pretty cheap and small.


A series resistor on the throttle wiper might work, but it'll probably have to be a fairly large value depending on the input impedance of the controller.

It's good to see that it's up and running!
The conversion looks really neat, especially after removing all those mechanical control linkages :)
I think the motors and controllers were the right choice, because they won't be stressed in normal use, but have the power to negotiate obstacles when necessary.
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Convert 1975 Afron Cherrypicker?

Post by Trogdor! » Wed, 06 Jul 2011, 04:11

With regard to charging, I was thinking the same thing - at the end of the day you drive to the nearest power point and just plug in.

However, individual 12v chargers don't seem that cheap. I bought an 8A smart charger from Repco that cost $180 - it seems to go through 4 or 5 stages, which is probably a good thing for the battery, but multiply that by 4 and it gets pretty expensive. Then there's Supercheap Auto chargers, but a colleague bought one of them for another site, and left hooked up to a battery for any length of time, it seems to routinely go mad and throw an error code.

Kelly provided 2 circuit diagrams - one was a voltage divider on the wiper with, from memory, 2.5k to ground and 2.5k in series with the wiper. I haven't analysed it too much, but I don't think it would be symmetrical in operation. The other was just a single 100k resistor in series with the wiper. They didn't advise what the input impedance was of the throttle line, so it's hard to know what effect it would have.

My 8 pot solution seems to work quite well, and I can adjust the settings for low and high speed from experience using the machine.

I'm pretty happy with the way it's turned out. I've been using it to tie up the sides of the netting now that the season's over, and it's so much more pleasant being able to move quickly and tweak the position as needed, and the machine is so quiet by comparison - obviously once you're in position, it's completely silent.

As you mention, the excess power in the system is needed when there's obstacles or adverse terrain. By comparison, the old setup had the ability to transfer up to the full 8hp to a single drive wheel if needed, and had a clutching system that allowed that power to be applied effectively. In converting to electric, I really didn't want to reduce or compromise that ability, rather I wanted it to be as capable as the IC version and better.

The next step is to wire up the power side properly, add in the lift control, then neaten up the control side wiring and finally go visit the sheet metal guy to sort out hoods and cowlings for the batteries, motors and hydraulic unit.

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Convert 1975 Afron Cherrypicker?

Post by Electrocycle » Wed, 06 Jul 2011, 04:33

I've used these before: http://jaycar.com.au/productView.asp?ID ... ATID=998#3

There's a 24v / 6A version, so two of those could be an option

They're a lot cheaper if you know someone with a wholesale account :)


This sort of thing could also work: http://jaycar.com.au/productView.asp?ID ... ATID=998#3

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Convert 1975 Afron Cherrypicker?

Post by antiscab » Wed, 06 Jul 2011, 14:51

the 12v 12A charger is $64.87 ea plus shipping through jaycars wholesale arm (electus).

couldn't find the 24v 6A charger though.

shipping to perth then canberra might negate the savings though.

you could get a trade account at jaycar (they give these to anyone that asks), but once you are at the top quantity price you won't get any cheaper.

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Convert 1975 Afron Cherrypicker?

Post by Trogdor! » Wed, 06 Jul 2011, 15:14

I've got a Jaycar trade card, but in my experience the discount tends to be bugger all - maybe 5% on a good day.

Is the battery imbalance thing likely to be that much of a problem? Admittedly these are second-hand units which have already done time in a phone exchange, but would get a a balancing charge once in a while.

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Convert 1975 Afron Cherrypicker?

Post by Electrocycle » Wed, 06 Jul 2011, 15:18

hmm maybe they've discontinued the 24v one. Jaycar still has a 24v part number down the bottom of the listing for the 12v one, but Electus don't seem to have it.
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Post by Trogdor! » Mon, 08 Aug 2011, 05:49

Probably time for an update - the machine's been put to work doing pruning - everything is still exposed with temporary wiring and control panel, which is useful to evaluate the ergonomics of the controls and what needs to be improved in the final layout.

I ended up getting a 48v charger from EV Works - I plan to do a balancing charge with a 12v charger once in a while - I might add individual voltmeters to each battery to keep an eye on the overall pack balance, as the 2kW hydraulics is still off a 24v tap (I have a 48v speed controller for it, just need to get motivated for the slightly complex installation).

Since pruning often involves the use of a chainsaw, I bought a cheap Ryobi 18v chainsaw from Bunnings and wired up a 24v tap (on the other pair of batts to the hydraulics tap), but it turned out to be a very poor, and dangerous alternative to the mains-powered chainsaw we normally use, which has me looking at 48v to 240v inverters - Mean Well do a 1500W inverter that includes support for charging via a solar panel, which is something I've been considering as a neat option as the machine is usually sitting out in the sun drawing no power while pruning or whatever work is done, however it'd add considerable cost, so for the moment we're running long extension cords to power the chainsaw.

For the moment I need to go see a sheet metal crowd to sort out covers for the motors, hydraulic pack and batteries.

All up, the it's a huge improvement on what it was, and is a pleasure to use, but there's still a heap of bits and pieces to get done before it's a safe, robust and fool-proof machine.

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Convert 1975 Afron Cherrypicker?

Post by Adverse Effects » Mon, 08 Aug 2011, 09:48

Trogdor! wrote: which has me looking at 48v to 240v inverters - Mean Well do a 1500W inverter that includes support for charging via a solar panel


if you where in QLD i would give you a 1.7Kw UPS that is 48 volt battery pack in it (dead)

you could simply use it to power the chain saw then when you get to the shed plug in the UPS and it would charge the battery's to

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Convert 1975 Afron Cherrypicker?

Post by T1 Terry » Mon, 08 Aug 2011, 15:02

Just get a cheapie inverter rated close to the max input of the chainsaw, this their most efficient operating range. Keep the solar seperate, combination units mean all is lost while one failed bit is repaired.
Was was the problem with the battery operated unit? Was it the chainsaw itself? maybe one of those Bunnings branded units with a few lithium batteries so one could be recharging off the pack while you are using the other. The Black & Deker 18v units are a good thing, expecially the aligator style unit, it would be brilliant for prunning small stuff.

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Post by Trogdor! » Mon, 08 Aug 2011, 15:44

48v inverters aren't that common (although the UPS idea is a good one - I might see if I can get one at the local IT auctions) and I was hoping that with a big-arsed unit I could use the machine as a mobile power-point for use with bigger tools like a demolition hammer, but I see your point.

The Ryobi was a lithium unit (which I bought without batts as I'd be using the main pack). The problem was that even running at 24v it cut very slowly due to low RPM and the chain missing every second tooth, which also made for a rough cut. The dangerous part was that it was underpowered, so in situations where a more powerful chainsaw would just rip through, this one would catch and then kick the saw.

The mains saw we use is a B&D Alligator with the bottom protective jaw removed (but with the top one in place). It's only about 550W but does a much nicer job, and as mentioned, is ideal for pruning where the thickest trunk is probably only 2" and green.

I'm thinking now whether I could get away with a 750kVA UPS, if I can find one that runs on 48v...

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Post by T1 Terry » Mon, 08 Aug 2011, 16:00

I purchased one these 48v 4kw units via evilbay for roughly $1,000 delivered http://cgi.ebay.com.au/ws/eBayISAPI.dll ... 0543331850. The contact man is Eric Hsiao and a very helpful person to deal with, he arranged for the voltage points to be reset to suit a lithium battery pack in 2 different units for us one a 24v unit and my 4kw 48v unit. The thing is big but not very heavy and all the bits inside are in modules (couldn't help myself, it wasn't here 10 mins and I had the covers off) so if there are any problems I'm assured the factory engineers walk you through the test proceedure to determine the faulty section and send a replacement board on an exchange basis so it doesn't need to go back to the factory. Mine is back in it's box at the moment, still fitting up the mates units to his motorhome conversion so I can't give an operating report unfortunately.

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Convert 1975 Afron Cherrypicker?

Post by Johny » Mon, 08 Aug 2011, 16:13

Adverse Effects wrote:
Trogdor! wrote: which has me looking at 48v to 240v inverters - Mean Well do a 1500W inverter that includes support for charging via a solar panel


if you where in QLD i would give you a 1.7Kw UPS that is 48 volt battery pack in it (dead)

you could simply use it to power the chain saw then when you get to the shed plug in the UPS and it would charge the battery's to
This sounds like a good offer. It would probably only be $40 for shipping and I've used companies where the receiver arranges everything (except packing) so it would make it easy for Adverse to "give away" (assuming that's what he meant).

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Post by Trogdor! » Mon, 08 Aug 2011, 16:22

One thing that came up when I was discussing the ins and outs of fitting an inverter to a machine is earthing - you're meant to connect the earth of the inverter to the chassis (and ideally also use an RCD) however many inverters tie earth/neutral to the -ve of the battery, and the manual for the Kelly controllers say it'll get angry if batt -ve is earthed.

Anyone know how common this is with inverters?

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Post by T1 Terry » Tue, 09 Aug 2011, 10:44

There is a unit called an RVD (Residual Current Device) now on the market that works in conjunction with the RCD to trip the breaker in a short to ground of either line in a floating power supply. I bought mine from Ian at http://www.powerstream.com.au/ because motorhomes have a real problem with this, if you make an earth neutral link in the motorhome it trips the RCD of an external power supply like a caravan park.
Having said all that, you only need an earth neutral link if you are going to use more than one class 1 appliance at a time from the power supply so as long as you followed that rule you can leave the inverter supply floating and not activate any earth neutral link but naturally an RCD would then be useless without an RVD attached.
Did that make sense?

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Post by Trogdor! » Wed, 07 Sep 2011, 03:08

Anyone know about taper bearings?

This is the guts of the wheel gearbox:
Image

And this is it in one piece and mounted:
Image

One side is making a crunching noise when in motion. It could be that the bearing is simply rooted, but I'm also wondering whether I applied the correct amount of pressure to each bearing.

When I pulled them apart, the old gaskets disintegrated, so I cleaned up the faces and cut out new gaskets from some gasket material I had lying about. However, it could be that the gasket I installed on each side is too thick and perhaps not pushing in hard enough on the taper bearing. The old gaskets comprised a number of thin ones sandwiched together, and perhaps there was a specific number to be used to achieve the correct pressure?

Any suggestions would be appreciated, as I don't want to go replacing the bearings only to have them prematurely die due to incorrect installation.

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Post by Adverse Effects » Tue, 13 Sep 2011, 19:33

Trogdor! wrote: Anyone know about taper bearings?

One side is making a crunching noise when in motion.


the noise it makes is it only when there is a load on it (sitting on the ground) or both when its loaded and jacked up

with ALL worm drives the gaskets (and i meen ALL) have a crucial job in aliening and the crush force on all parts

the main housing gaskets are crucial to holding the output drive bearings in the correct place and with the correct crush force

the output end cap gaskets control the preload on the taped bearings AND the alignment of the worm drive gear by having lots of extremely thin gaskets and changing the number total and number on ether end cap

there is also a set method of assembling the unit that is critical

just ask if you need to know it
Last edited by Adverse Effects on Tue, 13 Sep 2011, 09:40, edited 1 time in total.

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Post by Trogdor! » Tue, 13 Sep 2011, 20:10

Adverse Effects wrote: just ask if you need to know it


OK - how should I put it all together correctly?

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Post by T1 Terry » Tue, 13 Sep 2011, 23:27

when you pulled it appart can you remember what shims went where? These shims not only apply preload they are also crucial for component placement as advese effects has already stated. If you can't remember what went where you will need to track down a workshop manual of find out who the gearbox manufacturers are and contact them. there will be part numbers in the cases and end caps and this will help identify just what model/type it is. Tapered roller bearing always have preload, this is often measured by drag using a spring gauge pulled at the correct angle, all stuff you will only get from the manufacturer or a workshop manual. but if all else fails we can probaby fudge it :lol:

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Post by Trogdor! » Tue, 13 Sep 2011, 23:37

The shims were the stacked thin paper gaskets on the caps that held in the taper roller bearings. These disintegrated when the caps were pulled off, so very difficult to determine what the effective thickness was. I actually can't remember if there was a gasket between the gearbox halves - I used RTV silicone when it went back together.

Keep in mind the machine was made in 1975 in Israel, so manuals etc. are probably a little hard to come by, but I'll try contacting the manufacturer.

I do have a spare (seized) wheel gearbox, I'm wondering whether I can somehow analyse it to get the correct gasket thickness...

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Post by Adverse Effects » Wed, 14 Sep 2011, 07:20

ok this is going to be interesting to say the lest

the main housing will have had gaskets as the thickness of them will determen how much crush in on the outer race of the bearing set and yes you can compress them to much and change there shape and that will trash a bearing in no time

DISCLAIMER
*****this is the method i was taught to me 30 years ago by an old man that was involved in the designing of the original MINI differential setup and it is dam close to this type of thing******

take the housing and the outer bearing races put them in place as close to the correct place possible make up about 6 paper gaskets (3 each side ) you may not need this many but start with more than you need put on the 2nd half of the main housing and tighten it down about 1/2 as tight as you would for the finished job

*this is a bit hard to explane but easy to teach hands on*
now take a drift and a small hammer
the object here is to see how few gaskets you need to hold the race in place but not crush it
use the hammer to hit the drift to try and move the race
*this is a learned skill but you will get the idea*
the race shoud still move but take a light hit with a hammer but not a hit with just the drift (dose that make sense) tight but not locked in place and warped

that is the main housing
----------------------------------
i need to see some close up pic's of the end plates as to what way you do them

back front and side view of them please

when i see them i can explane the rest of the proses
Last edited by Adverse Effects on Tue, 13 Sep 2011, 21:23, edited 1 time in total.

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Post by T1 Terry » Wed, 14 Sep 2011, 17:00

The crush on the bearing cups can be measured using 3 strips of "Plastigauge" placed an even distance apart across the bearing cup, bolt it together, pull it part and measure the 3 bits of plastigauge, the clearance is the average of the three pieces. The trick is you need to put as small a feeler gauge as you have between the case halves at the bolt point, tighten the bolts till the feeler gauge grips and then remove the bearing cup and measure the plastigauge average measurement should be the same as the feeler gauge thinkness. Adverse Effects method works well but you really need the "feel" to get it right. You need to get this correct before moving on to the next stage, there is no guarantee there was or wasn't supposed to be a gasket between the 2 halves, Volkswagen and Subaru don't use gaskets between their case halves and they hold a crankshaft in between.
With the worm and gear placement it's a matter of getting the worm contacting the gear teeth in the centre of the worm and not at one end or the other. The gear also neds to be positioned so the worm runs in the centre, not one side or the other. once the placement is correct then the crush needs to be determined. The easiest way I can explain this is the the bearing caps need to pull in till there is resistance felt when turning the shaft, another 0.005" to 0.010" crush would sufficient so it you use a feeler gauge under the plates when you have the item positioned and the resistance to turn feels right you can measure how much shim you need. Gaskets are very hard to work with because they crush when compressed and this changes with gasket age. A metal shim and a coating of Loctite gasket eliminator or Hylomar or Wurth blue gasket compound will make sure you have no oil leaks, even the old “Stag” compound would work on a transmission case that didn’t suffer any high temp operation .
Maybe Averse Effects has an easier method.

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Post by Trogdor! » Wed, 14 Sep 2011, 17:05

Cheers for that - unfortunately I'm not near the machine at the moment, but I do have a parts diagram as provided by the manufacturer in Israel.

Afron Wheel Gearbox Parts Diagram

This looks to be a slightly newer version of my gearbox, but only in terms of the drive input - the main clamshell (which doesn't appear to show a gasket?) and output shaft ends are the same.

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Post by Adverse Effects » Thu, 15 Sep 2011, 04:52

Trogdor! wrote: but I do have a parts diagram as provided by the manufacturer in Israel.


nope can not really see the end plates well

i need to see if they push in to the housing or are flush all the way across
Image

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