Author Topic: Mounting a Tractor Hedge Flail (Read 70731 times)

awemawson · « **on:** July 21, 2014, 06:08:59 AM »

Several years ago I bought a Twose 276 Hedge Flail. It originally would have mounted on 'axle brackets' but this one had been converted to mount on the standard 'Three Point Linkage'. Theoretically this makes it easier to mount and also able to be fitted to any tractor with a three point linkage.

awemawson · « **Reply #1 on:** July 21, 2014, 06:23:22 AM »

Now the very day that it arrived a neighbour borrowed it, along with my tractor, but unfortunately he rang me an hour later to say he'd broken my tractor

The flail being on the three point linkage, and being a very lop sided and heavy load, had put more strain on one lifting arm than the other, resulting in the cross shaft breaking due to the torque - an 1 1/2" diameter high quality steel shaft

He mended it as those were the terms of the 'lend', but it meant that I wasn't prepared to mount it up again in that configuration.

Now I've bored you all witless in threads such as the 'enlarging a hole' thread where I was attempting to take the load off the hydraulics and take it elsewhere:

http://madmodder.net/index.php/topic,9728.0.html

But those attempts also resulted in failure - far too much twist due to the lop sided load. So I decided to convert in back to 'Axle Bracket Mount' hence the thread a few weeks ago about 'Glueing Metal Back On':

http://madmodder.net/index.php/topic,9885.0.html

The original 'fore and aft' spars on the flail had been chopped off and brackets welded on for the three point linkage. Now these spars are 100 mm square box with 6 mm wall thickness, and I had intended just to weld bits back on to bring them back to the original length. But thinking of the huge torque that they have to withstand I decided to replace them in their entirety. Theoretically they just bolt onto the very substantial hydraulic tank, but it remains to be seen how easily they come off.

This is what they looked like according to the parts book, which is the only documentation that the original manufacturer has after suffering various take overs

awemawson · « **Reply #2 on:** July 21, 2014, 06:29:52 AM »

Now none of the mechanics of the axle mounts is particularly difficult, but what is difficult is measuring up to decide where to put them and how big to make them, so I cast around to see what I could find.

A set of brackets designed for my tractor (Ford 4600) but for a different flail turned up on eBay - they were for a Bomford and he also had the 'jaw fittings' which are rather more self-aligning than the Twose ones (which I couldn't find anyway)

awemawson · « **Reply #3 on:** July 21, 2014, 06:32:03 AM »

So having at last completed the change of the right hand axle oil seal yesterday I could mount the brackets and start deciding how to glue the lot together.

Here is a picture of a Bomford flail with very similar brackets

awemawson · « **Reply #4 on:** July 21, 2014, 06:35:46 AM »

So this morning I started unbolting the jaws from their original mounts - easy peasy - just four nuts and bolts on each - well not quite - they we unbelievably tight and I had to resort to unothodox methods to hold the bit down while swinging on the 3/4" socket drive with a long pipe

awemawson · « **Reply #5 on:** July 21, 2014, 06:37:17 AM »

So having got them off, I mounted the jaws on the brackets, which I'd bolted to the axle yesterday

awemawson · « **Reply #6 on:** July 21, 2014, 06:42:18 AM »

This allowed me to start measuring up how it would interface to those two spars I was about to make. I had made up a timber 'mock up' of the spars accurately set to replicate their spacing and width, as having the differential 'lump' and the pto gubbins in the way otherwise made measurements impossible.

First offering up implied that the 'jaws' nicely fell on the centre line of the spars - but this was wishful thinking as the jaws obviously weren't set on the stands quite parallel

Never mind they fall within the width of the spar - I intend to cut deep slots in the spars -insert the jaws and weld them together.

awemawson · « **Reply #7 on:** July 21, 2014, 06:44:08 AM »

This shows the off set of the jaw centre line in a spar end

awemawson · « **Reply #8 on:** July 21, 2014, 07:00:37 AM »

So I placed an order for the new 100 x 100 x 6 mm box section and the very heavy angle and plate need to replicate those spars. All came from Austen Knapman who carry a very wide range of steel sizes - and deliver for a not too exhorbitant fee:

www.austenknapman.co.uk

So the next thing to do is work out how to jack up the flail to remove the original spars - needs serious support as it's a bit heavy and I'll be under it

But I also need to drain the 25 gallons of hydraulic oil from it's tank and fit either a 'Quick Disconnect' or maybe just a gate valve. At the moment the hydraulic pump that turns the flail head is just hanging on umbilical pipes making fitting difficult onto the pto drive. If it is separable it will be much easier

vtsteam · « **Reply #9 on:** July 21, 2014, 07:30:05 AM »

It's a beast for mount torque. Hope this works!

It wants wheels back there somehow, though I can't think of any particularly convenient or even useful way. that would work.

The articulated mowers I've seen the town run have a side frame mount, mid tractor.

awemawson · « **Reply #10 on:** July 21, 2014, 11:19:53 AM »

Oh yes Steve - it had better work this time

I want to remove the pump from it's umbilical pipes so that I can install it on the tractor and see how much room I need to leave for it. So I started off by draining the tank:

First assemble enough empty oil drums - this necessitated a trip to the local recycling dump where I could loose the old oil that I replaced in the tractor back axle escapade - this provided two empty x 25 litre drums. A quick hunt round found another 25 and two 20 litre drums

awemawson · « **Reply #11 on:** July 21, 2014, 11:24:03 AM »

Now the pamphlet that I have on this flail says that the tank holds 25 UK gallons - so that is about 114 litres. we have 115 litres total capacity so we should be ok - shouldn't we

The filler cap and filter are too small for my transfer pump, so take them off:

awemawson · « **Reply #12 on:** July 21, 2014, 11:29:52 AM »

Hook it up to a convenient tractor standing close by and off we go.

Only a little bit of spillage - honest gov'

So the level is now below the output tapping, so I've been able to remove the plumbing and measure pipe sizes (1 1/4" BSP out of the tank - 1" BSP to the pump, 3/4" BSP out of the pump)

I've decided to use two 1 1/4" gate valves with a union between them to allow full bore out of the tank in such a way as the only oil spilled on disconnect will be the volume of the union. The output of the pump will retain an umbilical pipe, which as it is at a high level can be disconnected and stoppered without oil loss.

Order for pipe fittings placed . . . . next I can put the pump on the tractor for measurements.

NormanV · « **Reply #13 on:** July 21, 2014, 02:10:36 PM »

Andrew, you take on some massive tasks, but always succeed. Well done, keep on inspiring us lesser mortals!

awemawson · « **Reply #14 on:** July 21, 2014, 02:40:04 PM »

Thanks for your kind words Norman - your casting epic is no small task

awemawson · « **Reply #15 on:** July 22, 2014, 04:31:22 AM »

Now that the tank is pretty well empty I could remove the hydraulic pump and put it on the back of the tractor to help in measurements. Needless to say the hoses are in an atrocious condition having had the pump swinging on them every time the flail was disconnected from its host tractor. Another reason for making it detachable. The hoses are not in fact under any significant pressure but they definitely need replacing.

I had one little oops when draining the oil - there is a little plastic cap on the lower end of my transfer pump that popped off and fell to the bottom of the tank

Need somehow to rescue it so it doesn't get dragged through the gear pump.

So here is the pump mounted on the PTO shaft of the tractor:

awemawson · « **Reply #16 on:** July 22, 2014, 04:39:26 AM »

This then allowed me to make a mock up of the tank position, which is represented in these pictures by the 'builders trestles'

They are positioned in the photos as close as is possible to the back of the tractor, but I think in practise I will move the tank structure back 3" to make access a bit easier and make more room for the bracket that holds the 'control standard'. This is a 1" vertical rod, cranked like a starting handle, with the hydraulic levers mounted on it - they project about 4 foot forwards and need to 'arrive' poking through the rear window and comfortably close to the drivers seat. The crank in the standard allows some adjustment, but I suspect that it will be 'suck it and see' when it comes to mounting it.

Anyway, a bit more of the mock up. The timbers represent the new spars, and will be slotted to fit round the 'jaw plates' and welded in place - and yes I know they aren't level - hopefully the real thing will be

awemawson · « **Reply #17 on:** July 22, 2014, 05:52:17 AM »

Managed to retrieve the lost plastic cap from the hydraulic tank. A torch showed nothing through the filler as it was always in the way, so I soldered a 12v torch bulb to the end of some stiff 'twin and earth' wire, poked it into the tank, and lo and behold there it was.

Harpooning with a sharpened 2.5 mm welding rod, and then hooking it up saved the day. All this is really putting off the time when I have to crawl under the tank and unbolt the original spars - just not decided how to support it yet - the legs it stands on are integral with the spars

vtsteam · « **Reply #18 on:** July 22, 2014, 07:04:05 AM »

Looking good, Andrew. I like the remote flashlight idea, too. Another thing to remember.

awemawson · « **Reply #19 on:** July 23, 2014, 05:30:56 AM »

Today has been a superb morning as far as progress is concerned

I started by removing the 'standard' that holds the hydraulic controls - I had previously removed it so bolts were not seized. Bit awkward in that a 1" bar with a lot of weight on top slots into a pair of holes - you can fairly easily lift it out of the lower holes, then it starts wanting to twist - brought in the heavy guns, used the fork lift to take the weight, and laid it all still connected to its plumbing across the tank

awemawson · « **Reply #20 on:** July 23, 2014, 05:38:15 AM »

Then I started loosening all the various bolts that hold the two spars on. They were all amazingly quite easy to undo - I've been spraying 'Plus Gas' on them for the last few weeks.

But while underneath I made a VERY useful discovery. The right hand spar is mounted on a sliding 'Tee nut' arrangement, meaning that the spacing of the spars is adjustable by up to 3" - so all my worrying about exact off sets for mounting the jaw plates onto the spars is irrelevant - they can be made symmetrical and adjusted to fit the brackets

awemawson · « **Reply #21 on:** July 23, 2014, 05:43:58 AM »

So now to support the tank so that the spars can be removed safely.

I ended up placing axle stands under the right hand side, and matching the integral jack that is at the rear with a pile of timber baulks - gently lifting with the fork lift it to take the weight off the legs that are part of the spars, and transfering it to the new arrangement.

Took a bit of fiddling, as it is now balanced on five points (the four mentioned and the flail head itself)

awemawson · « **Reply #22 on:** July 23, 2014, 05:46:27 AM »

So get on with it and remove those spars

OK here you go then:

awemawson · « **Reply #23 on:** July 23, 2014, 05:50:12 AM »

I've been thinking about this job for quite a while, and as usual things seem more difficult in imagination than reality if you just take a step at a time.

So now I need to start cutting metal and make the new spars incorporating the 'jaw plates' from the Bomford flail and the design of the rear end from the Twoes flail.

So a bit of heavy cutting and welding - lets hope my plasma cutter still works, it's not been out to play for months !

awemawson · « **Reply #24 on:** July 23, 2014, 07:56:37 AM »

So take a 3 metre length of 100 x 100 x 6 mm box section and cut it to length. Shame the chop saw won't quite cut 100 mm so we had to do a quick rotation of the box half way !

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Author Topic: Mounting a Tractor Hedge Flail (Read 70731 times)