All the below info applies to the Kuhn 3002 and 4002 power harrows also some of the folding ones with the same beds and some other models.
We find the Kuhn Power harrow to be very good, but nothing's perfect and one fault we've discovered with the Kuhn is no grease filler in the bed. Apparently Kuhn designers expected these machines never to leak, however we've discovered this is not the case.
In order to fit a filler hole, see photo above, you will need a hole saw around 40mm, some 2 inch water pipe fittings and a welder. The bed grease level needs to be about half way up the gear teeth so it's best to drill the hole directly over the teeth of one of the gears but not where the gears mesh because it will be difficult to see the level at that position. Measure the centre to centre distance between two adjacent rotors and divide by 2 which will give you the radius of the gears. Chose a position for the hole, not too far from the left to right centre of the bed, then drill the hole, maybe 80 or 100mm in front or behind the forward to back centre of the bed, one radius distance from the centre of the chosen gear i.e. over the teeth of the gear. Be very careful not to drop the plug into the bed. Stop drilling before breaking through and then remove the swarf and prise out the plug. Minimise the swarf entering the bed. Fabricate a filler cap as required and weld it around the hole just made. You might also provide a breather, while you're on the job, with a piece of pipe or hose from your new filler cap to a region of minimum dust, see below and photo above. For safety, do not run the machine while topping up, but you will need to run it after topping up, in order to level out the grease, and then check the level again. If your machine is fold up you will need to run it for a minute or two before checking the grease level and in order to maintain correct grease distribution always unfold when parked. For more info please ring 01609 773607 and ask for John Parlour.
Packer Bearing Maintenance.
Frequent greasing of the packer bearings is essential because the grease will help to flush soil out of the dust covers. All ways pump grease in until it oozes out of the dust covers. Periodically check for wear of these bearings because if wear is rectified in time money can be saved. To check for wear, lift the machine off the ground then place a crow bar under the flange on the end of the roller then push down against the arm in order to lift the roller, if there is 2mm or more of movement then replace the bearings. Replacing bearings at this stage may avoid the need to replace the housing and dust covers thus saving money, also if the roller is free to move in the bearings, it is impossible to set the scrapers correctly and may result in excess wear of the roller due to it scraping on the scrapers. Your local bearing stockist will normally keep these bearings but it's essential to get the correct ones as some unsuitable ones will fit. Just quote these numbers and your bearing dealer will know what you want, UC308 or SBX0852. We stock these bearings. The only difficulty in changing these bearings is that you need a special socket to remove the nut on the end of the stub axle, you could borrow ours if you like. Pics and more tips to follow when I get chance.
Ingress of water into Kuhn power harrow bed and gear box
We have heard that Kuhn power harrows will take in water when left out in the rain. We have also seen evidence of this when going inside them in the form of rusty gears and bearings. We now keep ours under cover over winter.
We recently experienced a problem with one of ours and also a customers machine leaking bed grease from under the gear box. We decided that this may be due to water in the bed evaporating when being heated during work and thus building up pressure in the bed and blowing out the grease. Changing the grease in one of these machines is a major operation so we decided to fit a breather in order to relieve the pressure. In both cases the leakage stopped. Our machine already had a grease filler point so we drilled a hole in it, attached a pipe to run up inside the A frame to a region of less dust and with the pipe end facing down to help prevent dust falling in. Not shown in the picture. Of course this doesn't address the problem of rusty gears and bearings. Pics and more tips to follow when I get chance.
Bed repairs on these machines aren't difficult but most are time consuming. The rotor seals can be replaced from below but it's critical to get the correct seal and fit it correctly see 'Centre shaft falling out' below or we can advise.
A common problem is the bottom of the rotor bearing housing wearing away due to string and wire wrapping around the rotors. This can be rectified without a major strip down. What we do is weld a piece of hydraulic ram tube to the bottom of the housing, or you can make a collar on a lathe, the ram tube we use is 90mm id x 110mm od. It's not a popular size but A5 Hydraulics, Darlington, ask for Nick, has always come up with the goods, or we might have some on stock. Warning, welding can cause contraction thus causing nipping of the bearings, it is possible to keep the welding away from critical areas, we can advise. The rotors are easily removed but the timing isn't obvious, please check before removing. When refitting, keep the splines and tapers clean and dry, Loctite the M16 bolt and tighten to 221 lbs / ft.
Most other bed repairs, including replacing rotor bearings, will require a major strip down. Replacing rotor bearings requires removing the lid from the bed then remove the relevant cogs so as to expose the bolts holding the bearing housings in place then remove these bolts and housings. Don't mix up the parts. The reason for removing the housing is so as to check the bearing preload on re assembly. Further info to follow. On final reassembly the m36 x 1.5 nut needs to be Loctited and torqued to 450 lbs / ft. This paragraph still under construction, March 2020.
Centre shaft falling out.
It has been known for the vertical drive shaft from the gear box to the bed to fall out. This is caused by the failure of the circlip. Earlier models use a thinner circlip, I believe, 2mm thick. The later ones are, I believe, 3mm thick. This thicker circlip requires a larger groove in the shaft and a thinner spacer in order to allow space for the thicker circlip. Also the splines just above the circlip can crumble thus putting more stress on the circlip, see picture above. The later parts fit the earlier machines so long as you replace all three parts together, shaft. circlip, spacer. Replacement of these parts requires the bed top to be removed. When reassembling it is important to use the correct rotor oil seal and to press it in to the correct position, same with all the other rota seals. You will need a seal press / gauge, this device is easy to make if you have a lathe. Ring me if you need more info, or you could borrow ours. The seal is double lipped, metal cased, no. 65-90-13 R6, available from your local bearing stockist, cheaper than genuine, but be careful they might try to fob to off with something else. It's important to get the correct parts.
Follow this advice entirely at your own discretion, I accept no responsibility for any loss, damage, death or injury due to following this advice.
If you know anyone you think might find this useful please feel free to copy and email it to them. Please include this URL. www.jparlourandson.co.uk