Help required. Taper lock bush. I think thats what its called.

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Alasdair

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Hi there hope someone out there has come across a taper lock bush. Its for fitting flywheels to shafts. I have a replacement but not sure how to fit it. Its not woodwork related I am afraid as its on a Howard rotovator but thought someone who works on lathes etc might have come across them. Its a slightly tapered round block in cast steel with a slot and two grub screws and the key for the shaft. It fits over the shaft and then pushes into the flywheel to lock it in place.
1646580061415.png

Any help appreciated
 

Argus

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The picture shows only half the assembly. Where's the rest? This is the inner, male section of the pulley that goes on the shaft. The other half has a corresponding tapered female section in the centre and the belt grooves on the outside.

It's the second picture down in this link which shows what it looks like assembled.

Fitting is easy;

  1. First read onwards, then assemble it all together loose on the bench so that you know what to expect. It may be possible to slide the assembled pulley on complete, but they do occasionally put up a fight aligning the shaft, key and pulley.
  2. Clean the shaft and all the mating parts... get old oily stuff off to clean metal.
  3. Put the outer section loose over the shaft, with the larger opening of the taper outwards.
  4. Slide the key in place.
  5. Slide the inner section onto the shaft, smaller size inwards, larger diameter outwards, and slide over the key so that it is central.
  6. Lift and slide the outer section over the Inner section and line up the screw holes.
  7. Insert the screws loose, but ensure that the whole thing is assembled.
  8. It should be able to slide on the shaft at this point - align it all where it needs to go.
  9. Tighten the screws evenly a little at a time each side. Tight but not breaking point.
  10. Put your belts on etc......
  11. Have a cup of tea.
Good luck
 
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Alasdair

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Thanks very much. The other part is part of the flywheel itself. It was moving towards the end of the shaft due to the bush being cracked Luckily there is a metal bar to stop the flywheel coming off. God knows how far it would have travelled if it had come off. I managed to source a new one but wasnt sure if I tapped it in tight and then tightened the grub screws or if the grub screws pulled it tight. Will have a go. Never come across this type of fixing before. I assume its so you can align the flywheel with the drive pulley. The flywheel with belt groove is about 60cm diameter and is solid cast steel. Its heavy duty as were all the old machines
Flywheel pic (similar)
1646584848289.png

Many thanks again
 
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Argus

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No problem.
It's not an uncommon fitting, though a bit expensive. They tend to get used as a replacement on motors where the pulley size is changed.
It's advantage is that it can accommodate slight slight discrepancies in different shaft diameters.

Please make sure that the tapered sections on the wheel and the insert align and are the same angle. Mixing different makes of taper pullies may not always mate exactly when assembled ........ which may explain the broken bit.
 

Inspector

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With the type I am used to seeing the screws/bolts are tightened evenly to draw the parts together. Don't graunch them up tight, there is a proper torque. To remove the pulley the screws/bolts are removed and put in other holes and tightened and they separate the two parts. Main thing is to snug the screws evenly. Does the manufacturer have any instructions on their website?

Pete
 

Alasdair

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The new part seems exactly the same as the old one. I bought the machine cheap as it didn't run and replaced the engine and then discovered the belt kept pinging off. Checked the alignment and the flywheel was well out. I reckon the broken one is original as it had orange paint on it. Will compare the angles though and check the angle in the flywheel centre.
Thanks again
 

Alasdair

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Hi pete, The machine is from the past. Probably late 70's The part I got on ebay a while ago so no instructions. Will google and see if I can find the correct torque for fitting which makes sense. There are internal grooves in the bush which I assume grip the shaft.
 

Inspector

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Alasdair

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Hi pete I have the key from the old one but the grooves I was referring to are machined very slightly into the internal facing that contacts the shaft. They are almost like a grip system on the old one but the new one is smooth. Will clean up shaft and flywheel, degrease and fit today if I can. Thanks for the fitting PDF info the torque is 20Nm for that size (1210 3/4"). I will also check as you mentioned the angles are the same and its a perfect fit before tightening.
 

Argus

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The square key on the shaft was termed a 'Woodruffe Key', at one time in the UK and was intended to position the pulley and to prevent undue rotative strain and slippage on the shaft when starting under -high-torque. It just needs to be a tight, but sliding fit - you shouldn't have to force it into any of the grooves.

Never seen slight grooves on the insides of the pulley, though.... new one on me - it sounds counter productive in terms of tight contact on the shaft. But, someone, somewhere must have thought that one through.

The reason that I mentioned the importance of matching the slopes of the two halves is that those taper-lock pulleys came in manufactured sets and the machined surfaces of the two halves were exactly matched.
Parts from different manufacturers may not be the same and may not mate correctly. Which may explain why the old one cracked.

Anyway, good luck!
 

Alasdair

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Thanks Argus, The other half is part of the drive wheel (machined into centre so I hope they fit together. There are no spares available for this machine unless I find some on ebay etc. Everything else is sound just this bush that is cracked. I measured the old one and it seems identical. Will find out when I try and fit it.
 

Artysmarty

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Hi there hope someone out there has come across a taper lock bush. Its for fitting flywheels to shafts. I have a replacement but not sure how to fit it. Its not woodwork related I am afraid as its on a Howard rotovator but thought someone who works on lathes etc might have come across them. Its a slightly tapered round block in cast steel with a slot and two grub screws and the key for the shaft. It fits over the shaft and then pushes into the flywheel to lock it in place. View attachment 131022
Any help appreciated
Hi
The 2 tapped holes marry up to same blank holes on bush. Start both grub screws and tighten up evenly. This compresses the Bush on to shaft.
To remove from shaft, take out both grubs and screw one onto the tapped hole. This then pushes the flywheel away from bush and allows removal.
Bear in mind, they must be a matching pair
 

J-G

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The square key on the shaft was termed a 'Woodruffe Key',
Oh no it wasn't!!

A Woodruff Key is a 'half-moon' shape which sits in a slot cut with a Woodruff Cutter. A Square key is just a short length of material, often with rounded ends, which sits in a groove cut into a shaft sometimes of limited length cut with an end-mill but usually continuing to the end of the shaft.
 

Concizat

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As a matter of interest, which model do you have? Or is it one of the agricultural models.
I have a Howard 700 which I bought about 15 years ago, supposedly refurbished, which I intended to take down to my place in France.
Somehow it never happened and it has sat in my garage since then. Did start it a couple of times and, being 2 stroke, it was very smoky and noisy.
I've got all the manuals for it and the engine but never did anything to it.
 

Alasdair

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Hi concizat, I think its a howard 350 or a later dowsdale 350 It had the briggs 5hp fourstroke engine but the valve springs were broken and difficult to source spares so replaced it with a loncin honda copy. This one has seen no real work and in really good order. Great machine when its going and nothing seems to stop it. If the bush is wrong I may have to send the drive wheel off to get a matching one machined to fit. If your doing yours up make sure you change the gear oil in the rear drive. I filled mine with kerosene and ran it then drained and refilled as the original gear oil was so thick and emulsified it wouldnt drain. Hope the bush fits the drive wheel
Alasdair
 

Inspector

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You can check the fit by putting some Prussian Blue, Dykam or a felt marker on the bushing and put them together in your hands with a gentle twist and see if the ink is reasonably evenly transferred from one to the other. If it is you're good to go. If it only contacts at one end or the other then some adjusting may be in order.

Pete
 

Alasdair

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Hi pete just removed drive wheel and checked fitment. The bush seems to fit perfectly (snug fit both ends but will try some marker to make sure. Only thing I havent checked is the threads of the grubscrews. They look the same when compared to the original but they may be imperial. I am hoping as the new bush is for a 3/4" shaft they will be the imperial and the same thread. Will post any further success or problems.
 

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