Countax mower, cant remove deck pulleys

[Peter.N.]

As above K18 42" deck. bearing seized on small front blade, successfully removed and new bearings fitted but the two larger blades cannot remove the pulleys, removed the bolts, pulleys only appeared to be a push fit with a key but I can't move them.

They are not rusted as far as I can see, have applied liberal amounts of penetrating fluid and tried levering them, solid. Used a bearing puller and only succeeded in bending the pulleys, have tried hitting the top of the shaft with a large hammer and drift and applying heat, moved a fraction but that's all.

Help!

Peter

 

[Burnerman]

I'm almost certain these are just parallel shafts with a key Peter - no tapers around. I apply significant pressure with my 2 or 3 legged puller, apply heat with my Mapp gas torch and then strike the end of the puller shaft....have you tried that?
It may take a day or so with the penetrating oil if it still won't budge.
Regards
John

 

[Peter.N.]

Thanks John

I thought if anyone knew you would . I have applied some heat but only with a plumbing torch. The first one came off with no trouble at all, I was only going to change one as it had seized up, did that one OK, then spun the others and the noise indicated they needed doing as well. I did the puller up really tight and its bent the pulley.

Peter

 

[Burnerman]

Pulleys for these are around the £30 mark - I guess you may have to cut it off if the damage is significant.
For me, I’d wind the puller on again tightly and get more heat in there.....but of course you may damage the bearing grease seals.
It looks like you are at the point of no return!
John

 

[Peter.N.]

Thanks for your optimism John. I do have an ancient carbon ark brazing tool that I used with my welder many years ago, I might try that tomorrow, if I can find it, although my auto dimming mask seems to have packed up..

Peter

 

[AndyM535]

I know this is an old thread but I've got the same problem. It seems the pulley shaft is parallel but the keyway in the pulley is tapered. As the pulley is otherwise symmetrical it's easy to put them on the wrong way round. The pulleys on my deck are fitted with the wide end of the taper outwards, suggesting the key was hammered into the slot with the pulley on the shaft. I think the correct way to fit them is to put the key into the shaft, then slide the pulley over the shaft and key, wide end inwards so that a puller will always be able to pull the pulley off the shaft. The way that they are fitted, the end of the key is below the pulley so there is no way to pull the key out and the key acts as a wedge when you try to remove the pulley with a puller. So far I've got one pulley off, with a 10 tonne hydraulic puller that completely destroyed the pulley. Now I know the problem I'll try and drill out the keys to remove the other two.

 

[Peter.N.]

I'm still here. To get mine off I had the assistance of a local mechanic and his acetylene torch, even when red hot they were still reluctant to move, we did get them off eventually but I had to replace the pulleys and grind the end of the shafts down to get them back on again.

Coincidentally I have been using it this afternoon - in the rain. It packed up last time I used it, fuel tank outlet blockage and I only fixed it today. We have some visitors coming on Wednesday to look after the house while we are away and if I hadn't cut it they would probably got lost in it.

Peter

 

[conny]

We used to come across tapered keys in pulleys in engineering. The best answer we found was, drill and tap the end of the taper key. Screw in a small eyebolt and hook a slide hammer into the eye bolt. Then heat up the pulley as hot as possible and as quickly as possible, (we used to use oxy-acetylene with a small fierce flame). This expands the pulley before the heat gets to the shaft and the key should come out using the slide hammer.
Just be careful of your fingers with the slide hammer!

 

[Burnerman]

I've never known gib keys - parallel or tapered - being used in such light applications as mower pulleys, but for sure they had their place in heavy flywheels on diesel engines and other heavy duty applications.
If I recall correctly, the taper was 1/100 typically and they were always hellish to shift.
I do have a puller somewhere that grips the gib head whilst 3 other screws force down on the flywheel boss or whatever.
John

 

[Peter.N.]

These were so tight John that I bent the pulleys out of shape trying to remove them with a puller. Never thought about heating the pulleys although its obvious really, anything else you want to remove you heat the part with the largest diameter, makes the centre hole bigger.

Peter

 

[conny]

These were so tight John that I bent the pulleys out of shape trying to remove them with a puller. Never thought about heating the pulleys although its obvious really, anything else you want to remove you heat the part with the largest diameter, makes the centre hole bigger.

Peter

@Pete.N, the problem with a tapered key, (slightly different to a gib key because it doesn't have a shoulder), is that no matter how hot you get the pulley, it will pull on to the taper even tighter. I have never understood the reason for taper keys with the means to extract them. Much better with a proper gib key or, even better, a taper lock bush.

 

[Peter.N.]

I don't understand them either, I thought a key was a key. Anyway two new pulleys later and its OK now if a bit battered.

Peter

 

[AndyM535]

It's not a gib head key and the key isn't tapered. The slot in the pulley is cut at an angle to the axis of the pulley so it is deeper at one end than the other. We bought the mower in a well used condition and the seller included some spare deck bearings. I now think that at some point the bearings have been changed and the deck was wrongly re-assembled with the pulleys upside down.

The problem is if you put the pulley on the wrong way round. I think the correct way is to put the key in the slot in the shaft, then slide the pulley on. It will only go on with the deep end of the slot at the bottom and will come off more easily with a puller as removing the pulley doesn't require the key to move.

On the other hand, if you fit the pulley to the shaft and then tap in the key, you can only do that with the deep end of the pulley slot at the top. Even if you don't drive the key below the top of the pulley when you fit it, the dome washer and bolt will push it flush. This makes removing the key first extremely difficult as there is no way to grip the key and no access to the underside to drive it out. If you are lucky you can remove the pulley with a puller and the key will slide in the shaft slot and come out with the pulley. Most times though the key will not move, so as the pulley moves the key is wedged tighter into the slot.

I removed the first pulley with a hydraulic puller and it only came off when the central hub of the pulley split (with quite a bang!). I think the drill the key, tap the hole then extract with a slide hammer approach suggested above sounds like the most likely and cheapest way to fix this.

 

[Peter.N.]

Sounds exciting.