Help! RCK60-24B rebuild, something isn't adding up!

[Brewer]

Hi all, I'm rebuilding my deck after the gearbox failed. It's taken me a while to get back to it, and while I'm pretty sure my old parts are well organised, I'm already stumbling.

First problem is with the gearbox / centre spindle. I'm reusing a spacing collar (#170), that slips over the shaft between the upper oil seal and the bearing. In reassembling, I find that the bore of this collar is a couple of mm larger than the shaft (much more than just wear) - so it is apparently free to wobble around a couple of mm off centre if it so chooses. Does that seem right?! The new and old shafts match.

It isn't even apparent (to me) what purpose it serves. If anything it would seem to transfer any vertical forces from the gearbox to the inner race of the bearing. I'm not doubting Kubota's engineering but I would have thought this would be less desirable than allowing the shaft to slip within the inner race if such forces were occurring?

And what about the off-centred-ness? It's probably true that thick grease and centrifugal force would combine to keep it fairly well centred, but does this sound like Kubota design to you?!

 

[Delmar]

Hi Brewer. Not sure I can offer any real help, other than advice to trust the engineering. Those gearboxes are almost bulletproof. Every single failure I've ever seen was due to operator not noticing leaking oil seals; oil leaks out = friction and heat = broken and welded gears! Good luck with the repair.

 

[100 td]

Hard to tell from the diagram. What runs inside seal 40? It looks larger than the shaft, the pulley boss or the spacer?

 

[Brewer]

Every single failure I've ever seen was due to operator not noticing leaking oil seals

Reckon you can add another one to your list! Bota book says replace them every 2 years IIRC. Another lesson learned the expensive way

What runs inside seal 40? It looks larger than the shaft, the pulley boss or the spacer?

It's the pulley boss - the spacer sits in greasy heaven on the shaft between it and the bearing. I guess it aims to protect the bearing by transferring any upward thrust to the pulley/shaft/crown gears - although to my (inexpert) eye it seems equally likely to pass unwanted thrust in the opposite direction, in the event that the gearbox and deck become able to move against each other.

In checking again the difference in diameter is about 1mm. Still enough that it just doesn't seem right, but I can't find any explanation for it.

I have reassembled the centre spindle now, wobbly spacer and all, but it will be a while before I finish the others and run it up to speed, so there's still time to avoid a disaster...

 

[Brewer]

Just giving this a bump in case anyone else has any ideas about that wobbly spacer?

 

[Dave_eng]

Designs do change and parts often do not reflect older designs.

You mention a 1 mm gap.

Once you are certain you are putting the parts together correctly, I would suggest contacting Loctite in Australia

http://www.loctite.com.au/loctite-Australia-and-New-Zealand.htm

They have excellent products for mounting cylindrical bearings and sleeves that might well take up the 1 mm gap.

If you go the loctite route follow their instructions especially on the cleanliness absolutely.

Some photos would be of more help for those trying to understand your problem and provide advice.

Dave