Potterton Puma Fan problems

[protobikes]

The fan in my Puma 80 perm pilot is causing problems. Rear bearing is OK. Front appears to be a bit stiff. I managed to get it going again but it is noisy. I would like to try new bearings. The motor cooling fan can be released easily, but I cannot get the main fan off the shaft. I found the grubscrew and released it, but the fan would not come off the shaft. Is there a trick? There appears to be a groove round the base of the boss, so maybe a gear puller would do it.
I hope to retire it as soon as Icesave pay out, so I do not want to spend serious money on a new fan assembly.
Are the bearings special? They are a standard size but they operate in a hot environment. Are they made without lubrication? Is there a high temp lubricant that might help it limp along a bit longer?

Thanks - Jonathan

 

[protobikes]

I find I can get high temp stainless bearings quite easily, so I just need to get the fan off the shaft.....

JW

 

[sbgasman]

have changed bearings on fans ,first thing to do is clean shaft with emery even if it looks clean,then use some small pullers to remove,i ground the ends of pullers for a good fit,be very carefull with impeller as these are balanced

 

[protobikes]

Thanks very much for the reply. The end of the shaft is black. I should have thought of cleaning I have probably put it off balance already with my efforts to get it off. If it comes out smooth enough I will see if I can rebalance it.
The next question is - where id you get a puller that small?

Thanks again - JW

 

[sbgasman]

got them from halfords(i think)but that was about 10 years ago,you could probably get some off fleabay,mine are about 100mm*50mm good luck

 

[protobikes]

I have some cheap and nasty ones but they would need a lot of grinding. RS have a nice looking set for £26.56, but I don't know if it would fit in. I'll have a look at Halford and maybe some tool suppliers. Obviously, I don't want to spend anything near the cost of a new fan assembly! One site offers part exchange recon fans, but I can't take mine out of service.

Thanks again for the help - JW

 

[Agile]

Most main impellers are held on by a nut ( often LH thread. ) and sometimes can be a little difficult to get off.

I usually manage to sort them out by applying heat with a blow lamp and then taping the shaft with a hammer and drift.

I cannot envisage what you grip on with a bearing puller.

The motor cooling fan is usually the difficult one to get off. If you do then they will not usually be tight enough when they are refitted.

What is the reference number for the high temperature bearings that you have identified and have you had a quote on the price?

Tony

 

[sbgasman]

Tony,the fans we had to repair where apollo's the impellers came off quite easily a small allen grub screw attached it to the shaft,the pullers were used to remove the bearings as they were harder to get off,the bearings were skf around £30 per pack of 10 Damian

 

[protobikes]

The bearings are SKF626ZC3GJB. Simply Bearings stock them. Probably much better spec than original. The boss on the fan is about 11mm deep, 22mm across. Near the base there is a groove about 1.5mm wide. That is what I need to grip. The 6mm shaft protrudes about 7mm from the boss.

I had a hint from a friend. Find a washer that is about the right diam and thickness. Cut in half and slot into the groove. Then any old puller should be able to grip the washer. I have some grotty car pullers. I think it will come free once it has moved, so I probably won't need a puller with a 6mm driver. I will hold the jaws in place with cable ties to make it less fiddly.

If I have to make a puller, I have an old bike chain tool. The thread is 10x1 and I have a tap, so I could make the rest of it. Just rather not waste the time. Would need to be decent steel and tempered.

I am away tomorrow but I will give it a go on Friday and let you know. I want to establish I can move the fan before I pay for bearings.

Anyone know about lubricant? I might have to eek the existing bearings out. I have some graphite powder lock lubricant which might help.

Thanks for all the help

Jonathan

Jonathan

 

[protobikes]

You know, it might be easier to drill and tap 3 holes in the fan, make a corresponding plate and use 3 bolts to pull it off. Easier than making a puller. The work might change the fan balance, but any of this violence might do so.

What is the fan made of? It is at work at present so I can't check it out. If it is aluminium it may be too soft.

Jonathan

 

[sbgasman]

i think it is ali,with the recon fans i think they will send it to you with a surcharge which is refunded when you send your old one back hth Damian

 

[Agile]

The fans blades are ali but the boss is steel.

For a one off drilling and tapping is the answer and just two holes would probably be enough.

My heat method has never failed me but I dont do many!

You cannot get grease into a dried up bearing! An HT grease like wheel bearing types would probably be best.

Tony

 

[protobikes]

I drove the fan back on the shaft a little, cleaned up the end of the shaft with some Dremel tools. Made a puller from 5mm aluminium strip, drilled and tapped 2 holes. The fan is surprisingly hard. I didn't try a magnet on it.

The fan pulled off the shaft easily. Tony was quite right to say the motor fan was hard to get off. I think it was muck on the shaft between the fans and damage done by the main fan grub screw. I worked a very thin strip of emery between motor fan and casing. With a bit of work it came away. It needed a bit of the same work to get the bearing off the shaft.

It is all back together and running now. I didn't want to buy the new bearings until I was sure I could get it apart. Should be easy to get apart again when I get them.

Cost nothing so far.

Thanks for all the help everyone.

Jonathan

 

[Agile]

When the motor fan has started moving all you should need is some thich oil on the shaft to help it slip off.

The problem is usually that it stretched and becomes too loose to stay on the shaft.

Tony

 

[protobikes]

New bearings fitted. Fantastic difference. Really quiet and smooth. Tick over was as noisy as flat out is now. DIYnot scores again!

Thanks - Jonathan