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Fan Gear Box rebuild ??
Has anyone torn down and rebuilt the gear box that runs the fan? Mine appears to need new seals and from looking at Catbase drawings it look like there is 1 seal on the end of each shaft. Are there any special tools or surprises that I could run into rebuilding the gear box?
Thanks
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10 Replies
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no surprises . simple. check for grooves where old seals ran. might shine up a little before reassembly. No springs to send things flying into space! Bob
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The hardest part is the pullys they do not mount on the shaft like you might think, they are two pieces that lock togather to lock in place on the shaft loosen the bolts on the pully and with any luck they seperate and slide right off in a perfect world but you know how that goes. They don’t like a lot of phisical assistance seperating and the use of a regular puller does not work. If every thing comes apart as planned, extream care is needed in the alignment of the hub position then the tightning of the two parts togather to not get any wobble just be real slow and real even. The gear case is a piece of cake just seperate and the seals just fit in the slots, havce fun!!
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Robert and Bill,
Thanks, that’s the information I was looking for. I thought the pullys looked a little wierd. I will order the seals today.
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Have gear box out of bus and bolts removed from pulleys, but can not get pullys to budge. Looks like the inner split ring is frozen to the outer pully part. Bill mentioned that a reguler pully will not work. Any ideas on how to get the pullys off the shafts?
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If it is a standard taper-loc you should see jacking holes in the inner sleeve shoulder, if so install the bolts and tighten a little on each one and it should jack the sleeve out of the outer pulley.
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Success !! The bolts that hold the two pieces of each pulley together also fit in the holes that push the 2 parts away from each other. Used a lot of penatrating oil, time and patience and the pulleys finally came apart.
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What I learned working on the gear box that powers the fan.
Getting the pulley off the shafts turned out to be the hardest part for me.You will need the get 1 qt. of oil from Prevost. Part number 180217, Synthetic oil Mobil SHC 630, About $77 a qt. OUCH!A google search for SCH 630 will get the oil at a much cheaper price.
Before you do anything, take pictures of each pulley and how it is mounted on the shaft. Take precise measuerments of where the pulley is mounted on the shaft so when you put it back together and will go back in the same location.The pulleys are made up of 2 parts.Part 1 is a inner ring that slides over the shaft and has a split / cut in the ring that allows the part to be compressed or expanded a little. It also has a taper that matches a taper on the inside of the belt pulley. There are also 3 large holes for bolts to pass thru and three tapped holes that the same bolts can be used in.Part 2 is the actual pulley that the belts run on. It has three tapped bolt holes and a taper on the inside diameter of the pulley that mates with the taper on part 1.trick # 1: While the gear box is still bolted into the bus take the time to loosen all the bolts on the pulleys and the hex head bolts that hold the gear case together. All the bolts on my gear box were very tight and I did not loosen them until I had removed the gear box from the bus, big mistake.Now remove the gear box by removing the 4 large bolts at the bottom of the gear case. I was able to get to these bolts with a long extension from under the bus.trick # 2: Put some penetrating oil in the area where the inner part 1 mates with the taper on the inside of part 2 (the pulley). Let it soak in for an hour or two.To remove the pulley: Remove the 3 bolts (green arrow) holding the two parts together then use the same bolts in the tapped holes (Red Arrow) of part 1 (the part that is on the shaft) and use them to push the pulley off of the back of part 1. You may need to use more penetrating oil and wait for it to soak in.Trick # 3: Once the pulley is pushed off the back of part 1, use a medium size screwdriver or small chisel and put it into the cut in part 1 (Yellow Arrow) and drive it in with a few mild hammer hits. That spreads it a little and allows you to pull part 1 off the shaft. Now you can pull the pulley off.Taken the case apart and replacing the seals was easy.Putting it back together was not difficult.Put the pulley over the shaft.Put the screwdriver or chisel back into the split of part1. Slide part 1 onto the shaft and position it based on the measurments you made BEFORE you took it all apart.Once it is in the proper place remove the screwdriver and that locks part 1 in place.Now slide the pulley onto the back of part 1 and use the 3 bolts thru the larger holes in part 1 and thread them into the tapped holes in the pulley. Tighten up the bolts a little at a time so the pulley is pulled onto the taper in an even fashion. The idea here is to keep it straight and not let it get tilted which will cause a wobble in the pulley when it turns.Put the oil in, mine took about 3/4 of a qt.Start it up and and make sure the belts run true and the pulleys do not wobble.ALL DONE.
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Great info Andre, maybe we should add to articles?
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I was thinking that I purchased Mobil SHC 630 at Advanced Auto for less than $20 a quart. I just did a web search and found it from $17 to $27 dollars a quart.
Ken
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Ken,
CatBase list SCH 634 and when I looked for that on line I could not find it. So I ordered it from Prevost and they substituted SCH 630 which appears all over the internet.
I just checked CatBase agian and see that it also list SCH 630.
It seems that the SCH 630 is much cheaper and available from many places on line.
I will edit my post to add info about the availability of SCH 630.
Thanks
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