Been working on a Michigan Transaxle steer axle for my Pettibone Extendo 88 ( https://imgur.com/a/cN2PcQo ). I should be re-assembling the axle soon, and looking for opinions of spindle bearing nut installation. The service manual calls for the use of a special tool ( https://drive.google.com/file/d/1Gh0Rlvxrhwfkye7xBK6IHC8x_QUv6PYC/view?usp=sharing ) which I do not have. The bearing nut is supposed to be torqued to 600-700 ft-lbs. I removed the bearing nut via a steel drift pin that was softer than the bearing nut material. Hard to tell, but it didn't seem like it had that much torque applied. If any mechanic out there has experience with this sort of assembly, what would you do? Make a tool so the nut can be torqued, or just try to guesstimate the torque via a hammer and drift pin upon re-assembly? Based on the radius of the bearing nut, I calculate the striking force needed on the drift pin to reach 700 ft-lbs torque is 3500 lbs... Don't think I can achieve that with a 6lb hammer. This tells me that nut did not have 700 ft-lbs on it. There was no play in the spindle bearings before disassembly.
It all depends on what the bearings are: taper roller, angular contact, or what? Do you have a cross section or exploded diagram, or post photos of the bearings.
Your bearings will swell a bit when they get hot. You need to have a bit of room for that. I usually seat the bearing good and solid, then back the nut off about 1/4 to 1/2 a turn depending on the thread pitch of the hub.
They are tapered roller bearings. I don't have the bearing part numbers but I know the cones mount on a 3.375" diameter spindle. No cross section in the manual but this should help: ( https://drive.google.com/file/d/1c1NyXgZstnNb2yiRar5qamok_uXuyfyQ/view?usp=sharing ) Items 13 & 14 are the cup/cone, item 18 is the spindle, and item 11 is the locknut in question. I would normally do this too, yet the manual states to torque to 600-700 ft-lbs. The machine weighs around 22,000 lbs, maybe they want a preload on the set of tapered rollers so there is never any play. The bearings will heat up and grow, but so will the spindle that the bearings are mounted to. I've never assembled a wheel hub of this size, plenty of old automotive applications where I leave a bit of play, but this is different? Like I said, there was no play in the bearings before I disassembled, the nut was tight, had to hammer it loose, but I don't think it had 700 ft-lbs on it...
I will also add that a mechanic has been into this planetary before, as it looks like at one point in time it exploded. I see shrapnel damage on some of the parts. Maybe that guy didn't have a tool either and just tapped it tight with a drift pin, getting nowhere near the required torque.
Are you sure you're not supposed to back it off after torquing the nut? That would be the standard procedure with any roller bearing. The torque is a way to make sure the bearing is seated.
From the Pettibone manual: The bearings are tapered roller, the cups are pressed into the hubs, the cones are slip fit over the spindle hub, you don't seat anything with the bearing nut if the cones are properly seated when installed with a driver.
I wouldn't assume anything, is there a section with recomended torques? that might have a procedure like "700# then back off then..." That's standard procedure, 700 lbs torque on a bearing like that is way more than I'd expect for a bearing that size as FINAL TORQUE.
It’s highly unlikely that hub would turn at 700 lbs of torque without a 6 foot cheater pipe. I have learned that Pettibone service manuals are vague in details and a lot of mis information has been printed in them in the past.
Now we know it's just an opposed taper roller bearing arrangement, I, personally would treat it like any other similar truck size wheel bearing: tighten the nut until the bearing starts to bind then back off to the nut to the nearest position that allows the the nut to be locked in place.
Yeah, that is why I am here, because what they are telling me to do in the manual does not seem correct at all. I paid $120 for the Pettibone manuals, and out of all the manuals I have bought for various machines, these are the worst for sure. All the pictures are photo copies of photo copies of photo copies, etc, very hard to make out any of them. And they keep referencing "torque specifications" , but there are no tables of specs/capacities.