enginesrus
Mechanical
I'm thinking in the early 1940's the engineers would be able to figure this one out pretty easy. Things like this are pretty difficult for the younger generation engineers.
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This fellow points out engineering stupidity 7
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TugboatEng
Marine/Ocean
Damnit, more of this crap? Bearings with inside shaft rotation run with clearance on their outer diameter and require lubrication of the outside of the outer race. ALSO, modern bearings come packed with polyurea grease and nincompoops love pumping their favorite lithium soap flavor everywhere without regard undoing 80 years of advancement.
cibachrome
Automotive
Sorry. It's fake news. I currently own several mowers in 48", 72", 84" and a 9' haybine widths. These bearings run hot and when they go thru a heat up and cool down cycle, they draw in the grease because of the expansion and contraction of the corn head grease. The way I know this is because I used to use alternating red and green grease applications. When you remove the spindles to clean out the dirt and grime, you can track the color of the grease exiting the bearing(s). When abusers bend a spindles and it needs to be replaced, the evidence is clear. My neighbors abuse their machinery way beyond the intended design levels because they are idiots and morons, so I get the full database of grease migration.
BTW: I no longer use the red grease because my wife once offered me a freshly baked filled donut while doing mower maintenance. I thought I had leaked some rasberry filling all over my T-shirt, but it wasn't donut filling.
BTW: I no longer use the red grease because my wife once offered me a freshly baked filled donut while doing mower maintenance. I thought I had leaked some rasberry filling all over my T-shirt, but it wasn't donut filling.
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enginesrus
Mechanical
Not sure if I understand the comments? If the bearings are fine as is then why have a zerk fitting to grease them? Most of those permanently sealed bearings from off shore, never seem to have enough lube to start with. The guy shows that the bearings are not being lubed from the zerk in the video. So what is the "FAKE NEWs"?
TugboatEng
Marine/Ocean
ERU, the lube pack quantity of a bearing is based on its expected operating speed. The higher the speed the lower the volume of grease that should be in the bearing. Excess greases causes overheating.
ERU, did you just ignore the whole explanation about lubrication of the outside race of rolling element bearings?
ERU, did you just ignore the whole explanation about lubrication of the outside race of rolling element bearings?
enginesrus said:
I know I'm wasting these keystrokes, but.. The 'fake news' is that greasing through that zerk doesn't do anything. Greasing that zerk 1) pushes grease against the seals, which will draw grease through them as the bearing sees temperature cycles. 2) greases the outer race of the bearing, which it needs.
Note that the guy pulls the bearings out, and they are bone dry. Then complains that they are running rough.
Well... if he didn't grease them, the fact that they are running rough is not a surprise.
Fake news.
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LionelHutz
Electrical
Why exactly does the outer race need grease on the outside of it?
TugboatEng
Marine/Ocean
With inside race rotation the outer race is typically a clearance fit in the housing and will move some due to thermal expansion and may even rotate with the rest of the bearing. Without lubrication there would be fretting and housing wear. The outside race spinning does eventually wear out the housing, this is a common failure mode for large gearboxes.
LionelHutz said:
To build on what Tugboat is saying - notice how easily the bearing pops out when he just taps it with a screwdriver? That indicates a pretty loose clearance fit. Even if it was tighter, and still a clearance fit, you'd need a puller to get it out without it cocking in the bore. The fact that you can just touch it and it drops out indicates it's a loose fit, which would need to be lubricated if you want to maximize the life of the bore.
LionelHutz
Electrical
I'd be more concerned with the shaft dropping out of the bearings so easily. that should have been an interference fit.
cibachrome
Automotive
There is considerable belt tension on the spindle(s). The moment keeps the spindle in good contact.
TugboatEng
Marine/Ocean
Ideally the shaft would have had some interference. Some manufactures opt not to. If you've ever opened up a motorcycle engine/transmission, with the exception of the main bearings, all other bearings are usually clearance fit inside and out.
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enginesrus
Mechanical
The main problem with this whole design is you need almost a tube or more of grease just to fill up the whole unit, before the grease could even try to pass through the seals. Most folks doing the greasing are only going to put in 3 or 4 pumps and that will do nothing. This whole sealed friction-less bearing deal makes me think of the Porsche IMS bearing problems, nice that the old timers never did that on the old aircraft engines. One of the fixes for the engineering failure of the IMS
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TugboatEng
Marine/Ocean
ERU, engineers know mechanics are stupid and can't be trusted to use the right grease. That's why they prefer non-greasable designs.
For example, chassis lubricants for ball joints and such need to be silicone based as petroleum greases are incompatible with the EPDM sealing elements. No average mechanic keeps silicone chassis lube in their tool box and can't be trusted to not reach for whatever is close by. Therefore, the smart engineer removed the zerk fitting completely.
For example, chassis lubricants for ball joints and such need to be silicone based as petroleum greases are incompatible with the EPDM sealing elements. No average mechanic keeps silicone chassis lube in their tool box and can't be trusted to not reach for whatever is close by. Therefore, the smart engineer removed the zerk fitting completely.
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enginesrus
Mechanical
The Porsche IMS has nothing to do with "mechanics are stupid" comment. It takes those stupid mechanics to figure out how to make something work that the stupid engineers couldn't figure out. Take a stupid mechanic like Smokey Yunick for example.
Rare and often stuck in one company that hired them; I knew of one engineer that we wanted to hire, but the lack of a degree made HR unbudgingly stubborn in refusing to OK the hire.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
TugboatEng
Marine/Ocean
My grandfather was an example. He spent time at Cal Poly but was hired by Rocketdyne before completing his degree. He then worked for Bechtel and then finished his career with Aerojet (formerly Rocketdyne).
Coming back to this thread today as my cheapie rider's mowing deck is singing like it has a bad bearing ~10 years and 500 hours later. Naturally this occurs when I have procrastinated and the grass is embarrassingly tall. It has no zerk nor other means of lubricating the deck spindles, and I pressure wash it weekly to stave off the rust worms. We shall see how deep this hole becomes.
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