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This fellow points out engineering stupidity
7

This fellow points out engineering stupidity

This fellow points out engineering stupidity

(OP)
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.
https://www.youtube.com/watch?v=d3eC2OIg85o

RE: This fellow points out engineering stupidity

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.

RE: This fellow points out engineering stupidity

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.

RE: This fellow points out engineering stupidity

(OP)
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"?

RE: This fellow points out engineering stupidity

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?

RE: This fellow points out engineering stupidity

No to mention cibachrome's post which states that fresh grease does get past the seals.

je suis charlie

RE: This fellow points out engineering stupidity

Quote (enginesrus)

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"?

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.

RE: This fellow points out engineering stupidity

Why exactly does the outer race need grease on the outside of it?

RE: This fellow points out engineering stupidity

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.

RE: This fellow points out engineering stupidity

Quote (LionelHutz)

Why exactly does the outer race need grease on the outside of it?

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.

RE: This fellow points out engineering stupidity

I'd be more concerned with the shaft dropping out of the bearings so easily. that should have been an interference fit.

RE: This fellow points out engineering stupidity

There is considerable belt tension on the spindle(s). The moment keeps the spindle in good contact.

RE: This fellow points out engineering stupidity

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.

RE: This fellow points out engineering stupidity

(OP)
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 https://www.youtube.com/watch?v=S8Pu6BMgqAs

RE: This fellow points out engineering stupidity

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.

RE: This fellow points out engineering stupidity

(OP)
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.

RE: This fellow points out engineering stupidity

I know a few "engineers" that don't have a degree. Smokey was one. Pretty rare though.

je suis charlie

RE: This fellow points out engineering stupidity

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! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: This fellow points out engineering stupidity

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).

RE: This fellow points out engineering stupidity

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.

RE: This fellow points out engineering stupidity

Happened to me. Yes, there is no means of lubricating the bearings. The pulley is two stampings rivetted together, enclosing the bearing. As mine is a thousand years old there are no spares, so I had to drill all the rivets out of the pulley to take it apart, put a new bearing in, and then rivet the pulley back together. It's lasted one season so far!

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: This fellow points out engineering stupidity

I've had similar issues on my 2001 Deere but fortunately they're common enough that not only does Deere still supply replacement parts, but also the aftermarket at a more comfortable price point. If I can eke out another 6 seasons with this machine, that will do, then I'll be ready to retire and move somewhere away from this midwest hellhole and leave the riding mower (and maybe large scale mowing altogether) behind.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: This fellow points out engineering stupidity

My Toro might be a cheap assembly of plastic and tin but it is fairly simple, built with disassembly/maintenance in mind, and Toro does give free access to their maintenance manuals online which show how to replace individual spindle bearings. It only took ~30 mins total to remove the deck, blades, pulleys, and spindle shafts. I discovered one of the spindles' lower bearings seized and after a few hours searching online then in person at various box, ag, and other stores, could only find a non-sealed version of the bearing I needed locally. Given lousy weather reports and an inability to source bearings until today (Monday), I decided to lube and run the seized bearing. I carefully popped the seal out with my knife, blasted the rusty ball bearings with brake cleaner then penetrating oil, and carefully worked everything until freely rotating. I then relubed it with grease, reinstalled the seal, and reassembled the deck. I am sure the seal has lost some of its effectiveness but the bearing didn't seize, sounds decent actually, and our 1.5 acres was mowed so I'm calling it a win.

RE: This fellow points out engineering stupidity

4

Quote (enginesrus)

It takes those stupid mechanics to figure out how to make something work that the stupid engineers couldn't figure out.

Guess who figured out a fix for the dreaded 996 IMS problem?

Engineers.

At this point, man, everyone gets your schtick. We engineers are all morons, everything was better in 1949, we should all go back to acre sized drafting rooms full of dudes wearing skinny ties and smoking lucky strikes all day while they draw pencil on vellum.

We get it. We're all stupid. You know better. You know everything.

There. Does that satisfy you enough to stop posting this nonsense?

RE: This fellow points out engineering stupidity

(OP)
SwinnyGG, No not all. Some are very good at what they do.

RE: This fellow points out engineering stupidity

As in every occupation.

je suis charlie

RE: This fellow points out engineering stupidity

Sturgeon's law is the adage that “ninety percent of everything is crap”. This suggests that, in general, the vast majority of the works that are produced in any given field are likely to be of low quality.

https://effectiviology.com/sturgeons-law/

RE: This fellow points out engineering stupidity

To me, the stupidity in that design is it even having a grease fitting. That was probably required by marketing. Properly chosen sealed bearings last a VERY long time in a non-commercial use lawnmower deck.

RE: This fellow points out engineering stupidity

Especially when modern bearings use polyurea grease which I have never seen sold at an auto parts or DIY store.

RE: This fellow points out engineering stupidity

The incompatibility of grease systems makes me long for oilers. No thickeners means nothing to harden and block the bearings. Even with compatible greases, oil loss still leaves thickener that is difficult to remove.

Tugboat - Gotta look in the farm department: https://www.walmart.com/ip/John-Deere-Polyurea-Thi...

RE: This fellow points out engineering stupidity

RE: This fellow points out engineering stupidity

I just pointed out it's available from places people currently shop. Online stores count. It's not unfindable. It may be better that way as mixing greases is a great way for those with no background in lubrication to destroy equipment and grabbing a tube from the shelf will do that.

In a tangentially lubrication-related case, a chain was sued over the sale of automotive oil that destroyed engines. It included SAE 30, SAE 10W-30, SAE 10W-40 weight oil. The problem being that no car since around 1930 had an engine designed for SAE 30 oil, and no cars after 1988 would use the other two. How-so? Because the fine print said "SA Specification" (30) and "SF Specification" (10W-30 and 10W-40). https://www.carcomplaints.com/news/2021/dollar-gen...

For the typical consumer, lubrication is a minefield. For them grease is grease and oil is oil.

RE: This fellow points out engineering stupidity

That's a rather BS lawsuit. I doubt any newer engine would suffer catastrophic damage using those oils. Maybe an earlier long term failure, but that would mean using that oil it's entire life and probably owning it from new to well over 100k miles before seeing the failure. If you owned it used, then how can you determine it was the oil vs a previous owners other abuse?

RE: This fellow points out engineering stupidity

That was an interesting video. It wasn't clear why the bearing he showed us was "gritty" but I have to wonder if there isn't an application or bearing quality problem rather than a lack of lubrication. The grease inside didn't look terrible and I didn't notice any signs of overheating. It's a slow-speed application but could have high shock loading and possible misalignment.

I worked for a highly-regarded UK dynamometer manufacturer right out of university and learned that grease content and quality is critical in high-speed applications. The bearings specified were the sealed type in most applications or open and oil-mist lubed in very high speed applications such as when connected to gas turbines. The policy of allowing customers to lube bearings via grease fittings was deemed to be the reason for failures. Having no knowledge of this technology I absorbed everything I was told.

At a job decades later I was tasked to fix an issue with our industrial slurry pump product (used in mining) which frequently had bearing failures. The existing manufacturing docs called out for the two sealed bearings to have one seal removed at assembly and the OEM grease washed out and replaced to 100% fill with with a "marine-grade" grease. Apparently there was a concern that water could enter the bearing and somehow this marine grease would allow it to survive. They were assembled much as they were in the lawn mower situation but with grease fittings near each raceway.

Needless to say I ECN'ed the docs to retain the bearing's OEM seals and grease fill as supplied and eliminated the grease fitting. Sure enough the relevant marketing dude steps in (who had originally conceived the design) and demands to know why I'm changing it, because "obviously" the lube needed to be refreshed.

RE: This fellow points out engineering stupidity

That $56 is for 10 tubes.. $5.60 is dang reasonable for any grease.

Keith Cress
kcress - http://www.flaminsystems.com

RE: This fellow points out engineering stupidity

KiwiME - you left out what the results of the changes were. I'm assuming better life????

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