Motor Oil 101

[B.D.F.]

Ego and testostorone I assume is why you bother. I mean we are barely 400, 500 generations away from caveman status, and only maybe 1,400 generations since our final species development (see sig. line for help here) and while we have evolved, that evolution has certainly not kept up with our knowledge growth. So it is pretty natural to want to beat your chest and be right rather than being correct. I feel the same urge, I just fight it with reason and logic.

I think the on- lookers have more then enough information here to form their own conclusions. 

I bid you good day. :-)

Brian

I feel like this is another conversation with a politician. Why do I bother?

So for a clarification to the onlookers, let me respond in this manner.

<snip>

[B.D.F.]

Where? Acedemia? Is that a school for learning card tricks? A skin disease that looks like a sports wrap on the face?

See, there is that testosterone and ego.... 

Lighten up Steve, it is just oil and I don't think either one of us sells the stuff, right?

Brian (reason says leave it alone, ego says 'go get 'im!'.... still hoping for reason to win)

BDF, I have an idea- rather than operate in acedemia, let's work in the real world.


<snip>

[enim57]

Take the pressure of the oil, multiplied by the area of 1/2 of the bearing journal and multiply them. Then tell me how 40 PSI of oil pressure across a couple of square inches of area, yielding 80 pounds of force is resisting four tons (8,000 lbs. ) of downward pressure in a conventional 350 cubic inch V-8 engine.....

Using the same logic that pressure from the oil pump cannot overcome the downward pressure makes me wonder how oil would get in there by its own means without pressure.

Regards, Russell

[B.D.F.]

Excellent- I always wanted to be correct but remember, now I'm going to quote you on that being correct part :-)

I cannot even remember why I am over here on the C-10 side....? I don't normally read this part of the forum. Never had a C-10 and never formed an opinion about the oil used in them either. ??

Youse guys should come over to the C-14 side and we'll chat about KiPass- it is great fun, never ends and beats the tar out of an oil thread every single time. 

Brian

Problem here is that everyone is correct.

Properly designed crank bearings lubricated by oil under pressure are far superior and will last much longer than similar ones that are submerged in oil or splash lubed.  That said, I do have a heck of a lot of hours on my Briggs powered push mower.

Steve is spot on that  high revving engines such as those we ride really call for oil pressure in the bearings.  Because these motors have zero oil pressure on cranking and start up, I also bet he lubes the crap out of them when he assembles engines because that provides some lubrication at a critical moment too. 

[B.D.F.]

I feel a disturbance in the force.... Note the time of this post.

 

Brian

[Steve in Sunny Fla]

Using the same logic that pressure from the oil pump cannot overcome the downward pressure makes me wonder how oil would get in there by its own means without pressure.

Regards, Russell

When you consider centrifical force constantly trying to throw the oil away from the crank, it's obvious that the faster the crank rotates, the less splash oiling works, and pressurized oiling is the only way to overcome the mechanical forces.

Brian, none of this was chest beating or ego. We have different opinions. You are obviously an educated guy. I'm not. In fact, usually I'm to dumb to realize I can't do something when an educated person tells me "you can't do that, it doesn't work", so I just do it anyway. Steve

[B.D.F.]

Nah, my mistake. Not even a minor disturbance.

 

Brian

I feel a disturbance in the force.... Note the time of this post.

 

Brian

[B.D.F.]

http://www.valorebooks.com/textbooks/fundof-fluid-film-lubrication/9780070259560   $35 including shipping. Education is easy, it is tenacity that is harder to find.

I don't really think this is a matter of opinion.... of course, that is just my opinion about your opinion of what you claim is an opinion in the first place. 

If you are really interested, this is a machine that has five (5) spindles, uses hydrodynamic bearings to support them, and does not have a pressurized lube system. The oil is fed from above and distributed to each spindle as the spindle group rotates; each spindle only gets lubed when it is at the top of the spindle housing. The original Davenport design is over 100 years old and has been in continuous use for all that time. Odds are, you have many things right around you that fell out of one of those machines..... maybe like the pins on the ends of a nearby fluorescent lamp tube?  http://www.davenportmachine.com/about.asp  I have seen those machines so heavily loaded that the spindles themselves are visibly deflected yet spindle seizures are virtually unheard of. Top spindle speed is ordinarily 3,883 RPM and once running they typically run for days or weeks without being stopped other than to reload stock.

Brian

<snip>

Brian, none of this was chest beating or ego. We have different opinions. You are obviously an educated guy. I'm not. In fact, usually I'm to dumb to realize I can't do something when an educated person tells me "you can't do that, it doesn't work", so I just do it anyway. Steve

[enim57]

When you consider centrifical force constantly trying to throw the oil away from the crank, it's obvious that the faster the crank rotates, the less splash oiling works, and pressurized oiling is the only way to overcome the mechanical forces.

Yes that's what I was getting at. Brian is correct about how a hydrodynamic bearing and its lubrication works but the problem is getting the oil between the surfaces and keeping it there. In relation to its practicality for automotive use the Wikipedia article points out the following:
"Hydrodynamic bearings rely on bearing motion to suck fluid into the bearing, and may have high friction and short life at speeds lower than design, or during starts and stops. An external pump or secondary bearing may be used for startup and shutdown to prevent damage to the hydrodynamic bearing"
Another problem is expansion/contraction of surfaces due to heat.

Regards, Russell

[enim57]

In the Davenport machine website a rebuild includes "Lubrication system with motorized pump".
The tech specs for the Davenport HP shows:
"[Constant Low Pressure Lubricator #SB-2446-1
(Ways and Servo Motors)

Required Lubricant
Mobil Vactra (Heavy)

Reservoir Capacity
8 Liters

Lube Pump Output
100 cc/min.

Pressure Setting
25-30 psi

System Voltage
480 V, 50/60Hz 3 Phase, 50 Amp"

Regards, Russell

[B.D.F.]

Wrong machine. Anything with servos is not 100 years old.

You want the Model B. All mechanical. Besides all that, the spindle is lubed through a port to the outside of the spindle housing that rotates and is only lined up with the feed line in one position of the five index positions (it is a five spindle machine). Don't make me get Kirby to take a photo with a Davenport spindle bearing....

Seriously, trust me on this one- I have stood next to them and all their splendid 103 decibel glory (make the bones of your head conduct sufficient vibration that ear plugs don't work). I would lie to you guys but not about this- I would save it up for something more important.... Really.

Hydrodynamic bearings do not work on nor do they need, a pressurized feed. At least beyond the pressure needed to move the fluid into the bearing itself (rule #994: fluids move ONLY because of a pressure differential); gravity feed is fine and dandy. Again, think about it: the pressure supplied to the oil galleys in an engine is never 100 PSI, always less. To push a hydraulic cylinder piston forward within the cylinder, what is required is enough pressure and enough piston area to generate sufficient force to move whatever is resisting it.

Hey, just thought of an excellent example: the wrist pin inside of any engine.... no pressurized lube there but it bears the same pressure as the con rod and main bearings. There ya' go, if pressure was necessary to make a con rod bearing work, how could the wrist pin survive the same amount of force without any pressure? The reason is because of the pressure gradient w/in the oil film.

Brian

In the Davenport machine website a rebuild includes "Lubrication system with motorized pump".
The tech specs for the Davenport HP shows:
"[Constant Low Pressure Lubricator #SB-2446-1
(Ways and Servo Motors)

Required Lubricant
Mobil Vactra (Heavy)

Reservoir Capacity
8 Liters

Lube Pump Output
100 cc/min.

Pressure Setting
25-30 psi

System Voltage
480 V, 50/60Hz 3 Phase, 50 Amp"

Regards, Russell

[Steve in Sunny Fla]

 I have done some light reading, and understand the difference between what BDF and I are saying.

BDF is speaking about "hydrodynamic bearings" and he is correct, in that the rotational speed of the shaft alone builds the bearing wedge from the bearing fluid. This type of bearing is only applicable over a set rpm range.

 I'm speaking about "hydrostatic bearings" which need an external pump to provide the bearing fluid. This bearing is applicable regardless of speed, because it doesn't rely on speed of the parts to develop the bearing wedge.

Problem is, we're talking about motorcycle engines, so any discussion of hydrodynamic bearings is rendered useless by the functional nature of the application. Hydrodynamic bearings would be a gross misapplication in this case, so I don't understand why that was interjected into this conversation from the get-go.  HTH, Steve

[gPink]

You guys are entertaining.

[B.D.F.]

OK but who is more entertaining? Me or him? Who is it? C'mon, you have to pick.

 

Brian

You guys are entertaining.

[B.D.F.]

There ya' go Steve, fixed it up for ya.

Do some heavier reading and see the range that hydrostatic bearings work within. Not heavy reading but less light that what you've done so far.

You are right Gary, this is entertaining! And I have been wasting my time on this forum for year on KiPass.... 

Now you guys do know we passed the line of good sense some time back, around the time Steve said something like 'I don't know why I bother....'. At this point the only thing left is the humor.

So Steve, if we do meet at the national, I'll buy you a drink (of your choice) and you can give me your theories on gravity while you pour it up your gullet. No, wait, I mean down your gullet. [duckin', grinnin' and runnin']

Brian

I have done some light reading and I am going to try and be right from a different angle. If that doesn't work, I will do some light drinking and come up with another story.
<snip>

[Steve in Sunny Fla]

wow Brian, you sure know how to handle an olive branch 

 Here. I'll give you a chance to get the last word, not that you needed any coaxing...

I'd like to know why you interjected your knowledge on hydrodynamic bearings when the subject is motorcycle engines and hydrodynamic bearings aren't germaine to the application?  And why bother to take me to task, when virtually everything I posted about the functionality of the bearings used in our engines was correct? Steve

[T Cro ®]

wow Brian, you sure know how to handle an olive branch 

 Here. I'll give you a chance to get the last word, not that you needed any coaxing...

I'd like to know why you interjected your knowledge on hydrodynamic bearings when the subject is motorcycle engines and hydrodynamic bearings aren't germaine to the application?  And why bother to take me to task, when virtually everything I posted about the functionality of the bearings used in our engines was correct? Steve

Seems to me that this thread has more than run it's course; thus I'll have the last word...

And the word is CLOSED ...