Complete Roller engine Where is it?

[Guest]

We have roller camshafts, roller rockers and race applications have roller bearings for camshafts.

Why is there no complete roller engine in production yet? roller rod and crank bearings coupled with the above would reduce rotational drag and heat and significantly reduce the load caused by the oil pump by which I nearly sprained my wrist priming with a drill once to give an indication of how much drag it creates. Roller bearings would only require a continuous drop or splash of oil to maintain allowing for much lower oil pressure. There is no doubt a roller bearing would go on non stop for miles probably hours before failure due to lack of oil compared to the current friction bearing setup.

Couple that with the strongest lightest in weight metals for the rotating assembly and engine efficiency should increase substantially resulting in more power from the same engine platform and much better economy.


I would like to conduct an experiment like this one day and maybe even take it to a serious level by attempting to use exhaust gases to open and close valves.

I didn't know roller bearings were being used at all in a crank or rod capacity until a search yielded this:

http://www.dansmc.com/roller_bearings.htm

[ForcedFirebird]

I have also often thought about this. Could you imagine the dtonation resistance of a needle bearing set? The stoutness and reliability would be unmatched. Too bad it would be an expensive and time consuming production.

[3400-95-Modified]

there is the biggest issue of getting the bearing on to the crank... in motorcycle applications stuff is all pressed together, so the journal is pressed into the crank and through the rod at the same time, which is why you will typically see a stroker rod kit also include the crank...

It would be very interesting to see how you could make a bearing for a standard cap style rod... I guess you could use needle bearings but you would have to be sure there is no seam where the caps/race go together and also hold the bearings in there during assy...

Very interesting topic but probably way to expensive to produce, for the general public at least... MAYBE usefull on high HP motors but not if they need to come apart often for inspection.

I found this after searching for it...

As far as auto engines are concerned, the use of needle bearings is fraught with problems. Whilst the rolling friction is seemingly low, assembly is complicated by the need to fit a needle roller round a journal which may be several webs along a crankshaft rather than at each end (as in a 2 stroke moped engine) Nomatter the lubrication pressure supplied, any wear which accumulates at a journal is uncushioned by oil and crankshaft rumble and overreaching of the con rod follows with chatter exacerbating the problem and eventual reduction of bumping clearance to nil. At rest, the bearing quickly drains down of residual oil and the exposed rollers and face surfaces are rapidly attacked by corrosive combustion by-products remaining in the crankcase. For a regularly used low cost and disposable moped engine the deterioration is acceptable but for those engines used infrequently (for example in a light aircraft) the extent and rapidity of bearing failure compromises apparent economy of installation and leads to unreliability.

By contrast, a shell bearing is easy to assemble and renew, cushions heavy thrust reversals all the time adequate oil is provided and accommodates and tolerates considerable wear. At rest the assembled bearing retains oil which inhibits corrosion of the journal even when exposed to corrosive atmospheres.

One disadvantage of shell bearings is the low tolerance to high temperatures and loads which break the oil cushion, in those cases the shell lining material, popularly known as white metal may reach melting temperature.

Low stressed engines use a white metal alloy mainly of lead and tin while high load engines use alloys including aluminium for greater strength, though tougher white metals demand nitrided crank journals for longevity.

Roller thrust bearings are notoriously unreliable in auto applications as failure leads to speedy engine destruction while white metal thrust bearings continue to carry thrust loads even when the white metal is worn down to the steel backing.

Most British Leyland (Austin Morris) 1100s power unit failures arose from the collapse of the 2 needle roller bearings which supported the idler gear between the engine and underslung gearbox. Needles which sat beneath the oil surface in the gearbox/sump survived corrosion until they were damaged by circulating swarf in the lubricating oil shared with the dirty engine.

Shell (or bushing) bearings do not touch the shaft. Oil supplied by a pump assures that oil is forced between the shell and the shaft. Thus the weight and friction is carried by liquid. This is why it takes many miles to wear out a modern set of main bearings. And as they do wear oil pressure drops and clues the operator in that the bearings are needing replaced... as well as the oil pump.
Needles in a heavy pounding situation tend to get flat spots and tend to make rounded splines around the shaft. This would be started also by the split in the sleeve. Needles are as mentioned in another post are hard to install and replace in a journal where they can't be slipped over the end. Many cases studies have ended in faiure. Engines are a harsh condition, one reason is that needles need an endless ring to run in, ... in order to install one on a crank it must be split, ... now you have a seam somewhere, not so kool. Needle bearings need clean pure oil. The carbon deposits that carry through an engine will flow through a shell/journal connection but crush and deposit in a roller needle action. This damages the needles.

So actually "friction setup" isn't true since with a oil pump and pressure the rods are riding on a cushion of oil and only have friction under high load where the pump cant support that cushion layer, so as some noted when you find significant wear on crank or rod bearings its time to refresh those and also replace the oil pump.

[geoffinbc]

Roller bearings would not last as a crank or rod bearing. Once you had detonation they would be toast. No second chances. The oil wedge formed in a friction bearing has the same properties as any liquid. It is non compressible. So it will not fail as long as the supply coming in is equal or greater than the supply leaking out of the clearances. Roller cam bearings would be great since there is only torsional forces on a cam.

[Joseph Upson]

I thought about most of those concerns and it is important to know how old the posted article is to determine whether or not it is still relevant in the face of modern technological advances in metallurgy.

The fact that roller bearing technology is being used in engines as we speak is a testament to its benefit over the common friction bearings despite the oil film which still has a coeffiecient of drag and once you consider the complete or near non existent discussion across the forums of needle bearing failure in roller lifters which can experience brutal forces in a valve float situation, perhaps the technology is there but the cost effectiveness is not.

Another reason I ask about the date of the article is because no one is changing lifters and rockers in 60 degree engines after failed gaskets have leaked coolant into the engine so there goes the corrosion theory there.

I doubt the lifter bearings encounter the kind of load that would be seen as a crank or rod bearing but then again we would need to calculate lbs per sq/inch to be sure considering lifter roller bearings have a preload usually in excess of 100 lbs due to valve springs and that load increases exponentially above and beyond the max spring load as a function of increasing rpm and ramp rate.

I would suspect more vulnerability from detonation in the rod bearing than the actual crank bearing and the bearing seam would probably be trouble free if instead of a butt joint being used on a half bearing set a clasp joint liking to interlacing your fingers was used or what you see in existing camshaft bearings.

If the article is fairly rescent then I must relent, otherwise I believe it is very possible and not as expensive as one might think with bearing containment being machined into the cap enclosures. Hot wax is easily malleable after it hardens and can be used to hold bearings in place during assembly as one method, there are others.

I don't know how often motorcycles have bearing failures with this technology now, I do know that they tend to experience far greater rpm stresses and the fact that they are incorporated in this capacity at all in these engines is further proof that the idea is not so far fetched.

Actually the lifter preload doesn't start until lift begins but it is much greater than the spring rate due to leverage since the long end of the rocker is on the valve stem side.

[3400-95-Modified]

First part was posted in 03, second part in 05... not wicked new but still relevant I'm sure.

[geoffinbc]

Roller crank bearings have been used before. WWII German tanks used roller main bearings but that fact made them notoriously un-reliable, expensive to make and impossible to repair in the field. All reasons why allied tanks were a dime a dozen and more reliable.

Having roller bearings may sound like a cool idea but it is just not practical. A friction bearing will take more abuse, more load and more speed than a roller bearing of similar size, all at a fraction of the price. Lets just say you figure out a way to fit roller bearings into your engine. After all the machining costs, labor and parts what cost will you be at? How reliable will it be? What if you break one and all the chunks go through the engine and then you have to make another one? At least when you destroy a friction bearing you usually only ruin the bearing insert and the journal. Now how much does it cost doing it twice maybe even three times to get it right? Then consider if you even gained any power and if you did how many dollars did it cost per horsepower?

[Joseph Upson]

This isn't about speculative cost and risk, not much of what we do on this site is otherwise we'd simply buy a used V8 car (practical, dependable and cheap) with the money we spend pumping up the V6. This is about enginuity and expression of skill through creativity in an effort to improve upon an existing concept.

[sprucegagt]

Having roller bearings may sound like a cool idea but it is just not practical. A friction bearing will take more abuse, more load and more speed than a roller bearing of similar size, all at a fraction of the price. Lets just say you figure out a way to fit roller bearings into your engine. After all the machining costs, labor and parts what cost will you be at? How reliable will it be? What if you break one and all the chunks go through the engine and then you have to make another one? At least when you destroy a friction bearing you usually only ruin the bearing insert and the journal. Now how much does it cost doing it twice maybe even three times to get it right? Then consider if you even gained any power and if you did how many dollars did it cost per horsepower?

In thinking along these lines, I have to ask. What is the benefit? Cam bearings are not big friction monsters and the 60V6 block already has priority mains oil feed. Oil temps are not a problem and other than maybe one person here, I don't know of anyone running such a radical cam that this would even possibly be worth the machine shop costs.

[Joseph Upson]

In thinking along these lines, I have to ask. What is the benefit?

Is that to suggest roller rockers, roller cams, and ball bearing turbos are an enigma because there is no apparent benefit over the previous designs they replace?

Is it true that shell bearings can handle more rpm than ball bearings, given that most high rpm electric motors use some form of roller bearing as opposed to a friction bearing? (I really don't know), and if they can does it really matter in a gasoline engine which would not spin at a high enough rpm for it to be an issue.

Block work to accomodate such a modification was an option not necessarily a requirement. Bearings can be made to have housings clamped into place in the same manner the current bearings are. The most likely machine work would be align boring the mains to a large enough bore to accomodate the proper size bearing. Align boring and main cap upgrades are already being done as routine block work so that doesn't make it an expensive quest.

This is just an idea that I'm very confident we will see some version of at some point. The cost to produce an experimental engine may pale in comparison to the potential benefit that can result. Let's say it takes $2k to produce the test motor and it works fine and produces a fuel economy increase of 12% (mind you it takes a lot of energy to turn that oil pump at current pressures). Gas prices are going to be $5 before the end of the year, if I could add 6 mpg hwy to my fuel economy it would be worth it.

And as far as cost goes, I bet it would be a lot less labor and investment intensive as developing the variable valve timing in a DOHC motor that's for sure from a production stand point.

You may think that's a stretch at first but to me it's about like carbuerator vs. fuel injection.

You may frown on the idea now, but some years from now when you are sitting behind one of my 50 mpg gas powered 300 hp V6 engines, write a letter to the company referencing this thread and I'll invite you to the plant for a "How It's Made" walk through.

Be easy guys.

[onefastV6]

I was honestly thinking about the same thing the other day.... when I was researching bearings for a project that I am working on. (Re-designing the shaft on a RSM supercharger)

There are a lot of things that manufacturers need to improve on ....engine design is one area that could stand further innovation and development. Weight is another area, I got into a debate with my dad on fathers day regarding the weight of cars. In his case he has a 07 Mazda 6 in which the owners manual states it weights 4200 lbs! Engine improvements along with lighter vehicles would go along way in increasing fuel economy.

[Joseph Upson]

I was honestly thinking about the same thing the other day.... when I was researching bearings for a project that I am working on. (Re-designing the shaft on a RSM supercharger)

There are a lot of things that manufacturers need to improve on ....engine design is one area that could stand further innovation and development. Weight is another area, I got into a debate with my dad on fathers day regarding the weight of cars. In his case he has a 07 Mazda 6 in which the owners manual states it weights 4200 lbs! Engine improvements along with lighter vehicles would go along way in increasing fuel economy.

Precisely my sentiments, unfortunately us Americans are "hoggs" and have the gall to point the finger at places like China for their effect on the cost of fuel as if they shouldn't be entitled to live in the wasteful manner that we do.

There's very little sensibility going into cars except for what the resent turn of events involving gas prices has brought about. It's all about squeezing as much attention grabbing garbage as you can into a rolling platform in hopes to sell the most. You really don't need a television screen to help you back-up or an automated system to do it for you among other things. I'm not going to tell you what I think about what to me is a 10 cylinder short bus masquerading as a family vehicle under the name Excursion, that probably chews up about $30 in gas a day in average commuting distance. Of course there are not many, but the ones I've seen were not being used in the capacity their size would dictate.

To each his own, but to all who own anything like it and uses it in the capacity of the typical passenger car (one or two people driving to work) I don't want to hear you whine about fuel costs.

$8 per gallon gas prices will restore much of the practicallity in driving from point A to point B because unlike Europe who's been in that range for years, increasing fuel costs is hitting us hot and heavy fast and we can't afford it because the financial increase is going across the board, not just sticking to gasoline, we are paying much more everywhere and pretty soon the crime rate is going to soar in response to it!

[bszopi]

And its only going to get worse, across the board, with the floods in Iowa affecting the corn this year. But that's OT...

[ForcedFirebird]

Precisely my sentiments, unfortunately us Americans are "hoggs" and have the gall to point the finger at places like China for their effect on the cost of fuel as if they shouldn't be entitled to live in the wasteful manner that we do.

There's very little sensibility going into cars except for what the resent turn of events involving gas prices has brought about. It's all about squeezing as much attention grabbing garbage as you can into a rolling platform in hopes to sell the most. You really don't need a television screen to help you back-up or an automated system to do it for you among other things. I'm not going to tell you what I think about what to me is a 10 cylinder short bus masquerading as a family vehicle under the name Excursion, that probably chews up about $30 in gas a day in average commuting distance. Of course there are not many, but the ones I've seen were not being used in the capacity their size would dictate.

To each his own, but to all who own anything like it and uses it in the capacity of the typical passenger car (one or two people driving to work) I don't want to hear you whine about fuel costs.

$8 per gallon gas prices will restore much of the practicallity in driving from point A to point B because unlike Europe who's been in that range for years, increasing fuel costs is hitting us hot and heavy fast and we can't afford it because the financial increase is going across the board, not just sticking to gasoline, we are paying much more everywhere and pretty soon the crime rate is going to soar in response to it!

I hate to get political, but WHOA, wait a second...

Before you bash someone for driving a high-consumtion vehicle, step back and think for one second and tell me what vehicle can carry a faimily of my size with provision for more than a few hours.

How do you think I feel being on the other side of the coin, and the days of a station wagon big enough to fit nine are long gone? My Excursion has been in my family for two years and has seen less than 10,000 miles and I do feel your anger towards a mother of one driving a vehicle with almost single digit per gallon mileage while she heads down to the next county to get the best deal on shopping - but America has all but fogoten that we are a family-oriented country and that it's really a bleesing to have children - all the while they are punishing the avg income families because we work and pay uor bills while the non-working families (I should say non-ambitious) get government help. My wife had to have emergency cancer surgery in fear of death, and her being the primary financial responsibility we couldn't even have this state help us with chidrens' medical bills during that time because we were "financially capable", all the whilst our house was on the verge of forclosure due to 1/2 the income vanishing.


Back to topic...

After much thought and talking with my machenery mentor needle bearnings would not take the abuse due to the "dominoe" effect where if there was the slightest damage to one of the rollers, would cause catastrophic results, whereas the clam bearing might be merely scratched.

The possability of using a true ball-bearing on a cam would not be cost-inaffective, but trying to impliment ball bearings into a cank or rods would prove difficult after rebuilding the spindle on a 5hp CNC machine - I couldn't imagine the bearings in the lathe capable of handling 21" material 36" long with a 35hp machine.

Cam bearings in a roller form would be interesting

[ForcedFirebird]

/rant, sorry, I'm just as upset that I can't afford to go and see family even - plane tickets for 6, or 11mpg. I guess mom is going to have to wait to see my children. Pumps stop at $75