Mercedes-Benz W165 Grand Prix engine in 1:3 scale

[Vixen]

Thanks Brendon, Per and Dave for calling in. Your encouragement is always welcome.

Like you, Per and Dave, I am also waiting to see how these crankshafts turn out.

I have made a small start. The first opp is to face one side of the crankweb and turn the main bearing journals. The main thin section ball races are used to align the sections of the crankshaft. The main bearings are quite beefy; 20mm diameter.





Stay tuned; there's lots more crankshaft stuff to follow

Mike

[Zephyrin]

Hi,
the installation of all these one-piece connecting rods on the crankshaft does not seem to me a very simple and obvious operation...I await the continuation with impatience!
I always sit comfortably to look at this thread, because I spend a very long time on it...

[kvom]

Does inner race of conrod go over outer race of crank?

[Vixen]

Hi,
the installation of all these one-piece connecting rods on the crankshaft does not seem to me a very simple and obvious operation...I await the continuation with impatience!
I always sit comfortably to look at this thread, because I spend a very long time on it...

Hello Zephyrin and kvom

I am attempting to make the built up crankshaft in a similar way to that of the Auto Union engines, throughout the 1930's  and the way Mercedes Benz turned to with the W196 engine in the 1950's. All these engines used Hirth couplings as can be seen in the attached photo.





Mr Schillings has shown us an easier? alternative, method to the complex Hirth coupling in his well known book, which uses the inner part of a ball race to achieve the required shaft alignment with pegs to transmit the torque.





We shall have to wait and see how well it turns out

Mike

[cnr6400]

Hi Mike, Question - on the journal "tubes" - are these tubes keyed somehow to the crank pin halves? I don't think I'd want to depend on loctite for that job, necessarily. 

[Vixen]

Hello cnr6400,

Sorry for any confusion. It's my fault for using an older, out of date, illustration showing a hardened steel 'tube' at the big end bearings.     Dave (Steamer) helped me with some of the drawing work, a while ago.

The current design uses thin section, roller bearings at both the big end and main bearings. I will be using the big end roller bearing inner to align the big end journals in a similar way to the main bearings. Both will have fitted pins to transfer the torque, rather an Loctite. That should provide the added advantage of allowing the crankshaft to be dismantled should a bearing replacement be required. (I hope that is never required).

The points of contact, shown by the blue circles are critical to the alignment process, while the faces with the red crosses have clearance, so they do not interfere with the alignment process.

Cheers

Mike

[Vixen]

Not much to show for three afternoons of lathe work. All 16 crankshaft discs have completed the first opp, ie. facing and main bearing register, which produced a bucket full of curly blue swarf.





This is how a main bearing looks, when two crank webs are bolted together.





So far; so good

Mike

[cnr6400]

Thanks Mike! sounds great! following along...

[ddmckee54]

I don't remember if you've told us or not, but will there be any type of pressure oiling system in the crankshaft?  Or will everything on the bottom end be splash oiled?

Don

[steamer]

Not much to show for three afternoons of lathe work. All 16 crankshaft discs have completed the first opp, ie. facing and main bearing register, which produced a bucket full of curly blue swarf.





This is how a main bearing looks, when two crank webs are bolted together.





So far; so good

Mike

Mike I know what you mean....a lot of chips for a bunch of hockey pucks!!   the other side of the part doesnt provide anymore satisfaction as they still seem like hockey pucks.....stick with it, eventually you  get to stack them into a crank and it all comes together!!

Dave

[Vixen]

Dave, Don thanks for calling in. It's always good to get questions and feedback.

Don, I described the oil pipework (the snake pit) way back in Reply # 377 and the battery of pressure and scavenge pumps even further back in time, in reply # 191.  Geez, I've been at these engines for a long, long time 

Roller bearings do no not need a high pressure oiling system but the do like a constant flow of oil at low pressure. One of the pump sections, in the pump block, supplies the flow of oil, which is piped to the five main bearing caps. The oil is sprayed into each of the main bearings, the resultant splash then lubricates the big end bearings and the cylinder walls, before being sucked out of the dry sump by the two scavenge suction pumps. The scavenged oil flows through a cooler and back to the oil tank, where it settles and de-airates before returning for another pass through the engine.     Simple really ??????

Only Mercedes Benz could make it that complicated. 



Cheers

Mike

[Hugh Currin]

Mike:

Great progress. You have more patience than I'll ever have.

It sounds like the alignment of the crank depends on these disks, that left and right need to be parallel to the n-th degree. Did you do anything special to assure this parallelism? When I saw the diagrams above about alignment I thought of machining left and right sides in the same set-up. But I couldn't come up with a way to do it. An indicator on the back side would be hard because of the jaws getting in the way. Maybe soft jaws? Can you align the disks (rotation) for the least run-out and keep that orientation? Or are they parallel enough not to worry about this tolerance stack-up? Inquiring minds want to know.

Again a marvelous undertaking. Outstanding skill and patience. Thanks for the write-up.

[Vixen]

Hello Hugh, thanks for calling in.

Yes, maintaining parallelism between both sides of each crank-web is absolutely essential. Like you, I have though up and devised many different ways to try to get both sides truly parallel, most of these ideas have been discarded as not quite feasible for one reason or another.

You ask, What did I eventually decide to do? Hugh, that's a bit like turning to the last chapter of a 'who dun it' novel to find the answer, before reading the book. All will be revealed as I proceed.

However, since you asked, here's the overall plan

In the first opp, one side of each crank-wed and main bearing journal was turned dead square, concentric and true. The first face will be bolted tight against a freshly faced off face plate and hopefully the second face will then also be true and parallel to the first. The rotational positioning will rely on using the crankcase as a jig to align the individual crankshaft sections and test for squirm and run-out before drilling the drive pins. I considered using 'Vee' blocks but believe the line bored crankcase will hold all five the big end bearings in-line, much more securely.

For those who may be interested, you will find more about my adventures with line-boring the crankcase between Reply #294 and Reply #317

Well that's the basic plan. We will have to see how well it stands up to the first encounter with reality.   
There is still a lot to do, so there is still plenty of time for it all to turn into a disaster movie. 

Cheers   

Mike

[Vixen]

Again, not much to show for another couple of days in the shop.

The first photo shows my sacrificial faceplate mounted in the four jaw chuck. The faceplate has been bored 20mm dia to match the main bearing spigot on the crank webs. The face of the faceplate was then given a light skim to ensure it's working surface was true and square with the lathe's axis.





Here you see one of the crank webs bolted to the faceplate using the central bolt, which will eventually be used to build up the whole crankshaft. Then I could do the second opp; which was to turn the outside diameter of each crank web square and true to the big end journals





As I said, not much to show; but here are the 16 crank webs turned and one side faced. Just a bunch of shiny hockey pucks. 





Cheers 

Mike

[Kim]

Looks like a lot of work to me! And they each have to be a different size, just to complicate things.  Nothing can be simple on this engine, eh?   

Kim