Wartsila L32 Camshaft Drive Backlash

[Redroof]

Hi all, hoping someone knows more than me!
Looking for a half decent description of how to carry out the camshaft drive gear backlash measurements on a Wartsila W7L32 Engine.
The manual has no description or explanation at all, just mentions that it should be done and gives tolerances.
I have even asked a service engineer contact and he said just put the dial gauge on and use a suitable lever...... and that's it.
Any other engine (MANs, MaKs, Daihatsus, B&Ws, Holeby) it's been a piece of cake and simply feeler gauges. I feel a bit daft as a C/E asking this, so feel free to ridicule etc, I just want to do it right!

Cheers all

[Merlyn]

When you say " backlash " I take it you are referring to the gear train backlash in the teeth and not, as the Service engineer thinks camshaft end float using a pinch bar and a clock gauge? You haven't perchance got one of those anti chatter arrangements on the front end of the camshaft with two independent straight cut ( spur ) not helical gears with one spring arrangement fitted? Seem to remember Wartsila experimenting with this set up as for some reason they thought perhaps the gear train backlash was causing too much noise? Bit weird I thought.

[Redroof]

Cheers Merlyn, nope end float is taken already using the method you mentioned.
Don't have the spring set up you mention, sounds like the mechanical overspeed set up on a Bergen KRG though..... There is no vibration damper on the 7 cylinder engines apparently the 7 units makes it considerably less shakey than any other configuration!
Just plain old gear train backlash.
I've had a pinch bar in and a clock on the teeth but cannot get anywhere near the tolerances of 0.25 - 0.55mm, I can only find 0.15mm ish on all 6 of the engines! They cant all be incorrect, so it has to be me and my method!
Cheers!

[Merlyn]

I have to transport myself back to the early sixties here when we were shown how to cut gears using a horizontal milling machine and a dividing head. I can remember it well, I have learnt in life that things I am interested in stick, and other stuff just falls away over the side, the only way of learning the latter would be the old parrot fashion method. So as I remember your engines have timing gear camshaft Spur gears cut, ie straight teeth as opposed to Helical. I allways found it easier to measure backlash in Spur cut gears as you don't have such a large surface contact area to measure as in the case of Helical cut gears. Now we have to remember the meshing arrangements and surface contact areas coming into play when the gears turn. To start with we have to remember that backlash measurements in spur cut gear trains are to be taken ONLY at the PCD ( pitch circle diameter ) point of the tooth. This is the clearance between the two " kissing " gears and is located approx. between the Addendum and the Dedendun point of the teeth which is about halfway up the tooth. As in the case of setting up pre loaded/engaged teeth we can use engineers blue to show exactly the surface contact area between the teeth. However we have to remember that the two teeth in contact with each other at TDC with inlet / exhaust valves rocking will not be the same two when the crank is rotated 360 degrees. Using CNC milling today and much closer limits being attained theoretically the backlash measurement should be the same at any given point of the crank turn and of course the camshaft or idler gear running at half speed. So utilising a hand who rolls his own baccy out with his fag papers and into the PCD exact point and hand crank over the engine. Well, that's what we were taught but obviously it is the principle used. Out with your micrometer, find a stiff bit of cardboard a few thous . wider than your top limit and off you go. Make sure you are not going on holiday that night though as all the combinations of teeth contact surface areas degree wise are many and will possibly take that long that should you be using a rechargeable inspection light you may well be in darkness before you finish the job if you intend to do them all. Perhaps Warsila might say to do only a few spaced out ones degree wise but I really don't know about that one, but it's the old story, if you want to know all the clearances then you must do them all.
Can't really see how you can use a clockgauge on the backlash test though as you need to measure, as I said before the gap twixt the teeth. Should you use the feeler gauge method be sure to measure on the Pitch Circle Diameter line only, it where the Addendum joins the Dedendum on the tooth. Best of luck if you are to do all seven dwarfs, I should be most interested how long the First one takes you to do versus the Seventh one? Don't know what the book time is to do not just one turn but at least four turns. Never worked out if you tippexed one tooth how many other teeth you would come into contact in during several revolutions? If you get bored let me know so I can file the info for maybe future use age. Be interested in the outcome.

[JK]

http://www.akustinenseura.fi/wp-content/uploads/2013/08/Gao.pdf

courtesy of Merlyn

[Merlyn]

Giving the matter further thought, ( as you do ) and thinking back over the years another method of measuring gear train back lash has sprung to mind. I will call it the MMM System ( Merls Magical Measurement System ) for I have never seen or heard of it being done before, however with care and utilising ( for me anyway ) the 1960's era technology concerning the taking of leads I feel it could maybe prove successful.
For those of you not overfamiliar with this subject I will attempt to explain as follows.
Should you not have any rolls of bearing leads then some 80/40 % electrical solder will suffice. ( 80% lead and 40% tin content )
Be sure you Mike up the OD of the solder to ensure it is slightly over the top limit stated.
Timing case cover off and degrease all gears, using maybe Mr Loctite glue carefully cut lengths off the roll equating to teeth width. Carefully attach the cut lengths of the solder to the exact PCD circumference diameter on all exposed teeth to run from the front of the teeth to the back face. Scribe the PCD onto the gear face with a pair of dividers.
Taking one of the Wartsila engines on this model I refer to we have a crank drive gear of 54 teeth driving an intermediate gear of 54 teeth whose other end has 29 teeth ( all cut from one parent metal ) which then drives the cam gear of 58 teeth.
Now we have already got a large no of teeth from which to take measurements from and in order to ensure no teeth are to be left out we have to ensure many turns of the crank are carried out.
Taking perhaps a photo of the end elevation of all the timing gear and we can then cut and make up out of stiff cardboard copies of each gear and teeth to ensure that when we place each and every bearing lead on it we have the correct setup displayed, it as per the timing gear, we can make use of any timing gear marks as a reference start point.
Applying Mr Loctite glue to the exact PCD diameter attach each and every lead across each and every tooth and fuel shut off wind the engine over slowly to obtain the maximum no of teeth readings.
Marking the teeth not done apply Mr Locktite Let Go Fluid and carefully detach every lead and place apon the cardboard cutouts you have made up making sure you duplicate each and every tooth, as per the engine.
Winding the engine over to expose all teeth you have not done repeat the process.
Now having superimposed all your cardboard cutouts with your leads out with your micrometer and start the long process of evaluating your resultsand carefully recording same.
Lot of work, I normally only do timing gears when doing piston liner/ crank grind overhauls although I do note the pitting and spalling present and damage to the gears shown on my previous write up caused possibly by the additional spring loaded gear forced against the other gear it's driving reducing at least the necessary oil clearance gap.
This reminds me of a demonstration by Wynns Oil Additives some 35 years ago, one roller bearing ( just one roller, no tracks ) detached from a large gas turbine rotor bearing in a jig, held by a counterbalance weight and driven by an electric motor. A few turns with engine oil splash lubed against it and Lo and behold, it's just like you held it against a grinding wheel and a big flat appears on the face up against the grinder.
Out of the jig with the bearing roller, in with another one, on with Mr Wynns and rev her up and 20 minutes later hey presto, no flat present!
That poor old timing gear shown on my last posting clearly shows that by being forced against the other tooth with no room for lub oil clearly shows how aged the gear has become before its time.
So TTTT for now, off to file for my patent in case someone else steals my idea.
In conclusion allways remember what your dear old Mum taught you " The Old Songs Are The Best " ie in this case The Taking Of The Leads Lives Forever. "
PS Don't forget to get the correct handed bearing lead substitute when purchasing , ( rotation wise that is )