enginehistory.org

[kmccutcheon]

Anybody know what an oil skate is? We keep seeing this term in P&W recip manuals, and speculate it refers to gear thrust surfaces. A picture would be great.
_________________
Kimble D. McCutcheon

[rwahlgren]

Here is a use of the term
From a manual.

6-66. OIL SKATES.
All oil skates shall have the outer contact edges rounded to a minimum
0.020 inch radius to assure oil feeding action. The triangle point of the oil skate shall not protruded past the mating surface, as oil spillage will occur and excessive oil flow could result.

[kmccutcheon]

But have you found any PICTURES of an oil skate?
_________________
Kimble D. McCutcheon

[rwahlgren]

I have been looking.

Here is this usage of it.
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http://www.enginehistory.org/Piston/P&W/R-4360/r-4360_service.shtml
#3 line
Item lll
Front Main Bearing Lubrication — planetary magneto drive oil feed passage increased from 0.030 inch to 0.060 inch, metering oil jet to front cam removed, pressure oil skates incorporated in the planetary magneto drive gear, front main bearing removed and re-lead indium plate at each overhaul.

[rwahlgren]

Found it.

From Technical Order T.O. 2R-R4360-53 ---
6-66. OIL SKATES. All oil skates shall have the outer contact edge rounded to a minimum 0.020 inch radius to assure oil feeding action. The triangle point of the oil skate shall not protrude past the mating surface, as oil spillage will occur and excessive oil flow could result.
6-457, MODIFICATION OF MAGNETO PLANETARY GEAR. If not previously accomplished modify the magneto planetary gear, Part No. 203741 and 106096 as follows:
a. Using a suitable universal surface grinder, having an appropriate magnetic work table equipped with suitable grinding wheels and coolant, grind the newly designed oil skates in the thrust face of the magneto planetary gear in accordance with dimensions and locations shown in Figure 6-129.
b. Using a surface grinder equipped with a suitable grind wheel and coolant, grind the michelles on the thrust face of the gear in accordance with dimensions and locations shown in Figure 6-129.

Figure 6-129

It looks like the longer cut out is the main oil skate that runs straight from the center and the short one must be the Michelles cut? Not the best engineering drawing in my opinion. And yes on the thrust face of the magneto planetary gear.

Its saying the cut should not break through the face of the gear at the radius point at the bottom of the drawing, the drawing shows the .020 radius around the edge, that is almost impossible to accomplish in the old days of no CNC. It must have been hand worked.

I spent a bit of time hunting for this.


Edit (12-6-2020 10:57 pm Pacific time)
Part number 203741 Replaces 106096, Magneto Planetary Drive Gear.

[kmccutcheon]

Great job tracking this all down, Bob. I think we've all learned something.
_________________
Kimble D. McCutcheon

[rwahlgren]

Kim, did you get the pictures I emailed? Not sure if it worked.

Also notice the manual says (modification of magneto planetary gear)
That maybe misleading, though I haven't checked the part numbers given.
The drawing and other information is saying the magneto planetary DRIVE gear is to have the oil skates.
It would be nice to have the photos posted here.
Notice the dotted line on the drawing for the michelles cut that would be established by the grinding wheel diameter, the info says use a surface grinder with a suitable grinding wheel and coolant. This is typical of many
aircraft parts drawings and especially in the old days, helps increase the cost and time to machine parts. The lack of dimensions that have to be calculated.

[admin02]

[avasko]

Oil skates? Granted I had little contact with the big Wasp Major. It would appear that "oil skates" were a design feature beloved by them. Fortunately, they kept them inside the engine.

The only way I saw the internals of an engine (except in school), was through the hole in the case when we changed a cylinder. Oh yes, when I was a Lead Mechanic of a crew involved in the conversion of ex-UAL Stratocruisers from Curtiss Electrics to Ham Standards. We did remove a couple of nose cases for shipment to Pratt for modification and installation of oil feeds to the prop. When exposed, the internals were full of lots of oily gears and maybe an oil skate or two.

Did work on changing a couple of nose cases on Wright TC-18 engines, but only removal. That's easy but oily. Disconnect stuff, remove fasteners and it just falls off. Hard part is putting it back on.

I was able, when a Director for EAL, to tour the huge engine shop had built. Of course, it was all turbines by then, but EAL did everything including plating which was scary. I would not want to work around vats of acid, fumes, dissolved heavy metals and lots of amperes of current.

I take my hat off those folks bent over a surface grinder modifying an oil skate. They never got to sit at an FE's panel during a hours-long runup or try to start a stone-cold R-2000.