How to grease Main Gear Thrust Bearing?

[Paul462]

Help, Everybody!


The Service Manual for our 1968 C337C calls for greasing the main gear thrust bearings every 500 hours. It's that time (first time for us), so we looked for the grease fitting. NO SUCH LUCK! (no grease fitting - drat). Our Service Manual calls for disconnecting and inspecting the universals, disconnecting and re-positioning the hydraulic actuator, and then SLIDING the forged saddle off the shaft (after removing two through bolts), as illustrated in vivid black and white in Fig. 44.

We removed the two through bolts and gently attempted to slide the saddle off the shaft - no joy. Rapping smartly with a brass hammer (as opposed to rapping stupidly with same) didn't work, nor did copious amounts of WD40 and heating the saddle with a heat gun, all followed by more intelligent rapping with the brass hammer - the saddle won't budge.

So the question: has anybody run across this conundrum when it's time to grease the main gear thrust bearings, and how do we get these consarned saddles off their respective shafts?

Thanks!

Paul Rooy

[Paul Sharp]

Haven't seen a post go this long here with no input that I can remember. I guess nobody has messed with that bearing yet or the right people just haven't read it for some reason.

[Paul462]

Really! 128 views, no words of enlightenment.

For everyone's info, we talked with Cessna and also CPA's Tom Carr. Cessna's attitude was basically "You want to take the saddles off the shafts to grease the thust bearings?! What do you wanna go do that for? You sure you want to do that?" Cessna offered no method to remove the saddles from the shafts.

Tom Carr says the feedback he gets from the field is that people seem to be dripping straight 50 weight oil into the bearing during annuals without doing any disassembly - grease is too thick to flow in, and apparently some engine oil is better than nothing.

We tried heating the saddles with a heat gun, while simultaneously cooling the shafts with bags of ice - no joy.

We ended up spending probably 35 - 40 man hours unbolting and re-bolting the hydraulic actuator (which required removing the mains, unbolting the universals from the actuator, disconnecting the hydraulic supply lines, and dealing with the Mekano set from hell which held in the actuator in place, featuring several virtually inaccessible nuts and bolts close to the belly of the plane), and ended up dripping in Aeroshell 100, which made the bearings sound less dry. Live and learn! I must say it was easy to check the tire pressures with the mains removed from the plane...

Paul Rooy

[Paul Sharp]

What a story! Very interesting, and at lest perhaps your experience will help others know about this item.