Need Instructions to take apart Tail Rotor Transmission

[lperagallo]

When I had a bad auto and a boom strike, the tail shaft sheared off at the outside bearing. I have a new shaft with gear and need to know how to take it apart so I can put in the new gear and shaft. The gear looks fine, but the shaft came with the gear already mounted. Also what is the procedure to set the gear back lash?

Help is appreciated

[cbergen]

Let's see if I can do this without pics, later I'll post it similar to the tail setup.

First off remove the gearbox from the boom and disconnect the arrow shaft from the input shaft of the gear box.

In the body of the gearbox, the cylindrical portion that fits inside the tail boom, you will find three holes. 2 of them are for the bolts that secure the gearbox to the boom. The third has a setscrew in it. Remove this setscrew.

Now slide the whole input shaft w/ gear "forward", disengaging the gears.

Now remove the silver phillips head screw that is used to retain the right hand output shaft bearing. You should now be able to push the whole output shaft assy to the right, pushing the gear out of the large diameter bearing on the left. This may take some pressing, alternatively you can give it light taps on the gear itself, being careful not to damage the bearing.

This will now also push the right hand smaller bearing out of the cage. Remove this bearing from the shaft, and the brass tubing along with it. You can now remove the gear and shaft out of the cage.

With the output shaft out of the way, you can now look into the end of the input shaft. The end with the gear on it. There you will find another setscrew. Remove it.

By sliding the input shaft rearward, you can now access the gear retaining pin, push it out with your 1.5mm allen driver.

You can now remove the input gear from the shaft.

Install your replacement gear, lining up the holes for the retaining pin, using your 1.5mm driver to help line things up. Install the retaining pin, making sure to center it in the assy, in other words, it should be slightly below flush on both sides.

Install the setscrew in the end of the shaft, with loctite, seating it against the retaining pin. Slide the whole input shaft assy w/ gear fwd, out of the way.

If removed, install the large diameter bearing into the left side of the gearbox, with the flange to the inside. Now angle the new shaft, w/ gear installed, into the left side bearing bore, then back the gear into the large diameter bearing. Kinda like parallell parking!!

Install the brass tube onto the shaft, then the left side bearing, pressing it into the cage. You may need a deep well socket, sized the same as the outer race of the bearing, to help push the bearing into the gearbox.

Reinstall the phillips head screw, using loctite.

Set the gear mesh by pushing the input shaft assy to the rear until the gears engage, setting minimal backlash, while still able to spin freely.

Reinstall the sescrew in the body of the gear box, in the cylindrical portion that fits into the tail boom, using loctite, to secure the input shaft in place.

Be careful not to overtighten (Gorilla torque, and it really takes some force, but have seen it done!!) and crush the inner tube spacer between the bearings.

Complete assy as instructed in the manual.

HTH,

[Malorie]

Sorry for the link to THAT PLACE ;)

Here you go...
http://www.runryder.com/helicopter/gallery/2555/TR_Gearbox.html

Click on "Markup" on the left, click on Step One or Step Two in the left window, then click on the "Zoom Fit" icon at the top.

Malorie

[lperagallo]

Chris and Malorie,
Thanks for the details. It reads and looks as though it's easy once you do it te first time.
Lou