Removing RPM Gearbox Flange bolt and Drive Flange

[stress]

RPM Gearboxes use Loctite 640 Sleeve Retaining Compound on the drive flange bolts and on the splines on the drive flanges. This stuff is many times stronger than Red Loctite. Loctite 640 works up to 400 F. This is strong enough to cause the drive flange bolt to brake during removal. It is best to use heat when removing the drive flange bolt.

What worked best for me when removing the drive flange bolt is to heat the bolt with a oxy-acetylene torch with a small tip, so the bolt head is a mild red color and spin the bolt out fast. After 30 seconds the Loctite 640 starts getting hard again. When the bolt head is mild red color the bolt threads are at a lower temperature and the gearbox drive shaft acts as a heat sink drawing heat off the bolt.

I used new bolts when I put it back together.

Loctite® Sleeve Retainer 640™ is a high temperature anaerobic adhesive that secures slip and press fit assemblies. Adds up to 3,000 psi holding power. Restores fit to worn or out-of-tolerance assemblies. Prevents surface corrosion. Works to 400°F. Mil Spec: Mil-S-46082B Type II. ASTM-D5363: Group 4 Class 1 Grade 2.
Loctite® Sleeve Retainer 640™ - Henkel

Locite 640 technical Data Sheet
http://www.all-spec.com/downloads/lo...31_120209s.pdf

[stress]

The way I removed the drive flange from the gearbox was to put a gear puller on the flange and put a tension load on the flange. I used my oxy-acetylene torch with a small tip to heat the drive flange around where drive shaft and drive flange where they set on each other. When the flange started sliding off the drive shaft I tighten the gear puller more until the the flange stop moving. When the flange stop moving I heated the flange some more and repeated the process.

You will need to replace the gearbox seals after this. The seals can be replaced with out taking the gearbox apart.

[K-fab]

Great post. I've bent more than a couple puller plates trying to get them off the stubs.

[stress]

To replace seal pull the sleeve out that sets on the drive shaft

[stress]

next remove seal with screwdriver. In the picture I have my took apart my gearbox for other reasons. If the gearbox was still assembled I could have put a screwdriver between the drive shaft and seal and pop it out

[yoshi]

I've had to remove them quite a few times. I lay the box on it's side, then I put a thick round piece of steel over the bolt, usually 3/4" in diameter and 5/16" or thicker (depending on what slugs I have sitting around as drops from the cnc plasma), then I take the tig, and with no wire just heat the middle. It does not try to burn a hole through it, it just puddles the middle a little on the surface and gets stupid red hot.

It takes seconds to get the slug cherry red.

I give it a few more seconds to transfer the heat to the bolt, use pliers to grab the slug real quick then it breaks right loose.