What's the difference between an HG and OC-3??

[nailcreek]

Hello ... can anyone tell me what the difference between an HG and OC-3 is?  I'm due to come into possession of a crawler which I think is a HG (Blake thinks so as well), but what is the difference between the two?

[John Schwiebert]

I have a friend and they sold quite a few of both. There is very little difference between a LATE HG and the OC-3. In fact a few of the last HG models had the improved OC-3 final drives. Later HG models from in 1950 also have the IXB engine. The font idler is different on the OC-3 but they had a kit to put these parts on an HG. So now you know some things

[John Schwiebert]

One other thing you might check is on the left side of the engine block will be an engine number and a model identification. If it is an IXK it is an HG. Also look behind the mag on the block for a casting date for the year and the month the block was cast.

[pvcarey]

I have one of each, all that I have found is the hg has the front idler that has a rib that rides on the inside of the track chain, the OC3 has flanges that go on the outside of the chain, and some changes in the bearings on the final drive. that is all that I have found.
Ron

[thecatskinner]

The rear sprockets changed from cast to segmented steel as well.
By 1950 the only thing that changed with the official conversion to OC was the decals.
My HG was one of the last built and in all ways but the decal it is an OC.

[Blake Malkamaki]

Nailcreek's picture.