Caterpillar 12 8T circle reverse

Hi, D2 Cody.
From what you have posted, it seems to that the problem is inside the control box, probably with either the dog clutch or the drive gear but possibly the control fork for the front dog clutch. If memory serves me rightly, early models of Cat 12s had both dog clutches on one gear controlled by one fork while late models had separate dog clutches for the front and rear gear trains with separate forks for each dog clutch. I don't know when the changeover was.

BTW, that circle reverse control drive shaft also carries the gears that distribute the incoming power from the vertical power shaft to the rest of the gear train in the control box. If you have to get it out, you will need to remove the universal yoke in front of the cab and also take out the half-moon key after you have removed the yoke.

I would suggest starting by draining the oil from the control box and removing the front cover so that you can inspect the 'innards' to see what is the problem. The dog clutch control fork would be the easiest fix. There is nothing really frightening in there. You just need to look carefully at it and 'figger' it out. The correct parts manual can help heaps. If you have that, you will be ahead of where I was any time I ever had to go into a control box.

Just my 0.02.

Takes a s/n to get the right answers.

Serial is 8T15616

There aren't any shear pins in the control tower other the on the tower main drive shaft. Seems you have a control problem. Controls for that s/n came in the original version or field installed option.

Hi, Old Magnet.
To the rescue - AGAIN. Thank you, Sir.

Hi, D2 Cody.
In O.M.'s first image, you can see that the gear at the front of the control box - nearest the levers - only has one set of teeth while the gear shown at the back of the box has 2 sets of teeth, a straight set and a bevelled set. Because of the detail of the cutaway, these 2 gears are shown on different shafts in the diagram.

Under that bevelled gear, you can see another bevelled gear laying horizontal in the bottom of the control box. That gear is on the top end of the vertical power shaft coming into the control box. The shear pin that Old Magnet mentioned is at the bottom of that shaft inside a swinging door flap between the operator's feet. That is not your current problem by the what you describe.

If you still have all other functions on the 'push away' side of the control box, the best bet I can think of is a problem with the dog clutch or the engaging mechanism on that control shaft. I can't see that your are going to be able to fix it without going into the control box itself. As I said earlier, don't be frightened of it. Take your time and observe it all to see what makes it tick and you will likely have no problems.

Just my 0.02.

[attachment=40267]0217171113a.jpg[/attachment]
Hopefully pic shows up this is my first time. This is the shear pin at bottom of shaft running up into box. My question is does it look like the bottom piece where the bolt comes into from the top is broke in two

Pic showed up but is up side down

Yes, picture is upside down and it looks like the ear that receives the shear pin is broken/split.
Going to need to replace or repair coupling assy. 8B3010

Hi old magnet,
Boy I'm sure glad you are a member of this forum Thank you so much for all the help over the years. Do you know what a guy does about this problem. Also could that be the reason the blade will circle right then go a little bit left then just make the lever chatter and not do anything? Also it looks like a bearing is out because there is a bearing that is sliding up and down on the shaft above the shear pin.