Komatsu WA700 park

Our Komatsu WA700 is loosing too much brake oil. Checked Front and Rear differentials and found them overfill. The park brake pressure switch is also broken and leaking. My question is does the park brake chamber use hydraulic oil or brake oil because they have different tanks. Hydraulic oil tank is not getting low, its only the brake oil tank getting low.
I just want to eliminate all other factors before I pont to the brake oil leaking into the axle oils.

I've never worked on a WA700, but have plenty experience on WA600 machines. A serial number or at least a Dash number on the machine would help narrow down what you have.
If the machine is set up like a WA600, the park brake set up on the WA600 was air operated. The service brakes were air over hydraulic and there are two reservoirs under the left side ladder to the cab of the machine. One booster and reservoir for each axle. There was a pin in each air can with a physical switch that served as an over stroke indicator which set the alarm in the cab when the system ran out of fluid. The brakes used regular hydraulic oil and not brake fluid. If the brake oil is filling the axles, then the piston seals are leaking and you will have to pull tires and final drives to get to the brake parts. The brake chambers and finals can come off as one piece if you have the little brackets that hold the two components together. If you do that job there are three releasing spring brackets that force the disks and frictions apart when the brakes are released. Make sure and replace those as the brakes will chatter when the springs are broken.

if you say its got brake oil tanks its a -1
as i recall the park brake is hyd controlled with no way for oil to transfer as its a pinion brake on the f/a.

The serial number for this WA 700 machine is 50037. It is using too much brake oil. We are suspecting that it is pushing brake oil into the differentials because we found them over full. It has got an oil leak on the park brake pressure switch. We are not too sure what oil circuit does the park brake operate with. We are just trying to eliminate all other brake oil external leaks.

With that serial number it is likely a Dash 3 build between 2000 and 2003. I would guess the park brake operates from the hydraulic system with a solenoid controlled open/close valve. It appears that you don't have a service manual for the machine?

Last year my 450-3 front brakes where doing the same thing. Just a heads up, if you have Komastu (Modern Machinery here) do it, be ready to have some sticker shock.