Your 450 Dozer is essentially the same as my 450 Loader. There are two hydraulic "systems" on this beast. The first system deals with hydraulics to the blade cylinders, or what I like to call the accessory hydraulics. The tank for this hydraulic fluid sits behind the seat and is part of the fuel tank assy. Looking at the back of the machine, the dip stick/filler is on top of the tank to your right.
The accessory hydraulics have a filter that is accessable behind a panel on the right hand side next to the seat. Looking at the right side of the machine, the panel panel is opened from the outside. Basically its the compartment opposite of the battery compartment.
The pump for the accessory hydraulics is located in front of the engine right under the radiator. It bolts to a coupling that connects right to the crank.
Now the other hydraulic system runs the drive. The dip stick for this system is located right under the operators seat. Looking at the right side of the engine you will see a large 2" hose that runs from the screen filter assy to the charge pump. The screen filter assy is bolted to the firewall and it contains, you guessed it, a filter screen. The hydraulic fluid is drawn up from the resovoir under the seat, and through this filter. The other end of the big hose goes to the "charge pump" which is located on the engine right under the generator. The charge pump provides pressure to the torque converter.
Marlowe mentioned the final drives. There are two. Looking at the back of the machine you will see them on the left and right just inside the tracks. They are simply gear housings. About halfway up on the back of these housings is a plug where you fill them. Somewhere towards the bottom of the gear housings I think there is a drain. The finals do NOT take hydraulic fluid, they take gear oil just like the rear differential in a car.
Now, what oil do you use? Marlowe is right, use TCH in both hydraulic systems. This is especially important in the drive system. TCH is available from Case. I don't think its the same thing as HyGuard, and its certainly not the same thing as regular hydraulic fluid that you might get from NAPA. My Case dealer sells something I think is called Hy-Tran which is suppossed to be a subsitiute for TCH, however, I've got a really good parts man at my Case dealer who told me that Case was recommending substituting Hy-Tran for TCH but changed their minds. They now recommend TCH again, especially for the drive hydraulics. I ended up with Hy-Tran in the accessory hydraulics and TCH in the drive on my machine.
One leading cause of lack of motive power is either low drive hydraulic fluid or a clogged screen filter. If you have not done so you really should change out all fluids and filters. At the same time crawl underneath and look for weak or mushy hoses that should be replaced. It ain't cheap to do this but its certainly worthwhile as dirty hydraulics will certainly ruin something much more expensive.
If you don't have it, now is a good time to at least get the operators manual for your machine. I have found this book to be pretty good for telling you what you need to do. I also recommend the factory service manual and parts manual. The service manual is pretty expensive (like $150 used and over $200 new). If you are going to do your own routine maintenence I'd recommend the service manual. I think the parts manual is not too pricy and its good at showing you exploded views of how things go together.
Another maintenence item to check is the oil in the front idler wheels. These often go unattended until too late. The front idler wheels will have a little screw plug that you take out to fill them. I believe they take 30 wt. motor oil.
Thats a start. Drop me a line if I can answer any questions for you. The 450 is a great little machine.
1968 Case 450