How does a Case 450 drivetrain work?

Hello,

My dad has a Case 450 crawler front end loader. Sometimes when you first start it, it takes a while for the torque converter pressure to get high enough to move.

I was just wondering if someone could explain in simple terms how the drive train of one of these crawlers work? There is a cylinder hydraulic pump and a drive-train hydraulic pump right? Also, is the torque converter like a hydraulic-powered motor, or something else? It appears that the control levers are just hydraulic spool valves that engage different hydraulic clutches for high/low forward/reverse. But I don't really understand what the torque converter and hydraulic pump do? In an automatic car there isn't a hydraulic pump for the torque converter right? I found a diagram online that appears similar to how the Case 450 works and included it below.

Thanks,
-Hunter

The torque converter moves power from the engine to the input of the transmission. While doing this it can allow several things to happen, the engine can continue to turn while the machine is stopped and in gear. It also can transfer power while allowing the engine and transmission input to operate at different speeds, it can increase torque while doing this by letting the engine rpm raise into a higher torque band. It also acts as a cushion during gear changes. I am sure there are other attributes I am missing but those are the main things. The attached video of how a torque converter works explains its internal workings much better then I can. To simplify it even more say your dad has a 5 gallon bucket half full of water, he is the engine connected to the impeller as described in the video. You have a empty 5 gallon bucket, you are the turbine and you connect to the transmission input as described. Your dad is going to throw the water out of his bucket as if he was going to put out a fire. You are going to catch the water in your bucket. As the water hits the inside of the bucket the force you feel of the bucket trying to go behind you is the essential method of transmission of power through the torque converter. We have to disregard the fact that gravity is adding forces in my example. Also I will mention now the explanation of a lockup clutch does not apply in your application. Yes an auto trans in a car also has a hydraulic pump or fluid pump if that makes it less confusing. In the car trans it has the same purpose as in your dozer trans. The pump is needed to fill the converter with fluid. It also circulates fluid through the converter for cooling. It also circulates fluid for lubrication. It also provides pressurized fluid to operate hydraulically applied clutches as directed by the shift control valves. In the second linked video of ..how a power-shift works.. the explanation of the trans starts at 3:50 and right at 5 min there is an animation of a clutch pack application. One thing that can happen to a torque converter that may be a cause of your problem is the following. Once the torque converter has run it is filled with oil. Somewhere in the system there is generally a one-way check valve that will not allow the fluid to drain out when the machine is shut off. So that when you restart and put it in gear there is no delay while the converter is refilling. Maybe someone will chime in if this is a common problem for this machine. Have you changed filters or fluid on it? If you want to do any diagnosis on your machine I strongly suggest you get a service manual for it. This site sells hard copies. A more economical way would be a PDF version, look at a site called Farm Manuals Fast. Just a word of caution, if you find a site offering free download of a manual be very leery, virus dumpers like to pose as such sites.
How a torque converter works

Power shift trans

. The answer to all your burning questions can be yours for less than 100$ these are reprints of the factory manual
Case 450 manuals

Thanks so much, that makes sense. I think this part of the diagram is what was confusing me. I thought the hydraulic pump was turning the impeller in the torque converter, kind of like a hydraulic powered motor. But what you are saying is that the hydraulic pump just fills the torque converter with oil, and circulates cool oil through it. The engine driving one half of the torque converter impeller is what makes the output of the torque converter spin, not the hydraulic pump.

I think what confused me is that on a crawler like this the hydraulic pump is physically separate from the torque converter. I guess in an automatic transmission car the torque converter is a sealed unit, and not fluid is pumped through it.

I assume this is because the cooling requirements for a crawler are a lot more demanding than for an automatic transmission in a car, so the fluid in the torque converter needs to be pumped through an oil cooler by the hydraulic pump.

Oh grasshopper, you have failed to glean all knowledge provided. You missed my sentence talking about the ..fluid pump.. that said .. In the car trans it has the same purpose as in your dozer trans.. So in all cases save a minimal few a fluid drive torque converter has fluid circulating through it for cooling. In the attached photo it is showing the part of a GM Turbo Hydromatic 3 speed automatic transmission which was a very common transmission used from the late 60s through the mid 80s. The part shown is where the torque converter mounts. The hole shown in the shaft is how the oil is pumped into the converter. Yes, the cooling required for an automobile torque converter is way less then needed for your dozer but still needed. The auto trans in these newer diesel pickups you see towing fairly large loads on 3 axle trailers are basically the same configuration as a rear wheel drive car. I think you would agree that there is some heat generation going on there. For the oldsters on here the one example of a fluid torque converter that did not have fluid circulation was from back when the traveling carnivals came to town. Specifically remember the tilt-o-whirl ride being powered by an Allis 4 cylinder power unit. In the drive train was a sealed torque converter. Also, Hunter the ..grasshopper.. opening to this reply was a line from the Kung Fu TV series from the early 70s. Yes, my age is starting to show.

Haha, thanks I have learned a lot. So autos still have a hydraulic fluid pump, it just isn't pumped in the side of the torque converter like with the crawler.

So low torque converter pressure could cause it not to move in two ways. Either the torque converter doesn't have enough fluid and can't transfer the torque, or there isn't enough pressure to engage the friction clutches in the power shifter (which seems more likely to me). I guess if it isn't moving but the output shaft of the torque converter is spinning than it is definitely the clutches not engaging.

Well, this grasshopper has learned a few things for sure.

So not to mislead you, I have never worked on the machine you have nor am I familiar with how it is assembled. Since I am now getting in this conversation over my head I just looked at some online parts diagrams for it. I see it is a bit different because it looks like the torque converter is a separate unit from the transmission. It looks like there may be a driveshaft in between the converter and the trans. When put it in gear you say you could see the converter output turning but the machine was not moving, in most cases being able to see that is impossible because that shaft would be completely enclosed. That would indicate as you said the problem is in the transmission and not the converter. So in this case the actual hydraulic pump that runs the blade cylinders may also provide hydraulic flow for the shifting in the transmission. Because in this case when the machine is working properly while it is stopped and in a gear the for mentioned driveshaft will be stopped and the converter in ..stall.. So if nothing is turning in the trans it cannot turn a pump to provide hydraulic flow. I am providing a link to parts diagram. This is an alternative parts site to the official CNHI site which is apparently receiving a huge update so it seems to be a little uncooperative. The name of the parts site is avspare, just beware of the adds they like to sneak in. Here is a copy paste of more instructions for using it.. To view more parts sections of your machine go to the small blue print at the top that shows the model you are searching usually by number 4. If you click that it opens the unit parts section just as if you searched for your model in the CNHI page. The diagrams may be fuzzy but if you click them they open like a photo and are clearer. In the part description if you click on the part number it will open up the application list for it. There are a lot of adds on it so beware of those. I also have never tried to buy parts through that site, if you go that way I have found they ask you to email for a quote. That makes me apprehensive.
If you are going to do more diagnosis to this machine or try to repair it, the manuals are a must have. Also if you have more direct questions when you get into it there is a ..Crawler and Dozer.. topic section here as well.
Alternate parts diagrams

I believe you will find the torque converter/transmission charge pump is located on the rear right side of the engine front cover and driven off the timing gears.

As SVcummins suggested you need a set of manuals which will have info on how the system works and diagnostic checks to help pinpoint your problem.

This post was edited by Jim.ME on 03/04/2022 at 02:18 pm.

you more then likely have a hole in your charge pump suction line it runs along the right side frame rail it's a steel pipe and it lays in the dirt and they like to rust out or a stone will rub hole in it i have changed both of mine out with rubber hyd. hose just left the old line in place ran new one along side NOT fun you must drop crash pans on the under side they are heavy because they will be full of dirt