Machine is a 1995 Dresser 515C. We purchansed it off of a car dealer that closed. We bought it with 1300 orignal hours. it was used only for snow and its cherry in and out and was garaged When we bought it we changed all fluids and filters. Drained all of the hydraulic oil and cleaned the hydraulic tank. The problem it has is if you turn the wheel even a hair you lose all of the bucket functions and pretty much need to floor it to get the arms or bucket to function. If you don't touch the wheel the hydraulics work great. Steering always worked fine no matter what you are doing. The bucket levers use a solid rod going into the valve instead of a cable and there is zero play or leaks anywhere. The pump is a simple gear pump that was already looked at by a hydraulic shop who told me it looked brand new inside any idea whats happening? Or need any other info? thanks
I haven't worked on one of these machines, but I'd wager a bet that it has a priority flow divider and that's your problem. The PFD is what is generally used with a single pump working multiple functions, like steering and loader, and provides the necessary oil flow/pressure to work these functions without one function (loader) affecting operation of the other function (steering).
do you have the correct filters? if the micron is too small the filter may be restricting the oil, thus only allowing you one function at a time. maybe there is air in the system. just a few guesses.
I'm thinking there was a power amplified steering in that unit but it has been so long since I worked them I don't remember for sure. Do you have a hydraulic schematic for that machine?
A "power amplified steering"? Wow, I admitted I didn't know this machine, but I didn't see this coming! I still think we're on the right track of a component/system that ties steering and loader functions together. Yeah, a hyd schematic would be a big help right now.
Those machines always had the loader and steering tied together by use of what they called a switch pump. I'm sure there are two pumps that feed into a single valve block. The problem with memory that I have on this machine was whether or not there are pilot lines from a rotary steering valve or a sector gear and link going to a valve mounted on the back half of the machine. At any rate that steering valve block gave us problems on larger machines. There were some spools that shifted oil between steering and loader that got stuck at times. I just can't remember all the particulars.
Was that Burlington Dodge's machine ? Winn equipment in Windam Nh probably be able to tell you more if you call the service dept.
Yes it was Its still in Burlington I do have a hydraulic schematic. I'll see if I can get it posted
I believe John C hit it on the head. I believe there is a switch pump and a work equipment pump. The switch pump will put oil to the work equipment when steering is not used. Work equipment pump is always for loader operations. I believe you have a third pump that is always dedicated to steering also. The fourth pump would be the trans pump. Hang on, i will go and check the parts books, be back in a little bit.
The only pumps i have seen are the gear pump and the charge pump for the trans. There is a large block under the cab that goes out to both loader and steering functions. Appreciate you checking a parts book for me. Hopefully you can pinpoint it
sorry, had puter problems yesterday. Your machine has one pump, I was thinkink of a different model. Your "priority valve" is located in the steering valve. It gives priority to steering, when the steering demand is met, all remaining oil goes to the loader valve. I suspect something is broke,worn or stuck in the priority valve portion of your steering valve.
sent you a parts diagram.
I never recieved it. Where did you send it to? My PM box is empty but if you want to e-mail it to me you can send it to [email protected] . Thanks Dave
sending it again, it is a pdf document, you got adobe?
Yes I just got it. Very much appreciated. Which piece exactly am I looking for in the diagram?
items 48,49 and 50 are the priority valve