figure this one out

[pagliaccio matto]

Today the third replacement pump faied. Judging by the symptoms of this failure it seems identical to the first two. Aparently there is a small defective part of some sort inside the pump that has been causing the trouble. This time the pump lasted only twenty hours. I predict that these pumps will continue to fail until the manufactuor corrects the problem or recalls the defective pumps.

 

[NJBill]

Mr Matto
Sorry to hear your news, try to stay as sane as possible in these difficult times.
I realise you have an 1850, as compared to my little 422, therefore
the items may look different. In the attached pic of the first two sections of my power train which I name Variable Volume Pump part one and part two, do you have to send both of these pieces or only the first part?
The first part only has one oil port, coming off the top and going to the tank. the second part has the oil feed from the filter going into the side, and all other connections into this section are for driving the wheels. On the first section from which I removed the paint, is the area which was designated by the manufacturer for the I D Plate. Other than the two small holes for that plate is the number 14 steel stamped into the metal, this number corresponds to the steel stamped # 14 stamped into the top of section two. PT obviousaly knows who made this pump, and probably has the same information about yours.
My original curiosity still has me wondering, is the first part the pump, and the second part simply a valve body. That's why my question is what did you send and receive, and why I asked if you could send photos of the parts you received. In other words what is the pump ?????
I know I'm a pain but thanks for listening anyway. Bill

 

[Bob999]

My original curiosity still has me wondering, is the first part the pump, and the second part simply a valve body.

According to his profile Mr. Matto has a 2425.

You might find this article about variable displacement pumps helpful:

Howstuffworks "How Caterpillar Backhoe Loaders Work"

 

[NJBill]

Bob
Thanks for the correction on the model, so the pump could look like the one on my 422, and the article I found very interesting.
Of course I styill do not know which items Mr Matto had to send back to PT. There is no oil feed into Part one from the exterior, it must obviously pass from Part two where the feed comes from the filter. In this case where is the swash plate? Part two distributes the oil to all parts of the wheel system only,
which has a return to the tank from the treadle.
In which of the two parts was the problem? In some cases it would be very easy to check manufacturers system if the parts had some Identification, but we don't know who made the darned things.
I truly feel sorry for Mr Matto, it's like going to the doctor whoi gives out a prescription, with the words take these and see me in X days/weeks.
Bill

 

[Bob999]

Of course I styill do not know which items Mr Matto had to send back to PT.

My understanding is that the variable displacement pump used on the PT is comprised of a charge pump--to provided oil under low pressure to the variable displacement pump--and the variable displacement pump. My further understanding is that from the PT perspective the charge pump and the variable displacement pump are considered a single unit.

Therefore I had understood that Mr. Matto had returned the assembly that includes the charge pump and the variable displacement pump for repair/replacement.

Hopefully Mr. Matto will correct my understanding if it is incorrect.

 

[NJBill]

Bob,
Because the oil enters the second section, and leaves by the first section, it's pretty obvious they could be called one. The reason I asked for photos of the parts PT requested, and replaced, or "repaired", I was hoping to see the connection points between the two, to see how the oil went into the first section and how it was used for the wheel circuit.
We'll never know now.

 

[pagliaccio matto]

Thank you for your responses and support. I have installed the 4th pump and so far everything is working o.k. I am far from an expert on these pumps but I do believe that the charge pump and variable dispacement pump are considered all part of the pump unit as they are interdependent. However, it is possible to repace one and not the other as was the case with the last pump replacement I performed. I replaced the v.d. pump but kept the charge pump this time. I'm still not sure exactly how these pumps work or if my terminology for them is correct but I can replace them in 45 min. now!

 

[J_J]

Thank you for your responses and support. I have installed the 4th pump and so far everything is working o.k. I am far from an expert on these pumps but I do believe that the charge pump and variable dispacement pump are considered all part of the pump unit as they are interdependent. However, it is possible to repace one and not the other as was the case with the last pump replacement I performed. I replaced the v.d. pump but kept the charge pump this time. I'm still not sure exactly how these pumps work or if my terminology for them is correct but I can replace them in 45 min. now!

Do you have three pumps, and do you have pictures of the three with identification. Those lines from the treadle, probably operate a squash plate to control direction of the wheel motors. Do you have two hydraulic motors attached together on the engine, commonly known as a piggy back situation?

 

[NJBill]

Thanks for stepping in JJ. The first thing I asked for were back and front pictures of the pieces beiing sent to the experts. I also poimted out the absence of an identification plate on the first section.
I'm sure we will never know the correct terminology for the drive train parts, call them pumps , motors, or maybe just oil movers.
I keep hoping for something positive out of Tazewell, in the way of information. Thanks again.