Loss of Hydraulics AND power to the wheels

[Allan Novice Tractor Owne]

Hello, I have a 2005 or 4 Terraplane 38hp tractor. Made in China. I've been using this tractor for about 4 years or so (wish I had bought a new one), and have performed a few repairs on the hydraulics (pump ruptured and spilled hydraulic fluid into the engine oil reserves), and now I'm onto my next repair.

Tractor barely moves. I crank up the RPMs a bit to motivate her to move, but if I'm trying to back up a hill or drive up one (moderate pitch), it slows down to a stop. Had to use the bucket last week to assist backing me out of a tight spot.

Which is weird, because I also have a problem with my hydraulics. Fluid is fine, just replaced the fuel filter (one of the symptoms required this step), but still when I start the tractor I can not raise the bucket. Cranking up the RPMs will kind of lift it slowly for a few inches (3-6), but then the bucket stops moving. I can, however, dump the bucket and use it to back up (angling it down then up when pressed against the planet), but I can't lift anything, not even the bucket.

The box blade in the back, I can raise that easily enough. But it's also not under a load.

Question is this, what can affect both the power to the wheels and the power to the bucket?

 

[Sportsman762]

I have never worked on a terraplane or any CN tractor so I am shooting in the dark. Does the tractor have a gear or hydrostat transmission? If it is geared then the hydraulic pump could be in the rear like it is on many tractors. If the clutch is slipping bad or a coupling in the transmission has let loose then it could be not transmitting power to the rear and therefor taking out the pump and traction. One way that might work is to engage the pto and if it stops spinning or slows down lots when the tractor will not move and hydraulics will not work then it would indicate an issue with the clutch or transmission. However this might not work if the clutch is a two stage and the pto clutch is good and the hyd pump is on the transmission not the PTO.

Sorry for the winding explanation as its hard to figure out what I cannot see.

 

[Allan Novice Tractor Owne]

Very hard to troubleshoot what one can't see. I'm a medical equipment maintainer, and outside the typical question "is the device plugged in?" I have to see it and play with it to determine symptom and fault.

So this isn't a hydrostat tranny. My son has a tractor with hydro. So I have a clutch (I thought about a slipping clutch), and I typically keep it in Low 1-4 as my property is hilly and rocky. I do have a PTO, never thought to check it. I'll run the troubleshooting method described above for the PTO today during lunch.

I've replaced part of the hydraulic pump... I call it that. On the right side of the machine there is a manifold in which two "pumps" are butted up against each other adjacent to the engine block. I replaced the rear of these two when the impellor inside crapped out. Been running fine since (about two to three years), and even though I haven't proven it, I think the lead (front) of these two "pumps" has become much like myself, old and slow moving. Suspicion only, would like to confirm. There's one hydraulic line that comes out of the lead pump, so it may serve a primary function.

I bought a hydraulic hose set that came with gauges to see if I was pushing the pressure needed, but the couplings were far too small so we returned that. My thought was to interrupt the lines that I could and validate operating psi.

I didn't realize the hydro pump could be in the back. The hydro fluid stick and opening to top off is directly under the seat, so a pump in the back makes sense.

 

[Sportsman762]

Do not deadhead the pumps!!! the relief valve is built into the valve, deadheading the pumps will cause them to explode (you better hope its an internal failure).

 

[Allan Novice Tractor Owne]

Do not deadhead the pumps!!! the relief valve is built into the valve, deadheading the pumps will cause them to explode (you better hope its an internal failure).

What does deadhead the pump mean?

 

[Sportsman762]

What does deadhead the pump mean?

The pump must be able to pump fluid from the reservoir through the system and back to the reservoir. Normally if your using the hydraulics to do something like extend a cylinder when it reaches full stroke the pressure will jump to the max psi (around 2500 psi depending on model) and the pressure relief in the valve will open up sending flow back to the reservoir. Deadheading is when you block the flow prior to a relief valve causing the pressure to exceed the max psi next the fluid will find the weakest link and break it. I had a stuck relief valve on a system I was testing and when it blew it broke the 5000 psi gauge despite being a 2500 psi max system, I have no clue how high the pressure climbed to.

I bought a hydraulic hose set that came with gauges to see if I was pushing the pressure needed, but the couplings were far too small so we returned that. My thought was to interrupt the lines that I could and validate operating psi.

This is what concerned me. I am not sure what interrupting the line meant, but it sounded too much like taking a hose off and putting a pressure gauge on the pump aka deadheading.

I am guessing but your tractor probably has two pumps, one in the front on the engine for steering, and one in the rear for 3pt and auxiliary hydraulics.

 

[Allan Novice Tractor Owne]

The pump must be able to pump fluid from the reservoir through the system and back to the reservoir. Normally if your using the hydraulics to do something like extend a cylinder when it reaches full stroke the pressure will jump to the max psi (around 2500 psi depending on model) and the pressure relief in the valve will open up sending flow back to the reservoir. Deadheading is when you block the flow prior to a relief valve causing the pressure to exceed the max psi next the fluid will find the weakest link and break it. I had a stuck relief valve on a system I was testing and when it blew it broke the 5000 psi gauge despite being a 2500 psi max system, I have no clue how high the pressure climbed to.


This is what concerned me. I am not sure what interrupting the line meant, but it sounded too much like taking a hose off and putting a pressure gauge on the pump aka deadheading.

I am guessing but your tractor probably has two pumps, one in the front on the engine for steering, and one in the rear for 3pt and auxiliary hydraulics.

Okay, sorry for the delay. Yes, it was exactly what I had planned to do. Fortunately, the set I bought was the wrong size and I saw the warno prior to reordering.

So I had two symptoms, and I was trying to correlate the two to a single fault. I was wrong, my clutch is aging, however the power to the wheels remains. Perhaps I had over pushed the machine and as it got hot the wheels lost their magic. I had been using the bar thruster (found out later that I should use that when I'm working fields, however in my yard the topography is... not flat), so the recommendation was to leave the idle low and use the gas pedal to move. this works.

This led to the second symptom, bucket will not raise. It would go down, I could tilt the bucket to lift the front end... but I could not lift a softball in the bucket. I did see some very light oil at the ends of the lift bucket cylinders. So I ordered two new cylinders banking on my old set having a leak, and voila, the machine is working in accordance to the manufacturer's specification.

I'm learning a lot more about hydraulics with this machine since there are no mechanics in San Antonio, just brand specific technicians that probably do a great job providing they are trained to do the work, but they're useless here as they won't work on anything save for those machines they've been taught in.

This machine has two hydraulic pumps, both are attached to the engine block on the driver's right side. I had to replace one twice to get the machine working correctly a few years ago. Now, I'm just waiting for the next malfunction. The machine has earned it's cost and repairs. I think I've yanked out forty to fifty cedar trees and moved countless tons of rocks. I wouldn't be upset if the machine crapped out on me today, but I guess that's not true either. It's definitely paid for itself.