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Discussion Starter #1 (Edited)
Hi all,

I've owned my 1023e for about a year now. I've had a couple other hydrostatic tractors before moving up to the 1023e....I'm now actually contemplating moving up to a 3 series. Last night I realized I don't have a firm grasp on how the hydrostatic and hydraulics actually work on my tractor. More specifically what's utilizing how much of the engine power when.

I know there's a pump that I assume is run off the engine, but I'm a bit lost from there. Is the pump always running and taking a load off the engine, or another way to put it are the hydraulics using any engine power when the tractor and all hydraulics are all sitting idle? Is there a certain amount of rpm/throttle that operates the pump at its give amount of full flow?

From the feel of my pants while operating the tractor I know that more engine throttle/rpms will increase the land speed of the hydrostatic drive of the tractor itself, but to me it feels like that the loader hydraulics only get stronger to a certain point of throttle/rpms but anything past that point seems to feel like it has diminishing returns on loader performance.
 

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Hi all,

I've owned my 1023e for about a year now. I've had a couple other hydrostatic tractors before moving up to the 1023e....I'm now actually contemplating moving up to a 3 series. Last night I realized I don't have a firm grasp on how the hydrostatic and hydraulics actually work on my tractor. More specifically what's utilizing how much of the engine power when.

I know there's a pump that I assume is run off the engine, but I'm a bit lost from there. Is the pump always running and taking a load off the engine, or another way to put it are the hydraulics using any engine power when the tractor and all hydraulics are all sitting idle? Is there a certain amount of rpm/throttle that operates the pump at its give amount of full flow?

From the feel of my pants while operating the tractor I know that more engine throttle/rpms will increase the land speed of the hydrostatic drive of the tractor itself, but to me it feels like that the loader hydraulics only get stronger to a certain point of throttle/rpms but anything past that point seems to feel like it has diminishing returns on loader performance.
Pump runs continually. Volume pumped equals speed of function. Pressure equals power applied.
Hydrostatic are parasitic, in other words you lose engine HP to them. That is the short abridged version.

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Power or pressure is constant for a given pump above a given RPM, the only thing that varies to any extent is the volume and that is dependent on the pump displacement as well. Larger the tractor, more volume and more pressure.

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Discussion Starter #4 (Edited)
Pump runs continually. Volume pumped equals speed of function. Pressure equals power applied.
Hydrostatic are parasitic, in other words you lose engine HP to them. That is the short abridged version.

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Thanks for that. So if the pump is constantly running, and is parasitic always eating up some engine HP, am I correct in assuming that amount of engine power that the pump eats up increases in correlation with RPMs until it gets up to the aforementioned max pump pressure? Or is the parasitic power used up by the pump static and has no correlation with the engine RPMs or the flow rate of the pump?
 
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Thanks for that. So if the pump is constantly running, and is parasitic always eating up some engine HP, am I correct in assuming that amount of engine power that the pump eats up increases in correlation with RPMs until it gets up to the aforementioned max pump pressure? Or is the parasitic power used up by the pump static and has no correlation with the engine RPMs or the flow rate of the pump?
I would think the static pump draw of HP is the same without load. Once you start using power then I belive the parasitic losses increase. In other words the pump probably loses a percentage across the range so if that is 5% you would multiply that by the HP shown in the the power curve. But now I am out of my knowledge base totally, so hopefully Kenny Will jump in here and correct me. But this is my limited understanding. Hopefully I will learn some more with others answers!! But getting to be an old dog......

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This is how the hydraulics make the tractor move forward and backwards:


As for the implements...

Let's look at your loader. The pump is continuously circulating hydraulic fluid, which is at a certain pressure, regulated by a pressure release valve. Whatever that valve is set to, if the pressure exceeds that setting, the fluid is diverted through that valve. That's why you can't really work your hydraulics too hard. If you try to lift something too heavy, it just won't move. It won't hurt the system.

So as fluid circulates through the pump, part of that loop is constantly under pressure, which comes from the pump. The cylinders that lift and lower your loader have valves connected to them, which you control with the SCV (the joystick). When you pull back on the stick, the valve to the lift cylinders opens and fluid is pumped into them, which forces them to expand, lifting the bucket. You control the rate of flow by opening the valve a little or fully. When you release the stick, that valve closes and it stops moving. If you keep it back after the bucket goes all the way up, the pressure increases because you're pumping fluid into the cylinder but it has no where to go, so then the relief valve takes over and the fluid goes there and keeps circulating.

When you push the stick forward, a different valve opens which sucks the fluid out of the cylinder, causing it to contract, and so the bucket lowers. Float mode depressurizes the cylinder and allows the fluid to drain out or flow in without any resistance beyond the size of the passages it has to travel through, so the bucket lowers with gravity and can go up and down as needed.

I hope this helps.
 

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When you push the stick forward, a different valve opens which sucks the fluid out of the cylinder, causing it to contract, and so the bucket lowers.
Actually the loader uses double acting hydraulic cylinders. When you lift, it causes fluid to flow to one side of the cylinder and when you lower, it causes fluid to flow to the other side.



This is an over simplified diagram that doesn't show the control valve but you can see the concept.
 
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Actually the loader uses double acting hydraulic cylinders. When you lift, it causes fluid to flow to one side of the cylinder and when you lower, it causes fluid to flow to the other side.

This is an over simplified diagram that doesn't show the control valve but you can see the concept.
Thanks for the correction! I always wondered about that.
 

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Hydraulics

Hi there

Following on from what was said above there hydraulic pump will have a pressure relief valve set to lift at the desired system pressure. The point of diminishing returns as you have mentioned would be the point at which the relief valve lifts. Whilst lifting the relief valve in itself is harmless, the oil itself will experience a shear heat which will cause the additive pack in the oil to break down and varnishing will form in the hydraulic system. In order to maintain peak performance use a quality oil, ideally a fully hydrocracked synthetic oil (there is a good one from Conoco in the US, I think it is Megaspin 46).

Hope this helps. I've spent 20yrs with injection moulding machines, so base my comments on that experience.

Regards
Graham
 

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Keep in mind.. There are different systems. The hydrostatic drive and the implement system, which includes sub systems. They operate differently. Have seperate pumps and such but share fluid and reservoir. You all's best bet is to buy the tech manual and read the theory of operation of each system. The 1 series is a good one to start on to understand the operation as it is a basic system with little interference of electronic controls. Each of you has touched on various theories. Each of you has a piece. Now read that theory of operation and you'll have it.

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Discussion Starter #11
I may be starting to convolute my own understanding a bit here. I guess the main theory I'm trying to get grasp on here is when and how, and how, much engine power/load comes into play in terms of operating the hydraulics.

If there is more than one pump is a constant amount engine power set aside for all the pumps at all times? Or are the various pumps constantly taking various loads on/off the engine as the pressures rise up to the point of the actuating the above mentioned pressure relief valve?

Here's an example of what I"m questioning in practice while 'out in a field' at this point. Say you have a 25hp tractor with a 20hp pto rating. If you're running a PTO implement at the required PTO RPM and the tractor is sitting idle with no input to the function of the hydraulics whatsoever are going to be getting 20hp or more to the PTO? Vice versa if you you're running a PTO implement while driving full speed and operating the loader are you getting less than 20hp to the PTO?
 

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I may be starting to convolute my own understanding a bit here. I guess the main theory I'm trying to get grasp on here is when and how, and how, much engine power/load comes into play in terms of operating the hydraulics.

If there is more than one pump is a constant amount engine power set aside for all the pumps at all times? Or are the various pumps constantly taking various loads on/off the engine as the pressures rise up to the point of the actuating the above mentioned pressure relief valve?

Here's an example of what I"m questioning in practice while 'out in a field' at this point. Say you have a 25hp tractor with a 20hp pto rating. If you're running a PTO implement at the required PTO RPM and the tractor is sitting idle with no input to the function of the hydraulics whatsoever are going to be getting 20hp or more to the PTO? Vice versa if you you're running a PTO implement while driving full speed and operating the loader are you getting less than 20hp to the PTO?
Yes. As the hydraulic load or PTO load increases, the governor in the engine adds more fuel to create the needed power to keep things going until the load reaches the point there isn't enough fuel. When this happens, the RPMs drop. It doesn't matter what load you put on the engine, you only have so much HP. So if you are using 15HP on a chipper on the PTO, you only have a few more HP left to run everything else, to include the hydraulics. Luckily there aren't too many situations where you need to use both the PTO and use large amount of hydraulic power.

A pump is a load. As your hydraulic needs increase, aka, lifting a heavy load on the loader, the pump has to supply the pressure and flow required to raise that load. As the requirements to raise the load increase, so does the power required to run the pump. It's no different than if you went for a jog running down a path. If you encounter a hill, you have to exert more energy to run up the hill. On the backside of the hill, you can relax a bit as your body weight pulls you down. If you were running with a wheelbarrow, your load has increased. Perhaps you started a new workout routine and started to swing your arms back and forth like you were boxing. Not the same exercise as running, but doing both activities adds more work for you to do. See the correlation? The engine doesn't care what the load is whether it's a shaft it's turning, a pump it's turning, or wheels. It's all just resistance or work. More work requires more power.
 

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Yes. As the hydraulic load or PTO load increases, the governor in the engine adds more fuel to create the needed power to keep things going until the load reaches the point there isn't enough fuel. When this happens, the RPMs drop. It doesn't matter what load you put on the engine, you only have so much HP. So if you are using 15HP on a chipper on the PTO, you only have a few more HP left to run everything else, to include the hydraulics. Luckily there aren't too many situations where you need to use both the PTO and use large amount of hydraulic power.

A pump is a load. As your hydraulic needs increase, aka, lifting a heavy load on the loader, the pump has to supply the pressure and flow required to raise that load. As the requirements to raise the load increase, so does the power required to run the pump. It's no different than if you went for a jog running down a path. If you encounter a hill, you have to exert more energy to run up the hill. On the backside of the hill, you can relax a bit as your body weight pulls you down. If you were running with a wheelbarrow, your load has increased. Perhaps you started a new workout routine and started to swing your arms back and forth like you were boxing. Not the same exercise as running, but doing both activities adds more work for you to do. See the correlation? The engine doesn't care what the load is whether it's a shaft it's turning, a pump it's turning, or wheels. It's all just resistance or work. More work requires more power.
Very good analogy. I was trying to reply also but I was getting too technical!
You are correct in that it would be unusual to be running hydraulics and PTO at the same time. However it happens quite frequently by error. Example would be an out of adjustment 3pt hitch that is dead heading when all the way up. It will most certainly rob power.

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Discussion Starter #14 (Edited)
Yes. As the hydraulic load or PTO load increases, the governor in the engine adds more fuel to create the needed power to keep things going until the load reaches the point there isn't enough fuel. When this happens, the RPMs drop. It doesn't matter what load you put on the engine, you only have so much HP. So if you are using 15HP on a chipper on the PTO, you only have a few more HP left to run everything else, to include the hydraulics. Luckily there aren't too many situations where you need to use both the PTO and use large amount of hydraulic power.

A pump is a load. As your hydraulic needs increase, aka, lifting a heavy load on the loader, the pump has to supply the pressure and flow required to raise that load. As the requirements to raise the load increase, so does the power required to run the pump. It's no different than if you went for a jog running down a path. If you encounter a hill, you have to exert more energy to run up the hill. On the backside of the hill, you can relax a bit as your body weight pulls you down. If you were running with a wheelbarrow, your load has increased. Perhaps you started a new workout routine and started to swing your arms back and forth like you were boxing. Not the same exercise as running, but doing both activities adds more work for you to do. See the correlation? The engine doesn't care what the load is whether it's a shaft it's turning, a pump it's turning, or wheels. It's all just resistance or work. More work requires more power.
Thanks for that. I'm feeling fairly comfortable with it all now.

My last question and then I'll leave everybody alone. Does the above reference apply to the how engine HP/torque affect the actual power, speed, or dirt pushing grunt of a given hydrostatic drive of a tractor? For istance I believe that a 1023e and 1025r have the same pump and hydraulic capacities. The 1025r obviously has a couple more HP than the 1023e. Would the 1025r'a hydrostatic drive be more powerful due to the couple extra horses being able to better run the hydraulic capacities (pressure or volume) of what I assume would be the same hydrostatic drives shared between the two tractors, in a similar fashion as to what was described above?
 
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