Comparison Dual Hydraulic Pumps?

[Tractorable]

I was looking at a compact tractor brochure recently and it advertised that the machine has dual hydraulic pumps. My question is, do all compact tractors have dual hydraulic pumps? or do only some tractors have this feature? What are the advantages of dual pumps over a single pump?

Thanks

 

[kennyd]

Many do, but certainly not all. The advantages (usually) are more hydraulic flow is directed to implements since one is dedicated for steering control.

 

[Rock Crawler]

Kenny, maybe you know this...

When you see subcompact and compacts spec out hydraulics, they all seem to list 2 flow rates and a total. Does that mean that they absolutely have dual pumps (one for power steering and one for implements) or can it be that a tractor has a single pump but flow is split post-pump to get those numbers?

Example would be Massey Ferguson GC1720 shows 6.8 GPM total hydraulic flow, 4.8 GPM implement flow and 2.0 GPM power steering. Would a small sub actually have a dedicated mechanical pump just for the power steering? I was assuming (make an *** out of you and me) that the specs were engineering wizardry derived from some form of priority fluid flow control from a single pump?

 

[rca97ag]

I was looking at a compact tractor brochure recently and it advertised that the machine has dual hydraulic pumps. My question is, do all compact tractors have dual hydraulic pumps? or do only some tractors have this feature? What are the advantages of dual pumps over a single pump?

Thanks

All compacts do not have two hydraulic pumps. The ones that do have a pump that is dedicated to steering. The ones that don't usually have a priority valve and when you are picking something up with the loader you loose steering or you can not lift until you stop steering.

You really will not notice the effects until you've had enough time in the seat to not have to think about the loader joystick controls.

 

[kennyd]

Kenny, maybe you know this...

When you see subcompact and compacts spec out hydraulics, they all seem to list 2 flow rates and a total. Does that mean that they absolutely have dual pumps (one for power steering and one for implements) or can it be that a tractor has a single pump but flow is split post-pump to get those numbers?

Example would be Massey Ferguson GC1720 shows 6.8 GPM total hydraulic flow, 4.8 GPM implement flow and 2.0 GPM power steering. Would a small sub actually have a dedicated mechanical pump just for the power steering? I was assuming (make an *** out of you and me) that the specs were engineering wizardry derived from some form of priority fluid flow control from a single pump?

Rock,
The way OEM's play games with specs there is just no way to be sure. In your example there could be two pumps, or just one with a priority valve setup to direct 2.0 GPM to the steering circuit. The only real way to know is to ask a competent sales person (if you can find one LOL) or parts guy, or look at the parts diagrams your self if you can, I know JD's are online free and I think Messik's has the Kubota ones.

 

[Grandad4]

All compacts do not have two hydraulic pumps. The ones that do have a pump that is dedicated to steering. The ones that don't usually have a priority valve and when you are picking something up with the loader you loose steering or you can not lift until you stop steering.

You really will not notice the effects until you've had enough time in the seat to not have to think about the loader joystick controls.

A single pump setup should be designed with enough capacity so the steering is not interrupted when you operate the loader or vice versa. An occasional momentary hiccup from the priority valve is not much cause for concern, but I would stay away from any tractor that regularly freezes one function while another operates. Something to check for when doing a test drive.

 

[MossRoad]

Crank the steering all the way to the right lock, then while operating the loader curl/dump function while driving in a circle, see if you can steer out of the lock, or see of you can dump/curl while steering.

Mine has three pumps. One for propulsion (four wheel motors), one for the hydraulic implements, and one for the steering/FEL. The steering circuit goes from the pump, through the steering valve, through a power beyond port on the steering valve, then to the FEL valves, and back to the tank. I have steering priority. On a few occasions I've had the steering at full lock to one side and couldn't operate the FEL. Just barely letting off the steering in the opposite direction allowed the FEL to function.

So, lots of machines are different. All have their intricacies. Most can be worked with. But best to know what you're getting into before purchase or before you are surprised.

 

[jenkinsph]

I was looking at a compact tractor brochure recently and it advertised that the machine has dual hydraulic pumps. My question is, do all compact tractors have dual hydraulic pumps? or do only some tractors have this feature? What are the advantages of dual pumps over a single pump?

Thanks

What most of the new tractors use is a two section pump. One set of gears (narrow) for power steering and a wider set of gears for implement flow. To lower the cost the two gear sets share common shafts with a spacer between the sections.
Below is an example of a two section hydraulic pump. You can get a wide range of choices for the pump flows too.

 

[4570Man]

My l3240 only had one pump (that I found at least ). It had a steering flow and the other flow listed separate. I could steer, and operate the loader at the same time without issues. The lift and curl also worked perfectly at the same time. I've used other tractors that didn't, and that would be a huge downside for me.

 

[Dave M7040]

Here are two examples on "how it is done" on Chinese made tractors.

The first is a Ty304. It has two hydraulic pumps. One for the hydrostatic power steering and the second for the lifter and other rear remotes.

The next tractor is a Lenar

It has only one pump. The steering is protected by a priority valve and the lifter, backhoe and FEL are also powered from the same pump.

A replacement pump was $75. Now machine is like a new one according to its owner.

This is the Lenar priority flow valve for the steering.

The real challenge with the Chinese machines is that the manuals don't keep progress with important changes in their product.

Dave M7040