Getting the most from tractor hydraulics with power beyond

Variable

Closed centre hydraulic systems differ by using a variable displacement pump, which charges the hydraulic system, essentially trapping oil under full pressure, ready for use.

If there is no demand, the pump does not circulate oil, which means lower heat build-up, reduced fuel consumption and reduced power use.

A closed centre system supplies oil in response to a pressure drop anywhere in the system, and when a spool valve is opened the pump steps up to deliver flow.

A development of this has led to load sensing, using a line that returns to the pump. Its purpose is to trigger the pump’s swash angle to increase flow in response to a valve being operated. Flow sharing is a big benefit, as oil is supplied on demand.

While it offers considerable advantages in terms of fuel efficiency, it can be a little more complicated to set up implements correctly using spool valve flow and timings, to make the most of a tractor’s hydraulic capability.

To combat this, power beyond is an extension of this functionality, and delivers oil to an implement without having to use the tractor’s spool valves.

WHAT IS POWER BEYOND?

MARTIN Hamer, Fendt’s national sales manager, says: “If you are running a potato harvester with eight hydraulic functions and your tractor only has five spools, how do you operate the additional three functions? The answer is, you do it with power beyond.”

Power beyond sees implement makers integrate a hydraulic valve block on the machine, which allows the machine to be configured to precisely optimise all flow and pressure settings to make the most of implement performance. This can then be managed directly from the tractor’s load-sensing capability.

At this point, spool valves become redundant, and operating such an implement then requires a tractor with power beyond capability. This uses a small-bore, load-sensing trigger line, plus a high-flow oil supply line and a free-flow return.

Performance

Its sole function is to offer extended hydraulic performance to run complex implements, instead of relying on tractor spool valves, and is viewed as a plug-and-play, hydraulic system.

“Power beyond simply moves the oil flow to the implement, instead of relying on the tractor having enough spool valves to control hydraulic functions,” says Mr Hamer.

“Implement control can then be through a dedicated machine control box, or through an IsoBus universal terminal.”

EFFICIENCY GAINS

MR Hamer says: “Importantly, power beyond takes away the need for constant pumping by using a spool valve to push oil around an implement.

“It also eliminates the need to dial-in spool valve flow and pressure settings too, and this contributes to greater fuel efficiency.”

Pottinger’s UK sales manager Shaun Groom agrees. He says: “With increasingly sophisticated implements, such as forage wagons or combi-balers, there is a huge requirement for hydraulic services.

“The tractor is unlikely to have enough spools to run a machine efficiently, and power beyond is the solution.

“Yes, it adds cost to the implement, but it also delivers greater efficiency and improves productivity without putting more of a burden on the operator,” he says.

“Using load sensing hydraulics on an implement is simply a logical move that eliminates the need for an operator to spend time fine-tuning flow and time-based settings with spool vavles.”

He points out that a non-load sensing system can have its oil flow influenced by other spools.

“A hydraulic fan drive on a seed drill is a good example of how insufficient oil flow can impact on performance,” he says.

“Lifting the drill at the headland and pulling the marker arms can cause the fan speed to slow – and on a wide drill, with 72 outlets, you need a lot of airflow. The last thing you want is a slow-down on the fan.

“Load sensing cures this, and power beyond makes more oil available exactly where it is needed, without causing the oil to overheat or the pump to cavitate trying to keep up.

“And Pottinger, like many others, includes the ability to run its implements on non-power beyond tractors,” he says.

“It needs a spool to be put into constant pumping, and is less efficient, but it still allows the implement to be used.”