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Computerized Hydrolic ControlsTechnology Update
Computerized Hydraulic Controls

Greater precision in a simpler system

By Lorne McClinton

For Farm Tek Advances

The hydraulic system is the heart and soul of the new generation of tractors and combines. Hidden away inside tractor and combine consoles are computers with microprocessors that simplify operator controls and add the precision farmers need to do a better job.

Today, computers are used to control almost all hydraulic systems. Pat Lourigan, lead hydraulics engineer with Case IH Magnum Tractors says, "Transmission controls are the most obvious example of computerized hydraulics with obvious advantages. Tractors controlled by electronics can be shifted more smoothly. You don’t have to clutch your tractor anymore to make a shift; you hit a button and you are in the next gear up or down.

Today, operators want to control many different functions from within the tractor, says

John Deere's Gordon Weigardt, "If you needed a lever for everyone of those functions, your whole right hand console would be full of levers. Electro-hydraulics gives you more compact controls with better ergonomics."


Electro-hydraulic controls work by replacing mechanical linkages and assemblies with either a solenoid or force motor. They convert electrical signals into a mechanical force which is used to move pilot valves, variable orifices or nozzles, depending on the type of valve. They also can be used to move directional spool valves.

"The hydraulic system becomes simpler using computerized electronic controls," Lourigan says. "They are less complex than mechanical valves. I’d say they are more reliable because of their simplicity. You don’t need to worry about mechanical linkages failing, but you do have to watch for bad connectors. One bad connector can take your entire system down."

To date, electronically controlled systems have been used primarily to replace mechanical linkages. In John Deere’s 8000 series tractors, all mechanical linkages have been replaced by electronics. This is a good example of hidden technology since short of tearing apart the console, the operator notices few physical differences in the machine, but the controls are easier and more precise to use.


The new hydraulic systems are for the most part self-diagnostic. "We build a lot of intelligence into the system so it can identify its own problems," Lourigan says. "A message centre tells the serviceman and the customer where the problem is."

Self-diagnostic capabilities also enhance the electronic load sensing system built into John Deere’s 3-point hitch. Sensors measure the force on the hitch, and electronics send signals to either raise or lower the itch to keep the force constant.

"The next step is to integrate this system into a more computerized system like the global positioning systems to incorporate automatic guidance controls," Lourigan says. "We could use the hydraulic system on the tractor to accurately place fertilizer and seed and seed density using information recorded in the prior year. In the future, all this will be controlled hydraulically from the tractor."


Extend the life of your hydraulic system

"Proper control of hydraulic systems boils down to three things," says Don Riddell with Imperial Oil. "Keep it cool, keep it clean and be sure to select the right viscosity."

Selecting hydraulic oil with the proper viscosity for your weather conditions is the most critical step to hydraulic system longevity. An oil which is ideal for summer use may be to heavy in cold winter conditions. Esso makes three different transmission, differential and hydraulic fluids (TDH) Hydraul 50, Hydraul 56 and Hydraul Extra.

Hydraul 50 oil has a lighter viscosity specifically developed for use at temperatures as low as –35C. Hydraul 50 is recommended for year round use in equipment requiring lighter viscosity or as a winter grade oil to replace the heavier Hydraul 56.

Hydraul 56 is designed for systems that require heavier grades for summer operation. It’s suitable throughout the year in areas where temperatures stay above –25C.

Farmers who use the same equipment in both winter and summer would benefit by spending a bit more money and switching to Hydraul Extra. This is a synthetic oil that can be used in both winter and summer. It maintains proper viscosity year around.

Increased temperature in hydraulic systems can lead to many problems including increased oil oxidation, damage to seals and loss of viscosity. All these can lead to increased maintenance work.

Keep your hydraulic system as clean as possible. Special care should be taken when adding oil or making repairs. Use proper handling methods to reduce the chances of dirt and other contaminants getting n the system which can damage hydraulic components. A good filtration system will go a long way in reducing the level of any contaminants.

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