Specified HYDAC valves in electro-hydraulic control loops for load holding meet the challenge of precise load lowering and energy efficiency.
Contemporary tractors are powerful feats of mechanical engineering and precision and wheel loaders aren’t far behind them.
However, it’s been an ongoing issue for the agriculture industry to lower loads precisely, particularly when tractors and wheel loaders are in the forward holding position.
Counterbalance valves have proven not to always be useful in these applications because they don’t facilitate the desired combination of energy efficiency and stability.
Improved energy efficiency order of the day
Energy efficiency is magnified in these applications as it’s directly related to the electrified machine‘s battery design.
This constitutes a weighty cost driver for the machine manufacturer and it’s for this reason it has become increasingly challenging to balance out energy efficiency and stable load holding.
Electro-hydraulic load holding offers full control
In this instance, the electro-hydraulic load holding function emerges as a solution with many benefits. This is because the basic function of conventional load lowering is kept even with electro-hydraulic systems.
Software can keep inlet pressure at a minimum level
Here software can be used to keep inlet pressure at the minimum level required. This avoids cavitation, and full control of lowering movement is maintained.
Special valves required
The hydraulic part of the control loop is carried out by replacing the conventional downstream counterbalance valve with a pilot-operated, proportional, poppet-type flow control valve.
Reduced power loss with electro-hydraulic load holding
Electro-hydraulic load holding keeps power loss low through maintaining inlet pressure as low as possible. This is contrary to conventional systems where power loss is most significant when large volume flows are needed with low leading loads as required pressure control is at its highest.
For the efficient implementation of these systems, pilot-operated, proportional, poppet-type flow control valves from HYDAC come in handy.
These valves have already proven themselves in gravity-lowering applications with and without a pressure compensator.
Basis for precision and dynamic performance
The pilot-operated, proportional, poppet-type flow control valve range from HYDAC can be easily implemented to reduce the tension between energy efficiency and stability.
The precise controllability of these valves, even at high differential pressures, offers the ideal prerequisite for implementing these types of control systems.
HYDAC’s own solenoid system acts as a basis for precision and dynamic performance.
Effective fine control geometry and therefore precision is made possible by a large solenoid stroke.
A high solenoid force, which enables a valve design with large pilot cross-sections, also leads to highly dynamic valves.
For this reason, HYDAC valves react extremely quickly to electrical signals and lead to a stable load holding function.
The HYDAC product range includes a large variety of valves with various nominal sizes and characteristics and is therefore ideally suited to a large number of applications.
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