Cartridge Valves

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Command Controls founder Connie Kosarzecki remembers when the cartridge valve was introduced in the 1950s. At the time, two companies were making special-purpose hydraulic cartridge valves.

"Each cartridge valve was designed to perform a specific function, and then a valve cavity was designed to encompass the valve," says James Incledon, Jr., marketing manager, Command Controls Corp., Elgin, IL. "Most of the valves during that time were designed with many differing cavities."

In the late 1960s and 1970s, a new approach to cartridge valve design emerged in which the cavities were designed on the existing technologies of the SAE straight thread O-ring port designs, allowing a great deal of interchangeability.

In recent years, cartridge valves have responded to the market's needs through the development of new products, expansion of functionality and improvements in core specifications, says Michael G. Guhde, division marketing manager, Hydraulic Cartridge Systems Div., Parker Hannifin. New proportional valves controlling direction, flow and pressure are now taking over many applications once thought to be reserved exclusively for sectional valves. Cartridge valves are also performing multiple jobs in a single cartridge, such as flow controls with integral relief functions, or directional valves with built-in compensators.

"Cartridge valves have seen improvements in core performance areas, as well," says Guhde. "Leakage rates have decreased by as much as 75% in some cases, pressure ratings are extending up to 350 bar for standard products and 700 bar for some specialized applications, and power curves are now wider and offer greater responsiveness."

Customers today are more concerned about leakage and cleanliness. Beyond the obvious environmental and safety issues, leaks indicate the system is not completely sealed, which means contaminants can get in and could lead to the premature failure of a hydraulic system. "This is also the same reason customers are more concerned about cleanliness," says Incledon. "Command Controls uses an oversized spot face which gives additional seating area, thereby reducing the possibility of a cartridge valve backing out and allowing leakage or contaminants."

Thelma Gutierrez-Anderson, product manager at Eaton's Hydraulics Operations, Eden Prairie, MN, says some of the trends they are seeing "include use of more proportional valves. We also see more customers moving to higher pressures on mobile applications."

Paul Spratt, marketing manager for HydraForce, Lincolnshire, IL, says the company's customers are looking for design flexibility and performance optimization. Logic elements provide the designer with many options for system configuration, sizing, pricing and function. "The customer is able to develop and execute purpose-designed circuit concepts using a combination of standardized components to achieve customized performance benefits. This configuration flexibility allows customers to design vehicle specific solutions for a wide variety of applications, even for lower volume machine options or for special application conditions. These needs increase as vehicle performance, efficiency, safety and convenience requirements advance in a highly competitive global environment."

Logic valves are available in many different configurations with an expanded range of features and sizes enabling use in flow, pressure and directional control circuits. By using smaller piloting elements to control larger logic valves, circuits are more efficient and more cost effective. Changes include the addition of multi-function features within a single cavity which reduces complexity, reduces size, lowers weight and improves reliability.