Hydraulic Cartridge Valves: Engineering Excellence

Introduction to Cartridge Valves

Cartridge valves are often colloquially referred to as "valves without pants" in the hydraulic industry. This humorous moniker stems from their unique design where the hydraulic functional components lack an outer housing. Unlike a traditional hydraulic non return valve that typically comes with its own enclosure, cartridge valves must be installed within a manifold block to operate effectively.

When a cartridge valve is installed in such a block, the block itself no longer contains purely hydraulic pathways but becomes an integrated manifold. This integration is what gives these systems their exceptional efficiency and compactness. The hydraulic non return valve, when designed as a cartridge, benefits significantly from this integration, providing reliable flow control within a much smaller footprint.

One of the key advantages of cartridge valves is their complete separation from pipe connections, a feature that distinguishes them from many other valve designs including certain types of hydraulic non return valve configurations. This separation allows for easy replacement without the need to disconnect any pipe fittings, significantly reducing maintenance time and costs.

Compact Design Advantages

The "pants-less" design of cartridge valves - their lack of an outer housing - allows multiple valves to be compactly arranged within a single manifold block. This configuration creates an extremely space-efficient hydraulic system where even complex circuits can be integrated into a surprisingly small volume. A hydraulic non return valve, for example, can be positioned alongside other control valves within the same manifold, eliminating the need for separate mounting spaces.

The advantage of this compact design becomes increasingly pronounced as system complexity grows. What might require extensive piping and multiple discrete components with conventional valves can be integrated into a single manifold when using cartridge valves. This not only saves space but also reduces potential leak points, improves response times, and enhances overall system efficiency.

Among all available mounting and connection configurations for hydraulic valves, including various hydraulic non return valve designs, the cartridge type offers the most compact solution. This attribute has made cartridge valves the preferred choice in applications where space is at a premium, from mobile hydraulic systems to industrial machinery.

Integration in Hydraulic Systems

Figure 6-17b illustrates the transformation that occurs when traditional line-mounted components (shown in Figure 6-2) are replaced with an integrated cartridge valve manifold as shown in Figure 6-17a. This transformation demonstrates the remarkable space savings and system simplification achievable with cartridge valve technology.

Figure 6-17a: Assembled Manifold Block (Zoeller-Kipper, 1995)

This integrated manifold contains multiple valve functions within a single block, including pressure control valves, directional control valves, and a hydraulic non return valve. The compact design eliminates the need for extensive external piping.

Figure 6-17b: Installation in Host Machine

The same manifold shown in Figure 6-17a installed in its operational environment. Note the significant reduction in external piping compared to traditional systems. The integrated hydraulic non return valve functions seamlessly within this installation.

The integration of multiple functions into a single manifold block offers numerous advantages beyond space savings. It reduces pressure losses through shorter flow paths, minimizes potential leak points, simplifies system design, and improves overall reliability. A hydraulic non return valve integrated into such a manifold benefits from these advantages while providing essential flow control functionality.

Types of Cartridge Valves

Cartridge valves are primarily categorized into two main types: slip-in (cartridge) type and screw-in type. Each design offers specific advantages for different applications, and both can incorporate a hydraulic non return valve function depending on system requirements.

1. Slip-in Type

Often referred to as cover plate cartridge valves, this design features a valve body that is held in place within the manifold block by a cover plate (see Figure 6-18). This design was invented in the 1970s and has since become a staple in many hydraulic systems, including those requiring a reliable hydraulic non return valve.

Figure 6-18: Cover Plate Cartridge Valve (Bosch Rexroth)

Component Identification:

• 1 Cover Plate - Secures the valve assembly within the manifold block
• 2 Valve Body - Contains the functional components of the valve
• 3 Valve Spool - Controls the flow path through the valve
• 4 Spring - Provides the return force for the valve spool
• 5 Manifold Block - Contains the valve and forms the hydraulic pathways
• A Inlet/Outlet Port
• B Inlet/Outlet Port
• X Control Port

Because the cover plate can be secured to the manifold block with multiple bolts, sufficient clamping force is applied to hold the valve body securely within the manifold. This robust mounting method allows the design to withstand high operating pressures, making it suitable for demanding applications where a high-pressure hydraulic non return valve is required.

Cover plate cartridge valves are often referred to as two-way cartridge valves because they control the flow between two ports. This design can function as various types of valves, including as a hydraulic non return valve, depending on the specific configuration of the spool and spring.

Cover plate cartridge valves are versatile components that can function as either on-off valves or proportional valves. When configured as on-off valves, they simply control the opening and closing of a flow path, earning them another common name: logic valves. In this configuration, a hydraulic non return valve function can be easily implemented to prevent backflow in specific system circuits.

When used as pressure relief valves, these cartridge valves effectively limit system pressure by diverting flow when pressure exceeds a set threshold. In this application, as with a hydraulic non return valve, precise control is maintained with relatively small openings, allowing even large 100mm diameter valves to handle flow rates exceeding 7000 L/min.

A notable characteristic of cover plate cartridge valves is their reliance on additional pilot control valves to operate. This dependence on external control has led to another colloquial term: "brainless" valves, as they require direction from other valves to function. This is true even for a hydraulic non return valve implemented as a cartridge valve, which may require pilot pressure to override the check function when necessary.

Due to their relatively simple design with few moving parts and a short spool, cover plate cartridge valves can be manufactured in large sizes while maintaining reliability. This makes them suitable for high-flow applications where a standard hydraulic non return valve would be impractical due to size constraints.

Figure 6-19: Cover Plate Cartridge Valves (25-160mm Diameter) - Taifeng Intelligent, Shandong, 2009

This image demonstrates the size range available in cover plate cartridge valves, including models that incorporate hydraulic non return valve functionality. The ability to manufacture these valves in large diameters allows for their use in high-flow applications while maintaining the benefits of cartridge valve technology.

The versatility of cartridge valves, including those designed as a hydraulic non return valve, makes them indispensable in modern hydraulic systems. Their compact design, high performance, and ease of maintenance continue to make them the preferred choice for engineers seeking efficient and reliable hydraulic solutions. Whether used in mobile equipment, industrial machinery, or specialized systems, cartridge valves provide the integration benefits that help optimize hydraulic system performance.