At Hydra Power Systems, we’ve built our reputation on delivering the highest-quality hydraulic and pneumatic solutions to industries across North America. Since 1970, we’ve been the trusted partner for companies requiring precision, reliability, and innovation in their fluid power systems. As one of the nation’s premier distributors with operations in Portland, Oregon, and Birmingham, Alabama, we maintain the largest Sun Hydraulics inventory in the USA, ensuring our customers have immediate access to the components they need.
Why Sun Hydraulics?
Sun Hydraulics has been setting the standard for screw-in hydraulic cartridge valves since 1970. Their innovative floating cartridge construction and cavity design approach allows products to operate precisely and reliably at higher pressures and flow rates, even in the most demanding applications. What sets Sun apart is their unique engineering philosophy: products that are fast, dirt-tolerant, stable, and exceptionally robust.
Sun’s cartridge valves are offered in five primary sizes, with flow capacity and controlled horsepower doubling with each successive size. This scalability, combined with their ability to handle pressures up to 5,000 psi and flow rates up to 400 gallons per minute, makes Sun Hydraulics an ideal partner for the diverse applications our customers require.
Our Top 10 Sun Hydraulics Products
At Hydra Power Systems, we’ve identified the most popular Sun Hydraulics components our customers rely on day in and day out. Here’s an in-depth look at these essential products:
1. Counterbalance Valve with Pilot Assist
Category: Load Holding | Capacity: 15 gpm (60 L/min) | Cavity: T-11A
The CBCALHN is a workhorse in motion control applications. This counterbalance valve with pilot assist is specifically designed to control overrunning loads, making it essential for applications like mobile equipment booms, hydraulic cranes, and man-lifts.
Key Features:
- Pilot-assisted relief valve controls flow from load to directional valve
- Check valve allows free flow from directional valve to load
- Factory set for consistent, reliable performance
- Designed for zero leakage when properly set at 1.3x maximum load pressure
- Can be installed directly in actuator housing for added protection
Common Applications:
- Construction equipment stabilizers
- Material handling lifts
- Agricultural implement control
- Marine deck equipment
This product is also known as a motion control valve or over-center valve. Its pilot ratio design lowers the effective relief setting, providing precise load control while preventing dangerous load runaway conditions.
2. Direct-Acting Relief Valve
Category: Pressure Control | Capacity: 25 gpm (95 L/min) | Cavity: T-10A | Max Pressure: 5000 psi (350 bar)
When you need fast, reliable overpressure protection, this product’s direct-acting relief valve is your first line of defense. This normally closed, pressure-limiting valve is designed to protect hydraulic components from pressure transients and spikes.
Key Features:
- Extremely fast response time (2 ms typical)
- Smooth and quiet operation
- Essentially zero leak (10 drops/min maximum at reseat)
- Dirt tolerant and immune to silting
- Suitable for cross-port relief circuits
Technical Advantages: The direct-acting design means it responds immediately to pressure changes without the lag time associated with pilot-operated valves. This makes it ideal for preventing overpressure conditions that could damage expensive hydraulic components or create safety hazards.
The valve features Sun’s floating style construction, which minimizes the possibility of internal parts binding due to excessive installation torque or cavity machining variations – a critical feature for field serviceability and long-term reliability.
Applications:
- System overpressure protection
- Cylinder port protection
- Pump unloading circuits
- Shock absorption in mobile equipment
3. Pilot-Operated Balanced Piston Relief Valve
Category: Pressure Control | Capacity: 25 gpm (95 L/min) | Cavity: T-10A
While direct-acting relief valves excel at preventing overpressure, the pilot-operated balanced piston relief valve is designed for pressure regulation. This is the valve you choose when you need to maintain a constant system pressure regardless of flow variations.
Key Features:
- Accurate pressure regulation
- Low pressure rise vs. flow characteristic
- Smooth and quiet operation
- Moderately fast response
- Easy adjustment for field tuning
Why Pilot-Operated? Pilot-operated relief valves are used when you need to regulate pressure rather than simply prevent overpressure. The balanced piston design ensures consistent performance across varying flow rates, making it ideal for applications where precise pressure control is critical.
The valve is suitable for use in cross-port relief circuits and will accept maximum pressure at port 2, providing versatility in circuit design.
Common Uses:
- Main system pressure regulation
- Load sensing circuits
- Constant pressure hydraulic supplies
- Industrial press controls
4. Pilot-Operated Pressure Reducing/Relieving Valve
Category: Pressure Control | Capacity: 10 gpm (40 L/min) | Cavity: T-11A | Max Pressure: 5000 psi (350 bar)
The Pilot-Operated Pressure Reducing/Relieving Valve is a sophisticated three-port valve that performs dual functions: it maintains a constant reduced pressure at the outlet while providing full-flow relief protection. This makes it essential for circuits that require a secondary pressure lower than the main system pressure.
Key Features:
- Reduces high primary pressure to constant lower pressure
- Full-flow relief function from reduced pressure port to tank
- Low hysteresis and flat pressure-flow characteristics
- Three-port design for maximum flexibility
- Interchangeable with other reducing/relieving cartridges of the same frame size
How It Works: It reduces pressure from inlet port 2 to a controlled lower pressure at port 1, with relief capability to tank at port 3. If the downstream pressure exceeds the setting, the valve automatically shifts to relieving mode, protecting the secondary circuit from overpressure.
Applications:
- Clamping circuits requiring lower pressure than main system
- Pilot pressure supply circuits
- Multi-pressure hydraulic systems
- Secondary actuator circuits with different pressure requirements
Important Consideration: Control pilot flow rates of 7-10 in³/min (0.11-0.16 L/min) are required for optimal operation, so proper circuit design is essential.
5. Pilot-to-Open Check Valve
Category: Directional Control | Capacity: 15 gpm (60 L/min) | Cavity: T-11A | Pilot Ratio: 3:1
The Pilot-to-Open Check Valve is a critical component for load-holding applications. It allows free flow in one direction while blocking reverse flow until pilot pressure commands it to open – making it essential for holding vertical loads or preventing unintended actuator movement.
Key Features:
- Non-sealed pilot design
- Steel seat for durability
- Non-vented configuration
- 3:1 effective pilot ratio
- Physically interchangeable with counterbalance valves of the same frame size
Operation: The valve allows free flow from port 2 (valve side) to port 1 (load side) while blocking flow in the opposite direction. Pilot pressure at port 3 opens the valve, with the required pilot pressure being directly proportional to the load pressure at port 1.
Critical Application Note: Pilot-to-open check valves should be mounted as close to the actuator as possible to provide maximum protection in the event of hydraulic hose or line failure. These are locking valves designed for load holding – not motion control valves. For motion control applications, counterbalance valves should be used instead.
Typical Uses:
- Vertical cylinder load holding
- Safety locking for elevated platforms
- Emergency stop functions
- Hydraulic brake circuits
6. FLeX Series 2-Way Solenoid-Operated Directional Valve
Category: Directional Control | Capacity: 10 gpm (40 L/min) | Cavity: T-162A | Series: FLeX Series 0
This component represents Sun Hydraulics’ advanced FLeX Series technology. The pilot-operated, normally closed directional poppet valve combines low leakage with high reliability, making it ideal for modern electro-hydraulic control systems.
Key Features:
- Extremely low leakage (less than 1 drop/min or 0.07 cc/min)
- Reverse flow check allows flow from port 1 to port 2
- Zinc-nickel plating standard for 1000-hour salt fog protection
- Designed and tested to 10 million operational cycles at full-rated pressure
- Compatible with wide variety of coil options (740 and 747 series)
FLeX Series Advantages: The FLeX Series valves exceed NFPA test standard T2.6.1 R2014 for fatigue and burst pressure ratings. They’re engineered for demanding environments and offer higher flow rates than competing valves of similar size.
The valve includes Sun’s floating style construction to minimize binding, ensuring reliable operation even under challenging installation conditions.
Applications:
- Electrohydraulic control systems
- Remote directional control
- On/off flow control
- Load isolation circuits
- Industrial automation systems
Coil Flexibility: Available with various voltage options and surge protection, the DFBGXCN can be configured for your specific electrical requirements with connector options rated up to IP69K for harsh environments.
7. Line Mount Manifold
Category: Manifolds | Type: Line Mount | Cavity: T-11A
The Line Mount Manifold is a versatile line mount manifold that serves as the foundation for compact, integrated hydraulic circuits. As the “plumbing” that connects cartridge valves, Sun manifolds like the ECI enable system designers to create efficient, leak-free hydraulic control systems.
Key Features:
- Compact design through 5-axis compound drilling
- Lighter weight than traditional manifold designs
- Fewer leakage points and construction plugs
- Lower manufacturing cost compared to 3-axis straight hole drilling
- Compatible with T-11A cavity cartridges
Sun’s Manufacturing Innovation: Unlike traditional manifolds made with 3-axis straight hole drilling, Sun uses 5-axis compound drilling technology. This advanced manufacturing method allows for:
- More direct fluid paths
- Reduced pressure drops
- Smaller overall package size
- Enhanced reliability
Material Advantages: Sun manifolds are constructed from 6061-T651 aluminum, one of the most corrosion-resistant aluminum alloys available. Importantly, Sun does not anodize their aluminum manifolds – and for good reason. Anodizing can reduce fatigue life by 20-50% by creating a brittle surface that initiates cracks under pressure cycling.
Applications:
- Custom integrated hydraulic circuits
- Mobile equipment control packages
- Industrial machinery manifold assemblies
- Replacement for stacked valve configurations
8. Line Mount Cross Pilot Manifold
Category: Manifolds | Type: Line Mount Cross Pilot | Material: 6061 Aluminum | Port Size: SAE 6
The Line Mount Cross Pilot Manifold is specifically designed for cross pilot applications, where pilot pressure from one valve controls another. This configuration is common in sophisticated hydraulic circuits that require sequencing or load-sensing capabilities.
Key Features:
- Two mounting holes (0.34 inch / 8.6 mm diameter, through body)
- Two open cavities for T-11A cartridges
- SAE 6 port compatibility
- 6061 aluminum construction
- Maximum pressure rating: 3000 psi (210 bar) for aluminum construction
Design Advantages: The cross pilot design allows for efficient pilot signal routing between cartridges without external plumbing. This results in:
- Faster response times
- Fewer potential leak points
- More compact installations
- Reduced system complexity
Critical Pressure Consideration: While manifolds can be constructed from ductile iron for higher pressure ratings (up to 5000 psi), aluminum manifolds like this are limited to 3000 psi (210 bar) regardless of port size. System designers must carefully consider maximum system pressure when specifying manifold materials.
Applications:
- Load-sensing systems
- Pressure-compensated circuits
- Sequential valve operations
- Complex logic circuits
9. Logic Element Valve
Category: Directional Control | Type: Logic Element | Capacity: 25 gpm (95 L/min) | Cavity: T-11A
Logic element valves are the building blocks of sophisticated hydraulic control circuits. These unbalanced, vent-to-open valves serve as 2-way switching elements that enable complex hydraulic logic without the need for electronic controls.
Key Features:
- Spring-biased closed design
- Port 1 serves as pilot source
- Functions as check valve in reverse direction when vent is blocked
- Opens when port 3 is vented with sufficient pressure
- Enables pure hydraulic logic circuits
How It Works: The component remains closed in the 1-to-2 direction when port 3 is blocked, functioning as a check valve from 2 to 1. When port 3 is vented, the valve opens (provided sufficient pressure exists to overcome the spring force). The valve closes when the combined forces at port 3 and spring pressure exceed the sum of forces at ports 1 and 2.
Applications:
- Hydraulic sequencing circuits
- Load-sensing control
- Accumulator charging/discharging
- Hydraulic logic gates
- Energy-saving circuits
Advantage Over Electronic Controls: In harsh environments or safety-critical applications, pure hydraulic logic offers advantages over electronic controls: no electrical components to fail, inherent reliability, and operation independent of electronic signals or sensors.
10. FLeX Series 2-Way Direct-Acting Solenoid Valve
Category: Directional Control | Capacity: 9 gpm (34 L/min) | Cavity: T-162A | Series: FLeX Series 0
Rounding out our top 10 is the 2-Way Direct-Acting Solenoid Valve, another member of Sun’s advanced FLeX Series. This direct-acting, normally closed valve offers the advantages of FLeX technology in a fast-response, direct-acting design.
Key Features:
- Direct-acting design for fastest possible response
- Pressure-balanced for reliable operation
- Low leakage performance
- Bidirectional flow control (flow or blocking in both directions)
- Suitable for load-holding applications when configured as normally closed
- Designed and tested to 10 million operational cycles
Direct-Acting vs. Pilot-Operated: Unlike the pilot-operated 2-Way Solenoid-Operated Directional Valve, this is direct-acting, meaning the solenoid directly controls the poppet position. This provides:
- Faster response time
- Simpler construction
- Higher reliability in certain applications
- Better performance in lower flow applications
Safety Feature: In the event of power failure, the valve automatically closes, making it ideal for safety-critical applications where loss of power should result in load holding or system shutdown.
Applications:
- Emergency stop circuits
- Fail-safe load holding
- High-speed directional control
- Battery-powered mobile equipment
- Safety interlock systems
FLeX Series Benefits: Like all FLeX valves, the DTBFXCN features Sun’s floating nose design, zinc-nickel plating for corrosion resistance, and compatibility with a wide range of coil voltages and connector options.
Why Hydra Power Systems for Sun Hydraulics?
Largest Inventory in the USA
We maintain the most comprehensive Sun Hydraulics inventory in the United States across our Portland and Birmingham facilities. This means same-day or next-day shipping on the components you need most.
Expert Technical Support
Our team doesn’t just sell components – we design complete hydraulic systems. With decades of combined experience, we can help you:
- Select the right valve for your application
- Design custom manifold circuits
- Troubleshoot existing systems
- Optimize performance and efficiency
Custom Manifold Design and Manufacturing
Beyond component distribution, Hydra Power Systems specializes in designing and manufacturing custom integrated circuit hydraulic manifolds. We use AutoCAD, Inventor, and Vest’s MDTools software for design, and Mastercam X7 for programming our CNC machining centers.
Our proprietary methods for deburring, cleaning, assembly, and testing ensure that every manifold we produce meets the highest quality standards. Whether you need:
- Proportionally controlled vacuum manifolds
- Actuator-mounted manifolds
- Electronic governor manifolds
- Custom high-pressure or low-pressure filter manifolds
We have the expertise and equipment to deliver.
Strategic Locations
With facilities in Portland, Oregon, and Birmingham, Alabama, we provide coast-to-coast coverage with localized service. Our strategic positioning ensures:
- Rapid shipping to customers nationwide
- Regional technical support
- Reduced freight costs
- Local inventory management
Industry Experience
Since 1970, we’ve served diverse industries including:
- Nuclear power plants – where reliability is non-negotiable
- Hydroelectric facilities – demanding precision and longevity
- Mobile equipment – requiring robust, field-serviceable solutions
- Marine applications – where corrosion resistance is critical
- Agricultural equipment – needing versatile, adaptable systems
- Construction machinery – demanding high performance under harsh conditions
- Industrial manufacturing – requiring consistent, efficient operation
The Sun Hydraulics Advantage
Floating Cartridge Construction
Sun’s proprietary floating cartridge construction is a game-changer for system reliability. Traditional cartridge valves can bind if installation torque is uneven or if cavity machining has slight variations. Sun’s floating design accommodates these real-world installation conditions, ensuring:
- Consistent performance across varying installation conditions
- Reduced sensitivity to torque specifications
- Better tolerance of machining variations
- Extended service life
Comprehensive Product Line
Sun offers cartridges in five primary sizes (Series 0, 1, 3, 4, and Series 4.4), with each successive size roughly doubling the flow capacity. This scalability means you can use the same design approach across different machine sizes – just scale the cartridge size to match your flow requirements.
Interchangeability
Within each frame size, Sun maintains physical and functional interchangeability across valve families. For example:
- All 2-port relief cartridges of the same frame size are interchangeable
- All 3-port counterbalance, load control, and pilot-to-open check cartridges share the same cavity for a given frame size
This interchangeability simplifies inventory management, enables rapid troubleshooting, and provides design flexibility.
Quality and Testing
Every Sun cartridge valve is manufactured to exacting standards and undergoes rigorous testing. FLeX Series valves, for example, are designed and tested to 10 million operational cycles at full-rated pressure – a testament to Sun’s commitment to longevity and reliability.
Maintenance and Service Considerations
Field Serviceability
Sun cartridge valves are designed with field service in mind:
- External seals are serviceable – Sun offers replacement seal kits for all cartridge models
- Internal components are not field serviceable – cartridges are replaced as complete assemblies
- Seal kits are application-specific – converting external seals doesn’t ensure fluid compatibility due to internal seals
Troubleshooting Tips
Cylinder Drift: If experiencing cylinder drift, don’t automatically assume a failed counterbalance valve. Also check:
- Cylinder seal leakage
- Oil temperature changes causing volume changes
- Whether the counterbalance valve seat has been damaged (contamination or shock)
Pressure Inconsistency: For pressure control valve issues:
- Verify the valve is within its adjustment range
- Check for contamination in the pilot section
- Ensure pilot drain paths are not blocked
- Confirm proper spring range selection for application pressure
Slow Response: If valves seem sluggish:
- Check for proper pilot flow rates (especially on pilot-operated valves)
- Verify oil viscosity is within specifications
- Inspect for contamination restricting flow paths
The synergy between Sun Hydraulics’ engineering excellence and Hydra Power Systems’ distribution expertise, technical knowledge, and manufacturing capabilities creates unmatched value for our customers. These top 10 products represent proven solutions to common hydraulic challenges, backed by decades of field experience and continuous innovation.
From pressure control to directional control, from load holding to logic functions, these components form the foundation of reliable, efficient hydraulic systems across countless applications and industries.
Ready to experience the Hydra Power Systems difference? Contact us today to discuss your hydraulic component needs, custom manifold requirements, or system integration projects. Our team is standing by to provide the expertise and support that has made us a trusted partner since 1970.
Moving Forward with Sun Hydraulics and Hydra Power Systems
The 10 components highlighted in this article represent just a fraction of the Sun Hydraulics product line available through Hydra Power Systems. Whether you’re designing a new machine, upgrading an existing system, or troubleshooting a hydraulic issue, our team is here to help.