RDDA-LAN RDDA-LWN CBCA-LHN CBBA-LHN Sun Hydraulics Relief Valve 350 bar

Product Overview

⚠️ Important Brand Attribution Note

All models in this product range have been verified to belong to Sun Hydraulics brand, not Parker as may be implied in the original title. Sun Hydraulics is a globally leading manufacturer of screw-in hydraulic cartridge valves, renowned for high reliability, superior performance, and exceptional interchangeability. Model attribution is as follows:

• RDDA-LAN, RDDA-LWN: Sun Hydraulics RDDA series Direct-Acting Relief Valves

• CBCA-LHN: Sun Hydraulics CBCA series Counterbalance Valve with pilot assist

• CBBA-LHN: Sun Hydraulics CBBA series Motion Control Valve with pilot assist

RDDA series direct-acting relief valves are normally closed, pressure-limiting valves designed to protect hydraulic systems from pressure transients. When inlet pressure (port 1) reaches the set value, the valve opens, allowing flow from port 1 to tank (port 2), throttling flow to limit further pressure rise.

CBCA-LHN and CBBA-LHN are counterbalance valves with pilot assist, designed to control overrunning loads. They allow free flow from the directional valve (port 2) to the load port (port 1), while the direct-acting, pilot-assisted relief function controls flow from port 1 to port 2. The pilot pressure at port 3 reduces the effective setting of the relief function by a factor of the pilot ratio (3:1).

Our complete range of Sun Hydraulics cartridge valves strictly adheres to OEM technical standards, achieving 100% direct interchangeability with original components. Every unit undergoes 100% simulated operating condition bench testing prior to shipment, ensuring performance parameters are fully consistent with genuine Sun Hydraulics products. Direct replacement significantly reduces equipment downtime and maintenance costs.

Technical Specifications 

RDDA-LAN (Direct-Acting Relief Valve)

• Product Series: Sun Hydraulics RDDA series direct-acting relief valve

• Model Code: RDDA-LAN

• Brand: Sun Hydraulics

• Product Type: Direct-acting relief valve

• Cavity: T-10A

• Maximum Operating Pressure: 350 bar (5000 psi)

• Adjustable Pressure Range: 35 – 210 bar

• Maximum Flow Capacity: 95 L/min (25 gpm)

• Leakage at Reseat: ≤ 10 drops/min

• Valve Hex Size: 7/8 in

• Installation Torque: 30 – 35 lbf·ft (approx. 40 – 47 Nm)

• Seal Material: NBR (standard)

• Spool/Poppet Material: Hardened, precision ground steel

• Operating Temperature Range: -40°C to +93.3°C (NBR seals)

• Recommended Filtration: ISO 4406 Code 16/13 or better

• Compatible Fluids: Mineral-based or synthetic hydraulic oils, viscosity 45-2000 SSU (6-420 cSt)

• Response Time: Approx. 2 ms

• Mounting Type: Screw-in cartridge

RDDA-LWN (Direct-Acting Relief Valve)

• Product Series: Sun Hydraulics RDDA series direct-acting relief valve

• Model Code: RDDA-LWN

• Brand: Sun Hydraulics

• Product Type: Direct-acting relief valve

• Cavity: T-10A

• Maximum Operating Pressure: 350 bar (5000 psi)

• Maximum Flow Capacity: 95 L/min (25 gpm)

• Leakage at Reseat: ≤ 10 drops/min

• Seal Material: EPDM

• Design Feature: Sun floating style construction minimizes internal binding risks

• Mounting Type: Screw-in cartridge

• Compatible Fluids: Phosphate ester fluids (EPDM seals)

• Caution: EPDM seals must not be exposed to petroleum-based fluids

CBCA-LHN (Counterbalance / Motion Control Valve)

• Product Series: Sun Hydraulics CBCA series counterbalance valve

• Model Code: CBCA-LHN

• Brand: Sun Hydraulics

• Product Type: Counterbalance valve with pilot assist

• Cavity: T-11A

• Maximum Operating Pressure: 350 bar

• Adjustable Pressure Range: 70 – 280 bar

• Maximum Flow Capacity: 60 L/min

• Port Configuration: 3-port

• Pilot Ratio: 3:1

• Recommended Housings/Accessories: ECV/S (1 cavity) or YEV/S (2 cavities)

• Mounting Type: Screw-in cartridge

• Function: Free flow from port 2 to port 1; pilot-assisted relief control from port 1 to port 2

CBBA-LHN (Motion Control / Counterbalance Valve)

• Product Series: Sun Hydraulics CBBA series motion control valve

• Model Code: CBBA-LHN

• Brand: Sun Hydraulics

• Product Type: Counterbalance valve with pilot assist

• Cavity: T-11A

• Maximum Operating Pressure: 350 bar

• Adjustable Pressure Range: 70 – 280 bar

• Maximum Flow Capacity: 20 L/min

• Port Configuration: 3-port

• Pilot Ratio: 3:1

• Recommended Housings/Accessories: ECV/S (1 cavity) or YEV/S (2 cavities)

• Mounting Type: Screw-in cartridge

Key Technical Advantages

1. Direct-Acting Relief Valves – Fast Response & Zero Leakage (RDDA-LAN / RDDA-LWN)

RDDA series direct-acting relief valves feature a normally closed design with extremely fast response (approx. 2 ms). When inlet pressure reaches the set value, the poppet opens rapidly, throttling flow to limit further pressure rise. The valve delivers essentially zero leakage, with leakage at reseat not exceeding 10 drops/min. The spool/poppet is manufactured from hardened, precision ground steel, ensuring long-term wear resistance and dimensional stability.

2. Dirt Tolerant & Immune to Silting – Reliable in Harsh Environments

RDDA series relief valves are dirt tolerant and immune to silting. The valve design is insensitive to oil-borne contamination and debris, maintaining stable opening characteristics and pressure control accuracy even in applications where fluid cleanliness is difficult to maintain. This makes them particularly suitable for construction machinery, mining equipment, and other harsh-environment applications.

3. Counterbalance Valves – Pilot Assist & Smooth Load Control (CBCA-LHN / CBBA-LHN)

CBCA-LHN and CBBA-LHN are counterbalance valves with pilot assist, specifically designed to control overrunning loads. Key functions include: free flow from port 2 to port 1; and direct-acting, pilot-assisted relief control from port 1 to port 2. The pilot pressure at port 3 reduces the effective relief setting by a factor of the 3:1 pilot ratio. These valves effectively prevent runaway loads and enhance operator safety.

4. Sun Floating Style Construction – Reduced Binding Risk (RDDA-LWN)

RDDA-LWN incorporates Sun Hydraulics’ patented floating style construction. This design significantly reduces the risk of internal parts binding due to excessive installation torque or cavity/cartridge machining variations. This innovative design enhances installation reliability and extends service life.

5. 100% Direct Interchangeability with Standardized Cavities

All models utilize Sun Hydraulics standard cavity designs—RDDA series uses T-10A cavity, while CBCA/CBBA series use T-11A cavity. All cartridge valves within the same cavity size are physically and functionally interchangeable. This standardization ensures 100% direct interchangeability without any manifold modification or system adjustment.

6. 100% Simulated Operating Condition Testing

Every unit undergoes 100% simulated operating condition bench testing prior to shipment, ensuring consistent, stable performance at rated pressure and flow.

Application Areas

• RDDA-LAN / RDDA-LWN (Direct-Acting Relief Valves) :

  • Hydraulic system overload protection and pressure limiting

  • Cross-port relief circuits

  • Load holding applications

• CBCA-LHN / CBBA-LHN (Counterbalance / Motion Control Valves) :

  • Load control and run-away prevention for excavator booms, arms, and buckets

  • Overrunning load control for cranes and lifting platforms

  • Smooth cylinder lowering control for injection molding and die-casting machines

  • Hydraulic motor braking and load holding for mobile machinery

Expert Maintenance Tips

1. Verify Model and Cavity Compatibility Prior to Installation

All models are screw-in cartridge valves. Confirm that the manifold cavity matches the valve—RDDA-LAN/RDDA-LWN require T-10A cavity, while CBCA-LHN/CBBA-LHN require T-11A cavity. Different cavity sizes are not interchangeable.

2. Correct Installation Torque

• RDDA-LAN: Recommended torque 30 – 35 lbf·ft (approx. 40 – 47 Nm)

• RDDA-LWN / CBCA-LHN / CBBA-LHN: Refer to Sun Hydraulics technical manual specifications

Use a torque wrench for precise torque control—never exceed the specified value. While Sun’s floating style construction reduces binding risk, over-torquing can still cause body distortion or seal failure.

3. Seal Material Selection

• RDDA-LAN: NBR seals, suitable for mineral-based hydraulic oils

• RDDA-LWN: EPDM seals, for phosphate ester fluids only—must not be exposed to petroleum-based fluids, as this will damage the seals

• CBCA-LHN / CBBA-LHN: Refer to specific model seal configuration

4. Pressure Setting and Adjustment

RDDA series relief valves have adjuster screw seals exposed to system pressure—system pressure must be relieved before making adjustments. Correct procedure: check current setting → relieve system pressure → adjust valve → re-pressurize and verify new setting. For optimal repeatability, select a spring range where the desired relief setting falls in the mid-to-high range of the spring’s capabilities.

5. Back Pressure Effects

Back pressure at the tank port (port 2) of RDDA series relief valves directly adds to the valve setting at a 1:1 ratio. Ensure tank line back pressure is as low as possible, or account for it during setting.

6. System Cleanliness Management

Although RDDA series offers good contamination tolerance, recommended system cleanliness is ISO 4406 Code 16/13 or better. CBCA/CBBA counterbalance valves have tighter internal clearances and require higher cleanliness levels.

7. Periodic Functional Checks

Perform functional checks every 2,000 operating hours or annually: RDDA series—verify cracking pressure accuracy and leakage within specification; CBCA/CBBA series—verify pilot assist function and load holding reliability. If abnormalities are observed, arrange for servicing or replacement.