Atos’ DHZO and DLHZO series are both proportional directional valves used across industrial and mobile hydraulic systems, and the naming convention alone doesn’t make the distinction obvious. The real difference comes down to onboard electronics, feedback type, and the level of control precision each series provides.
Here’s how the two compare, and what it means when you’re specifying a replacement or evaluating a unit for repair.
Onboard Electronics
The DHZO series is typically paired with an external amplifier card rather than integrated electronics, keeping the valve body simpler and separating the electronics for easier field replacement. The DLHZO series integrates the amplifier directly onto the valve, reducing wiring complexity but tying the electronics and mechanical body together as a single serviceable unit.
Feedback and Precision
Because the DLHZO’s integrated electronics typically include onboard spool position feedback, it holds tighter control precision and better repeatability under varying load than a DHZO paired with a basic external amplifier. The trade-off is that a DLHZO’s integrated electronics and mechanical spool need to be evaluated and repaired together rather than as separable components.
Repair and Calibration Considerations
When a DHZO valve fails, the external amplifier card and the valve body can often be diagnosed and repaired independently, which can simplify troubleshooting. A DLHZO requires calibrating the onboard electronics and spool feedback as a matched pair — using generic calibration data instead of the exact model’s parameters will produce a valve that tests inconsistently even after mechanical repairs are complete.
Which One Belongs in Your System
If your system already has an external amplifier setup and values simpler field serviceability, the DHZO is often the right fit. If your application needs tighter closed-loop precision in a more compact package, the DLHZO’s integrated design is generally the better choice. Either way, matching a replacement to the original series and electronics configuration matters more than matching flow rating alone.
Not sure which Atos series is currently installed in your system, or need one diagnosed and repaired to spec? Performance Servo can identify the exact DHZO or DLHZO variant and rebuild it with tested, calibrated electronics.