Hydraulic Drive for OSA, built for 150 kgf/cm² closed-loop actuation.

Introduction

The Neometrix Hydraulic Drive for OSA is a purpose-built electro-hydraulic actuator designed to meet the demanding requirements of short-range, vehicle-mounted air-defence radars.

At its heart lies a compact, brushless synchronous motor directly coupled to a high-pressure gear pump, all mounted within a sealed, corrosion-resistant housing. By converting the 220 V/400 Hz electrical “command” signal from the fire-control computer into finely metered hydraulic flow, the unit precisely drives the radar antenna's actuator cylinder in both elevation and azimuth axes. This dual-drive approach (μ-drive for elevation, η-drive for azimuth) enables sub-degree pointing accuracy, rapid slew rates, and stable holding under recoil and vehicle vibration — all critical for maintaining a continuous track on fast-moving targets in adverse environments.

Beyond its primary role on the 9K33 “Osa”/Osa-AK (SA-8 Gecko) missile launcher, the drive's rugged construction and legacy interface make it a drop-in replacement for any turreted sensor package requiring closed-loop hydraulic actuation. Its standardized electrical connector and hydraulic ports ensure seamless integration with both Soviet-era and modern NATO-compatible fire-control systems.

Applications

The drive's versatility extends well beyond its primary role in the 9K33 “Osa”/Osa-AK air-defence system. On mobile radar platforms — whether tracked vehicles, 4×4 surveillance vans, or rapidly deployable coastal towers — the drive's sealed, vibration-damped housing and compact footprint allow for straightforward integration with onboard generators or NATO-standard power supplies. Its rapid “command-to-move” response (under 0.5 seconds) and sub-degree pointing accuracy ensure the Target Acquisition Radar remains locked onto fast-moving aerial threats, even during vehicle maneuvering, firing recoil, or harsh environmental conditions. Over-pressure safety valves and real-time pressure feedback automatically inhibit actuation on fault detection, preventing mechanical overshoot and safeguarding both equipment and personnel.

Beyond defence, these hydraulic actuators find homes in high-precision electro-optical/infrared (EO/IR) turrets, industrial test benches, and research labs. In EO/IR applications — such as stabilized camera gimbals for border security or search-and-rescue missions — the drives deliver sub-milliradian stability and smooth slew control, enabling uninterrupted high-resolution imaging and precise laser designator pointing. In aerospace and automotive test rigs, their configurable valve block and proportional throttle support repeatable fatigue and performance testing under high loads.

Furthermore, the drive's modular design makes it ideal for retrofitting legacy mechanical gimbals into closed-loop hydraulic systems, as well as for subsea and ROV deployments when paired with deep-sea–rated fluids and seals.

Technical specifications

Operating parameters

Under normal operation, the drive is connected in a closed-loop hydraulic circuit. Pressure ports A and B are alternately pressurized to actuate the cylinder rod, with each cycle monitored for leakage, stability, and noise. Functional testing includes continuous operation at rated input frequency for one hour and 20 actuation cycles under full load to ensure smooth cylinder motion and pressure stability.

Overhaul & maintenance procedures

Neometrix Defence follows a rigorous nine-step overhaul protocol:

1. Inspection & functional test: visual inspection and on-site functional trials to identify surface damage, loose fasteners, noise, and leaks.
2. Disassembly: systematic removal of tubing, valve box, pump casing, motor components, and transducers.
3. Fault diagnosis: detailed logging of wear, corrosion, damaged seals, and electrical anomalies.
4. Cleaning & surface preparation: air, acetone, and hot-water cleaning of all parts; emery-paper polishing for metallic surfaces.
5. Lubrication & greasing: application of clean hydraulic oil to moving parts and grease to bearings.
6. Component replacement: renewal of worn tubes, seals, nozzles, gaskets, bolts, washers, and filters.
7. Sub-component repair: varnish recoating of motor windings, safety-valve service, and throttle valve calibration.
8. Reassembly: sequenced assembly of pump, motor, valve box, transducers, and piping with torque-controlled fasteners.
9. Painting & surface finish: rust removal, primer and topcoat application, and final surface finishing.

Quality assurance & testing

• Factory Acceptance Test (FAT): validates motor RPM at 400 Hz, leak-free operation, pressure stability, and noise levels.
• Site Acceptance Test (SAT): includes dimensional checks, visual inspection, protective coating integrity, functional endurance, and environmental performance in the −40°C to +50°C range.

Conclusion

The Neometrix Hydraulic Drive for OSA combines precision, durability, and maintainability to meet the demanding requirements of modern air defence and surveillance platforms. With comprehensive overhaul support and stringent quality testing, it ensures uninterrupted performance in even the harshest operational environments.