Hengstler AX71 0539799 Absolute Rotary Encoder

Hengstler AX71/1213EK.72SGX-K0:5777 (Part No: 0539799) Explosion-Proof Absolute Rotary Encoder

The Hengstler AX71/1213EK.72SGX-K0:5777 (Part Number: 0539799) is a flameproof optical absolute rotary encoder engineered for high-risk offshore, marine deck machinery, petrochemical facilities, and heavy industrial automation. Encased in a massive, seawater-resistant AISI 316/DIN 1.4404 grade stainless steel housing (70 mm outer diameter), this instrument is designed specifically to operate without failure under continuous salt spray, high humidity, corrosive atmospheres, and mechanical shock up to 1,000 m/s².

This unit provides true multi-turn absolute position feedback via a synchronous serial interface (SSI) utilizing Gray code output format. With an overall resolution of 25 bits (13-bit single-turn resolution offering 8,192 steps per revolution, and 12-bit multi-turn tracking up to 4,096 complete rotations), the encoder eliminates the need for battery buffering or homing sequences following power interrupts. It carries comprehensive ATEX and IECEx flameproof certification (Ex d / Ex tb), certified for operation across Zone 1, 2, 21, and 22 hazardous environments.

Model Details:

• Manufacturer / Brand: Hengstler GmbH (Dynapar / Fortive Group)
• Full Model Code: AX71/1213EK.72SGX-K0:5777
• Manufacturer Part Number (MPN): 0539799
• OEM Customer Cross-Reference: National Oilwell Varco (NOV) P/N: 149217-001+71
• Order Model Deconstruction:
  • AX71: Heavy-duty, ATEX/IECEx explosion-proof series in solid stainless steel construction.
  • 1213: Total 25-bit resolution (12-bit multi-turn [4,096 revs] + 13-bit single-turn [8,192 steps]).
  • E: Wide input power supply rating: DC 10 V to 30 V.
  • K.72: Clamping flange mounting, IP67 environmental sealing class, 10 mm solid drive shaft.
  • SG: Synchronous Serial Interface (SSI) configured for Gray Code transmission.
  • X-K0: Factory-sealed, integrated offshore-rated connecting cable, axial exit, 10-meter operational length.
  • :5777: Factory custom/application configuration tag for specialized marine, crane, and oilfield winch systems.

Technical Specifications

Terminal Allocations & Cable Wiring Schedule

Features

1. True Mechanical 25-Bit Gear Train: Combines 13 bits of optical single-turn angular resolution with a precision 12-bit gear reduction multi-turn train, maintaining absolute positioning throughout 4,096 rotations without external battery backups or optical counting rings.
2. Marine-Grade AISI 316 Stainless Steel Shell: Constructed entirely from non-corrosive DIN 1.4404 austenitic stainless steel, rendering the housing immune to chemical washdowns, offshore brine spray, and harsh drilling muds.
3. Certified Flameproof Ex d / Ex tb Enclosure: Fully certified under ATEX/IECEx PTB directives to prevent ignition in explosive volatile hydrocarbon environments (Zone 1/21 hazardous areas).
4. High-Integrity IP67 Sealed Shaft System: Features dual fluorocarbon (Viton) radial shaft seals that maintain ingress barrier security against high-pressure washdowns and standing water while tolerating shaft loads up to 100 N radial / 40 N axial.
5. Point-to-Point Noise-Immune SSI Interface: Employs RS-422 differential transmission with Gray code encoding to prevent multi-bit transit glitches, enabling reliable position reading across extended cable runs up to 100 meters.

Frequently Asked Questions

What is the primary difference between Hengstler AX70 and AX71 series encoders?

While both series share identical electrical circuits, resolutions, and explosion-proof internal architecture, the housing materials differ. The AX70 utilizes an anodized aluminum enclosure (approx. 1.4 kg), suitable for indoor industrial and paint production environments. The AX71 is manufactured from heavy-duty AISI 316 / 1.4404 grade stainless steel (approx. 4.8 kg), designed specifically for marine splash zones, offshore oil rigs, chemical processing plants, and food-grade corrosive environments.

Does the AX71/1213EK.72SGX-K0:5777 lose its multi-turn position if system power is cut off?

No. The AX71 1213 utilizes a mechanical reduction gear train for multi-turn revolution counting (up to 4,096 absolute turns). Unlike battery-backed electronic counters that can drop tracking during extended ship layup or dry docking, the AX71’s position is recorded mechanically by physical gear positions. True absolute position is instantaneously read and transmitted over the SSI bus the moment electrical power is restored, eliminating the need for homing cycles.

Can the AX71 0539799 replace the National Oilwell Varco (NOV) P/N 149217-001+71?

Yes. The Hengstler 0539799 with configuration code AX71/1213EK.72SGX-K0:5777 is the direct OEM manufacturer component supplied under NOV part number 149217-001+71. It shares the identical 10 mm shaft diameter, clamping flange pattern, SSI Gray code 25-bit format, and 10-meter potted axial cable.

What is the maximum permissible clock frequency for this SSI encoder?

The internal optical sensor and RS-422 drivers support SSI clock frequencies from 100 kHz up to 1.5 MHz. However, on marine deck installations with the standard 10-meter factory cable, or when extending signals back to a remote I/O rack, signal propagation delay requires adjusting the PLC/master clock frequency. Recommended operating parameters are 100 kHz to 250 kHz for runs up to 50 meters, and up to 400 kHz for short panel runs under 10 meters.

How do I verify if the encoder’s shaft seal maintains its IP67 explosion-proof barrier?

During overhaul or survey inspection, examine the shaft runout and check the Viton radial lip seal for hardening, cracks, or salt crusting. The explosion barrier depends on precision dimensional tolerances along the flameproof path of the shaft collar. If there is noticeable radial shaft play (>0.05 mm) or axial end-play exceeding 0.1 mm, the bearings must be replaced by an authorized ATEX certified facility to prevent hot gas propagation in explosive environments. Always replace external shaft V-rings during scheduled winch maintenance.