SD Series Mobile Slewing Drive Planetary Gearbox

Planetary Gear Transmission

Power enters via the input shaft coupled to a hydraulic axial-piston motor or IEC electric motor. The sun gear meshes with multiple planet gears orbiting inside a fixed ring gear. Load is shared across all planets simultaneously — delivering 3–5× higher torque density than equivalent parallel-shaft gearboxes at the same size and weight.

By stacking 1 to 4 planetary stages, the slewing planetary gearbox achieves gear ratios from 5:1 up to 3,000:1, keeping the motor, gearbox, and output pinion in a perfectly aligned coaxial arrangement.

SAHR Brake & Load Holding

The integrated Spring Applied Hydraulic Released (SAHR) wet multi-disc brake sits between the motor and first reduction stage. It engages automatically whenever hydraulic pressure drops — preventing uncontrolled rotation under full suspended load without any operator action.

This eliminates the need for an external brake in most crane configurations and meets FEM 1.001 Section I crane safety requirements out of the box.

Industry-Leading Torque Density

Planetary architecture distributes load across all planet gears simultaneously — achieving 3–5× higher torque density than parallel-shaft gearboxes at the same weight and envelope size.

Integrated SAHR Safety Brake

Built-in spring-applied multi-disc brake holds static loads on power failure. FEM 1.001 compliant — no external brake required for most mobile crane slewing applications.

Bolt-On OEM Replacement

Dimensionally identical to Bonfiglioli 700T, Bosch Rexroth GFB, and Dana Brevini SD. Zero machine modification — swap, reconnect hydraulics, and run within hours.

Universal Motor Compatibility

Accepts axial-piston hydraulic motors, orbital motors, and IEC electric motors. Optional integrated valve block creates a complete slewing drive gearbox with hydraulic motor unit.

Precision Low-Backlash Output

Precision-ground gears and heavy-duty tapered roller bearings deliver accurate, repeatable load positioning. Optional eccentric housing for on-site backlash fine-tuning against the slewing ring.

Harsh-Environment Durability

IP65+ rated with Viton FKM seals and marine-grade epoxy coating. Operates reliably in salt spray, sub-zero temperatures, and continuous high-dust construction or port environments.

🏗️ Modular Coaxial Architecture

🔬 Key Materials & Processes

Companion Product

Hydraulic Planetary Motor — Matched & Pre-Assembled

Q1 · Is the SD Series a true bolt-on Replacement of Bonfiglioli Planetary Gearbox 700T?

Yes — SD033–SD340 is dimensionally identical to the Bonfiglioli 700T1F, 701T1F, 703T2F, 705T2F, 705T2L, 706T2N, and 707T2N models. The following are all identical:

Q2 · Can the SD series ship as a complete slewing drive gearbox with hydraulic motor assembly?

Yes. We supply fully assembled, leak-tested units combining the SD gearbox with a matched hydraulic motor and valve block. Specify the following when ordering:

Q3 · How do I select the right model as a planetary gearbox for mobile crane slewing?

Provide four parameters — our engineering team confirms the correct model within 24 hours:

Q4 · What is the recommended maintenance schedule for the slewing drive gearbox?

Q5 · What certifications and standards does the SD Series comply with?

Every unit undergoes no-load run test, noise measurement, vibration check, and loaded performance verification before shipment.

Q6 · Can the SD series be used with an electric motor instead of a hydraulic motor?

Yes. IEC B5/B14 motor adaptor flanges are available for all SD models. Key points for electric motor configurations:

• Electric version does not include SAHR brake — an external electromagnetic or disc brake on the motor shaft is required for static load holding
• Commonly used in welding positioners, industrial turntables, robot base joints, and assembly systems
• Compatible with inverter-driven motors for variable speed control and closed-loop positioning via encoder feedback

Q7 · What is the expected service life of the slewing planetary gearbox?

Actual life depends on load class, duty cycle, lubrication quality, and operating temperature. Correct oil grade and adherence to the change interval are the single largest factors in achieving rated life.

Q8 · How does the eccentric mounting option work, and when is it needed?

On certain SD models, the output pinion axis is intentionally offset from the gearbox housing axis. By rotating the housing during installation, the engineer adjusts the centre distance between the pinion and the slewing ring bull gear — enabling precise backlash control without shimming or re-drilling mounting holes. This is most valuable when replacing a worn gearbox where the ring gear has experienced slight runout, or during initial commissioning of large crane slewing systems that require fine pinion-to-ring mesh adjustment on site. Simply loosen the housing clamp bolts, rotate the eccentric housing to the desired position, and re-tighten.

Q9 · What lubrication oil is recommended, and how much does the gearbox require?

Q10 · What are the lead times, and are custom gear ratios available?

Need a specific ratio? Contact our slewing drive gearbox engineers with your target ratio — we'll confirm feasibility within 24 hours.