Mitsubishi HC-SFS102G1H AC Servo Motor with Reduction Gear

MELSERVO-J2S Series | 1 kW | 2000 RPM Motor | G1H Gearhead | Flange Output | IP65

When Speed Reduction Is Part of the Brief

Not every motion control axis calls for direct drive. Slow-moving rotary tables, articulated robot joints, indexing mechanisms, and precision feed assemblies often need more torque at a lower output speed than a bare servo motor can deliver — and they need that torque delivered with a consistent, predictable gear mesh rather than an external transmission that introduces its own alignment variables.

The Mitsubishi HC-SFS102G1H answers that need directly. It combines the HC-SFS102 AC brushless servo motor with a G1H reduction gearhead designed specifically for general industrial machine applications — producing an integrated gearmotor unit with a flange output shaft, built for real installation environments rather than just test bench conditions.

Base Motor Specifications (HC-SFS102)

The G1H Gearhead — What It Adds and Why It Matters

The "G1" designation in Mitsubishi's HC-SFS naming refers to the reduction gear variant engineered for general industrial machines. The "H" indicates a hollow flange output — where the gear output is delivered through a flanged face rather than a protruding shaft, which simplifies mounting to rotary tables, turret assemblies, and disc-type loads without requiring additional coupling hardware.

Available reduction ratios in the G1H family for the HC-SFS series are 1/5, 1/12, and 1/20. The ratio fitted to a specific HC-SFS102G1H unit determines the output speed and the proportional torque multiplication. At a 1/12 ratio, for example, the 2000 RPM motor input yields an output speed of approximately 167 RPM, while the available output torque rises in proportion to the gear ratio (less efficiency losses). This trades rotational speed for the holding force and torque density that compact gear-driven mechanisms require.

Compared to Mitsubishi's G5/G7 precision gear variants, the G1H is engineered for general industrial duty — optimized for robustness, load capacity, and serviceability across a wider range of application conditions rather than the ultra-low backlash requirements of optical or metrology equipment.

17-Bit Absolute Encoder — The Foundation of the Feedback Loop

Everything downstream of the control loop depends on what comes back from the encoder. At 131,072 pulses per revolution, the HC-SFS102's built-in absolute encoder sits well above the 16,384 ppr available on the standard HC-SF102 variant — an 8× resolution advantage that smooths low-speed motion and tightens the positional accuracy of the entire geared system.

Because the encoder is absolute, position data survives power interruptions intact. Restart a machine mid-cycle, recover from an E-stop, or resume after a planned shutdown — the control system reads the current position immediately on power-up, regardless of where the output shaft ended up. For applications involving vertical axes or precision indexing, that capability removes an entire class of potential errors from the operational picture.

Servo Amplifier Compatibility

The HC-SFS102G1H is controlled via the same MR-J2S servo amplifier family as the standard HC-SFS102. Compatible amplifiers for the 1 kW power class include:

The gearhead is mechanically attached to the servo motor and is transparent to the amplifier — no special amplifier configuration is required specifically for the G1H variant. The encoder cable connects via the standard CN2 port, and the motor power wiring follows the same U, V, W terminal arrangement as the rest of the MR-J2S family.

Application Fit — Where This Unit Belongs

The HC-SFS102G1H serves best where moderate output torque, compact packaging, and integrated position feedback are more valuable than raw speed. Documented application areas for the HC-SFS G1H series include:

• Rotary indexing tables — where precise angular positioning at low output speeds is the primary requirement
• Robot joint axes — shoulder and elbow drives on small-to-medium-sized industrial robots
• Turret assemblies — tool turrets on turning centers where stiffness at low speed determines repeat accuracy
• Conveyor and transfer systems — speed-reduced drives on indexing conveyors and walking beam transfers
• Winding and tension control — constant tension regulation across changing spool diameters
• Loaders and unloader mechanisms — compact drive packages in parts handling equipment

IP65 and Oil Seal — Standard Equipment, Not an Upgrade

Both the IP65 protection rating and the built-in oil seal come as standard on the HC-SFS102G1H. That combination matters for a geared motor: the gear unit itself runs in oil, and the interface between the motor shaft and the gearbox is exactly where fluid intrusion into the motor body would otherwise occur. The oil seal closes that gap. IP65 takes care of the rest of the motor body — blocking dust and water jet exposure from the installation environment.

The oil seal lip requires the gear oil level in the gearbox to be maintained below the seal contact point when the unit is horizontally installed. Mitsubishi's instruction manual specifies installation orientation restrictions for the G1H gearhead to ensure oil management works as intended — details worth confirming before final machine layout is fixed.

Frequently Asked Questions

Q1: What output torque and speed can I expect from the HC-SFS102G1H?

Output depends on which gear ratio is fitted — 1/5, 1/12, or 1/20. At the rated motor torque of 4.78 N·m, a 1/12 ratio yields approximately 47–52 N·m at the output (accounting for gear efficiency), while output speed drops to roughly 167 RPM at rated motor speed. Confirm the specific ratio on your unit's nameplate before sizing the application.

Q2: Is the G1H a precision gearhead, or a standard industrial type?

The G1H is the general industrial gear variant in Mitsubishi's HC-SFS gearhead range. It prioritizes robustness and load capacity for general automation tasks. For applications requiring minimal backlash — metrology equipment, semiconductor handling, or high-precision positioning — the G5 and G7 variants are the appropriate choices instead.

Q3: Does the gear ratio affect how the servo amplifier is configured?

The amplifier itself requires no special configuration for the gearhead. The encoder still reads the motor shaft position at 131,072 ppr. Position loop scaling for the reduced output speed is handled through the electronic gear ratio parameters in the MR-J2S amplifier — specifically the command pulse multiplier settings — which compensate for the mechanical reduction in the control calculations.

Q4: Can the HC-SFS102G1H be mounted in any orientation?

Orientation restrictions apply because of the gear oil inside the G1H gearbox. The motor must be installed in a direction that keeps gear oil below the oil seal lip on the motor shaft. Mitsubishi's servo motor instruction manual (SH030052) includes orientation diagrams for each reduction gear type. Ignoring these can result in oil migration into the motor body, causing insulation degradation and bearing contamination.

Q5: Is the HC-SFS102G1H still in production, and are spare units available?

The HC-SFS102 base motor and the G1H gearhead series belong to the MELSERVO-J2S generation, which Mitsubishi has phased out in favor of newer platforms. Complete G1H units are available through certified surplus and authorized refurbishment suppliers. Given the large installed base of J2S systems still running in production facilities globally, supply availability for both new old stock and refurbished units remains reasonably stable. Stocking a spare is advisable for facilities running multiple machines with this configuration.