One New Mitsubishi Servo Motor HC-SFS203BG1 HCSFS203BG1 HC-SFS203BG1 New In Box Factory Sealed

Mitsubishi HC-SFS203BG1 (HCSFS203BG1) — 2kW AC Geared Servo Motor, Brake + G1 Flange-Type Reduction Gear, MELSERVO-J2S Series

Product Identification

Part Number: HC-SFS203BG1

Also Searched As: HCSFS203BG1, HC-SFS-203BG1

Series: Mitsubishi MELSERVO HC-SFS (J2-Super Generation)

Motor Type: AC Brushless Servo Motor with Integrated General Industrial Reduction Gear (Flange Type) and Electromagnetic Brake, 3000 rpm base

Condition: New In Box, Factory Sealed

What This Motor Is Built For

There is a specific class of drive system problem that a standard servo motor — even a well-specified one — cannot solve cleanly on its own: applications where the load requires substantially more torque than the motor delivers at its natural shaft speed, or where the driven mechanism must turn at a speed range that a direct-coupled motor cannot run efficiently. That problem is what the G1 reduction gear addresses.

The HC-SFS203BG1 combines a 2kW, 3000 rpm J2-Super servo motor with an integrated general industrial flange-type reduction gear unit in a single factory-assembled package. The gear unit is flange-mounted — meaning the gear housing uses the motor's standard flange mounting interface and presents its own output shaft at the driven end. The result is a compact, self-contained geared servo motor that connects to the machine directly, with no external gearbox to align, couple, and support separately.

The "B" in the model designates the electromagnetic brake, which on a geared motor has an important characteristic: it is located on the motor shaft, before the reduction gear. The brake's holding torque at the gear output therefore equals the brake's rated hold torque multiplied by the gear ratio. A motor-side brake that holds 6.37 Nm becomes a highly effective load-side hold once the gear stage multiplies it — a significant mechanical advantage for vertical axes, gravity-loaded arms, and applications that need reliable position hold at rest.

The 17-bit serial absolute encoder built into the J2-Super motor provides the same 131,072 ppr feedback that all HC-SFS motors carry — and critically, the encoder reads on the motor shaft, before the gear reduction. The amplifier sees full motor-shaft resolution regardless of what gear ratio is installed, and the absolute position counter covers multi-turn tracking across the full gear output shaft range, maintained through power-off by the A6BAT battery in the MR-J2S amplifier.

Technical Specifications

The G1 Gear Unit: Engineering and Application Context

Flange Type vs Leg Type

Mitsubishi offers two general industrial gear configurations for the HC-SFS range. The G1 (flange type) mounts the gear unit against the motor's front flange, with the output shaft projecting from the gear housing. The entire assembly attaches to the machine via the gear housing's output-side flange face. The G1H (leg type) uses a foot-mounted gear housing that mounts via bottom pads rather than a flange face — suited for different machine layouts where the output shaft loads would be better supported by the housing base.

For most standard machine tool and automation applications, the G1 flange type is the more common choice. It integrates cleanly into any machine frame that would normally accept a flange-mounted servo motor, with the gear housing simply extending the axial depth of the assembly while presenting the output shaft at the same centreline.

What the Gear Ratio Does to the Output Numbers

The 6.37 Nm rated torque of the HC-SFS203 motor is the figure at the motor shaft before any reduction. Once the gear unit is in the circuit, the output shaft produces torque multiplied by the gear ratio, minus gear losses. At a 1/20 ratio and typical spur/helical gear efficiency of around 85–90%, the effective continuous torque at the gear output approaches 108–115 Nm — and the output shaft speed at motor rated speed drops to 150 rpm. At a 1/9 ratio, the same calculation yields approximately 48–51 Nm at 333 rpm.

This range of available ratios makes the HC-SFS203BG1 adaptable to a wide span of application requirements — from moderate torque at medium speed using the lower ratios, to high holding torque at slow output speeds using the higher ones. The specific ratio installed in a given unit is part of the order specification and is stamped on the gear housing nameplate.

Motor Encoder Resolution After Gearing

The encoder is on the motor shaft and reads 131,072 positions per motor revolution. At a 1/20 gear ratio, each output shaft revolution corresponds to 20 motor revolutions, and each motor revolution produces 131,072 encoder counts. The amplifier therefore sees 2,621,440 encoder counts per output shaft revolution — an effective resolution at the gear output that far exceeds what a standalone encoder mounted on the output shaft could reasonably deliver at this motor size. This is a meaningful advantage for slow-speed positioning accuracy: the control loop has very fine angular data to work with even when the output shaft is turning at just a few rpm.

Electromagnetic Brake on a Geared Motor

The electromagnetic brake sits on the motor shaft — between the encoder and the gear input stage. When the 24V DC is removed, the spring engages the motor shaft directly. Because the gear unit is in the torque path between the brake and the load, the load-side holding effect is the brake's rated static torque multiplied by the gear ratio. This amplified holding capability is one of the primary reasons for specifying a geared servo motor with a motor-side brake rather than a separate brake on the output shaft.

For vertical axes with gravity-loaded mechanisms, this has practical significance. The unbalanced gravitational torque appears at the gear output; the brake holds it at the motor shaft through the gear ratio. An axis with 50 Nm of unbalanced gravitational torque at the output would require only 2.5 Nm of brake holding torque at the motor shaft with a 1/20 ratio — well within the brake's capability.

Correct brake sequencing still applies. The MR-J2S amplifier's MBR (brake interlock) output must be used to control the brake relay, ensuring the brake only engages after the motor has decelerated to rest. Engaging the spring against a rotating motor shaft — even at the motor's lower mass and inertia — accelerates brake wear. The gear unit itself also imposes a constraint: under no circumstances should the brake be used to arrest a moving output load when that load's inertia is high. The amplifier must decelerate first; the brake holds what is already stopped.

Note on gear section protection: The motor body carries IP65. The reduction gear housing section is rated IP44 — protected against solid ingress and splash water but not against directed water jets or immersion. For applications in wet or wash-down environments, this rating should be verified against the environmental requirements before specifying this motor. Where IP65 across the entire assembly is required, the application should use a separately mounted servo motor and external IP65-rated gearbox combination.

Amplifier Requirements and Parameter Setup

The HC-SFS203BG1 pairs with MR-J2S-200 class amplifiers — the same amplifier series used for the standard HC-SFS203. From the amplifier's perspective, the motor is the HC-SFS203; the amplifier communicates with the motor-shaft encoder and controls motor current exactly as it would for a direct-drive application.

What changes with the gear unit is the electronic gear ratio parameters in the amplifier. The electronic gear function in MR-J2S amplifiers (parameters PA06 and PA07, or CMX/CDV) converts the controller's position command units into motor-shaft encoder counts. With a reduction gear in the drive train, the relationship between commanded machine movement and motor shaft rotation changes by the gear ratio, and these parameters must be set accordingly to maintain the correct correspondence between position commands and actual output shaft position.

In an MR Configurator (MRZJW3-SETUP) session at commissioning, this is set up as part of the axis configuration before first run. Incorrect electronic gear ratio settings produce following errors and abnormal axis movement on the first JOG test — always verify these parameters against the actual installed gear ratio before commanding any axis movement.

Compatible amplifiers:

• MR-J2S-200A — General-purpose analog/pulse command, position / speed / torque control
• MR-J2S-200B — SSCNET fiber-optic bus for Mitsubishi motion controllers
• MR-J2S-200CP — Built-in positioning with CC-Link interface

Typical Applications

Conveyor and transfer drive systems. Servo-driven chain and belt conveyors running at low output shaft speeds but requiring controlled positioning and consistent velocity use geared servo motors as their primary drive. The G1 reduction gear produces the low output speed from a high-speed motor without requiring an external gearbox, and the brake provides reliable index-position hold between cycles.

Rotary indexing tables at low speed. Indexing tables that rotate at slow output speeds — fewer than 60 rpm at the table — benefit from the high resolution that motor-shaft encoding provides after gear multiplication. Fine angular steps at the output shaft are resolved with high precision through the combined encoder and gear ratio, enabling accurate index positioning without a separate output-shaft encoder.

Worm-replaced servo drives on legacy machines. Machines originally designed around worm gearmotor drives — often requiring low output shaft speeds with high torque — can be retrofitted to servo control using a G1-equipped servo motor in the same approximate mounting envelope, gaining programmable speed profiles, torque limiting, and absolute position feedback in place of the original fixed-speed drive.

Packaging and labelling station drives. Station drives on rotary packaging tables, label applicator rolls, and seal-jaw mechanisms use geared servo drives to achieve the correct roll surface speed at the work point. The absolute encoder ensures that product register is maintained even after unexpected stops, without requiring a sensor recalibration cycle before resuming production.

Slow-speed hoist and vertical actuator drives. Vertical actuators where the mechanism naturally runs at low speed — short-stroke hoists, press feed axes, clamping mechanisms — use geared servo drives to achieve the required force at the load point. The motor-side brake on the HC-SFS203BG1 holds the output position through the gear ratio multiplication effect, providing reliable mechanical hold at rest.

G1 vs Other Reduction Gear Variants in the HC-SFS Range

The G1 is the standard general-purpose choice — cost-effective, compatible with common machine mounting configurations, and available in the widest range of ratios. G5 and G7 are precision gear variants with tighter backlash specifications, intended for applications where angular accuracy at the load point is critical. For most conveyor, transfer, and general motion applications, G1 is the appropriate specification.

New In Box, Factory Sealed

Factory sealed means the complete assembled unit — motor and integrated reduction gear — has never been installed or powered. Original Mitsubishi packaging intact, all connector covers and shaft-end protective caps in place. The gear housing was lubricated at the factory; no pre-installation lubrication service is required for units going directly into service within normal storage periods.

For machines awaiting this specific geared servo motor variant, new-in-box stock eliminates repair turnaround time and removes all the variables that come with repaired or refurbished units. The specific reduction ratio installed in this unit is identified on the gear housing nameplate — confirm this against the machine's required ratio before installation.

Frequently Asked Questions

Q1: What does the G1 suffix mean, and how does it differ from G1H, G5, or G7?

G1 designates a general industrial, flange-type output reduction gear integrated directly onto the motor. It mounts via the motor's front flange and presents a shaft output at the gear housing's outer face. G1H is the same general industrial gear concept but with a foot/leg-mounted housing instead of a flange mount — suited to different machine layouts. G5 and G7 are precision application reduction gears with tighter backlash specifications, used where angular accuracy at the output shaft is critical. For general conveyor, transfer, and standard motion control duty, G1 is the appropriate and most cost-effective choice.

Q2: What amplifiers are compatible with the HC-SFS203BG1?

The HC-SFS203BG1 uses the same amplifier as the standard HC-SFS203 motor: the MR-J2S-200 class. The three main variants are the MR-J2S-200A (general-purpose analog/pulse command), MR-J2S-200B (SSCNET fiber-optic bus for motion controllers), and MR-J2S-200CP (built-in positioning function). The amplifier communicates with the motor-shaft encoder as normal; the gear ratio is accounted for in the amplifier's electronic gear ratio parameters, not in the amplifier model selection.

Q3: The encoder is on the motor shaft — does the gear ratio affect position accuracy at the output?

The encoder's 17-bit resolution (131,072 ppr) is measured at the motor shaft. After the gear reduction, the effective encoder count per output shaft revolution is the base resolution multiplied by the gear ratio. At a 1/20 ratio, for example, each output shaft revolution corresponds to over 2.6 million encoder counts — a very fine positional reference. This means accuracy at the output shaft improves with higher gear ratios, and low-speed positioning on the output shaft benefits from the multiplied resolution.

Q4: Does the IP65 rating of the motor apply to the whole assembly including the gear unit?

No. The motor body carries IP65. The reduction gear section is rated IP44 — splash water resistant but not jet-wash resistant. If the application environment involves directed water jets, chemical spray, or heavy coolant exposure, this rating must be checked against the installation requirements. For full-assembly IP65 coverage, a separate servo motor and independently rated external gearbox should be considered instead.

Q5: How does the electromagnetic brake work on a geared motor, and does the gear ratio affect the holding force?

The brake is on the motor shaft, before the gear unit — it holds the motor shaft mechanically when 24V DC is removed. Because the load is connected through the gear, the load-side holding effect equals the brake's motor-shaft holding torque multiplied by the gear ratio. A higher ratio produces proportionally greater load-side hold from the same brake. The brake is a holding device only, not a stopping brake — the amplifier must decelerate the motor to rest before the brake engages. Always use the MR-J2S amplifier's MBR interlock output to sequence the brake relay correctly.