311 Series Planetary Gear Reducer — 40,000 Nm Inline Drive, Replacement for 311L1 to 311R4
311 Series Planetary Gear Reducer, 40,000 Nm, ratios 3.4–9,000, up to 540 kW. Inline & ring-output variants: 311L1–311R4. IEC/NEMA & hydraulic inputs. L2 & L3 ship in 5–7 days.

311 Series · 300 Family Inline Planetary
311 Series Planetary Gear Reducer — 40,000 Nm Inline Drive, 311L1 to 311R4
The 311 Series is a high-torque Inline Planetary Gear Reducer rated at 40,000 Nm continuous output, positioned within the 300-family as the step between the 309 (18,000 Nm) and 313 (55,000 Nm). Seven variants — 311L1, 311L2, 311L3, 311L4, 311R2, 311R3, and 311R4 — cover single-stage through four-stage reduction in both inline (L) and ring-output (R) output configurations. The Planetary Gearbox accepts IEC and NEMA electric motor flanges, axial-piston hydraulic motors, orbit motors, and plain solid input shafts, making it compatible with the widest range of prime movers in the 300-series family. All mounting dimensions are consistent with equivalent models from Bonfiglioli, Bosch Rexroth, and other major drive brands in this torque class.
40,000 Nm
Rated Output Torque
3.4 – 9,000
Gear Ratio Range
540 kW
Max Transmissible Power
7 Variants
L1 / L2 / L3 / L4 / R2 / R3 / R4
311 Series Planetary Gear Reducer — Technical Specifications
| Parameter | Value |
|---|---|
| Series & Variants | 311L1 · 311L2 · 311L3 · 311L4 · 311R2 · 311R3 · 311R4 |
| Rated Output Torque | 40,000 Nm |
| Max Transmissible Power | Up to 540 kW |
| Gear Ratio Range | 3.4 – 9,000 |
| Gear Unit Configuration | Inline (L-series) · Ring output (R-series) |
| Stage Count | L1 = 1 stage · L2 = 2 stages · L3 = 3 stages · L4 = 4 stages · R2 / R3 / R4 = ring-output equivalents |
| Output Mounting | Foot mount · Flange mount |
| Output Shaft Options | Solid with key · Splined solid · Splined hollow · Hollow with shrink disc |
| Input Configurations | IEC / NEMA motor adaptors · Flanged axial-piston hydraulic motor · Orbit motor · Solid input shaft |
| Brake Options | Hydraulically released parking brake · DC electric brake · AC electric brake |
| 300-Family Position | Sits between 309 Series (18,000 Nm) and 313 Series (55,000 Nm) |
Where the 311 Planetary Gear Reducer Sits in the 300-Series Range
The 300 series spans 1,000 Nm to 500,000 Nm across 16 frame sizes. The 311 occupies the mid-heavy bracket — enough torque for large conveyor and mixer drives, compact enough to fit in a mobile machine chassis.
| Series | Rated Torque (Nm) | Position |
|---|---|---|
| 309 | 18,000 | Below 311 |
| 310 | 25,000 | Below 311 |
| 311 ★ This Product | 40,000 | Current |
| 313 | 55,000 | Above 311 |
| 315 | 100,000 | Above 311 |
Full 300-series range (300–321) available. Contact us if your load requirement falls between listed sizes — we identify the correct frame.
Gear Ratio Calculation for the 311 Series Planetary Gear Reducer
Each planetary stage in the 311 Series follows the standard fixed-ring-gear formula. The digit in the model code (L1, L2, L3, L4) directly tells you how many stages are stacked.
Zring = ring gear teeth · Zsun = sun gear teethMulti-stage (L2 / L3 / L4): itotal = i1 × i2 × i3 × i4
Worked example — 311L3: Three stages, each at 5:1 → total ratio = 5 × 5 × 5 = 125:1. With a 1,450 RPM motor, output shaft speed = 1,450 ÷ 125 = 11.6 RPM at 40,000 Nm.
Finding the right stage count: Divide your motor speed by the required output speed to get the target ratio. Need 8 RPM from 1,450 RPM? Required ratio ≈ 181:1 — a 311L4 four-stage unit covers this range.
Send us your motor RPM, target output RPM, and load profile. We select the correct 311 variant and confirm whether the duty cycle falls within continuous or peak torque limits.
What Makes the 311 Series Stand Out Among Inline Planetary Gear Reducers
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40,000 Nm in an inline housing that shares the 300-series bolt pattern. Engineers specifying a 309 (18,000 Nm) or 313 (55,000 Nm) can upgrade or downgrade to the 311 without changing the machine frame interface, the motor flange, or the output shaft bore. This is the practical advantage of a coherent product family. - →
Seven variants from a single catalogue page. L1 through L4 cover ratios from 3.4 up to several thousand. R2, R3, and R4 add ring-output configurations for wheel-drive and winch-drum integrations where the output must distribute load radially rather than through a single shaft. - →
The 311L2 Planetary Gear Reducer is a proven replacement for Bonfiglioli 311L2 and equivalent units from Bosch Rexroth and Reggiana Riduttori. Mounting dimensions — bolt circle, shaft diameter, and input flange pattern — are matched to the original. No adapter plates or additional machining are required. - →
Four output shaft configurations cover the majority of OEM interfaces. Solid keyed, splined solid, splined hollow, and hollow with shrink disc are all available within the 311 frame — specifying the output type adds nothing to lead time on stocked L2 and L3 variants. - →
Brake options factory-fitted, not field-added. The hydraulically released parking brake, DC brake, and AC brake are all integrated inside the housing envelope. Adding a brake does not extend the axial length or require a separate caliper bracket — critical when fitting inside a compact mobile machine frame.
Industry Applications for the 311 Inline Planetary Gear Reducer
Large Conveyor Drives
40,000 Nm rated output handles head-pulley drives on overland conveyors carrying 800–1,500 t/h. The 311L3 with a ratio of 100–200:1 covers most medium-duty mine conveyor starting torque requirements.
Mixer & Agitator Drives
Twin-shaft concrete mixers, biogas digesters, and high-viscosity industrial agitators where S3 intermittent duty peaks exceed 35,000 Nm on start-up. The 311 absorbs these peaks without de-rating.
Marine Winch Systems
311R-series units (ring-output) couple directly to winch drum flanges on anchor-handling, mooring, and aquaculture feeding winches, eliminating intermediate shaft and coupling hardware.
Construction Equipment
Concrete pump truck drive heads, road milling drum drives, and piling machine rotary heads — applications where the gearbox must absorb material impact loads of up to 2× rated torque during cut-in.
Slewing & Turning Drives
Crane slewing rings, ship thruster drive trains, and solar-tracker azimuth drives where a compact Planetary Gearbox provides precise, high-torque positioning without worm gear efficiency losses.
Matched Components for a Complete 311 Series Drive System
The 311 Series input and output interfaces accept the following components directly. Sourcing the drive system as a matched package avoids interface mis-matches and consolidates freight.
| Component | Specification | How It Connects |
|---|---|---|
| IE3 Electric Motor | 55–200 kW, 4-pole, IEC B5 flange, 1,450 RPM | Bolts to IEC adaptor on 311 input — no intermediate coupling required on flanged versions |
| Agricultural Drive Sprocket | ANSI #120–#160 roller chain, 13–19T, splined or keyed bore | Mounts on splined solid output shaft for chain-driven agricultural and conveyor secondary stages |
| Marine Winch Drum | Ø 350–600 mm, 12–20 mm wire rope, SWL 10–50 t | 311R-series ring output couples directly to drum flange; no external bearing housing required |
| Hydraulic Axial-Piston Motor | SAE B/C flange, 200–500 cc/rev, 350–500 bar rated pressure | Flanges directly to 311 hydraulic input port; standard on mobile winch, crane, and track drive builds |
| Torsionally Rigid Disc Coupling | 20,000–60,000 Nm, steel disc pack, SAE flywheel bore | Connects motor to 311 solid input shaft; compensates angular misalignment up to ±0.5° without radial load on input bearing |
Frequently Asked Questions — 311 Series Planetary Gear Reducer
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Get a Quote on the 311 Series Planetary Gear Reducer — L2 & L3 Ship in 5–7 Days
Tell us your variant (311L1 / 311L2 / 311R3 etc.), required gear ratio, input configuration, and quantity. We return a confirmed price, dimensional drawing, and lead time within 24 hours.
311L1 / L2 / L3 / L4 / R2 / R3 / R4 · 40,000 Nm · IEC / NEMA / hydraulic input · Volume pricing from 5 units
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| editor | wm |
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