EDO Series Double Worm Gear Reducer

Three-End Zero Couplings at 200–900:1

IEC motor bolts to input flange — no input coupling. Each driven shaft slides into its respective hollow bore — no output couplings. Three connection points, zero coupling bodies, zero coupling guards, zero alignment steps. At ultra-high ratios where the driven equipment often operates in constrained environments (actuator housings, sealed enclosures, gas-tight digester heads), eliminating all coupling bodies from the installation envelope simplifies both the mechanical design and safety compliance.

Exact Co-Axial Synchronisation — Ultra-Low Output Speed

Both bores share one worm wheel — the speed ratio between them is exactly 1:1, permanent, with no chain stretch, no sprocket wear, no phase accumulation over time. At 1.6–7.25 rpm output (200:1–900:1), any timing error between two co-axial shafts becomes immediately visible as physical misalignment in the driven mechanism. The EDO makes this error physically impossible by sharing one wheel between both bores.

Double Self-Locking — Both Bores Held on Power-Off

Both worm stages self-lock simultaneously. Both driven shafts are locked against back-drive from either bore on power-off — without any external brake or latch. For gate valve twin-stem mechanisms where both stems must hold simultaneously against flow pressure, or for contra-rotating agitators that must stop simultaneously and stay stopped during maintenance access, this double self-locking delivered through both bores simultaneously provides positive mechanical hold at both outputs.

Replaces Two EDA Units + Synchronisation Shaft

Achieving co-axial twin slow-speed shaft-mount drives with EDA units requires two complete EDA units plus an inter-shaft synchronisation mechanism. The EDO replaces this entire assembly: two EDA housings, two second-stage synchronisation gear elements, two inter-unit couplings, and the associated alignment and maintenance for all of these — condensed into one housing, one oil fill, one maintenance service point.

One Motor + One VFD Controls Both Output Shafts

Both EDO output bores change speed proportionally when the VFD frequency changes — the 1:1 speed ratio between them is preserved at all VFD frequencies. Two separate EDA units with two VFDs require synchronisation programming and still have algorithm-dependent timing accuracy. The EDO provides hardware-guaranteed synchronisation that cannot be disrupted by control system logic, communication delay, or VFD parameter drift.

135-200 Stage Pair — Extreme Torque at Dual Output

The EDO 135-200 at 900:1 with 3.0 kW input delivers a combined theoretical output torque exceeding 8,000 Nm distributed across both bores simultaneously. At combined torque of this magnitude from a 3.0 kW motor, the EDO exceeds what any hydraulic actuator at equivalent power input can typically achieve — and does so with mechanical self-locking, not hydraulic pressure, to hold position.

Motor Power — Combined Bore Load Required

Motor power must cover the combined torque from both bores: P_input = (T₁ + T₂) / (ratio × η). This is a strict requirement — using single-bore torque for motor sizing results in motor thermal overload during normal combined operation. Small IEC motors at large EDO stage pairs produce very large combined output torques; confirm the motor thermal rating is adequate for the calculated combined input power.

Dual Shrink Discs — Both Bores

Both bores require individual shrink discs for all EDO stage pairs 70-120 and above, where output torques per bore can exceed 1,000 Nm even at moderate power inputs. Torque both shrink discs in cross-pattern sequence simultaneously to maintain symmetric clamping pressure on both bore faces. Asymmetric clamping (one disc fully torqued before the other) can generate lateral force on the worm wheel that affects bearing pre-load.

Torque Arm — Combined Reaction + Weight

The EDO torque arm must resist the combined reaction torque (T₁ + T₂) plus the gravitational moment of the motor-plus-reducer assembly. For large stage pairs (135-200 with motor), total assembly weight may exceed 120–160 kg — the gravitational moment at typical arm lengths (300–500 mm) can exceed the reaction torque in the arm anchor force calculation. Always include gravitational moment in the arm specification.

PAO Synthetic Oil — Continuous-Duty Thermal

Two separate oil fills (one per stage). Both stages require PAO synthetic ISO VG 220 for continuous-duty EDO installations at ratios ≥ 400:1 in 40°C+ Australian ambient. The combined load from both bores increases first-stage heat generation compared to an equivalent single-bore EDA — thermal rating must be verified at the combined power level, not single-bore.

Temperature Sensor — Large Stage Pairs

For EDO 100-155 and 135-200 in continuous duty, a PT100 on the second stage housing provides early warning of thermal overload before bronze wheel failure. At large stage pairs, thermal failure in the EDO affects both output drives simultaneously — repair cost and downtime impact is double that of an equivalent EDA unit. Monitoring is proportionally more valuable on the EDO than on any single-bore equivalent.

Oil Orientation — Both Stages, Both Bore Orientations

The EDO has both bores on the co-axial output axis. In vertical bore orientation (bore axis vertical, both shafts vertical), the second-stage oil level must be verified for this orientation independently of the first stage. Submit your complete installation orientation drawing to the technical team before commissioning — oil starvation in the second stage under vertical bore orientation is a common EDO failure in gate valve and vertical digester shaft applications.