WDKA and WDKS Series Worm Gear Reducers

WDKA — Deep Bore (WA-class)

IEC B5 flange input. WA-class hollow bore depth (HL = 150 mm at size 100). Ball bearings throughout. Correct for shock service factors up to 2.0. Sizes 40–175.

WDKS — Deep Bore + Tapered Rollers (WS-class)

IEC B5 flange input. WS-class bore depth. Tapered roller output bearings from size 80 — handles sustained axial thrust. Correct for shock SF ≥ 2.0 and combined radial + axial loading. Sizes 40–175.

📉 Key Face Pressure — Halved

At the same output torque, WDKA key face pressure ≈ 53% of WDK key face pressure. Fretting fatigue initiates when surface pressure exceeds the material’s threshold — the WDKA sustains shock torques that push well past the WDK’s fretting limit without initiating surface damage.

🔬 Micro-Slip Amplitude — Reduced

The elastic deformation of bore and shaft under load generates micro-slip at the contact surface. A longer bore distributes this deformation over more contact length, reducing micro-slip amplitude per unit — the direct mechanism that delays fretting corrosion onset in cyclic and shock-load service.

⚖️ Static Self-Locking Distribution

At ratios ≥ 30:1, the holding torque acts through the bore-shaft key connection. The WDKA’s longer key engagement distributes static load over proportionally more face area — reducing bore fretting under sustained gravity loads in vertical shaft applications and loaded gate actuators.

WA / WS-Class Bore Depth — Shock Tolerance

WDKA HL = 150 mm at size 100; WDKS matches this with added tapered roller support. Stone strikes on auger shafts, conveyor jam events, and emergency motor stops impose 3–5× rated torque transiently. The deep bore distributes this over sufficient key face area to prevent fretting initiation in conditions that consume WDK keyways within a single harvest season.

IEC Flange Input — Zero Input Coupling

The IEC B5 flange input eliminates the motor-to-reducer coupling entirely. In shock-load environments, jaw couplings regularly require spider replacement every 6–12 months — the WDKA/WDKS removes this maintenance item from the schedule permanently. Motor concentricity is factory-set to 0.05 mm TIR by the machined flange datum.

WDKS: Axial Thrust Capacity (Tapered Rollers)

Deep-groove ball bearings resist radial load only — sustained axial shaft thrust from screw conveyor flights or helical-cut driven elements overloads them rapidly. WDKS tapered roller output bearings at size 80+ carry both radial and axial load simultaneously as a rated condition. This eliminates the bearing failure mode that is the primary cause of premature hollow-bore reducer failure on screw conveyors across Australian bulk handling installations.

Size 40 — Smallest W-Family Shock-Rated IEC Unit

Size 40 at 0.12 kW is unique to the WDKA/WDKS within the WD range — no WDK size 40 exists. For small-frame shaft-mounted applications where IEC motor flange input and deep bore engagement are both required in a compact package, size 40 fills a gap that no other single unit in the W-family range covers.

W-Series Housing — Retrofit Without Structural Work

Upgrading a WDK that is showing early fretting signs to a WDKA at the same size number requires no baseplate modification — external housing dimensions match. The driven shaft bore diameter is the same; only the bore depth and bearing arrangement change. This is the correct specification upgrade path when shock loads intensify on existing W-series machines.

Self-Locking with Deep Bore Static Retention

At ratios ≥ 30:1, self-locking holds the output bore on power-off. The WDKA/WDKS deep bore distributes this static holding torque over 88% more key face area than the WDK — critical for applications where the driven shaft carries a sustained gravity load (loaded hoists, inclined conveyors, gate spindles) during the lock-up period between power-off and the next start.

PTO Adaptor + Friction Slip Clutch

For agricultural drives retaining tractor PTO input, a yoke-end IEC flange adaptor couples the PTO shaft to the WDKA/WDKS input face. A friction slip clutch calibrated at 1.5× rated input torque is mandatory — stone-strike events can generate 8–10× rated torque instantaneously; even the WDKS’s deep bore cannot sustain these events indefinitely without clutch protection as the first line of defence. Refer to PTO shaft and slip clutch specifications for yoke and spline sizing.

IEC Motor — Shock Application Selection

For shock-load applications, select a curved-jaw coupling design or a fluid coupling between the VFD and motor if direct-on-line starting is retained — these limit the peak startup torque transmitted into the WDKA/WDKS worm gear. Alternatively, a VFD with current limiting and soft-start ramp eliminates direct-on-line startup shock entirely and is preferred for WDKA/WDKS drives where controllable starting is feasible.

Shrink Disc — Mandatory for Shock Loads

For all WDKA/WDKS shock-load applications, the bore locking element must be a shrink disc — not a set screw. Uniform radial clamping across the full bore depth (150–260 mm depending on size) prevents the progressive set screw loosening that repeated shock torques cause regardless of bore depth. Specify shrink disc by bore diameter S and required transmissible torque with service factor applied.

Heavy-Duty Torque Arm (Sizes 120+)

WDKA/WDKS sizes 120–175 weigh 60–160 kg with motor. In shaft-mount configuration, the torque arm must carry both the reaction torque from the output bore and the gravitational moment of the motor-plus-reducer assembly. A dual rubber-bushed heavy-duty arm is required at these sizes — specify for combined dynamic and gravitational loading, not reaction torque alone.

PAO Synthetic Oil — Hot Ambient & High Ratio

At ratios 40:1+ in continuous duty in 40°C+ Australian summer ambient, PAO synthetic ISO VG 220 extends the thermal rating by 10–15% and service interval to 5,000 hours. For WDKA/WDKS units on grain or mineral conveyors that operate continuously during harvest campaigns where scheduled oil changes are logistically difficult, the extended synthetic interval is a material operational benefit.

PT100 Thermal Sensor (Sizes 100+)

NPT sensor port fitted at sizes 100+. On enclosed mining and grain handling conveyors where the reducer housing is not visually accessible during operation, a SCADA-connected PT100 provides overtemperature protection and trend data. Worm gear thermal failure in a bore-mounted unit at size 155 or 175 is a significant unplanned downtime event — monitoring is proportionally more valuable at larger frame sizes.