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Gearbox Speed Reducer

Vertical-to-horizontal gear reducer with a 10:1 speed reduction ratio.

Designed for conveyor belt applications, the reducer transforms 3 HP at 750 RPM into 75 RPM output, ensuring reliable performance through rigorous gear, shaft, and bearing analysis.

Scope Mechanical Design, Gear & Shaft Sizing, FEA • Client Professor of Ottawa University • Duration 4 months • Year 2024

/ Challenge

Design a standalone gearbox capable of transmitting 3 HP, reducing speed from 750 RPM to 75 RPM, while changing orientation from vertical input to horizontal output.

/ Solution

Implemented a two-stage reduction: spur gears (3.33:1) followed by bevel gears (3:1), achieving the target 10:1 ratio. AISI 4140 shafts and ball bearings ensure strength and reliability.

/ Results

Achieved stable operation below critical speeds, with calculated safety factors above AGMA standards. The design proved robust, efficient, and manufacturable.

> Workflow guided by AGMA & Design Thinking

Swipe →
  1. Req. & topology
    V→H • 10:1
  2. Stage split
    3.33 × 3
  3. AGMA factors
    J • I • Cp • Ko • Kv • Km
  4. Tooth stresses
    σb • σH
  5. Shafts
    4140 • Kt/Kf • Goodman
  6. Bearings
    L10
  7. Critical speed
  8. Housing / Lube
    Seals • Synthetic oil

Gear sizing & AGMA

Gear ratio split (3.33×3)AGMA bending/contact (σb, σH)Geometry factors J & IElastic coeff. CpDynamic factors Ko · Kv · Km

Loads & kinematics

Tangential & radial loads (Ft, Fr)Velocity measuresReliability factor

Shafts & keys

Goodman fatigueBeam deflection Keys & splines torque

Bearings

Equivalent load Required capacityLife L10Fits & tolerances (ISO)

Dynamics

Critical speed checkSurface endurance (HB→Sfe)

Lube & manufacturability

Lubrication & sealingManufacturability review
OVERALL RATIO
≈10:1
TEETH / PITCH
Spur 15/50 · DP=10 · b=1.25" · Bevel 15/45 · DP=6 · b≈1.08
VELOCITY / LOADS
V≈294.5 & 147.3 ft·min⁻¹ · Ft≈336 & 672 lbf
MATERIALS
AISI 4140 shafts · Steel spur & straight-bevel gears · Ball bearings
HOUSING / LUBE
Steel casing · Synthetic oil · Labyrinth sealing · Snap rings

Download the full project report

Access all calculations, CAD drawings, and design analysis in the complete PDF file.

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