Elevator Gearbox

I designed this gearbox as a part of a three-person team for our third year machine design final project. I was responsible for the preliminary force calculations, the shaft design review, the bearing selection and the enclosure design.

Problem Definition


  • Input Power: 10 kW
  • Input Speed: 1200 rpm
  • Input Type: Electric Motor
  • Output Speed: 200 rpm
  • Use: Elevator for people


  • Must be safe
  • Must reliably complete functions
  • Long life
  • Easy to fix
  • Minimal cost
  • Minimize size
  • Force Calculation

    I created this spreadsheet to allow for easy iterations of calculations. These numbers applied to the entire gearbox and would dictate the design of individual components. Fixed values were derived both from project specifications, and research on existing gearbox and elevator loads and safety factors.


    This table contains the results of the gear calculations. They were performed and checked by my teammates Eric Edwards and Adam Desjardins respectively. The rest of the components of the gearbox were designed to accommodate the gears, and therefore there were no iterations in this step.

    Gear drawings


    Above are two tables summarizing sample stress calculations on the shafts, and a table containing final shaft specifications. They were performed by my teammate Adam Desjardins and checked by myself. Multiple iterations with various materials and dimensions were needed before a successful design solution was found. Bearing selections were performed in parallel and often informed shaft design iterations. Shaft keyways have 1.5mm corner radii for milling.

    Shaft drawings


    These tables summarize my calculations on the bearing selection. The bearings needed to be doubled up in one location because the force was too large. Although the calculation was relatively simple, I had to be highly involved in the shaft design to ensure that the forces applied by the shaft and the shaft diameter would allow the required bearing life. The required life (20 years) was met with 96% reliability. Calculations were checked by my teammate Eric Edwards.

    Enclosure and Assembly

    Key enclosure features:


    Ice Mammoth
    Chimney Filter
    RF Power Supply
    Elevator Gearbox
    Small Projects