Since the beginning 2021, I’ve pursued a personal project that combines my love of outdoor sports and interest in machine design. The winch pulls skateboarders, skiers, and other riders. This page will be updated as the winch is tested and improved throughout Spring 2023.

Goals

  • Design and build an electric winch consisting of a DC motor coupled to a chain drive and a reel to pull a rider on skateboards, skis, wakeboards, etc.

Calculations

To begin designing the winch, I had to understand what forces the winch and its pulling mechanisms would see. I had just finished the Drill Powered Bicycle project, so I envisioned a motor and a chain drive pulling a wheel of rope.

  • Estimated the frictional forces that would have to be overcome to pull a ~200 lb rider on waxed skis in the snow

  • Wrote a MATLAB scripts to play with the many combinations of motors, gear ratios, and reel diameters that could achieve a rider speed of 25 mph

Component Selection

  • Based on calculations, decided on a reel diameter of ~8 in, gear ratio of 5:1

  • Selected a brushless DC motor and accompanying batteries and ESC based on operating voltages and current

  • Required selecting shafts, keys, couplers, bearings, sprockets, chain

  • Performed more Matlab calculations and ANSYS simulations

    • Ensure shaft diameters were wide enough

    • Plates thick enough

    • Keys and set screws wouldn’t shear

CAD

  • Utilized Fusion360 to model the winch and ensure that components fit together with enough clearance

  • Made engineering drawings and DXF files for manufacturing

Funding

  • Drafted a grant request and secured $700 in funding from CU Mechanical Engineering department

  • Ensured access to campus machine shop

    • Collaborated with campus machinists to create engineering drawings

Manufacturing

  • Soldered 8 and 10 gauge wire and XT90 connectors to create custom series connector for batteries

  • Manufactured aluminum plates and spacers

    • Waterjet cut initial standoff and reel plate designs

    • Utilized mill to add chain-tensioning slots and fabricate fairlead plate

    • Drilled and tapped holes for chosen screws

    • Cut standoffs and shafts, finished shafts on lathe

    • Polished and deburred

Controls

  • Programmed and manufactured remote to control winch operation with Adafruit Feather Transceiver breakout boards and 3D printed casing