Current Frame design
Sand Helper is a company that produces a specialized electirc wheelchair to provide beach access for anyone with mobility issues.
The current frame design uses angle iron to build a perimeter chassis with 3 levels. The lower level is the jackshaft chain drive.
Above that the motors are mounted along with the electronics. Above that is the seat and battery box.
There is a huge cost benefit to using angle iron, however it is labor intensive and no two frames are exact.
Redesigned frame for manufacturability and improved durability
My redesign attempts to improve manufacturability by creating symmetrical sub-assemblies. The sub-assemblies are made from sheet metal, where all mounting
holes are pre-cut.
The sheet metal parts are designed and bent to serve as many functions as possible to reduce part count during assembly. Some components have
been relocated as well. I moved the seat farther forward and made it lower to help those that are mobility impaired get in and out.
Another aspect of the redesign is the drivetrain. Currently, the chair uses motors and a chain-driven jackshaft to drive each side's wheels. The chain
necessitates having slack and a tension adjustment mechanism, which requires frequent maintenance. Additionally, the chain and sprockets wear quickly
due to sand abrasion.
My suggestion was to use a sealed worm gearbox, typically found on conveyors or in industrial machinery.
Finally, I suggested using
a Pelican waterproof case to house the electronics, as they are currently not enclosed.
