I have received many requests to do an overview of my air filter cart. I built this cart in 2007. It recently stopped working so this seemed like a good opportunity to make a video about the cart and fixing it. The cart works by drawing air in through three filters on one end. The partially filtered air is then drawn through a second internal filter and pushed out of the cart by the squirrel cage fan. The structure of the cart consists of a torsion box on the top and bottom with a leg at each corner. This makes an open internal space to house the fan and air plenum between the internal and external filters.
After pulling the cover off of the fan and motor, it appeared that the motor needed lubrication. There were not places on the motor to add oil or grease so I pulled the motor apart and added grease where the shaft was held by the motor housing. There did not seem to be any bearings for the shaft, just bushings. I got the motor back together and all seemed to be fine as it ran. Then a big arc came out of the motor! The fan had contacted some of the internal wiring. I put that motor aside and used a different old motor that I had. This second motor runs at a slower speed which I think is better for the filters as it does not draw as much air. The air filter cart is back together and running great.