Bennett Lin
Project Goals
Designed and fabricated a hydraulic scissor-lift cart to safely transport a 45kg battery with an integrated custom deadman brake system and tool mounts. The goal for this project was to make a new cart to replace the old battery cart.
Issues with the Old Cart
The deadman brakes did not work well, the wheels were making too much noise, and it had a hard time loading into the car due to poor steering.
New Cart Goals
New custom deadman brakes, modular disconnect of the handle, and 4 rotating caster wheels to improve steering. Additional add-ons are a tool mount for battery tools and a fire extinguisher mount.
Preliminary Design
I wanted to go with a large base. Decided on making the chassis out of 2x1 aluminum extrusion since they were affordable and easy to assemble. The dimensions were 17.5 inches width and 31.5 inches in length for the chassis. Also we were not going to purchase a new hydraulic, but renew the old cart's hydraulic, therefore, the hydraulic was hand measured and CADed, same with some cheap 6 inch caster wheels that were ordered. Additionally, with these caster wheels, we were able to modify them so that the back 2 wheels have locks that make them lock in spinning rotation, but not rolling, as that would be the job of the deadman brakes.
Scissor Lift
Scissor lift was made out of 0.25 inch material, manufactured from a CNC waterjet. 1 inch center rod and 0.25 inch diameter railing rods were CNC turned on a lathe.
Calculated linkage forces for the welded steel 2-bar lift with lever actuation, maintaining a 2x safety factor.
Rollers, Plates & Tabs
The railing rods will also have nylon rollers to roll smoothly on U-Channels attached to the cart chassis and bed, all mounted on a modular aluminum extrusion frame assembly. Reinforcement plate and tabs that connect to the hydraulic lift were manufactured from Fablight fiber optic laser cutting. Bushings for the center rods were ordered, and the shorter rods at the ends of the scissor lift were connected to 0.25 inch tabs on the chassis and bed.
Hydraulic Piston Integration
The scissor lift was installed on the chassis and the refurbished hydraulic piston from the old cart was integrated to raise the battery into the car from underneath.
Custom Deadman Brakes
Designed in Autodesk Fusion and resin printed in Tough 2000 at Formlabs. Included a 2 inch long, 120lb spring load spring for each brake, tied to a bike brake cable.
Spring load and torque were rated for the cart, and the brakes are mounted on a quick-release handlebar to facilitate battery installation.
Notices
Did not have time to design a cable reroute for better torque on the cable.
Finished Cart
A Milwaukee tool mount was added along with a tool mount and a 5lb fire extinguisher mount.
