OSE Wikispeed Local Motors Open Source Car Concept
Start with Wikispeed Frame from Wikispeed SGT01 page:
(image is STEP care of VariCAD Viewer)
Add a 50 hp Power Cube by Tom Griffing - to modify Wikispeed design to flexible hydraulic power.
Modify wheel drive for hydraulic motor drive.
Set up shop at Local Motors shop in Arizona. Fund via Kauffman Foundation to result in a minimum viable product in 3 months.
Next Steps
- Document the Steering module
- Document front brake module
- Design Interior Module for hydraulic pedals
- Extract carbon fiber composite techniques from Joe Justice
- Build an Aluminum version of Power Cube - simply with 4x4 tubing identical to steel tubing, but use 1/8" wall 4x4"s instead of 1/4" 4x4"s in steel.
- See Power Cube Modularity - tanks, engine, frame, hydraulics, and electrical are separate modules
- Selective Laser Sintering in Nylon 12 for hydraulic quick coupler fittings on low pressure side
Perspective from OpenSourceCitizen:
Hydraulic wheel motors a bad choice? There is a reason that there are no hydraulic driven cars and very few/expensive add-on hydraulic drive systems for big trucks(which only supplement the direct drive). The efficiency losses and heat build up is enormous with even expensive($3-7k each) closed-circuit hydraulic motors(radial-piston) & pumps(axial-piston) when used in this type of application as compared to direct-mechanical drive. This is even more magnified when trying to use wheel motors(instead of motors powering the wheels thru a transmission or even just a standard axle differential gear), the speed and torque range is physics-impossible, especially with cheap motors/pumps. The durability and versatility of hydraulics over direct-mechanical drive for low-speed/high-torque, clutch-intensive applications does not carry-over to the physics of the car-application. There are also control/biasing/differential issues with using multiple wheel motors as experienced on the Lifetrac but amplified to an unsafe level at 30+ mph. More viable would be to make the powercube capable of both hydraulic and shaft power output and not use hydraulics for the car application. The hydraulic pump could remain on the powercube on the opposite side of the crankshaft or it could be made to be quick attach for being swapped with the shaft connection. This is also useful for virtually all GVCS applications where high shaft speeds are required. It makes the build cost lower and reliability higher. This is industry standard for many applications like tree chippers that are direct-drive off one side of the engine for the high-speed grinder and have a hydraulic motor mounted on the other side for the feeder motor.
Also see: Local Motors
