LifeTrac Requirements

LifeTrac 6 is our latest release of the tractor, from which we define further requirements based on our learnings:

1. Uses modular wheel units
2. Uses modular power units. Standard operation involves using 1-4 Power Cube 7's.
3. Weight scalability. May be scaled in 1 ton increments by adding weigh-down units. M
4. Articulated Steering. Skid steering or steering column is depracated as non-generalizable to both large-scale wheeled and tracked machines. See notes on Steering below.
5. Drive torque scalability. Modular Geardown opiton. Design needs to allow for a geardown module to be placed adjacent to the modular wheel unit, for added power
6. Interchangeable wheels. Various wheels may be used, from rubber to metal to tracks, of varying sizes.
7. Interchangeable forearms. To allow for heavy (1 ton and up) front implememnts, forearms may be replaced - to accommodate bucket, bulldozer blade, backhoe, 6' trencher - to name a few.
8. Modular tubing quick attach plate. allows for both fingers and holes to be used as mounting mechanisms for implements.
9. Bolt-head non-interference. Additional modules such as power cubes must not have bolts sticking out from their respective frames, to allow for a tight fit between modules.
10. Hydraulic control panel allows for easy hose routing for power takeoff and scalability, including multiple power unit feed lines into specific hydraulic circuits."
11. Valve-controlled changeover from 2 to 4 wheel drive.
12. Ground-hugging pivot is used.
13. 3" shaft is used throughout for all shafting outside of sylinder pins.
14. Allows for exploration of design space on power and size scalability.
15. Allows for instrumentation retrofit for pressure and flow measurement.
16. Uses 1/2" quick couplers throughout, with power flow splitters/doublers and flow combiners for power distribution.
17. Uses joystick valves and foot pedals to allow for robust control.
18. Uses non-locking valves for the wheels.
19. Has an emergency brake for locking wheels built into the hydraulic system, in the form of a locking ball valve, easily accessible within the driver's cab
20. Has a top enclosure for driver safety, a seat belt, and a fully enclosed cab for rollover protection.

Discussion

1. Steering - The steering column is an industry standard way to achieve steering and will be used in high-speed OSE vehicles such as MicroCar and Tractor - above 45 mph. The steering column is a complex way to achieve steering, and is not necessary for gross devices such as slow-moving tractors. Further, the steering column is not applicable to/interchangeable between both tracked and wheeled machines, and it is difficult to build a modular steering column that can fit many machines. (Principle of Multipurpose Flexibility). The most robust, and fully scalable route to low-speed steering is articulation. In the limit of deka-ton wheeled machines, skid steering is not feasible, unless expensive shaft mounting is used such as in industry-standard bulldozers. For the OSE case, we are sticking to non-machined shafts which rely on low axial thrust to prevent axial slippage of the shafts within bearings - where axial thrust is minimized via articulation. In the articulated steering case, OSE proposes that clamping only, combined with standard off-shelf 4-bolt flange bearings - is a route to simple wheel mounting. This allows such shafts to be maintained or replaced in the field without the need for machining - such that this technology can be maintained in areas far removed from industrial supply chains.
2. Modular Power Units. The base power unit for OSE machinery is 27 hp. This allows for powering small devices such as microtractors and precision machines, while allowing for multiple power units to power larger machines such as bulldozers. Because the GVCS includes these 27 hp power units, and because one essential feature of the GVCS is scalability, we are exploring the limits of performance for stacking multiple power units. See Power Cube Development Path.