Power Cube v17.08

From Open Source Ecology
(Redirected from PC)
Jump to: navigation, search


Development Template


Visual BOM


Design Sprints

August 19, 2017


Master CAD Checklist


August 5, 2017



Other choices:

  • 12 gpm hydraulic pump - [2]




Part Library - CAD Modules

Master File

Frame module

Frame Fittings

See the ISO 7241-1 A for hydraulic couplers [3]

Fittings for frame and pump are: 3/4" for hex nip, 1" for hose barb. The ones below are 1/2" and 3/4" barb.

Other Parts


In order to make the Power Cube much more accessible, we can use a smaller engine - 18 hp - which is approximately 1/3 the effective cost of a 27 HP engine. This would allow us to make smaller machines possible, such as an 18hp walk-behind tractor. The lower cost of the 18hp option allows for wider replicability, and may allow operation without a hydraulic cooler in some applications - reducing cost and complexity significantly. Several major improvements include:

  • Design for stable operation with biomass charcoal pellets to move in the direction of renewable energy biofuels that are 10x as efficient as liquid biofuels to produce
  • Design for modularity - allowing for interchangeable hydraulic pumps. To date, we have not been using design-for-interchange (completely modular hydraulic pumps) due to the complexity of pump-to-motor coupling. By creating a smart coupling interface, hydraulic pump modularity is feasible, and is the next logical step. This would allow use of the Power Cube
  • Simplified frame CNC cut from metal sheet, as opposed to angle, as developed for D3D and as was discovered is easier to fabricate. With 13 IPM Welding Travel Speed - a frame can be laid up quickly and welded 24", 12 sides - in 1/2 hour. That is quicker than the standard power cube with angle, where most of the time was spent in setup and squaring. Squaring is automatic in the next case.
  • Material waste could be significant, but not if each side is cut in 2 pieces, so that 12 frame pieces are first welded into 6 sides, then the assembly is welded into the finished product. This moves steel sheet use efficiency from 30% to about 90% efficient for 2' frames.
  • Focus on even easier access to parts.
  • Remote throttle and starting cable.
  • Pull start for use without battery

Minimum viable product:

  1. Engine
  2. Pump with quick connects.

No hydraulic cooler, cooler fan, cooler grate and battery. Good for intermittent use, or coninuous below 75F ambient temperature.


  • 2 stage 28 gpm pump at high flow, 7 gpm at low flow, requires 16 hp of engine drive. [4]
  • High flow rate would require a larger 3.5" hydraulic cylinder on the drawer.
  • Solenoids are 26.4 - just 6% undersize but that is minimal and the machine runs at this flow only a small fraction of the time.

Thermal Design

  • With 18hp, there are conditions under which hydraulic cooling is not necessary.
  • Piston efficiency - 90-95% - [5]
  • Hydraulic gear pump efficiency - 85%
  • Dissipation is 25-40% of input power - 4.5 hp to 7.2 hp
  • For 18 hp, 5.4kW of heat dissipation may occur passively through the metal in the Power Cube
  • Heat goes into the hydraulic oil at every place in the system where there is a PSI pressure loss due to flow of oil without mechanical work being produced. -[Heat goes into the hydraulic oil at every place in the system where there is a PSI pressure loss due to flow of oil without mechanical work being produced.- [6]
  • Every square foot of tube heat exchanger at 50F difference dissipates 2hp of heat - [7]. Same source indicates about 1 hp heat loss from a hydraulic reservoir of 10 sq feet area at a 100F temperature difference.


  • 10 hp - no cooler - [8]
  • 13 hp - no cooler - [9]


  • 18hp,
  • Log splitter pump - [10] - only 8 hp for 13/3 gpm 650/2500 PSI

Data Collection

  • One of starter switch attachment bolts broke off
  • Fuel tank is too hard to fill with fan on top of power cube
  • Pull cord got tied up inside pull cord case

=Future Quality Control Learnings - verify bolt tightness on engine for all attachments

Future Work

  • Verification of fuel tank and engine attachments longevity - fuel tank or starter switch breaking off from vibration
  • Open source scalable engine with throttle control, gasifier-based