Power Cube Conceptual Design

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With Tank

  • Mild steel frame, 1/4" plate.
  • Provides a solid frame around Power Cube, such that it could be lifted
  • Lift hooks need be put on the frame.
  • Frame is CNC cut. Easiest method of frame production is to cut it with CNC. If build manually, use 2" angle
  • Includes 7 pieces of metal for frame, such that assembly is easy and self-aligning.
  • Tank is frame-integrated.
  • Breather is 1.5" pipe, with a welded 2" pipe over it.
  • 3D printed mesh basket with aluminum screen. OSE design. Goes into the breather.
  • all fittings are welded in prior to assembly of 7 frame pieces.
  • Location of fittings: suction lines are 2" from bottom
  • Return lines are as far to the top as possible, in line
  • Return lines have elbows inside the tank with pipes down to about 4" from the bottom to prevent air entrainment. (except slow case drains).
  • Filter location allows for screwing on of the filter. The filter screws on. Make sure in the finished power cube, the filter can be screwed off - ie, nothing blocks it from being unscrewed.
  • The simplest way to attach fittings into the tank is to weld the pipes right in: return lines are 3/4" pipe for filter, and 1/2" pipe for the other returns, and 1/4" pipe for case drain, and 3/4" for suction
  • Frame must be attached somehow to a frame of a tractor. Use 4 holes at the bottom frame member


  • There are 4 return line 1/4" fittings for case drains
  • Return line case drains are a 1/4" pipe welded into frame
  • Other side of case drain pipe is threaded for a 1/4" female quick coupler
  • There are 4 return line 1/2" lines for power
  • 1/2" return lines are 1/2" black pipe, with thread for a 1/2" female quick coupler
  • 3/4" return line is for the filter, and it's a 3/4" pipe, with thread on the receiving end for screwing in the filter
  • Make sure the metal part of the filter can be screwed in without interference once power cube is assembled
  • Sucktion lines have 1" ball valves.
  • Make suction pipe threaded, so that you put the ball valve on it
  • Put a barb (meaning a 3/4" pipe without threads) - on the ball valve - so that other power cubes can be attached to these.

Without Tank

  • Consists of 6 CNC cut plates
  • Tank is not included
  • Daughter power cubes use a suction line that goes to the mother power cube


  • For 10 gpm scale of power - use a 16 hp engine. 18 hp is ok, too.

Pump - 16-18 Hp Cubes

  • Pump used is a gear pump. This is inexpensive, and reversible. In other words, if you pump fluid through the pump externally via the outlet - and the pump should spin.
  • Examine Hydraulic Calculations for size required.
  • 10 gpm pump is standard to attain 3000 PSI (check this). You can use larger pump, but PSI will be lower
  • 9 spline coupler is favored so it has good grip while allowing for quick disconnection without any set screw
  • Pump power matches power of the engine
  • Suction hose sufficient according to Hydraulic Calculations
  • Attaches directly to tank
  • Should be low cost - $100 18 hp - under $6/hp
  • Typically has to be Clockwise (CW) to match the engine, which is counterclockwise
  • Attaches using SAE 2-bolt mount using a standard SAE pattern
  • Uses a self-made pump mount to facilitate use of widely available parts. Ours uses 2" Sch 80 pipe (about 1-7/8" inner diameter, and about 2.5" OD) with welded construction. This allows us to make a relatively short coupler.
  • We trim the engine shaft length to about 2" to reduce overall length by 1.5"
  • Welded coupler allows us to minimize length for optimal geometry, whereas standard mounts are longer and not guaranteed to have matching hole pattern even though they say they do
  • Coupler is a welded 1" to the 9 spline (5/8") shaft. This is welded from a cut off 1" coupler with 1/4" key + 9 spline coupler.
  • The coupler is welded by putting in a "coupler aligner piece" and welding, then taking the coupler aligner out
  • Typical use of hydraulic pump means that we put a quick coupler, 1/2", right on the pump. 1/2" is good for 12 gpm. The output is called the power hose. If output is 12 gpm or lower, then the fitting and hose can be 1/2".
  • Outlet coupler is mounted straight out, no bends, to minimize losses
  • Suction line is such that distance to tank is the shortest possible, and it bends gently without 90 degree angles
  • Suction line is 1"
  • Cost effective route for attaching suction line is 3/4" npt sch 40 black pipe + hose clamp.
  • typically pumps are SAE o-ring fittings, so inlet is typically a 1" SAE adpted to NPT female. Hose can attach to this pipe.
  • It is likewise convenient to use 3/4" black pipe on tank.
  • Make sure the way the power hose is such that you can quick couple to it without obstructing the power hose.
  • Quick couplers can handle the high pressure. Hose connections on output cannot be used, as they can only hold about 100 psi, and output pressure is 2000 or more psi
  • No airleaks must be present in the suction line so that the pump can prime, and of course so we don't have hydraulic fluid leaks.
  • Outlet line must be tight to 30 lbs of torque [1]
  • Cannot use standard pipe on outlets, as standard pipes are rated only for a few hundred PSI
  • Use only hydraulic duty (2000+ PSI) hose and fittings on outlet of pump.
  • Pump is parallel to engine - shaft of pump and engine align. When the pump is installed, the alignment with engine shaft must be such that there is no resistance. You can check this by for example pulling the pull start, or rotating the top of the engine - to make sure the engine is still spinning freely.
  • Dual stage log splitter pump may be used for better efficiency, but this is pump is slighly longer. The log splitter pump can be used for cylinder load only, as this would cause unpredictable speed jumps with motors.
  • Single stage gear pump can be used with both cylinders and motors
  • When tightening the hydraulic pump - make sure that you tighten evenly. Do not tighten one side more than other, as that may cause slight misalignment and lock up the pump-to-engine coupling
  • No need to use a set screw on the spline coupler.
  • The engine side of coupler requires set screw to hold the key in place. Otherwise you may lose or shear the key if the key falls out.
  • Pump coupler is mild steel plates, with bolt pattern that matches engine. See Engine Bolt Patterns.


  • Contains a mounting mechanism for the cooler, such as a grate
  • Must have sufficient cooling for the engine in the power cube. See Hydraulic Calculations
  • Mounting kit uses rubber mounts between pipes compressed by bolts.


Return Line Filter

Return Lines

Suction Lines


See Power Cube Genealogy for version.

Summary: the design is a scalable, modular, self-contained power unit of 28 hp with a structural frame that makes the Power Cube a plug-and-play component for building other machines.

The basic design requirements follow OSE Specifications and include:

  • Modularity - decoupling of power unit from machine
  • Modularity - bolt together design
  • Modularity - integrated structural steel frame makes the Power Cube either a standalone unit or structural part of another machine
  • Stock parts - uses easily-findable parts and stock steel
  • Modularity - consists of 11 modules that can be built in parallel
  • Lifetime design - bolt-together construction and quick couplers allow for ease of disassembly
  • Scalability - unlimited Extensive Scalability is feasible by using more Power Cubes in parallel. Tp date, up to 3 Power Cubes have been used on a single machine. See Stacking 3 Power Cubes.
  • Modularity - quick couplers are used to connect the Power Cube to other devices
  • Product Ecology - can be powered by the OSE Gasifier, is the core of a MicroTractor, and can be used to power or build other and larger machines. Can be stacked for bulldozer duty.

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