Brick Pressing Rate Calculations
Introduction
Under the assumption of incompressible flow and fixed hydrauilic cylinder volume, the brick pressing rate of The Liberator can be calculated for a given hydraulic flow rate.
Let's take 25 gallons per minute for the design flow rate of The Liberator II Beta v2.0.
The Liberator
The Liberator uses a 5x8x2 inch cylinder (diameter x length x rod diameter) for pressing, and a 2.5x14x1.125" cylinder for the soil loading drawer.
The effective volumes for both cylinders differ. This is because the cylinder rod takes up some volume - thereby reducing effective volume and force for the contraction part of the stroke. The expansion part of the stroke uses the full cylinder volume.
Main Cylinder Volume, D= 5 inches, D_rod=2 inches
- Cylinder volume (expansion volume) = 157 cu in
- Rod volume = 25 cu in
- Cylinder volume-rod volume (contraction volume) = 132 cu in
- Volume filled for a complete cycle of the cylinder (expansion volume + contraction volume) = 289 cu in
Secondary Cylinder Volume, d=2.5 inches, d_rod=1.125 inches
- Cylinder volume (expansion volume) = 69 cu in
- Rod volume = 14 cu in
- Cylinder volume-rod volume (contraction volume) = 55 cu in
- Volume filled for a complete cycle of the cylinder (expansion volume + contraction volume) = 124 cu in
One complete cycle volume
One cycle volume = 413 cu in
1 gallon = 231 cu in
1 cycle = 1.8 gallons of fluid
Pressing Rate Results
The results above yield 14 brick per minute results. After subtracting 10% for the slowdown of the pressing cylinder and similar losses for hydraulic inefficiencies, we obtain 11 bricks per minute.
Similar calculations and reasoning for for 2.5" thick bricks yield an overall results of 13 bricks per minute.
Update
For The Liberator II