Hydraulic Pumps and Cylinders Hydraulic Pumps will be rated with a pressure and flow rate deliverable. The Pressure is the output pressure of the pump and the flow rate is the volume of hydraulic fluid the pump can move in a given time. For this class we will not worry about line losses and head pressure losses and gains. That will be covered in Hydraulics class.

Hydraulic Cylinders Hydraulic cylinders will have a piston diameter (sometimes just called the cylinder diameter) and a total length it can be extended to. The force the cylinder can exert is dependant on the fluid pressure supplied to the cylinder and the cross-sectional area of the piston F = P*A The Speed at which the cylinder is traveling is dependant on the cross-sectional area of the piston and the volumetric flow from the pump Speed = Volumetric flow / A

Pascal’s Law A fluid at rest creates an equal pressure in all directions at any one point To add to this, the pressure is only dependant on the density (ρ) or specific weight (γ) of the liquid and the depth of the liquid (h) at that point P = ρgh P = γh γ = specific weight = ρ * g

Density and Specific Weight of Water For Water, Density 1000 kg/m3 1.938 slug/ft3 Specific Weight 9810 N/m3 62.4 lb/ft3

Pressure on a Submerged Surface Calculate the equivalent force on each wall and the bottom of a one foot long section of the trench shown filled with 6 feet of water 6 ft 2 ft

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Example 1: Determine the magnitude of the hydrostatic force acting per meter length of the wall. Water has a density of 1 Mg/m^3)

Example 2 – Determine the magnitude of the hydrostatic force acting on gate AB, which has a width of 2 ft. The specific weight of water is 62.4 lb/ft^3)