PSAA Curriculum Unit Physical Science Systems

Problem Area Energy and Power Systems

Hydraulic Power Transmission Lesson

What are some specific applications for hydraulics? Make a list of equipment and the specific applications of hydraulics. Why are hydraulics a part of so many pieces of agricultural and industrial equipment?

Learning Objectives Identify the components of a hydraulic system and explain its operation. Determine the efficiency of a hydraulic power system. Calculate the actual and ideal mechanical advantages of a hydraulic system. Explain the common uses of hydraulic systems on agricultural machines.

Terms Actual mechanical advantage Area Circuit Efficiency Force Hydraulics Ideal Mechanical Advantage Pascal’s Law Pressure Pump Reservoir Syringe Work

What are the basic components of a hydraulic system and the role each component plays in the system? Hydraulics is the science of liquid in motion. Air is compressible but liquids cannot be compressed. A system that uses oil or another type of liquid is known as a hydraulic system.

What are the basic components of a hydraulic system and the role each component plays in the system? A basic idea behind any hydraulic system is that when a force is applied at one point, the force is transmitted to another point using an incompressible fluid. The fluid is usually an oil and the force usually multiplied during the process.

Basic to any hydraulic system are: A pump, which creates pressure for the system. A rotor or cylinder, which transfers the hydraulic energy back into mechanical energy in the form of rotary or linear motion.  The cylinder in this lesson consists of a disposable syringe to transmit the energy.

Basic to any hydraulic system are: Lines, which transfer the hydraulic energy from the pump to the rotor or cylinder and return the energy to the pump. A reservoir to store a supply of fluid. Valves to control, or direct, the fluid and its movement. All the components make up the hydraulic circuit that completes the loop.

Hydraulic Power Transmission Laboratory Setup Diagram

Hydraulics (cont.) Pressure may be defined as the potential energy of a fluid power system. Applying pressure to some unit area develops force. Pressure is calculated by dividing the force by the area. Applying a pressure of ten pounds to one square inch area of a plunger in a hydraulic cylinder will exert a pressure of ten pounds on each square inch of the system.

Hydraulics (cont.) Pascal’s Law states that pressure exerted at any point on a confined static liquid is transmitted with equal force on equal areas at right angles to all surfaces.

Hydraulics (cont.) The scientific definition for work involves using a force to move an object. In hydraulics force and work are inversely proportional, meaning one must be sacrificed for the other in the system.

Hydraulics (cont.) In a hydraulic system involving two pistons, when one piston is six times larger than the other piston, a force applied to the smaller piston will appear six times greater on the larger piston, but the smaller piston will have to travel six times farther in travel distance.

How is the efficiency for a hydraulic system calculated? What factors affect the efficiency of the system? The efficiency of a system is usually calculated by comparing the output to the input of the system. In a hydraulic system, efficiency is determined by dividing the actual mechanical advantage by the ideal mechanical advantage and multiplying the result by 100 to obtain a percentage of efficiency.

Efficiency of the hydraulic system Efficiency of the hydraulic system in the experiment can be affected by various factors, the most obvious being friction.

Efficiency of the hydraulic system If the weights providing the force are not properly placed and the force does not push directly straight down on the hydraulic piston, additional force can be exerted horizontally between the plunger and cylinder wall. This outward force will increase the effort needed to lift the resistance and reduce the efficiency, because the actual mechanical advantage will be decreased.

How is actual mechanical advantage and ideal mechanical advantage calculated for a hydraulic system? Ideal mechanical advantage is the theoretical advantage that the system would have if there were no outside influences or limitations such as friction of the fluid or the plungers against the walls of the syringe or hydraulic piston. Ideal advantage assumes that there is no air present in the system and there are no fluid leaks as well.

Ideal Mechanical Advantage Ideal mechanical advantage in a hydraulic system is determined by dividing the area of the larger piston by the area of the smaller piston. Area of the piston is calculated by squaring the diameter of the piston, multiplying by pi (3.14) and dividing by 4. Area is reported in square units such as square inches or square centimeters.

Actual mechanical advantage Actual mechanical advantage is the actual advantage gained when all these limitations and factors are considered by comparing the loads placed on the system.  Actual mechanical advantage is determined by dividing the resistance force by the effort force.  The resistance force is the object(s) attempting to be moved by the hydraulic system.

What uses exist in the agriculture industry for hydraulics? Examples of hydraulics exist everywhere in the world, and agriculture is no exception when it comes to uses of hydraulics. From log splitters in your backyard to gigantic machines we see on construction sites, hydraulic equipment is amazing in strength and agility.

What uses exist in the agriculture industry for hydraulics? In construction zones, we see hydraulically operated equipment in the form of bulldozers, shovels, cranes, and forklifts. Another common piece of equipment at construction sites and agricultural facilities is the skid/loader using hydraulics to rotate the bucket, lift the bucket, and to raise and lower the bucket.

What uses exist in the agriculture industry for hydraulics? Large dump trucks usually have one cylinder or two to lift the bed. These cylinders telescope, which gives them a large range of motion for dumping loads, such as rock or grain. Even the brakes in our automobiles use hydraulics.

Review/Summary What are the basic components of a hydraulic system and the role each component plays in the system? How is the efficiency for a hydraulic system calculated? What factors affect the efficiency of the system?

Review/Summary How is actual mechanical advantage and ideal mechanical advantage calculated for a hydraulic system? What uses exist in the agriculture industry for hydraulics?