Basic Laws and Principles
This law of hydraulics is expressed as "Pressure = Force ÷ Area".
What is Pascal's Law?
This measures the rate of fluid moving through the system.
What is a Flow Meter?
These two are often paired together directly as a means of powering the movement of fluid.
What are the Pump and Prime Mover?
This system approach consists of : Setting a target cleanliness, selecting proper filters, placing them where they'll see enough flow, and taking samples to confirm your targets are being hit.
What is Contamination Control (Filtration)?
The amount of fluid transferred from the inlet to outlet of a pump in a single 360° rotation.
What is displacement?
The power of flowing fluid relative to mechanical horsepower (33,000 ft.lbs./min).
This is equal to (GPM x PSI)÷1714
What is Fluid Horsepower?
This can be used for leak testing individual components out of circuit.
What is a Porta-Power?
Hydraulic cylinders and motors can be classified as these.
What are Actuators?
These are the four purposes of hydraulic fluid.
What are transmitting power, lubricating moving parts, dissipating heat, and sealing clearances between moving parts?
This is often a very effective way to test zero-leakers.
What is a leak down test?
This is a standardized system of symbols used in hydraulic schematics in North America, and are the ones used on this course.
What are Hydraulic ANSI (American National Standards Institute) symbols?
Used in checking for excess heat.
What is a Pyrometer?
It protects the system from overload, prevents excessive force being generated by an actuator, and prevents the stalling of the prime mover.
What are Pressure Relief Valves?
These are the three types of failures.
What are Catastrophic, Intermittent, and Degredation?
This is knowing how a component works. It is an important part of the Eight Steps of Successful Diagnosis.
What is the Theory of Operation?
The rapid creation and collapse of bubbles in a fluid.
What is Cavitation?
This type of pressure gauge displays pressure using a needle linked to a flexible metal tube. With accuracies of 0.1-3.0%, they are often used in labs.
What is a Bourdon Tube Pressure Gauge?
Knowing these two most basic classifications of hydraulic components can aid in diagnosis of faults.
What are Leakers and Zero-leakers?
This type of maintenance waits until something breaks, often this can cause contaminants to spread through the system and lead to more repairs.
What is Reactive Maintenance?
Given a DCV is a leaker: to diagnose for this fault a leak down test should be performed over time, between 200psi and system pressure, across the ports.
What is DCV Leakage?
This should be your number one concern when working on hydraulics, or any equipment for that matter.
What is Safety?
Before beginning any diagnosis by opening lines, this state should be reached within the hydraulic system. This includes isolating accumulators.
What is a Zero-energy State?
These start, stop, and control the direction of fluid flow on hydraulic equipment.
What are DCVs (Directional Control Valves)?
Expressed as three sets of numbers separated by a slash (eg 17/15/13), this code is used to determine target cleanliness levels of a system.
What are ISO Range Codes
This test is done on either end of a cylinder (live-end or rod-end) when common issues with cross-piston leakage are noticed.
What is a Dead-Head test?