# Hydraulics and Pneumatics II

SKMT 222

## Course Description

Prerequisite: SKMT 220. Advanced course in fluid power designed for machine repair, pipefitters and plumber trades. Analyzes common hydraulic and pneumatic components and circuits. Includes building of machine tool circuits and troubleshooting special systems such as hydrostatic transmissions and electrohydraulic servos, and ladder diagramming of pneumatic control circuits. Covers mathematics and graphic symbols used in troubleshooting. Credit may be earned in SKMT 102 or SKMT 222, but not both. (45-0)

## Outcomes and Objectives

### Discuss objectives learned in Hydraulics/Pneumatics I.

#### Objectives:

• Remember the schematic symbols used in Hydraulic or Pneumatic drawings.
• Find and locate these symbols in both textbooks.
• Identify and locate these symbols on drawings.
• Locate components in circuits and identify where these components should be located within a circuit.
• Use a drawing to state that the specific circuit does "......etc......".
• State the basic laws of Hydraulics and Pneumatics such as "Pascal's Law" and the "Pressure-Force-Area triangle".

### Explain basic components of a circuit no matter how simple or how complex

#### Objectives:

• Cartridge valves:
• Proportioning valves:
• Servo valves:

### Recognize various circuits from drawings and be able to build them on trainers.

#### Objectives:

• Hydrostatic transmissions.
• Regenerative circuits.
• Intensifier circuits.
• Accumulator circuits.

### Recognize that normal conditions in any system will cause pressure drops.

#### Objectives:

• Apply the materials presented in class, working on the trainers, and using a chart in the Pease textbook (page 185) to determine potential pressure drops in a system using the following information:

### Recognize the hydraulic circuitry in an automotive automatic transmission.

#### Objectives:

• Explain how a torque converter works.
• Locate the hydraulic pump, explain how it is driven, and state what type of pump it is (usually a gear type).
• Locate the hydraulically operated brakes and clutches.
• Locate the planetary gear systems operated by the hydraulic brakes and clutches and explain how they are operated by the hydraulic brakes and clutches and that each gear speed of the transmission has its own planetary gear set.
• Understand directional valves route hydraulic pressure to the respective brake and clutch of the specific planetary gear set.
• Recognize that the shifting of the directional valves is controlled by vacuum, tachometer, and electronics, with electronics more so today.

### Work with and maintain fluid power equipment in a safe manner.

#### Objectives:

• Recognize the proper way to lockout or disable fluid power equipment in order to work on it in a safe manner.
• Recognize the sequence of operations of fluid power machinery in order to determine what should or should not happen in order for it to be operated in a safe manner.
• Describe how to locate the proper replacement parts to be used to properly perform a repair job.
• Use the proper tools when performing maintenance or repairs on fluid power equipment.

### Use fluid power with vacuum and pneumatics as the median.

#### Objectives:

• Compare vacuum with pneumatics.
• State some uses of a vacuum: a) lifting, b) molding, c) suction
• Explain that a vacuum is the difference between absolute pressure and atmospheric pressure.
• Convert in/Hg into psi and also the reverse.
• State advantages and disadvantages of pneumatics.i. Advantages: Fast, positive, clean, less chance of electrocution or shock, compact, no mess, versatile.ii. Disadvantages: Expensive, noisy, force limitations, not always smooth, leaks are common.
• State the laws which apply to pneumatics: a) Pascals's law, b) Boyle's law, c) Charles' law, d) Universal gas laws.
• Relate the gas laws to algebraic equations and formulas in order to calculate pressure, force, cubic-feet-per-minute, area, volume, velocity, revolutions-per-minute, inches-per-minute, and other various units related to pneumatics.
• Differentiate between components which are used in pneumatics and not in hydraulics and vice versa.
• Recognize the different types of compressors:
• Identify and locate the components of a pneumatic system

### Explain how air can be used for control purposes as well as doing useful work.

#### Objectives:

• Equate components of an air control circuit with its comparable electric components.
• Build a complete working air circuit with air controls on the trainers using an ANSI drawing.
• Learn to read a detached ladder diagram of an air control circuit and compare it with an ANSI diagram and notice that such a drawing is closely related to an electrical ladder diagram.
• Use a diagram of a control circuit with ANSI symbols to draw this same circuit in a ladder diagram.