Notes, summaries, assignments, exams, and problems for Technology

Mechanical Power Transmission Systems

Shafts and Couplings

A shaft is a rotating machine element that transmits power or energy. A shaft can also be cylindrical and support rotating parts without transmitting power. Couplings connect two shafts:

• Rigid Coupling: Shafts are aligned and maintain their position during rotation (using flanges and couplings).
• Flexible Coupling: Allows for slight misalignment between shafts during operation.

Gear Trains and Powertrains

A gear train refers to a pair of meshing gears. A powertrain consists of two or more gear pairs that alter the rotational speed of the final shaft.

Joints

Joints transmit motion and forces. These forces can be in opposite, same, or different directions.

Chains and Belts

• Chain: Ideal for dusty

Classification of Consumption Sites

Consumption sites are primarily classified as:

• Residential or Commercial: Buildings intended for living or business purposes.
• Office: Buildings specifically designed for office use.
• Industry-Specific: Facilities tailored to the needs of a particular industry.
• Industrial Concentration: Areas designated for a cluster of industries.

Load Forecasting

Load forecasting considerations for different building types:

• Housing: Residential buildings.
• General Services: Common areas and shared facilities.
• Shops and Offices: Commercial spaces and office buildings.
• Garages: Parking facilities.

Degree of Electrification

• Basic Electrification: Designed to meet primary usage needs, allowing for common household equipment (5750 W).
• High Electrification:

Development and Implementation of Demolition

1. Dismantling of industrial equipment.
2. Demolition or removal of bodies and covered ledges.
3. Demolition or removal of the deck.
4. Demolition of elements at each plant: interior partition walls, curtain walls, and cargo.
5. Demolition of structural elements: forged with beams, reinforced concrete slabs (one-direction, two-directions), beams, brackets, domes.

Types of Demolition

According to Procedure

1. Element by element.
2. With collapse.
3. Mixed or combined.

According to Media

1. Manual.
2. Mechanical.
3. Thermal.
4. By explosives.

Design of a Sanitation Network

• If the network is public: Mixed.
• If two networks (wastewater and stormwater): Separator system.

Basic Sanitation Network Requirements

1. Dispose of water seal to prevent the passage of air.

Machines and Energy

Machines use energy to perform useful work.

Fossil Fuels

Fossil fuels, such as coal, oil, and natural gas, can be burned to release heat energy.

Nuclear Fuel

Nuclear fuel, including uranium and radioactive materials like plutonium, can undergo fission reactions to produce electricity.

Renewable Energy

Renewable energy sources were the first to be used historically, powering machines such as mills.

Water Wheel

A water wheel utilizes the energy of flowing water through a system of blades. It has various applications, such as grinding wheat to make flour.

• Wheels running low: These are the simplest type, with the bottom submerged. The force of the water current moves the wheel.
• Current average: This type of wheel is used when the current

Rigid Couplings

Rigid couplings are used when trees are on the same axis and do not change their position. There are several types:

• Flange Couplings: These are based on placing two flanges on the ends of the shafts so that when tightening the screws, the flanges are joined together.
• Clamp Couplings: These use a tapered internal conical piece that is compressed when tightening the screws, pressing the two pieces together.

Mobile Couplings

Mobile couplings are designed to accommodate some degree of misalignment or movement between shafts.

• Couplings with Gaskets: These absorb minor irregularities through elastic rotation and allow for very little misalignment.
• Universal or Cardan Joints: These transmit motion between two non-aligned trees.
• Homokinetic

Laying Ground Facilities Project

The process involves several key steps:

• Research
• Determination
• Design
• Calculation of resistance
• Computation step of crack on the outside of the installation
• Calculation of contact and step voltages inside the installation
• Checking
• Research
• Correction

Wenner Method

The Wenner method is the most used and recommended technique to measure the resistivity of the ground.

High Voltage Open Circuit Procedure

1. Open the switch.
2. Open the disconnectors.

High Voltage Circuit Closing Procedure

1. Close the disconnectors.
2. Close the switch.

Lockout or Interlock Device

A lockout or interlock device is the set of operations aimed at preventing the operation of a device and maintaining it in a given position.

Verification of Absence of Tension

It is necessary... Continue reading "Grounding Systems & Electrical Safety Procedures" »

Operation of Drive Elements, Control, and a Hydraulic System

Hydraulic Group

Generates hydraulic energy. A motor-driven pump converts energy. If the flow encounters resistance, there is pressure to fit in the pressure relief valve. Fluid drains back to the tank through a filter. The tank stores and conditions the oil.

Hydraulic Actuators

Converting hydraulic energy into mechanical energy. Conversion by rotating movement (hydraulic motor, which is at the pump's traverse), or linear movement cylinder.

Cylinders:

1. Single-acting
2. Double-acting
3. Special
4. Plunger (double-acting piston rod makes)
5. Differential (double-acting 2:1 ratio S side plunger rod side)
6. Equilibrated (dual stem)
7. Telescopic (short length, big race)

Valves

Responsible for controlling flow regulation... Continue reading "Understanding Hydraulic Systems: Actuators, Valves, and Control" »

Technology Project Process and Building Materials

Technology Project Process

• Problem Analysis

  Tools for analysis, potential improvements, relevant knowledge, ideas, and theories.

• Technical Project

  • Idea Generation

    Each participant creates a sketch or drawing with a brief explanation detailing the object, its components, and operation.

  • Idea Selection

    Choose the most appropriate idea based on criteria such as potential for improvement, feasibility with available resources, frequency of suggestion, or innovative solutions to the problem.

  • Final Design

    Create detailed drawings, plans, and views of the object.

  • Material Selection

    Choose appropriate materials for each part considering technical, aesthetic, economic, and ecological factors, utilizing available resources.

What are Monomers and Polymers?

Plastics are formed by the combination of low molecular weight molecules called monomers. Polymers are formed by joining monomers.

• The union of monomers results in large molecules called polymers.

What is Polymerization?

Polymerization is a chemical reaction that joins monomers into large chains to build macromolecules called polymers.

Artificial vs. Synthetic Plastics

Artificial plastics are created by transforming natural materials. Synthetic plastics are created from materials such as oil and gas.

Thermoplastics vs. Thermosetting Plastics

Thermoplastics can be heated and molded multiple times. Thermosets can only be heated and molded once.

Plastic Applications

Thermoset Applications

• Phenol formaldehyde (PF) combined