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

Mechanisms

Mechanisms are components used to transmit or transform movement. They can transmit linear motion, used for raising objects, or circular motion, used to change speed.

Levers

A lever is a rigid bar that pivots around a fixed point called a fulcrum. One end of the lever applies a force, while the other end moves a resistance.

Types of Levers

Depending on the positions of the fulcrum, force, and resistance, there are three types of levers:

• First-Class Lever

  The fulcrum is located between the force and the resistance. Example: Scissors, which are essentially two first-class levers joined together.

• Second-Class Lever

  The resistance is located between the fulcrum and the force. Example: Wheelbarrows.

• Third-Class Lever

  The force is located between

What are Plastics?

In chemistry and technology, plastics are polymeric organic materials. They are giant molecules formed by carbon atoms linked with hydrogen, oxygen, and to a lesser extent, chlorine, fluorine, nitrogen, or silicon.

Key Properties of Plastics

• Affordable
• Low density
• Waterproof
• Electrical insulators
• Thermal insulators, although not highly resistant to heat
• Resistant to corrosion and weathering
• Resistant to many chemical factors
• Some are recyclable, but not all are biodegradable or easily recycled
• Easy to work with
• Burning some plastics can be highly polluting

Origin of Plastics

Polymers can be classified based on their origin:

• Natural: Occur spontaneously in natural products like cellulose, rubber, and casein.
• Artificial: Industrially obtained

Serrated cutting is a metal removal operation that can divide a piece into two or more parts by removing material between them. The manual process consists of the sawing and the forward movement of the saw. The effectiveness depends on operator skill and the number of sawing strokes per second.

Bow or Frame

This tool supports the saw blade. It consists of a rigid, U-shaped arch. At the ends of the arch are two mutually perpendicular blocks that hold the saw. One of these blocks is controlled by a mobile or wing nut, and a handle serves as a grip.

The arches of saws can be fixed or extensible. The advantage of the extensible type is that it allows the assembly of saw blades of various sizes.

Saw Blade

A saw blade is made of thin, laminated carbon... Continue reading "Serrated Cutting: Techniques and Tools for Metalworking" »

Oil Tank Functions and Design

The oil tank, or reservoir, serves several critical functions in a hydraulic system.

Key Objectives of an Oil Tank

• Store System Fluid: To provide an adequate supply of hydraulic fluid for the system.
• Contaminant Settlement: To allow contaminants in suspension to settle out of the fluid.
• Temperature Regulation: To help maintain the fluid temperature within desired limits by dissipating heat.
• Air Dissipation: To facilitate the release of dissolved air or foam from the fluid.

Baffle Positioning in Oil Tanks

The position of baffles inside the tank is very important. Firstly, they establish separation between the suction line and the return line, preventing aerated or contaminated return oil from being immediately drawn back... Continue reading "Hydraulic System Components: Functions and Principles" »

Nickel Steels

Nickel steels are known for their stainless and electrical properties. Nickel increases the tensile strength, yield stress, elongation, and impact strength or resilience of steel, while simultaneously reducing the influence of heat expansion. Steels containing 10 to 15% nickel can be hardened even with slow cooling.

Chromium Steels

Chromium imparts hardness and deeper penetration of the temper, allowing for oil hardening. Steels with 1.15 to 1.30% carbon and 0.80 to 1% chromium are used for film production due to their hardness. Smaller-scale applications use steels with 0.3-0.4% carbon and 1% chromium.

Chrome-Nickel Steels

More commonly used than chromium steels alone, chrome-nickel steels are employed in various ratios. Examples... Continue reading "Alloy Steels: Properties and Applications" »

Simple Machines: Core Concepts and Skills

Conceptual Content

• Simple Machines: Basic mechanical devices.
• Units of Measurement: Conventional and unconventional measures.
• The Lever:
  • Elements: Support Point/Fulcrum (A), Power Point/Effort (P), and Resistance Point (R).
  • Lever Classes: First-Class, Second-Class, and Third-Class levers.
  • Law of the Lever: Principles governing ideal and real levers.
• The Inclined Plane:
  • Law of the Inclined Plane: Principles governing ideal and real inclined planes.
  • Concept of Angle: Understanding the angle of inclination.
• Measuring Instruments: Dynamometer, Ruler/Scale.

Procedural Skills

Research Abilities

• Observation and description of the parts of a lever.
• Classification of different types of levers according to their class.
• Identification,

Classification of Heating Hot Water Distribution System Function Adopted

Bitubular Distribution

It is characterized by the existence of two tubes, one for supply and a return, mounted in parallel. This ensures a uniform water temperature. The power of the radiators can be achieved by uprights or anillos.

Monotubular Distribution

The entire set of pipes and radiators is bound by a single distribution pipe for hot water to form a closed circuit. The water passes through all the radiators, decreasing in temperature as it moves towards the final radiator anillo.

Radiant Heating Systems

Radiant heating systems operate at temperatures between 25 to 35 ºC, radiating heat from the bottom up evenly.

Function of the Expansion Tank

What is the function of the

1. Purpose and Scope

The purpose of this instruction is to identify the requirements for electrical installations in furniture and related items. The requirements of this instruction apply to:

• Furniture of all kinds, including office furniture, desks, exhibitors, panels, and similar fixed or mobile items.
• Furniture, mirrors, and bathroom items in rooms containing a bath or shower.

The receivers used in these facilities must meet the requirements of applicable European Directives, as provided for in Article 6 of the Regulation for Low Voltage Electro. To this effect, any furniture marketed with mounted electrical equipment (e.g., lights, switches, socket bases, etc.) shall be considered a receiver.

2. Furniture Not Installed in Bathrooms

Included... Continue reading "Electrical Installation Requirements for Furniture" »

Timber Protection Systems

Felling Season

The sap inside the tree at the time of logging can serve as food for fungi and insects. Therefore, logging should occur when sap flow is lowest, typically during the winter.

Sap Removal

It is necessary to remove the sap from the wood vessels. This is done by washing the timber to dissolve starchy substances.

Sap removal can be achieved through:

• Water Washing (Leaching): This process takes 1 to 3 months.
• Steaming (Vaporization): This method is much faster. The high temperatures used also kill insects and fungi that may have developed in the tree.

Drying

Drying aims to eliminate moisture from the timber. Key objectives include:

• Stabilizing the wood dimensions.
• Preventing the growth and progression of fungi.

• Increasing

Mechanical Motion Transformers

A. Rack and Pinion

This system uses a normal gear meshing with a gear of infinite radius (rack). The rack's teeth are trapezoidal, and the system's operation is reversible. Depending on which element is driving and which is fixed, we have:

• Pinion rotates, rack fixed: The pinion moves linearly. This is used in winches for manual carriage movement.
• Rack moves, pinion fixed: The pinion rotates. This has few current applications, formerly used in mechanical calculators.
• Pinion rotates in place: The rack moves linearly. This is used in drill presses, automobile steering, and automatic garage doors.

B. Screw-Nut

The most common application involves rotating the screw while preventing the nut from rotating, causing the nut... Continue reading "Mechanical Motion Transformers and Coupling Elements" »