Mechanical Engineering Links and Degrees of Freedom Grade 10 ST

What is Mechanical Engineering? Engineering is a branch of science and technology that focuses on the analysis and execution of technological projects such as building bridges, roads, bicycles, cars and televisions. Mechanical engineering is a branch of engineering that focuses on the design, production, analysis, working and improvement of technical objects

Linking in Technical Objects When there are more than two parts in an object there needs to be a link to hold the two parts together. Any part or fluid that holds together 2 pieces performs a mechanical function called linking

Characteristics of Links Every link can have only 4 characteristics Direct or Indirect Rigid or flexible Removable or non-removable Complete or partial

Characteristics of Links

Practice The link between the tire and the wheel is: Direct Flexible Removable Complete

Practice Link between the wheel and the frame Indirect Rigid Removable Partial

Degrees of Freedom of Movement In a technical object linking limits the possibility of independent motion of one part in relation to another. Ex: The link between the bicycle tire and the wheel. The tire will always follow the wheel. Therefore, this is an example of a complete link.

Degrees of Freedom of Movement Ex: The wheel and frame on a rollerblade. The wheel can turn even if the frame is immobile. Therefore, this is an example of a partial link

Degrees of Freedom of Movement There are 6 possibilities of independent motion 3 translational motions 3 rotational motions A part may have a maximum of six degrees of freedom.

Degrees of Freedom of Movement

Guiding Controls Guiding controls force moving parts to follow specific trajectory There are 3 types of guiding Translational guiding ensures the straight translational motion of a moving part Rotational Guiding ensures the rotational motion of a moving part Helical Guiding ensures both the translational motion of a moving part while it rotates about the same axis.

Examples Examples: The window has what kind of guiding? _____________________________ The axle on a bike provides what type of guiding? ____________________ The peanut butter lid has what type of guiding?_____________________

Adhesion and Friction Adhesion is the phenomenon that enables two surfaces to remain in contact with each other without slipping. Friction is a force that resists the slipping of one moving part over another Lubrication is the mechanical function performed by any component that reduces friction between two parts.

Five Factors that affect the strength of adhesion between 2 Surfaces

How to reduce friction? Apply a lubricant Polish the surface of the parts

Practice For each of the following situations, determine whether the strength of adhesion between the surfaces described will increase or decrease, and identify the factor affecting the strength of adhesion. a) between the soles of a worker’s boots and the shingles on a roof as the temperature rises over the course of the day increase  decrease  Factor involved: _________________________________________ b) between a hockey puck and the ice as the period advances and the ice becomes rougher c) between the wheel of a wheelbarrow and the road after the wheelbarrow has been emptied Factor involved: _________________________________________

Practice