Types of Mechanical Liaisons: Pivot and Sliding

This page explores two specific types of mechanical liaisons: the pivot and the sliding liaison.

Pivot Liaison (X-axis)

The pivot liaison allows rotation around a single axis, typically the X-axis in this example.

• Contacts: 1 point contact, 1 cylindrical surface contact
• Degrees of freedom: 1 (rotation around X-axis)
• Translations: [0, 0, 0]
• Rotations: [1, 0, 0]

Example: A door handle connected to a door demonstrates a pivot liaison.

Sliding Liaison (X-axis)

The sliding liaison permits linear movement along a single axis, in this case, the X-axis.

• Contacts: 1 straight line contact, 1 planar surface contact
• Degrees of freedom: 1 (translation along X-axis)
• Translations: [1, 0, 0]
• Rotations: [0, 0, 0]

Example: A drawer sliding in and out of a dresser illustrates a sliding liaison.

Both liaisons are represented with specific symbols in 2D and 3D diagrams, helping engineers and designers quickly identify the type of mechanical connection in a system.

Vocabulary: Degré de liberté mécanique (Mechanical degree of freedom) refers to the independent movements a body can make in three-dimensional space.

This page provides a clear comparison between two fundamental types of mechanical liaisons, highlighting their differences in allowed movements and practical applications.

Linear Annular and Linear Rectilinear Liaisons

This section explores two types of linear liaisons: the linear annular liaison and the linear rectilinear liaison.

Linear Annular Liaison (X-axis)

The linear annular liaison allows rotation around its axis and translation along two perpendicular axes.

• Contacts: 1 circular line contact
• Degrees of freedom: 4 (rotation around X-axis, translations along Y and Z axes)
• Translations: [0, 1, 1]
• Rotations: [1, 0, 0]

Example: The connection between a tennis ball and the tube of a ball launcher illustrates a linear annular liaison.

Linear Rectilinear Liaison (X-axis, normal to Y-axis)

This liaison permits translation along its axis and rotations around two perpendicular axes.

• Contacts: 1 straight line contact
• Degrees of freedom: 4 (translation along X-axis, rotations around Y and Z axes)
• Translations: [1, 0, 0]
• Rotations: [0, 1, 1]

Example: The interaction between an ice skate blade and the ice surface demonstrates a linear rectilinear liaison.

Both liaisons are represented with specific symbols in 2D and 3D diagrams, providing a visual shorthand for engineers and designers.

Vocabulary: Types de liaisons mécaniques (Types of mechanical liaisons) refer to the various ways mechanical parts can be connected, each allowing specific movements and restricting others.

This page introduces more specialized types of mechanical liaisons, highlighting their unique properties and applications. Understanding these liaisons is essential for designing and analyzing complex mechanical systems that require specific types of linear movement combined with rotational freedom.

Fixed Joint Liaison

This final section focuses on the fixed joint liaison, also known as an encastrement.

Fixed Joint Liaison

The fixed joint liaison completely restricts all movement between the connected parts.

• Contacts: 1 point contact, 1 cylindrical surface contact, 1 planar surface contact
• Degrees of freedom: 0 (no movement allowed)
• Translations: [0, 0, 0]
• Rotations: [0, 0, 0]

Example: The connection between a beam and a wall in a building structure demonstrates a fixed joint liaison.

The fixed joint liaison is represented with a specific symbol in both 2D and 3D diagrams, indicating complete restriction of movement.

Vocabulary: Liaison mécanique Animation (Mechanical liaison animation) refers to visual representations or simulations that demonstrate how different types of mechanical liaisons function and move.

This page concludes the exploration of mechanical liaisons by presenting the most restrictive type. The fixed joint liaison is crucial in engineering and construction where stability and immobility are required. Understanding this liaison, along with all the previously discussed types, provides a comprehensive view of how mechanical parts can be connected and constrained in various systems.

Highlight: The study of mechanical liaisons is fundamental to engineering design, allowing for the creation of complex machines and structures by understanding how different parts can be connected and how their movements can be controlled or allowed.