Engr Help

Free Body Diagram - - Detailed Example

Key Concept: A free-body diagram is a drawing of a body, or part of a body

(isolated from its surroundings), on which all the external forces and moments

acting on the body (or any part) are shown.

In addition to external forces and moments, all dimensions, angles, and the coordinate system must be shown to complete the FBD.

Steps: 1. Define the body or collection of bodies.

2. Define the surroundings

3. Replace the surroundings with their effects on the body or collection of bodies

4. Construct the Free Body Diagram of the body or collection of bodies

Example: The front end loader of a tractor consists of a bucket with center of gravity, G,

crowd cylinder, AB, lift cylinder CD, and loader arm ECF as shown

in the figure below. Let the weight of the bucket + material equal W.

Requirements: 1. Draw a FBD of the bucket and use it to find the force in crowd

cylinder AB.

2. Draw a FBD of the appropriate collection of members and use it to

find the force in lift cylinder CD.