Physical Science Applications in Agriculture

Unit

Physical Science Systems

Problem Area

Agricultural Mechanics and Machine Systems

Safe Handling and Loading:Balance and Center of Gravity

Lesson

What is a roll-over?

• Discuss tractor safety and rollover protection.

• Anyone personally aware of tractor rollovers.

• Discuss loading and transport.

• Have any of them dumped a load or heard of someone who has dumped a load?

Learning Objectives1. Define stability.

2. Explain the center of gravity.

3. Calculate the center of gravity.

Terms

• Balance• Center of gravity• Equilibrium• Stability

www.cdc.gov/www.galleri-bjorn.dk/.../pages/John%20Deere4.htm

What is stability?

• Stability – Refers to a condition of

balance.

• Center of gravity is critical to stability.

• If an object is tipped, but will return to its original position when released, it is in stable equilibrium.

www.alpaca-info.com/ranch.htm

What is stability?

• For a stable equilibrium condition, a plumb line dropped from the center of gravity will fall within the base of the object.

www.safetyline.wa.gov.au/.../lecture78/l78_03.asp

What is stability?

• If an object is tipped to a point where a plumb line attached to the center of gravity falls outside its base, an unstable equilibrium condition exists.

www.safetyline.wa.gov.au/.../lecture78/l78_03.asp

What is stability?

What is center of gravity?

• Center of gravity – Point at which all

parts or areas of a body are balanced.

• Balance – Stability or

equilibrium

iareh.usask.ca/rhep/.../slide0004.htm

THE CENTER OFGRAVITY ON A TRACTOR

What is center of gravity?

• The typical tractor has its center of gravity located between the front and rear wheels behind the midpoint of the tractor’s length and above the axle height.

• Center of gravity of an object will always seek the lowest possible position.

• If tipping an object lowers the center of gravity, the object will not return to its original position.

What is center of gravity?

www.alpaca-info.com/ranch.htm

Where is the center of gravity located on a tractor?

• Center of gravity of an object determines the stability of that object.

Where is the center of gravity located on a tractor?

• The center of gravity will always seek the lowest position possible; therefore great care must be taken when loading or hitching to prevent rollover.

• The external forces acting on a tractor pulling an implement can be quantified and analyzed.

Where is the center of gravity located on a tractor?

• Hitch height is an important variable in stability.

1. If hitch height is too high, the hitched tractor is not in equilibrium.

2. Hitching at a lower point or weighing the front of the tractor can prevent unsafe rollover conditions from occurring.

Where is the center of gravity located on a tractor?

Where is the center of gravity located on a tractor?

• The object will be stable if a plumb line dropped from the center of gravity passes through the base of the object.

Review/Summary

• What is stability?

• What is center of gravity?

• Where is the center of gravity located on a tractor?