04/20/23Baltimore Polytechnic Institute Engineering Practicum –

Dr. Smith

Cranes Are…•Lifting machines that can move loads vertically or horizontally•Used to move heavy loads by taking advantage of mechanical advantage

Cranes Are Used For…•Transportation•Construction•Manufacturing

04/20/23Baltimore Polytechnic Institute Engineering Practicum –

Dr. Smith

Transportation

Construction

Manufacturing

1500 B.C. – Shaduf used in early Egypt to lift water

515 B.C. – Pulley Crane used in ancient Greece

357 A.D. – Treadwheel Crane used in Rome 480 A.D. – Crane use declines with fall of Western

Roman Empire1225 A.D. – Treadwheel Cranes are re-introduced

in Europe during the Middle ages1340 A.D. – Slewing Crane used for dockside

loading1700’s – Steam Crane ushers in the modern

era

04/20/23Baltimore Polytechnic Institute Engineering Practicum –

Dr. Smith

Mobile•Mounted on a moveable base, usually some existing vehicle type (trucks, tractors, etc.)

Fixed•Stationary; usually erected in place

04/20/23Baltimore Polytechnic Institute Engineering Practicum –

Dr. Smith

Paved Surfaces

Rail

Air

Rough Terrain

Water

Tower Crane Luffing Crane

LEVERS PULLEYS

M.A. = number of strands supporting the load (minus the strand where the force is applied)

04/20/23Baltimore Polytechnic Institute Engineering Practicum –

Dr. Smith

L

F

d

d

F

LM.A.

1st

2nd

3rd

What simple machines are in use?

What is the mechanical advantage of: Just the pulley setup? Just the lever? The combined setup?

What is the tension force, L, in Newtons?

What is the applied force, F, in Newtons?

04/20/23Baltimore Polytechnic Institute Engineering Practicum –

Dr. Smith

Fixed•Stationary; usually erected in place

Parts•Base•Slewing Ring (Turntable)•Tower•Boom•Counterbalance•Load Line•Lifting Hook

04/20/23Baltimore Polytechnic Institute Engineering Practicum –

Dr. Smith

Tower Crane

Used in statistics, physics, chemistry and mechanics

Mechanical DOF The set of independent translations and/or

rotations that describe the position of a body or system

04/20/23Baltimore Polytechnic Institute Engineering Practicum –

Dr. Smith

What’s a translation?

A translation is a linear movement without rotation.

What’s a rotation?

A rotation is an angular movement about some axis.

2

)1

ddDOF

For an independent body in general motion,

where d is the number of dimensions.

For a system, we usually say DOF is the sum of the number of independent translations and rotations that are possible.

04/20/23Baltimore Polytechnic Institute Engineering Practicum –

Dr. Smith

How many degrees of freedom are in the Sketchup model?

04/20/23Baltimore Polytechnic Institute Engineering Practicum –

Dr. Smith

1. 2. 3. 4. 5. 6. 7. 8.

Define the ProblemBrainstorm, Research, Generate IdeasExplore PossibilitiesDevelop a Design ProposalMake Model/PrototypeTest and Evaluate Refine the DesignCommunicate the Solution

04/20/23Baltimore Polytechnic Institute Engineering Practicum –

Dr. Smith

1. Safety – is the product safe to use/construct?2. Reliability – will it work consistently over time?3. Cost – is it affordable?4. Quality Control – does it meet customer requirements?5. Environmental Concerns – does it harm the natural or

human environment negatively? 6. Manufacturability – can it be made?7. Maintenance – how easily can it be maintained or upheld?8. Ergonomics – how efficiently can the human body utilize it?