When slings are used to lift loads, safety professionals must ensure the weight does not exceed the safe working load limit (WLL) of the sling. If the weight is too great, the sling may break and drop the load— causing property damage, serious injury, or death. This lecture explores some basic concepts used to establish working load limits. The actual load the crane can lift is referred to as the 'Net Capacity'. The maximum load must never exceed the crane's Net Capacity! The Gross Capacity must include the weight of anything and everything that is mounted or stowed on the boom of the crane or hanging from the boom tip.
Factors that Affect LiftAll that is necessary to isto turn a flow of air. An aerodynamic, curved airfoil will turn aflow.
But so will a simple flat plate, if it is inclined to the flow. Theof an airplane will also generate lift if it is inclinedto the flow. For that matter, an automobile body also turns the flowthrough which it moves, generating a lift force.
Lift is a big problemfor NASCAR racing machines and race cars now includeon the roof to kill lift in a spin. Any physicalmoving through a fluid can create lift if it produces a net turningof the flow.There are many factors that affect the turning of the flow, whichcreates lift. We can group these factors into(a) those associatedwith the object, (b) those associated with the motion of the objectthrough the air, and (c) those associated with the air itself:. Object: At the top of the figure, aircrafthas a large effect on theamount of lift generated. The and will both affectthe amount of lift. The ratio of the wing span to the wing area alsothe amount of lift generated by a wing. Motion: To generate lift, we have to through the air.
The lift then depends on theof the air and how the object isto the flow. Air: Lift depends on theof the flow.
The lift also depends in a complex way on two otherof the air: its viscosity andits compressibility.We can gather all of this information on the factors that affectlift into a single mathematical equation called the With the lift equation we can predict how much liftforce will be generated by a given body moving at a given speed.You can investigate the various factors that affect lift by usingthe Have fun! Youcan use the browser 'Back' button to return to this page. If yourwant your own copy ofFoilSim to play with, you canit at no charge.Activities:.
Factors that Affect Lift:. FoilSim:. Wings:.
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