• Elevator motors operate a system of pulleys and counterweights to lift freight between floors.the elevator image by Pix by Marti from Fotolia.com
  
  People have lifted heavy objects with simple machines for thousands of years. Modern advances have improved upon these simple machines to create several types of devices to aid in lifting objects. Lifting devices might use air, hydraulic pressure, pulleys, gears, levers or a combination of these methods to lift objects. Using a lifting device can help to save you pain from lifting heavy objects and make everyday life more convenient.
  
  

Cranes

• A crane consists of a long arm that can swivel from side to side and uses various types of simple machines such as levers, pulleys and gears to lift objects. The main types of cranes are tower, jib-style and balance cranes. All types use a pulley system, and a hydraulic cylinder may power the arm of the crane. Large cranes play a role in the construction of tall buildings, but you can see small cranes in action in vending machines at any arcade.
  
  

Elevators

• Elevators transport people and freight vertically to different levels in buildings. Elevators use a motor to turn a series of pulleys, known as a sheave, and a counterweight to raise and lower the elevator car between floors. Commercial building regulations require an elevator in buildings with four or more floors. In addition to use in buildings, the same principle applies in the operation of conveyor belts and the lifting of roller coaster cars to the top of an incline, eliminating the loud clinking of the traditional chain and gears.
  
  

Vacuums

• Vacuum lifts use suction created by compressed air to lift objects. To illustrate the principle behind this lift, you could turn on a vacuum cleaner and use the hose attachment to pick up a thin plastic cup. Banks and pharmacies with drive-through windows commonly use this lifting device to move objects between the business and the customer. The customer places money or documents in a plastic canister, then an employee presses a button to activate the machine, which sucks the canister through a tube and delivers it inside a building.
  
  

Forklifts

• Forklifts load and unload heavy objects on pallets. The forks fit into the pallet and then lift it up and down. The lift mechanism runs on pressure within a hydraulic cylinder. The cylinder applies pressure to activate a bar with a rolling chain that pulls the forks up and down. Hydraulic wheelchair lifts and the lifts on the backs of delivery trucks also operate on this principle.