What is a crane?
A crane is a lifting machine which is used both to lift and lower materials and to move them horizontally.
Cranes have come into their present widespread application only since the introduction of engines, internal-combustion engines, and electric motors, beginning in the 19th century.
Classification of cranes
Cranes can be broadly classified into three groups-
1.Mechanical Cranes
2.Hydraulic Cranes
3.Pneumatic Cranes
Mechanical Cranes:- These uses one or more simple machines like engine,motor etc.to create mechanical advantage.
Hydraulic Cranes:- These cranes use a hydraulic system using an incompressible fluid.
Pneumatic Cranes:-These cranes use a pneumatic cylinder that impart a force by converting the potential energy of compressed gas into kinetic energy.
Pneumatic cylinder
Pneumatic cylinders are mechanical devices which produce force in combination with movement and are powered by compressed gas (air). A piston reciprocates inside the cylinder. A pump is used to supply air to the cylinder. The compressed gas expands and forces piston to move in the desired direction.
Pneumatic cylinder can be single acting or double acting
Machines are easily designed using standard cylinders & other components. Control is as easy as it is simple ON - OFF type control.
Reliability
Pneumatic systems tend to have long operating lives and require very little maintenance.
Because gas is compressible, the equipment is less likely to be damaged by shock. The gas in pneumatics absorbs excessive force, whereas the fluid of hydraulics directly transfers force.
Storage
Compressed Gas can be stored, allowing the use of machines when electrical power is lost.
Safety Very low chance of fire (compared to hydraulic oil).
Machines can be designed to be overload IN A SIMPLER WAY
A basic Pneumatic system can contain simply 3 things:
- An air supply (compressor)
- A 3/2 valve
- A single acting cylinder.
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