Machine that is used to lift or move a load with a great mechanical advantage, because much less force needs to be applied to the weight to be moved. It has two or more built-in pulleys to minimize effort.
These mechanisms are widely used in workshops or industries that load very heavy elements and materials to make lifting and placing these parts faster and easier on the different machine tools in workshops or warehouses, as well as loading and unloading them from the trucks that transport them.
[ hide ]
- 1 History
- 1 How we define a hoist
- 2 Parts of the hoist
- 3 Types of Hoist
- 4 Sources
It is the genius born in Syracuse in the 3rd century ANE., Archimedes , who designed the first pulley system at the request of his king and patron, Hieron II , tyrant of Syracuse, who worried about facing and defeating the army Roman, he commissioned the wise Syracusan with a machine capable of facing the enemy.
And so it was that the first system of pulleys or hoists was born: a kind of crane that, with an immense mouth like a pincer at its end, was capable of hooking and lifting enemy ships.
How we define a hoist
To define what a hoist is, it is necessary to be in the type of mechanisms designed to facilitate the transfer, drag or haul of heavy objects with the ease that it supposes, since in this way, the hoist, like any other type of pulley, minimizes the human effort and saves both human and mechanical energy. In generic terms, the hoist is a kind of pulley, of the type belonging to the so-called simple machinery, the pulleys, in their different variants, including the hoist, will acquire the shape and autonomy of work according to the purpose for which it is used.
Parts of the hoist
Parts of the Hoist.
- The fixed pulley’s mission is to modify the direction of the force (power) that we exert on the rope. The fact of exerting power downwards makes it easier to lift loads, since we can help ourselves with our own weight.
• The mobile pulley’s mission is to provide mechanical gain to the system. As a general rule, each movable pulley gives us a gain equal to 2.
• The rope (cable) transmits the forces between the different elements. Its tensile strength must be a function of the resistance value and the mechanical gain of the system, which in turn depends on the number of mobile pulleys and their combination with the fixed ones.
Types of Hoist
The pulley system can be both fixed and mobile hoists covered by a single rope, made of steel or other material – it will always depend on the object or load to be lifted. If the hoist is fixed, the axis does not move. It is also possible to change the point of application that allows this force to be applied. The hoist can be mobile or fixed, and can be attached to larger and more complex machinery. Mobile hoists can be attached to overhead overhead rails on roof rails. If the hoist is mobile, the fulcrum is on the rope and not on the shaft. This allows both rotation and translation and displacement movements.
The rig itself, ranges from the simple and simple rope pulley to the hoists presented as sophisticated machines that, starting from the use of electric motors, come to be composed, these hoists, as a base
of cranes with mechanical advance, with electrical advance and even with coupled cars until they have great power, we reiterate, always depending on the load to be lifted. Mechanical advantage is defined in simple machines as the quotient between the resistance force or load (R) and the applied force or power (P). If its value is greater than unity, this confirms that the effort must be less to perform a certain job or lift a specific load. Thus, on the contrary, if the value is less than unity, the mechanical advantage will be less because more effort will have to be made.