Mechanical Hoist refers to lifting of mechanical components to greater heights. There are various ways of using power to lift weight with little force. Examples of heavy machinery used to lift mechanical components include fork lift, pulley system, monster robot, and chain hoist and car jack. Mechanical hoist lifts or lowers load. It uses drum or lift wheels that have ropes or chains wraps. This device is operated either manually or electrically. It uses chain, fiber or wire rope to lift. Lifting hook attaches load to the hoist. Engineering in Kenya has more articles.
Different Types of Mechanical Hoist
There are various types of hoist characterized by either the lifting medium or the power type. Lifting medium includes the wire rope wrapped around the drum or a load chain that has been raised by a pulley and with special chain engaged profile. Powers used to lift Mechanical Hoist include hydraulics, electrical or air driven motors.
Hoists have been in use since 19th century but Mass production of Mechanical Hoist begun recently. They are designed in a way to ensure durability and great performance. There are those built as an integral part and others with a built up custom. Those of built up custom are a bit expensive.
Chain hoist types are also referred to as wire rope hoist. However, electrically powered hoist are the most commonly used mechanical hoist in the world. The most common type of portable hoists is the chain block and the cable type. The chain blocks have levers that actuate the hoist or may have a loop of chains that operates through the block. They usually activate the block to take the main lifting chain.
Another common type of Mechanical Hoist is the hand powered hoist. It is also known as the ratchet lever hoist. This type of hoist was developed by Abraham Maasdamof Deep Creeck in 1919. This came as an advantage in that, unlike chain block hoist, ratchet lever hoists operates in various orientation when lifting, pulling or binding.
Construction hoists are commonly used on large scale projects. The following terms are also used to describe the same type of hoists. These include, man lift, builder lifts or construction elevators. They are commonly found in major hospitals or high rise buildings. . Other examples of mechanical hoists are the mine hoists. These are used to raise and lower materials within the mine shafts.
Failures in a Mechanical Hoist
Failure in Mechanical Hoist results from fractures and fatigue especially when operated with heavier loads than their tensile strength. Most of the mechanical hoists have internal clutches. The clutches limit the hoist from lift loads that are above the set threshold.
Preventive mechanical maintenance should be done. This includes regular lubrication for tensile system. Hoists should lift weights of the appropriate threshold. For example pocket wheel chain causes fatigue –induced resonance for long lifts. Instead, wire rope drum should be fit for that speed lifting (18.3m/min). The wire rope should be put in the appropriate shape.
This is because wire hoist failures may cause the injury or even cause chain break.
Uses of Mechanical Hoist
Their uses include personnel, materials and equipment transportation form the ground to higher floors. These types of Mechanical Hoist have cages (one or two) that travel vertically along 25feet stacked sections. This is done to ensure stability. Today’s construction elevators are using motorized rack-pinion system to climb the mast sections at various speeds
In the past, human, animal, and water power were used to power the mechanical hoists. They were replaced by stationary steam engines. Modern mechanical hoists are powered by electric current. The recent predominant manufacturers of mechanical hoists have been Europe and United states. Asian countries and especially China are the recent emerging competitors especially in mass production of Mechanical Hoist.