A hoist can simply be defined as a device used for lifting or lowering loads via sets of chains or wheels. Therefore, lift hoist mechanism mainly highlights the various designs or types of lifts that are available in the market. Elevators are a common facility in almost every property today and, some authorities have even gone a step further to pass laws that require some buildings to have lifts. However, individuals can also acquire and install elevators in their homes or residential apartments to improve the quality of their lives due to the ability of the machines to enhance mobility across floors or staircases.
Types of Lift Hoist Mechanisms
Elevators generally operate on two fronts; rope-free and rope dependent. Since there are various kinds of elevators, it should be noted that lift hoist mechanisms also vary from one to another. However, there are four key types of lift hoist mechanisms that you should know.
Traction System
Traction elevators can either be designed with or without gears. Elevators that run on gears are powered by electric motors via AC or DC. Such elevators use gears to control the way in which elevators cars move to and from designated points. As the gears run, the roll steel hoist ropes over a drive sheave that is linked to a gearbox piloted by motors. Geared traction lifts are ideal for overhead and basement accessibility for speeds of up to 152 meter per minute.
Unlike geared elevators, gearless traction lifts have relatively low speed but, are also powered by electric motors. The elevators can reach up to speeds of 1,219 meter per minute However, the machine’s drive sheave in this case is directly tied to the end of the motor. During the design and construction of the lift, a brake is placed between the motor and gearbox or towards the end of the drive sheave to keep the machine in place.
The brakes used in gearless traction elevators are launched by a spring force and held open. In the event of a power failure, the brakes are engaged to prevent the lift from falling. However, there are also some whereby the brake can be in the form of calipers or disk to facilitate the movements of the machine.
Hydraulic System
Generally, hydraulic lifts are operated by pistons placed at the bottom of the machine to facilitate upward movements. They are mainly popular in low level buildings consisting two to five stories. However, they can also be installed in property with six or eight floors. The lifts have maximum speeds of up to 60 meter per minute. The machine room for hydraulic elevators is located at the lowest point next to the shaft.
Hydraulic elevators can be categorized into two classes; holed/conventional and hole-less hydraulic lifts.
Holed hydraulic elevators are constructed with a sheave that extends beneath the floor of the lift pit. This is meant to give room for the retraction of the pistons as the lift comes down. Some models have telescopic pistons that operates by collapsing, and requires that the hole below the pit is shallower. A holed or conventional lift can travel up to a maximum distance of 18 meter.
Hole-less hydraulic elevators are designed with a piston on either side of the lift car and can further be classified into, telescopic, non-telescopic and roped hydraulic elevators. Machines with telescopic pistons can travel up to a distance of 15 meter. Non-telescopic hydraulic elevators only have one piston and allow a travel distance of up to 6 meter. Roped hydraulic lifts on the other hand, have use a piston and combination of ropes to move the elevator for up to a distance of 18 meter.
Hole-less hydraulic elevators have been around for quite a long time, since the 1970s. They are mainly powered by a set of above-ground cylinders, making it ideal for establishments that are environmentally or cost-sensitive. The lifts are recommended for buildings with two, three or four stories.
Over the years, conventional hydraulic elevators have been quite popular in the market but are slowly losing their supremacy touch because of the arrival of modern generation of machines that are more affordable, require no machine room and enhanced with less mechanical complexity. Besides, modern hydraulic lifts are also designed with energy efficient features for power conservation.
Pneumatic System
This type of lift uses a vacuum that is located at the top of the lift car and a valve above the shaft to move the elevator up. In order to keep the cab on a particular level or floor, the valve is closed. The machine can either use a piston or diaphragm as a braking system in the event of a sudden increase in pressure on top of the cab. To facilitate downward movement, the valve is opened to give room for the accumulation of pressure above the shaft, enabling the lift car to freely move on its own.
Therefore, the ascent and decent of pneumatic lifts is achieved by regulating air pressure in a chamber on which the elevator is mounted. Besides, this also suggests the cab will automatically descend in the event of a power hitch. However, technical limitations experienced in the design and construction of pneumatic elevators have impacted a low capacity with regards to their use. The lifts usually accommodate up to about only three people.
Pneumatic elevators are recommended for existing homes or refurbished property because of their compact design, which does not require activities like excavation of pits or hoist ways.
Climbing System
Climbing elevators have their own power and can effectively execute ascension procedures individually. The propulsion can be conducted by combustion or an electric engine. These types of elevators are mainly used in towers or masts to facilitate easy access to parts of these establishments, especially during maintenance or surveillance. In most occasions, climbing elevators are used by building and constructions engineers, as well as electrical maintenance professionals in work sites.
Although only four types of lift hoist mechanisms are discussed above, it should be noted that there are several sub-categories from which you can always choose the best elevator for your property, budget and mobility needs.