Kone, a Finnish elevator company, first developed the machine room-less elevator in 1996.
Benefits from a Green Perspective
---this takes away the environmental concern that was created by the hydraulic cylinder being stored underground
Other Benefits
Facts
---national and local building codes did not address elevators without machine rooms
The first reference to an elevator is in the works of the Roman architect Vitruvius, who reported that Archimedes built his first elevator, probably in 236 B.C. In some literary sources of later historical periods, elevators were mentioned as cabs on a hemp rope and powered by hand or by animals. It is supposed that elevators of this type were installed in the Sinai monastery of Egypt. In the 17th century the prototypes of elevators were located in the palace buildings of England and France.
In 1852, Elisha Otis introduced the safety elevator, which prevented the fall of the cab if the cable broke. The design of the Otis safety elevator is somewhat similar to one type still used today. A governor device engages knurled roller(s), locking the elevator to its guides should the elevator move at an excessive speed. He demonstrated it at the New York exposition in the Crystal Palace in 1854.
In 1874, J.W. Meaker patented a method which permitted elevator doors to open and close safely.
The first electric elevator was constructed by the German engineer Werner von Siemens in 1880.
In 1882, when hydraulic power was a well established technology, a company later named the London Hydraulic Power Company was formed. It constructed a network of high pressure mains on both sides of the Thames which, ultimately, extended to 184 miles and powered some 8,000 machines, predominantly lifts (elevators) and cranes.
In 1929, Clarence Conrad Crispen, with Inclinator Company of America, created the first residential elevator. Crispen also invented the first inclined stairlift.
Pneumatic or "Vacuum" elevators operate without cables and can be installed more easily and quickly than their alternatives since their housing comprises prefabricated sections which are considerably narrower than conventional lift shafts. These sections are often transparent and afford the passenger a near 360° view.
Statistically speaking, elevators are extremely safe. Their safety record is unsurpassed by any other vehicle system. In 1998, it was estimated that approximately eight 100-millionths of one percent (1 in 12 million) of elevator rides resulted in an anomaly, and the vast majority of these were minor things such as the doors failing to open. For all practical purposes, there are no cases of elevators simply free-falling and killing the passengers inside; of the 20 to 30 elevator-related deaths each year, most of them are maintenance-related - for example, technicians leaning too far into the shaft or getting caught between moving parts, and most of the rest are attributed to easily avoidable accidents, such as people stepping blindly through doors that open into empty shafts or being strangled by scarves caught in the doors. In fact, prior to the September 11th terrorist attacks, the only known free-fall incident in a modern cable-borne elevator happened in 1945 when a B-25 bomber struck the Empire State Building in fog, severing the cables of an elevator cab, which fell from the 75th floor all the way to the bottom of the building, seriously injuring (though not killing) the sole occupant - the female elevator operator. While it is possible (though extraordinarily unlikely) for an elevator's cable to snap, all elevators in the modern era have been fitted with several safety devices which prevent the elevator from simply free-falling and crashing. An elevator cab is typically borne by six or eight hoist cables, each of which is capable on its own of supporting the full load of the elevator plus twenty-five per cent more weight. In addition, there is a device which detects whether the elevator is moving faster than its maximum designed speed; if this happens, the device causes bronze brake shoes to clamp down along the vertical rails in the shaft, stopping the elevator quickly, but not so abruptly as to cause injury. In addition, a hydraulic buffer is installed at the bottom of the shaft to cushion any impact somewhat.
Most recently, there was an incident in a modern cable-borne elevator that took place in a children's hospital in Seattle, Washington on October 9, 2007. The elevator involved was a ThyssenKrupp ISIS machine room-less elevator; The ISIS used Kevlar fiberglass ropes instead of conventional braided-steel ropes all other traction elevators use. One of the ISIS elevators broke free from its cables, slipping between the 6th and 4th floors; the Kevlar ropes were the cause of this incident. After the incident, ThyssenKrupp discontinued production of the ISIS and, the following year, replaced it with the Synergy machine room-less elevator, which uses conventional braided-steel ropes, making it much safer.
Past problems with early hydraulic elevators meant those built prior to a code change in 1972 were subject to possible catastrophic failure. The code had previously required only single-bottom hydraulic cylinders. In the event of a cylinder breach, an uncontrolled fall of the elevator might result. Because it is impossible to verify the system completely without a pressurized casing (as described below), it is necessary to remove the piston to inspect it. The cost of removing the piston is such that it makes no economic sense to re-install the old cylinder; therefore it is necessary to replace the cylinder and install a new piston. Another solution to protect against a cylinder blowout is to install a "life jacket." This is a device which, in the event of an excessive downward speed, clamps onto the cylinder and stops the car. This device is also known as a Rupture Valve in some parts of the world.
In addition to the safety concerns for older hydraulic elevators, there is risk of leaking hydraulic oil into the aquifer and causing potential environmental contamination. This has led to the introduction of PVC liners (casings) around hydraulic cylinders which can be monitored for integrity.
In the past decade, recent innovations in inverted hydraulic jacks have eliminated the costly process of drilling the ground to install a borehole jack. This also eliminates the threat of corrosion to the system and increases safety.
There are at least four means of moving an elevator:
Geared traction machines are driven by AC or DC electric motors. Geared machines use worm gears to control mechanical movement of elevator cars by "rolling" steel hoist ropes over a drive sheave which is attached to a gearbox driven by a high speed motor. These machines are generally the best option for basement or overhead traction use for speeds up to 500 ft/min (2.5 m/s).
Gearless traction machines are low speed (low RPM), high torque electric motors powered either by AC or DC. In this case, the drive sheave is directly attached to the end of the motor. Gearless traction elevators can reach speeds of up to 2,000 ft/min (10 m/s), or even higher. A brake is mounted between the motor and drive sheave (or gearbox) to hold the elevator stationary at a floor. This brake is usually an external drum type and is actuated by spring force and held open electrically; a power failure will cause the brake to engage and prevent the elevator from falling (see inherent safety and safety engineering).