Dumbwaiter,a small freight elevator

Dumbwaiters are small elevators intended to carry objects rather than people. Dumbwaiters are found within modern structures, including both commercial, public and private buildings, are often connected between multiple floors. When they are installed in restaurants, schools, hospitals, libraries, retirement homes or in private homes, the dumbwaiter generally terminate in a kitchen.

History

A mechanical dumbwaiter was invented by George W.Cannon, a New York inventor.

Cannon first filed for the patent of a brake system(US Patent no.260776) that could be used for a dumbwaiter on January 6^th ,1883.Cannon later filed for the patent on the mechanical dumbwaiter(US Patent no. 361268) on February 17^th, 1887.Cannon reportedly generated a vast amount of royalties from the dumbwaiter patents until his death in 1897.

One of the first non-mechanical dumbwaiters in the world was used bu Thomas Jefferson in his mountain home at Monticello,Virginia.He use it to limit the number of servants around the table to one,so that his guests could enjoy more of the view.

Description

A simple dumbwaiter is a movable frame in a shaft,dropped by a rope on a pulley,guided by rails.Most dumbwaiters have a shaft, cart and capacity smaller than those of passenger elevators,usually 50-450 kgs (100-1000lbs).Before electric motors were added in the 1920s,dumbwaiters were controlled manually by ropes on pulleys.

Early 20th-century codes sometimes required fireproof dumbwaiter walls and self-closing fireproof doors and mention features such as buttons to control movement between floors and locks on doors preventing them from opening unless the cars is stopped at that floor.Most dumbwaiter has external fixtures which contains floor destination buttons,floor position indicator,and built-in inter-phone or normal inter-phone.When a person is using the dumbwaiter,he/she opens the doors manually,load the goods,and closed the doors again before operating the dumbwaiter.After that,he/she pushed the floor buttons to send the dumbwaiter to the desired floor.Sometimes,the person may also using the inter-phone or telephone to contact other person on the other floors.

Type of dumbwaiter

Dumbwaiters typically have two types of landing:Floor type and window type.

Floor type

Floor type dumbwaiter is installed on the same horizontal level with the floor of the passage way to facilitate carriage of goods normally carried on the handcarts.This type of dumbwaiter is normally found in hotels,libraries,or corridor areas.Normally used to carry large goods such as tables.

Window type

Window type dumbwaiter is installed at the height of a man’s waist,so that users can use the dumbwaiter conveniently.This type is commonly found in libraries,offices,hospitals,restaurants,kitchens and other places.It is normally used to carry books,documents,medicines,kitchen utensils,food and beverages and other goods.

Large type

This type of dumbwaiter has a large cab with an external manual gate and it is similar to a normal freight elevator.But there are no buttons inside the car.Some large dumbwaiters may have interior light.Passengers are usually not allowed to enter or ride it for safety reason.Button panel is located on the outside,often has a digital floor indicator.

http://safeelevator.net/