Conveying Systems cover inter/intra-building transportation devices, such as elevators, handicap lifts, escalators, dumbwaiters, correspondence lifts, pneumatic tube systems, moving walkways and ramps, material handling systems, hoists and cranes, parcel lifts, and vertical conveyors.
Electric elevators are the most common, but hydraulic elevators can also be used for lifts up to 70` and where large capacities are required. Hydraulic speeds are limited to 150 F.P.M., but cars are self-leveling at the stops. On low rises, hydraulic installation runs about 15% less than standard electric elevators, but on higher rises this installation cost advantage is reduced. Maintenance of hydraulic elevators is about the same as for electric, but the underground portion is not included in the maintenance contract.
In standard electric elevators, there are two basic control systems: rheostatic systems for speeds up to 150 F.P.M. and variable voltage systems for speeds over 150 F.P.M. The two types of drives are geared for low speeds and gearless for 450 F.P.M. and over. As a rule of thumb, each added 100 F.P.M. adds about 20% to the total cost.
Freight elevator capacities run from 1,500 lbs. to over 100,000 lbs., with 3,000- to 10,000-pound capacities the most common. Travel speeds are generally slower and control systems less intricate than on passenger elevators.
Escalators, Moving Stairs
Escalators are often used in buildings where 600 or more people will be traveling to the second floor or beyond on a daily basis. Freight cannot be carried on escalators%3B therefore, at least one elevator must be available for this function. The carrying capacity of an escalator is 5,000 to 8,000 people per hour. The power requirement is 2 to 3 kW per hour, and the required incline angle is 30 degrees.