Elevator - Some Basic Knowledge II


In a hydraulic elevator, the car is lifted by a hydraulic-fluid driven piston mounted inside a cylinder. The cylinder, which contains oil or a similar substance, is connected to a pumping system. The pump forces fluid into the tank leading to the cylinder, when enough fluid is collected, the piston is pushed upward, lifting the elevator car on its journey.

When the car is signaled that it is approaching the correct floor, the control system will trigger the electric motor to gradually shut off the pump. To get the elevator to descend, the control system will send a signal to the valve operated electronically by a switch. When the valve is opened, the fluid flows out into a central reservoir, nd the weight of the car and its cargo pushes down on the piston, driving more fluid out and causing the cab to move down.

Hydraulic elevators are fairly common nationwide, but are usually found in low-rise buildings of less than six stories. This is probably why they are outnumbered by traction elevators.

One of the most important changes in elevator maintenance during the past 20 to 30 years is the apprenticeship training for elevator repairers and maintainers.

Journeymen now go through a four-year, state-certified apprenticeship program. In the past, there was education but there wasn’t a certified apprenticeship program. But now, responsible contractors only hire mechanics who go through this apprenticeship program.

Another far-reaching change in the elevator industry, as in all industries, is the computerization. Whereas elevators 40 years ago or so were either controlled by relays or by an older type of solid-state control. Recently, however, they are almost all computerized.

Many of the most recent design improvements in elevator design are also safety-based, particularly in newer computerized systems. One example is a device called a rope gripper, if an elevator should move on its own, the rope gripper will sense this and grip the cable, preventing it from moving further. And in general, in newer solid-state elevators, the car won’t move unless all the circuits are operating and all the doors are closed.

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