Elevators
are safe, thanks to hydraulics
The
Problem:
Everyday, elevators transport people from floor to floor, whether
they're in skyscrapers or buildings with seven floors or less.
They need to be safe and reliable.
Its
Solution:
According to the National Elevator Industry Inc., 70% of the
elevators in the U.S. are hydraulically driven, yet serious
elevator accidents are rare. We have hydraulics to thank for
this.
While hydraulic elevators installed before 1971 use a
single-bottom cylinder that could fail with age, elevators
installed more recently or updated use a double-bottom cylinder.
With a double-bottom cylinder, a relief orifice drilled into the
bottom plate converts it into a safety bulkhead, and a new bottom
plate is attached. In this design, pressure is still applied to
the bottom plate, but if a failure occurs, the orifice limits the
rate at which fluid can escape from the cylinder.
The orifice is sized to cause the elevator car to descend 5 to 15
ft./sec. Furthermore, the safety bulkhead is not likely to fail
because pressure is applied to it equally from both sides,
essentially canceling out reaction forces acting on it.
Related
Applications:
Any similar application used in tall buildings where safety is a
priority.
How
Hydraulics Improved this Application:
- Safe
- Practical
- Very reliable
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