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The Chew Building, San Francisco, CA
Contractor: Otis Elevator Co., Inc.
Major alteration of 1920 Otis overhead winding drum
corner-post. Lowered the machine room a landing. New
Hollister Whitney #54 machine, GEM controls, sling, platform
& cab and fixtures.
RCB Elevator Consulting, LLC and its associate structural
engineering firm, Eddington Engineering, performed all of
the elevator and building engineering required to make the
conversion. This included performing all field
surveys.
Project Description
This was a very interesting project in that the existing
top landing served the attic and the entrance was only about
4 feet high. It had been locked out for some time.
The access to the old machine room was via a vertical ladder
from a room at the attic at roof level. The hoistway
overhead was accessible from this room via a screen
enclosure. The motor-generator, installed during a
previous control alteration, was in this room as well.
It was decided to essentially abandon the original
machine room with the existing equipment disconnected but
largely left intact. The original access was closed
off and new access added from the outside for fire access
purposes.
By eliminating the low height top landing, we were able
to relocate the machine room to the attic/roof level with
sufficient overhead clearance. That attic overhead
room thus became the new machine room.
There was about a 4° slope in
the existing floor, accounting for a 10" difference in
elevation from one end of the room to the other. We
also found that the existing building beam framing the
hoistway at the lower end was insufficient to carry the load
for the new system at that end of the machine beams.
Fortunately, there was a second, parallel beam only a few
feet away.
Both problems of the slope in the floor and the beam
strength were solved by a adding bridging beams that spanned
the two existing building beams. That end of the new
machine beams connected to the bridging beams at their
midpoint via a steel block, which spread the load evenly
among the two building beams. A new, level floor of
metal deck plate was installed supported by the new machine
beams at the center and additional ship channels at the
outside.
There were numerous other engineering issues were resolved
relating to the corner-post elevator arrangement and the
very small hoistway size. We worked with the elevator
contractor and the many equipment manufacturers to work all
of these problems out during the design phase. This
greatly reduced the field labor, administrative costs and
elevator downtime resulting in a more profitable project of
higher finished quality and a satisfied owner.
Before Alteration
This view of the original machine room shows the original
overhead winding drum machine and an old relay controller
from a previous upgrade. This machine room was
accessible via a vertical ladder from the roof level.
Here visible are the ladder and the screened-in hoistway
overhead.
Looking down the top of the hoistway, the abandoned short
top landing and corner-post car top are seen.
The car top showing the antiquated equipment and tight
conditions.
After Alteration
This is the same room as seen in the picture above showing
the ladder and screening. The new Hollister Whitney
#54 isolated machine and new metal deck flooring are shown.
The new Otis Gem control system.
Drawings & Engineering
Click on the drawing above to open the full drawing set in
PDF format. To see drawings in landscape view, click
on your Adobe Reader's Rotate Counterclockwise image button.
Note drawings cannot be printed or altered. All
drawings and artwork are the property of RCB Elevator
Consulting, LLC and may not be used, copied, or in anyway
used without the owner's consent.
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The Chew Bldg.