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684 Ellis Street

684 Ellis Street, San Francisco, CA

Major alteration of 19-teens Otis basement winding drum, swing door passenger elevator.  New Hollister Whitney #44 basement O.D. machine, MCE controls, V/E sling, platform & cab and Adams fixtures. 

RCB Elevator Consulting, LLC and its associate structural engineering firm performed all of the elevator and building engineering required to make the conversion.  This included performing all field surveys, elevator design drawing preparation, elevator structural engineering and owner consultation.

Project Description

The Essex Hotel at 684 Ellis Street in San Francisco, California was one of the city's early hotels of some elegance and merit.  However, over the years time had taken its toll and the facility became one of the many  single room occupancy residence hotels that make up the colorful area of the city known as the Tenderloin.  As a part of the ongoing initiative in San Francisco known as Care Not Cash, this facility and many others like it are being renovated to provide supportive housing for the formerly homeless. 

One of the goals of Mayor Newsom's program in housing the homeless is to make the facilities ADA compliant and accessible to the disabled.  This presents challenges for converting these older facilities as many of the structural elements of the buildings limit what can be done, and this is especially true with respect the elevator.  The ADA law and the elevator code and industry standards prescribe the minimum car and entrance sizes required to accommodate a wheelchair and other accessibility devices.  Existing elevators and their hoistways in these older facilities are typically undersized as compared to these new standards.  The cost of increasing the hoistway size by moving walls, stairways, etc. and the structural work that such changes would require, as well as the loss of usable housing space, make complying with the larger elevator size requirements impracticable.

Therefore, the city and the mayor's office can establish a hardship requirement, as allowed by the ADA law, to retain a smaller elevator car.  Certain special measures are taken to accomplish this.  The intent of the code is for a wheelchair to enter the car and rotate 180 degrees to exit.  These smaller cars won't provide this turning radius, instead requiring the wheelchair to back out.  To assist in this, a second car operating panel and a mirror are required at the rear of the elevator car.  These features were provided as part of this elevator remodel along with full 36" wide, power operated entrances and all of the other standard accessibility provisions.

Calling this elevator job a modernization is a bit of an understatement.  Modernization is the common industry term - the technical code term is actually "alteration" - describing any work short of a full elevator replacement or new installation.  In this job, only the steel guiderails, machine base and overhead sheave beams were retained.  And these were either modified or reinforced.  For all practical purposes, it's a new elevator in an existing hoistway and machine room.

The core of the work is converting the elevator from an obsolete basement winding drum to a modern basement traction elevator.  Note that special care must be taken to structurally and seismically anchor the new basement traction drive machine.  It is insufficient to simply bolt the new machine down to the old winding drum machine base as the new machine weighs less, the new car & counterweight weigh more and there is no way to certify the strength of the old machine base anchorage.  Keep in mind, Otis probably didn't include seismic loading when designing the original anchorage.  Therefore, we design and structurally calculate a completely new machine anchorage separate from the old base.  In this job, it includes a vertical plate and angle assembly that is anchored to both the original elevator pit wall and new pit floor slab.  See more discussion on our page, Winding Drum Elevator Conversions

Another rather unique feature of this job was to provide a new car sling, platform and cab that replicate the original car's feature of having the car sling stile channels inset into the platform.  This allows for a wider functional car interior in front of and behind the stiles.  It also allows for a wider entrance.  This is one of the tricks to maximizing the car size to unusually small hoistways.  The cab interiors accommodate this with stainless steel formed channels that are set near to the web of the stile channels so as to minimize the stiles' intrusion on the car interior space.

The existing hoistway has a concrete encased building column in the front left corner, which restricted the width of the entrances.  We dispensed with the usual entrance corner angle strut to save space and instead suspended the entrance hanger plates with clip angles and wedge anchors mounted directly to the concrete column.  Another hoistway maximizing design we typically apply on these tight jobs when converting from swing doors to power-operated elevator doors is to place the new entrance packages outside the existing hoistway line and into the entrance lobbies.  This also relieves the need for entrance fascia as the edge of the entrance sill is set just into the line of the hoistway.

The final results are a functionally new, code compliant, accessible elevator that will take the facility into its new generation of use.  With the proven components used and quality installation workmanship, it may even approach the life span of its original.

Before Alteration  

This view of the original machine room shows the ancient basement winding drum machine.  The old mechanical selector can be seen at the left. 

The vintage open relay, city DC, rheostat controller with its open contactors.

Looking up at the original wood platform and drum safety.

The view of the pit and machine drum.  Note the rubber puck car buffers and lack of a counterweight buffer.

Note the 8 lb./ft. steel counterweight guiderail and 1/2" x 2" bar type support bracket.


See the original babbit bearing overhead sheaves.  Note the roping scheme with 2 ropes from the machine drum to the car, 2 ropes from the machine drum to the counterweight and 2 ropes between the car and the counterweight.  The original Otis un-switched flyball governor is seen on the right.


The original lobby entrance at left and the basement entrance at right are non-ADA swing door type.

After Alteration  

The new Hollister-Whitney #44 basement O.D. machine mounted to an 3/4" adapter plate, which is bolted to the original Otis machine base.  Note, no upthrust value is accorded to the original Otis base.

This view from the pit shows the new structural anchorage of the new machine, including anchorage to the existing pit wall and new pit floor.  This anchorage alone is calculated to hold down the machine, including seismic reactions.

A view of the new machine's drive & overhead deflector sheaves with seismic rope retainers.

The new solid state MCE VVVF-AC controller with the solid state seismic switch mounted to the floor slab to the left of the controller.  The original machine room was used but cleaned of all foreign utilities and new ventilation and services added.


The existing overhead sheave room with new Hollister-Whitney sheaves with seismic rope retainers.  Note the original overhead support sheaves were reused, with the upper level moved slightly, after structurally proving their strength per code.  The new Hollister-Whitney governor can be seen behind the sheaves.

The new E/V isolated car sling and platform with Hollister-Whitney #540 safeties and #379 roller guides.  Also note the repair work to the existing hoistway fireproofing.

The existing 15 lb/.ft. car guiderails and the 8 lb./ft. counterweight guiderails and brackets were structurally calculated to prove them compliant with the most current elevator code including seismic with respect to deflection criteria.  This picture shows an example of some of the structural reinforcing that the counterweight brackets required.

A view of the new sling, car top and GAL door operator.  Note the car is 9'-0" high, more furniture accommodating and vandal resistant than the standard 8'-0" high car.

The new stainless steel elevator car includes a standard ADA-compliant car operating panel in the front return.  It also includes an auxiliary COP in the rear wall and a mirror, as required by San Francisco's Mayor's Office on Disability Access. 

The new two-speed, power operated entrances are 3'-0" wide by 8'-0" high, providing full width access for wheelchairs.  Note the Smoke Guard drop down smoke curtain fixture over the entrance.

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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