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Winding Drum Elevators
  

Winding Drum Elevator Conversions

A very common type of elevator system commonly installed at the end of the 19th century and the early years of the 20th century is the Winding Drum Elevator.  Manufactured and installed by many early elevator companies, including Otis Elevator Company, Van Emmon Elevator Company and others, these systems are no longer typically installed in commercial applications.  They are, however, still a common hoisting method for single family residential elevators.

The winding drum elevator consists of gear-reduction drive machine, most often installed at the lowest level of the structure, with steel ropes that wind onto a fairly large diameter drum.  These elevators were most commonly counterweighted and the ropes (typically two) would extend from the moving car, over sheaves (wheels) located at the top of the hoistway, down to the machine drum, around the drum for several wraps, then off of the back side of the drum, against a deflector sheave, back up the hoistway and over another sheave and down to the counterweight.  As such, like on a modern traction elevator, when the car ascends, the counterweight descends.  Many of these systems also included a separate rope loop of two ropes that would connect to the top of the car and extend up the hoistway and over sheaves in the overhead and down to a separate section of the counterweight. 

These winding drum machines always included a mechanical/electrical limit device that would be set to determine if the car had reached either terminus of the hoistway.  This device was critical to the operational safety of the system as if it failed and the machine continued to run, the car or counterweight could be hoisted into the overhead beams.  Such an event could be catastrophic.  Conversely, with the more modern traction elevator system, if the machine continued to run when the car has reached its terminus, the landing of either the car or the counterweight in the pit would cause the machine to loose traction against the ropes and the car would stop.

It is for this reason and others that the winding drum elevator system is no longer typically installed for commercial applications.  Indeed, most commercial elevator codes and jurisdictions having authority no longer allow winding drums to be installed.  Until California adopted the national elevator code, ASME A17.1-1996, in October of 1998, one could not even modernize or alter an existing winding drum commercial elevator.  Alterations of these systems are currently allowed in California but the state has been threatening to adopt regulations not only to once again disallow their alteration, but to actually require their removal.  The proposed regulations, I am told, would allow an exception if the system were certified by a California licensed engineer.  This is something we (RCB Elevator Consulting, LLC) have looked into and have rejected as entirely unfeasible.  There is no practical way to truly certify the structural and operational viability without extensive metallurgical testing, anchoring investigations, etc., all of which would likely requiring destructive methods.  You'd have to "kill the patient" to see if it was well...  Also, the liability implications of "certifying" these old beasts would be tantamount to "buying" any and all future mishaps of the elevator; a fool's bargain at best.

In conclusion, the responsible approach for most of these octogenarians, nonagenarians and centenarians of the elevatoring world is to either replace them with or convert them to a newer, modern type of elevator system.  New replacement systems can include traditional holed hydraulic, roped hydraulic, geared traction, machine room less (MRL), and others. 

Converting the winding drum typically involves replacing the winding drum machine with a modern geared machine or the increasingly popular AC gearless machine.  Depending on the physical layout, the new machine may be located in the place of the old one, which were typically at the lowest landing (basement), or in the overhead.  Numerous other components must also be replaced typically including the overhead sheaves, counterweight, ropes, governor as well as the complete control and electrical systems.  Most often the counterweight guiderails need to be reinforced due to the increased weight of the counterweight.  We prefer to address the car rails as well.  Other items may need replacing including the car safeties, sling & platform, cab, entrances, etc.  Sometimes the only items remaining from the old elevator are the car and counterweight guiderails, and these are heavily reinforced.

Whether to replace of convert depends on a number of factors including whether the winding drum had wood or steel guiderails, the building rise, elevator speed required, the type and use of the facility, owner's budget, etc.  A major factor can be the structural limitation on the hoistway size due to existing physical building design realities.  Often the hoistway is wrapped by a stairwell and the structural building framing all preclude expanding the hoistway size to accommodate a modern sized elevator.  The way most elevator and building codes work, one can often "grandfather" the otherwise non-compliant elevator size based on these building structural restraints, often applying for an "economic hardship" waiver or variance to the current requirements.  Retaining the existing elevator, albeit altering it extensively including converting it to a traction elevator, may be the only recourse for a building owner.

If you have a commercial winding drum elevator and would like to investigate your options, feel free to give us a call. 

Richard C. Blaska
Principal
RCB Elevator Consulting, LLC


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