or
THE HYDRAULIC SLINGSHOT
or
THE TIBETAN TRIUMPH
or
THE GOOD YAK LIFT
The chiseled features of ageless G.I. Li regarded us much as a cold wind off the adjacent Himalayas. He resented having to share the great engineering tradition of his native Tibet with these strange Western interlopers who aren't even engineers but mere toilers in the elevator field.
Nevertheless, he was polite, bowing slightly, despite the frowns of the two Communist Chinese officials who accompanied us and where his "comrade bosses."
The need for foreign capital had overcome all scruples about dealing with "Western devils>" The People's Republic of China was opening a branch office of the Peiping People's Bank in San Francisco. To kill two jade birds with one stone, the 59 story building was to boast Chinese building technology, entirely. The various electro- mechanical trades had been invited to send representatives to all parts of China for training.
Having had limited experience with elevators although a few had been erected (borrowed western methods). The People's Democratic Vertical Transportation Commission (PDVTC) (newly-formed) turned to their Tibetan brothers for assistance.
Tibet, with high mountains and ancient monks, has a 5,000 year history of elevator construction, if the term 'elevator' is loosely constructed.
G.I. Li rose from the floor, more monk than engineer, took his arms from inside his sleeves and touched each of us on the top of the head. "First we must examine the ancient prayer wheel, for at its heart is the substance and the means." Thus began our education on the "roof of the world."
Several months later, we were back in San Francisco ready to work. We had sat at the feet of G.I. Li for what had seemed an eternity.
T. Grosch, the senior member of the expedition, was given the title "venerable" before we left and his assistant, Y. Barbero, the honored, if less important title, of "sweeper of pits."
The membership of Local 8, I.U.E.C. soon became adjusted to the sight of two of their members sitting quietly on the floor, their legs crossed and heads shaven. The saffron robes were taken to be some designer-uniform cooked up by an "up and coming" elevator company.
Before the first I-Beam was raised in the bank building, it must be sadly reported, that our mentor, G.I. Li was laid to rest at the base of his beloved Mount Everest. At our suggestion, the People's Bank named the building rising on the corner of Broadway and Market, the Li Building.
As of this writing the structure has been topped off and the single elevator is in the final stages of adjustment. There is no reason to have more than one elevator in the building in this building. This is the fastest, most reliable, efficient and responsive elevator ever designed and installed.
What follows is a declassified account of the new elevator technology. All security guards have been removed and the Chinese Intelligent Agency (CIA) has cleared the article.
The Li Building is already known to the San Francisco trades because of the clever use of structural bamboo l-beams. We must report that except for the machine beams, all elevator equipment is made of metal, bamboo having been found to weaken with the heat this high-speed elevator generates.
The maximum speed of the car is determined by the length of the run and car-deceleration distance. The deceleration distance is computed by the length of the run as determined at the start prior to car motion.
This calculation is determined with the use of a fast Sucuba (trade mark) computer and is performed when:--
We refer the readers to . It shows Diagram #1 a simple sheave with a roped car and counterweight and a friction brake on the sheave.
Assume that the counterweight is heavier than the car. If the brake is lifted, the car will accelerate upwards, its speed limited only by the system friction. If the car is heavier and the brake is lifted, then the reverse would be true.
This basic principle is called the Variable Weight Counterweight. A German engineer on leave from Volkswagen who lived in Tibet for ten years as one of G.l. Li's chief assistants called it the VW Principle.)
Making the counterweight heavier or lighter than the car is simply a matter of pumping water into the counterweight or letting it out.
Any knowledgeable reader can see that the idea allows for a smooth stepless acceleration to any speed desired if the counterweight is increased or decreased while the car is in motion by means of the pumped water. This is now possible as long as the counterweight weight can be determined accurately before and during motion.
Basically, this single car principle operation is a copy of the older U.S. patented Hale Elevator (purchased by the Otis Elevator Co.) See Diagram #1
In the improved Chinese development, the cylindrical counterweight moves in a separate shaft. The counterweight pit runby retardation is provided by a fluid (pat. pending) in the counterweight shaft pit. Go to footnote
A special chemical fluid (pat. pending) separates the retardation fluid from the water relieved from the counterweight shaft when a down direction counterweight motion is required (Diagram #2).
The measurement of the deceleration point is determined by a sophisticated "East is Red Laser Measurement Device" (ERLMD). It is accurate to one-tenth of an inch and even, in conjunction with the computer allows for minute stretches of the cables during acceleration and compression during deceleration.
The ERLMD assures that the slowdown distance point is matched to the speed at every moment. A possible ERLMD failure (once in a thousand years, Mainland astrologers assured us) automatically reduces the speed to a 1000 fpm and stops the car at the next landing, opens the doors and shuts the system down.
The elevator car has no travailing cables. Electric power for lights, signals, buttons, etc. is supplied by on-car batteries charged by A.C. inductor plates (Diagram #3) which are energized when the car is leveling at a landing.
Car buttons, safety circuits and car gate-closing indications are coded signals given from a miniaturized FM transmitter, received in the machine room by a receiver transmitter (VT). Any code failure causes the computer to stop the entire system. It should be pointed out that a Chinese musical scale is used for the coding to prevent American FM stations from affecting the car's operation.
(Elevators planned for Mainland China will use Western music).
As an added precaution, Muzak and Japanese Walkman type cassette players are banned from the building.
A Kelly control (K) compares sheave speed to cable speed so that excessive deceleration does not occur during emergency stops.
Piezoelectric crystals (I) supply cab load weighing as a check against the laser weighing when the car is stopped. A small variation between these two readings is allowed by the computer to compensate for compression errors in the cab isolation.
The assumption is that the car is at the bottom landing and the car weight is equal to the counterweight weight.
A passenger enters the car and presses the desired floor button.
A coded FM signal is transmitted to VT and the doors close.
The computer determines and compares the car weight difference between the empty car and the load from another FM signal supplied by the under-car-crystal (I) and the car position (resulting from minute cable stretch) supplied from the reflected laser signal (L).
No additional car buttons can be registered after the doors are fully closed. Thus, the known stop is fixed and it's possible for the computer to calculate the crossover point between acceleration and deceleration to accomplish the minimum flight time.
The Electric valve (V) opens to overbalance the counterweight (COO) with fluid from the overhead reservoir. The amount added is equal to the weight of the load of the car plus a fixed amount to overcome friction and a small fixed amount for counterweight overbalance.
The brake (B) lifts and the car accelerates, continuing to the predetermined point where deceleration begins. This point is calculated by the computer and compared to the constantly changing car position as supplied by the laser receiving device (L).
The car speed is fed from a tack generator (T) coupled to the main sheave in the overhead.
A variable output D.C. generator (G), also coupled to the main sheave affords acceleration-deceleration control to insure that this value never exceeds five feet per second, squared. Excess regenerative output is stored in the power unit (PO) for use when required. The PO receives a small trickle charge to start and hold the system with sufficient energy to overcome long periods of non-use (such as Chinese New Year week).
As the car reaches the deceleration point, an FM radio operated valve (X) under the counterweight opens. Sufficient fluid is dropped down the counterweight shaft to start deceleration. The car glides to a perfect stop as the mass of the moving system and the distance to the floor level and the rate of negative acceleration are all known constants.
With the car motion halted, the friction brake is applied. No releveling is required or supplied.
This computer is accurate to the point of calculating brake wear by 'counting' brake use and measuring it against a variety of local data such as weather and air pollution. It compensates for such wear and even calls the service man when the brake lining needs replacing. Leveling within one-one hundredth of an inch is considered normal.
Used weight fluid is returned to the overhead tank by a small high lift pump (P) that receives power from the stored potential at the power panel (PO).
A fluid sensor (t) in the reservoir determines when the pump is to function. Check valves are required but not shown in the diagram as are additional counterweight inlet valves (V) and a governor for safety applications.
The section sketch (Diagram #3) shows the Teflon fitted gland enclosed counterweight above a tapered portion of the counterweight cylindrical shaft. The excess overbalance fluid and tapered shaft act as a counterweight buffer as described in the fluid footnote.
With the car now under test and a controlled acceleration deceleration adjusted to 5 f.p.s.2, we experienced the following results:--
1) A 785 foot rise, brake to brake time of 25.059928
2) The maximum speed at the changeover position was 3,758.9892 feet per minute.
Space limitations only allow a few remarks about hoist ropes, the governor and the sheaves.
The car capacity on this job is 4000 Ibs; the car weight inclusive becomes 8000 lbs. The two car to counterweight ropes are of one-inch diameter, stainless steel, locked coil design with an ultimate strength of 260,000 lbs. per square inch each, supplied by People's Factory 74 of Danglo, China. The use of stainless steel is required because of the moisture in the counterweight shaft. Obviously, compensating ropes are not required, or desirable, since overbalance is a controlling factor.
During an emergency slowdown, the traction is increased by the use of a hydraulically-operated, variable-shaped sheave groove. The groove is of a round shape on all normal runs. When an emergency stop is initiated, the brake is applied with controlled pressure dictated by the Kelly (K) controller while the bottom of the round groove is allowed to retract radially and change to a 105 degree undercut.
The governor (not shown in the diagrams) is a pleasure to behold because its tripping speed is calculated prior to car motion.
Let's assume the car is to travel 25 feet, the approximate distance between two floors (above the lobby) at a maximum acceleration of 5 f.p.s.2. The cross-over point is (25 -. 2) at 12.5 feet. The maximum speed would be 670.82039. The governor would function at 737.90243 feet per minute or 10% above the computed top speed of the elevator.
In the case of a non-stop run for the total rise of 785 feet of the Li Building, the tripping speed would be 4,134.8881 feet per minute or 10% more than the 3,758.9892 previously figured as the top speed of the car for this rise.
Air resistance, computed at various predicted maximum velocities is stored in the memory of the Sucuba computer and is not included in the simple illustrative calculations supplied with this piece.
In addition to the variable overspeed tripping of the governor, there are included two Dual-digital accelerometers which give an electric stop signal if the fixed acceleration is exceeded. Any acceleration determined to be above 5 f.p.s.2 will initiate a mechanical governor trip followed by the application of the car safeties. A future paper will describe the unique safeties which can comfortably and safely stop a falling elevator at any speed (even if it were falling upwards in the event of a counterweight malfunction).
We were asked to comment about possible rope slipping. The reader would be advised to review ELEVATOR WORLD magazine, August '82, page 41 by George Gibson. Further studies can be made in the book "Electric Winders" by H. Broughton (1948) and specifically Chapter 10, in the section entitled, "Effect of Rope Velocity on the No-Slip Ratio." Behr's paper, "Winding Plants of Great Depths," did not fully develop the traction problem at high speed while the "Reid Report" of 1945 did discuss it.
The present groove lining material is a closely guarded Chinese secret. While in Tibet, we witnessed part of the manufacturing procedure. The lining is composed of 50% crushed rice hulls,30% aged yak clung, 15% rancid yak butter and 5% spittle from aged Tibetan monks (who have lived at least 30 years in the ratified atmosphere of the Himalayas). The process appears to be an act of superstition but the result is a material with a coefficient of friction higher than 0.39. This plastic-looking liner has its origins far back in the religious history of Tibet when it was used as a glue to hold fast spinning (1500 fpm) prayer wheels from flying apart and, as legend has it, a personal shield against certain fire breathing lizards said to inhabit the area.
The material is said to line the fallout shelters of the Grand High Lama of Tibet and the Chairman of the People's Republic of China. Why it is used for elevator shafts can only be surmised; perhaps its heat-resistant properties. The designers refused to say.
The Sucuba Computer is a revolutionary design, neither Continued overleap analogue or digital (in the Western sense), but consisting of hundreds of microabacii connected in series and parallel and divided by a group of gates. The secret is in the arrangement rather than the component parts which are manufactured in Philippine toy factories in the months following Christmas.
For license or purchasing information, contact the authors who have exclusive North American license for distribution. Those living in an area with a low water table, should check municipal and state codes before considering installation.
Naturally, the technical paper developed by Tom Grosch and Yves Barbero is the kind of analysis which passes over an editor's desk once in a lifetime. We hasten to provide full exposure, recognizing its relevancy for an era when energy conservation is an over riding concern. Knowing our readers would be interested in full biographies and photographs of such well~traveled authors we sought such information. The humility taught during months with the High Lama had not wore off; both wished to be merely described as "elevator people of San Francisco." To those questioning the Western attire, the photographs are Pre-Tibet (PT), taken before the discard of such extravagant apparel.
Passing such a well~researched article before ELEVATOR WORLD's Technical Communications Council (TCC) was, in this instance, a mere formality. However, TCC Member Stu Harwood's letter was of particular interest as the Canadian is the Council member living in a climate most closely approximating that of Tibet. Comments with corresponding validity from researchers, hydraulic engineers and Sinologists will be published.
The article on the "People's Elevator," or the "hydraulic slingshot" supplied one with a good yack (or is that yak?).
It was asked if Canadian icing conditions might affect this system--I can see some problems and some advantages. In your recent Arctic visit, if you saw any Esqulmau dog sledges, you are probably aware that the sledge runners are normally coated with a mixture of urine and mud, frozen hard, then filed smooth. This both cuts friction and protects the wooden runners (wood being scarce above the tree line). It struck me that a similar approach might be used on the proposed "happy hoist," on which the rail problem was inadvertently omitted. My proposal is to put the counterweight on an un-insulated outside wall and use the tried and tested "Esquimau mixture" on the wall to act as a counterweight guide system. Alternately a 25% mixture of horse buns could be added to the mixture before application to provide a binding element to compensate for the increase of elevator speed over that of a dog sledge. Anyway, I think it would fit in with the general concept even better than the "Arctic mixture."
Of course, this introduces a problem regarding moving water into the counterweight bucket and from the pit to the penthouse. Possibly a "cascade of ice cubes" could be used to transfer the weight from the penthouse storage area to the counterweight tank. As to returning the cubes from the pit, possibly a motor-driven prayer wheel in the pit with buckets on the circumference (like a Pelton Wheel) could pick-up ice cubes and pelt them up the hoistway to a deflector plate at the top for deflection into the storage bucket. There are some technical aspects which should not be overlooked: for example, the counterweight bucket might have to be enlarged, since ice weighs less than water; allowance would also have to be made forsome air space between the cubes. However, these are not insurmountable.
The counterweight buffer also offers a problem in a cold climate where a fluid might freeze. My suggestion would be to increase the height allowance and decrease the fit of counterweight in hoistway and use an air buffer. Possibly the efficiency of this could be improved by attaching a number of speaking tubes at the bottom and installing a bevy of politicians--one per tube--the resulting flow of hot air could appreciably improve buffer efficiency. Of course an overspeed buffer engagement might reverse the air flow and cause the politicians to eat some of their words (a consummation devoutly to be wished for.~).
So much for winter operation in a cold climate. But, what about summer? Considering the proposed guide rail facing --I'd move out, and advise the other tenants to do likewise!
I could make one safety comment. I think a high-speed prayer wheel could be installed in the car, for the convenience of passengers (if any). I'd also suggest that Messrs. Barbero and Grosch do the initial test ride in this hydraulic slingshot and see if there is any truth in the old saying "an engineer was hoist by his own petard." At /east it would meet the Mikado's (Gilbert and Sullivan) specification of making the "punishment fit the crime."
On the whole, a thought-provoking article which will produce many a good yak if published in ELEVATOR WORLD.
Stu Harwood, Consultant
The fluid in the counterweight pit is a layered multi~viscosity type that offers a gradual deceleration to a free-falling body. It's a well known scientific fact that at 50°F, pure water has a specific gravity of one (1) (which varies to 0.980 at a 150°F) while other fluids have a larger or smaller s.g. than that of water at an equal temperature.
This s.g. difference of the fluids in the counterweight pit provides for the varied deceleration in the unlikely event that the elevator car travels above the uppermost landing.
The counterweight retarding force, F. can be quickly estimated with the use of Stokes Law:--F = 6 anv (k) where,
a = the radius of the falling sphere.
n = the density of the encountered liquid. v = the striking velocity.
k = an empirical factor to correct for the shape of the bottom of the counterweight.
In addition, a tapered counterweight shaft (Diagram 3 ) is provided at the pit level as a precaution in the event foreign liquids accidentlly spill into the counterweight shaftway.
Not shown to scale in the diagrams is the counterweight outlet to the pump intake which insures that only liquid of the desired specific gravity will be returned to the overhead storage tank.
Return to Text
Return to Footnote
See also Abondoned Mine Elevators by Tom Grosch
See also More Adventures at Abondoned Sites by Tom Grosch
See also Tom's Collected Elevator Stories
Elevator Pinup (must be old enough to have an IUEC union card)
|
Enter 2 values |
International Union of Elevator Constructors: Yep! The International finally put up a site.
Tom Grosch can be reached at groscht@theriver.com
Yves Barbero can be reached at ybarbero@yvesbarbero.com
This The Elevator Ring site
is owned by Yves Barbero and Tom Grosch. Want to join the The Elevator Ring? |
|---|
| [Skip Prev] [Prev] [Next] [Skip Next] [Random] [Next 5] [List Sites] |
Page prepared by
Yves Barbero
Computer Consultant
Member, National Writers Union,
