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the additional property of requiring a very light force on the closing
lever, and is free from all jars so common to other forms of grips, due
to the elasticity imparted to its action by the floating pivot of the
closing lever. The grip requires about 40 lb. on this lever to close it.
As the carrier has to be attached and detached five times during the
passage from the loading to the discharge station, the troubles inci-
dent to these operations are five times as great as those on single-section
lines, the usual form of the great majority of aerial tramways. In
making a round trip on this line the carriers travel more than 26 miles,
and a special lubricating system is attached to them so as to pro-
vide an adequate supply of oil for the wheels and pins.

Section I is exceptional. From the loading terminal to Structure
4, a distance of 13 550 ft., the line crosses a gradually rising mesa
which serves as a fillet between the flat bottom of the valley and the
abrupt escarpments of the fault cliffs of the mountain. From Struc-
ture 4 onward, the line rises 800 ft. with great abruptness. It is evi-
dent that in hauling carriers up a line of this contour the track cables
and traction rope must be arranged so that the latter will never carry
sufficient tension to cause it to rise above the track cables. Such a
condition would be disastrous, as the carriers would be derailed. After
careful computations, the tensions were determined so that this sec-
tion operates perfectly.

Control Station No. 1 is unique in that it is equipped with driving
mechanism, tension sheaves, guide sheaves, and a horizontal angle;



738 AEKIAL TRAMWAY FOR SALINE VALLEY SALT CO.

and the ends of the building are developed into a pronounced rail
structure.

Control Station No. 2 is also equipped with driving mechanism,
and presents a reverse vertical curve in profile.

The summit is unusual in that Sections III and IV are controlled
from this point, both driving sheaves being mounted on the same shaft.
(Fig. 16.) Therefore, the power developed by the descending loads on
Section IV assists in raising those on Section III.

As the carriers are being lifted on Sections I, II, and III, there is
a possibility of the line reversing its direction of motion, due to the
unbalanced weight of the carriers on the loaded and empty sides.
Accordingly, each of these stations is equipped with a reverse preventer.
This device consists of a large circular plate fitted with shoes contain-
ing ball races under the control of a centrifugal governor. When the
governor is up to speed, the balls are restrained so that the plates run
freely. When the line stops, the balls immediately nip the plate, and
a reversal of motion is prevented.

Control Station No. 4 is also equipped with a reverse preventer to
stope a retrograde motion of the line in case it is loaded with "back"
freight destined for Saline Valley.

The drives of these stations are similar, except that at the summit
two sheaves are mounted on the same shaft, as before mentioned. They
consist of an 8-ft. grip sheave bolted to a brake run, 7 ft. 2 in. in
diameter, with a 12-in. face, and this, in turn, carries an 8-ft. spur
gear. The latter is driven by an 18-in. pinion mounted on a shaft
fitted with a friction clutch belted to a 75-h.p., Allis-Chalmers, 3-phase,
2 200-volt, induction motor. On Section V this motor acts as a dynamic
brake, instead of a driver. A grip sheave is one which carries a special
rim, in which there are about ninety-six pairs of toggle jaws.
These jaws are held open by gravity or by a special flat spring.
When the traction rope passes around the sheave, the pressure developed
on the bottom of the groove of these jaws is sufficient to cause them to
close and grip the rope tightly. This action increases the friction
between the sheave and the traction rope, thereby greatly promoting
its efficiency.

The brakes are of the compound differential type, and are actuated
by hand-wheels and screws; this method ensures that they will be
applied gradually during an appreciable interval of time, so that the



AEETAL TRAMWAY FOE SALINE VALLEY SALT CO.



^39



line will not be wrecked because of sudden stoppage, as would be
likely to occur with solenoid brakes.

The carriers are of special design, in that the hangers are made
longer than is standard, so as to provide proper clearance between the
traction rope guide rollers used in the rail structures on the ridges
running transversely to the location of the tramway.




72 dio. X 20 Face
Of BCOD Friction
Clutch PuUey



2-60 lb. R.R, Rail8-14 long

ELEVATION

Pig. 16. — Pakt of Control Station No. 3, Showing Drives for Sections III and IV.
Owing to the extreme length of the line, it was necessary to cover
the salt in order to protect it from contamination due to dust and
grease which might drop from the track cable. To obviate the neces^"
sity of removing this cover whenever the bucket is dumped, the latteJ?-'



740 AERIAL TRAMWAY FOR SALINE VALLEY SALT CO.

is cylindrical, and revolves about its trunnions independently of the
cover. Owing to the vibration of the carrier in passing through such
a great number of stations and structures, it was necessary to provide
a very positive keeper to hold the bucket latch in place. In the
locality contiguous to the tramway site there are winds of great
violence, promoted, no doubt, by the high temperature in the valley
and the cooled air of the summit. If the covers of the buckets were
not properly restrained, these hurricanes would blow them bodily
through the hangers ; therefore, it was imperative to design a dependable
latch to hold the covers in place.

The control stations are equipped with telephones, thus permitting
ready communication from one end of the tramway to the other. The
line riders, who are responsible for the oiling of the traction rope rollers
and the track cables of the several sections, are provided with line
'phones which can be attached to the wires conveniently, thus per-
mitting conversation with any of the stations from points along the
line. There is also a bell signal system for use in those operations
where conversation is not required.

The electrical transmission line is of the usual pole construction,
carrying copper wires for a 3-phase circuit. The voltage is 33 000.
The transformer stations are of the out-door type, and the voltage is
stepped down from 33 000 to 2 200 for use in the motors of the driving
stations.

The crew consists of two men each at the loading and discharge
terminals, as well as at Control Stations Nos. 1, 2, 3, and 4. In addi-
tion to this crew, four line riders are required to keep the track cables
and the traction rope rollers and guide sheaves in the structures and
towers in perfect condition. There is also a foreman who exercies a
general supervision of the line. The cost of labor and power for salt
transported is 4.6 cents per ton-mile.

Several methods of gathering the salt have been tried with indif-
ferent success. At present the plan is to flood the salt field by manipu-
lating the water which is piped from the springs. This fresh water
dissolves the salt rapidly. If the supply of fresh water is then stopped,
the evaporation caused by the summer sun is excessive, and pure salt
crystals gather in the brine. These crystals resemble flat plates, and
are easily shoveled into conical piles about 2 ft. high and 3^ ft. in
diameter at the base. Each pile is assumed to contain from 400 to



AEKIAL TRAMAVAY FOR SALINE VALLEY SALT CO. 741

500 lb. The piles are arranged in rows approximately 12 ft. apart,
the spacing between the piles being 6 ft. Mexican labor is found to
be most satisfactory in gathering the salt, and each man is supposed
to pile from 8 to 10 tons per day. Theoretically, the salt remains in
piles until the brine has drained. As the mother liquor contains the
majority of the impurities which might possibly contaminate the
salt, this step is additional insurance of its purity. However, the salt
does not drain freely, but remains damp for a considerable time. When
the salt is gathered, a buggy of a special type is used. These vehicles
are of galvanized iron and have a channel-like cross-section of body.
Owing to the field being soft, the rear wheels are 20 in. in diameter
and have a 12-in. face. The front wheels are 16 in. in diameter and
have a 4J-in. face. The bed is 3 ft. wide, 8 ft. long, and 6 in. deep.
The axles are attached rigidly to the body, so that curves are turned
by slipping the front wheels. These buggies carry from 500 to 1 000
lb. of salt, and are hauled across the field by a |-in. cable operated by
a gasoline engine. At the dumping point the wagons are pulled up
an inclined plane until they assume an angle of approximately 44°,
at which slope the wet salt slides freely into a hopper above a car
which has a body 30 in. wide, 4 ft. 6 in. long, and approximately 30 in.
high. The bottom of this car is hoppered both ways at an angle of
45°, so that the sides, instead of the ends, are used for doors. These
cars are operated on a double-track railway, about J mile long, by an
endless rope haulage system operating at a speed of 200 ft. per min.
A 10-h. p. gasoline engine will move seven loads and seven empties
on these tracks. The cars dump into a boot serving a drag conveyor
which elevates the salt to a point sufficiently high to command the
50-ton bins at the loading terminal. Here the tramway buckets are
filled by a lever chute of the ordinary type. The buckets are dispatched
from the loading terminal at the tap of an automatic spacing gong.
The rate established is fifty-six buckets per hour.

The tramway has carried material continuously at the rate of 23
or 24 tons per hour, and is an unqualified success. The stations, with
the exception of the summit, are not housed so as to permit readily
of winter operation, but the line is designed so as to prevent snow
and other weather conditions from interfering with its operation.

The line is not designed for passenger service, but the line oper-
ators use it in preference to going on horseback over the rugged



743 AERIAL TRAMWAY FOR SALINE VALLEY SALT CO.

mountain trails. A ride over this line is a never-to-be-forgotten expe-
rience. • Starting from either terminal, the passenger rises rapidly
to the summit, with a change from the torrid heat of the valley to
the chill of the mountain heights. The descent is a reversal of this
condition, so that it is difficult to dress properly to be comfortable
throughout the trip.

Acknowledgment is tendered to the following gentlemen, to whose
individual foresight, skill, and untiring energy are due the design,
erection, and initial operation of the tramway: Mr. White Smith,
President, Mr. Will Smith, Secretary, W. H. Leffingwell, M. Am.
Soc. C. E., Chief Engineer, Mr. Daniel Kuhnle, Superintendent, Mr.
M. O. Bolser, Electrical Engineer, and Mr. Harry Hilderman, Fore-
man of Construction, respectively, of the Saline Valley Salt Company ;
Mr. J. W. Smith, Local Manager, Mr. S. S. Webber, Chief Engineer
(retired 1914), Mr. William Hewitt, Mechanical Engineer, Mr. S. W.
Benson, Chief Draftsman, and Messrs. C. H. Wickham, L. T. Hays,
and T. J. Murphy, Eield Engineers, respectively, of the Trenton Iron
Company, and, later, Mr. R. H. Hall, Field Engineer, and Mr. George
Hall, Foreman, for the American Steel and Wire Company.



DISCUSSION OX AERIAL TRAMWAY '7453

Discussioisr



EiCHARD Lamb,* M. Am. Soc. C. E. — On studying this paper, with Mr.
reference to other plants which have been built, it is seen that it *™
describes novel features and conditions which were overcome with
difficulty.

At first one might wonder that such an expensive plant should
be constructed for handling so common and cheap a commodity as
salt, for a 7^-lb. bag of the best grade retails at present for 10 cents,
and lasts a family for quite a time. During normal times much salt
is brought to the United States as ballast for vessels, and is sold at
a low price.

Recently, the speaker was examining a cement stone deposit in
Alabama, and found, at a point 3 miles from tide-water, a salt deposit
from which most of the salt used by the Confederate States was
mined during the Civil War. A comparison of the plant described
by Mr. Carstarphen with a project to mine salt and deliver it by
cableway to tide-water from the Alabama deposit indicates that the
latter would have a great advantage. Later, the speaker visited the
Gulf Coast of Louisiana, and there found that vast deposits of salt
are now being mined and shipped by boat or train with little or no
intermediate transportation, and the owners cannot sell all they can
mine. However, it is presumed that the market was examined before
the Saline Valley cable tramway was built.

One of the novel features of this tramway is its excessive gra-
dients; the speaker knows of no other long cable tramway where they
are so steep. The only other plant in the United States which can
compare with it in length is that of the American Copper Company,
in Wyoming, 16^ miles long. In the latter, however, the maximum
vertical angle is about 20°, as compared with 40° in the Saline
Valley plant.

The undertaking was bold, in that such gradients had not hereto-
fore been overcome, and the success of the plant would depend on
the efficient service of the grip used. The speaker would have thought
that the Pohlig grip would have been successful; however, the author
states that the plant was not equipped with either the Pohlig or the
Bleichert grip.

In the Bleichert system the difficulty, on steep gradients, is that
in going up the steepest incline of the cable, just before surmounting
the saddle at the tower, the hauling cable is pulling somewhat down-
ward, and the resultant force has a tendency to retard the carriage.
In the system designed by the speaker, the hauling cable is kept
parallel with the bearing cable, and the downward pull is practically

* New York City.



744 DISCUSSION ON AERIAL TRAMWAY

Mr. obviated. This feature is used on the line of the American Copper

Lamb. ^

Company.

The speaker's discovery of this principle was due to the following
incident. A patented logging cable tramway had been erected by
parties who stated that it was practical. The bearing cable was
carried on A-frame supports. A trolley carriage ran on the cable,
and from it the log to be transported was suspended. Attached to
the log was a cable which was made fast to a whippletree drawn by a
horse. As the trolley approached the cable support, it had to ascend
the incline caused by the inherent sag in the cable. This direction
was one line of force in the parallelogram of forces. The direction
of the pull by the horse was horizontal. The resultant force, conse-
quently, was downward, and the trolley would not pass over the
support. The project was a failure, and the difficulty could not be
overcome under the conditions of the system.

If a trolley trackway is on a grade and a rope is attached to the
trolley to pull it in a horizontal direction up grade, the trolley will
not move. It is necessary to have the hauling and bearing cables
as nearly parallel as possible. The steeper the gradient, the more
difficult this problem becomes. Practical plants embodying this
principle were described by the speaker some years ago in a paper*
before this Society. An inherent feature of cable tramways is that
they must be built in an absolutely straight line. In the logging
cable tramway described by the speaker, in the paper referred to, the
sheaves carrying the hauling cable were hung so as to permit the
alignment to deviate from a straight line, but it had to be very nearly
straight.

In the Saline Valley line there are three changes of direction,
or four separate cable tramways joined by curved rail at the points
of deflection, with electric motors to operate the hauling cable at each
angle. At each control station the traction cable is made a imit
for that station only, and is driven by its own motor. The summit
station is arranged so that both the grip sheaves are on the same
shaft, and are controlled by a motor which supplies the difference
between the power required to hoist the ascending bucket and that
developed by the descending bucket. The power is not transmitted
around curves, as in surface cable-power street railroads.

The tension ordinarily used on cable tramways is about 30 000 lb.
per sq. in. of cable. The cable can never be stretched to approach
closely the horizontal; if so, it would be strained beyond its elastic
limit. The towers are usually about 250 ft. apart. Tension stations
are about 5 000 ft. apart. In some cases spans as long as 1 600 ft.
between towers have been operated successfully.

• Transactions, Am. Soc. C. E., Vol. XXXII, p. 44.



DISCUSSION OX AERIAL TEAMWAT 745

The Chilcoot Pass cableway was built mainly for the transporta- Mr.
tiou of passengers. For years this Pass had been traversed by miners
and others seeking gold, and it was so difficult that many lives were
lost there. The Trenton Iron Company built a cableway that carried
freight and passengers successfuly over the Pass. It was intended
to build the power plant on a plateau, named White Horse, near the
center of the Pass, but an avalanche buried the site, and it was with
difficulty that another could be found.

The power was furnished by a porcupine boiler in which the tubes
were of such weights as could be carried to the site by Indians. The
bearing cable could not be more than | in. in diameter, as it also
had to be transported by Indians. The transportation from Trenton
to the final location was more expensive than the material of the
plant. Great care had to be exercised in making the cable, as there
was one span about 1 500 ft. long. The first person to traverse the
line was a girl who used her canoe as a car.

H. F. ScHOLTZ,* Assoc. M. Am. Soc. C. E. — There are several Mr.
places in the Pacific Northwest where tramways for transporting logs
are in successful operation. The logs are taken out from places prac-
tically inaccessible by any other method. One instance is in the
Cascade Mountains, near Index, Wash., where logs as large as 6 ft.
in diameter are carried across a deep ravine and down a precipitous
cliff to the mill.

F. C. CARSTARPHEN,t M. Am. Soc. C. E. (by letter).— The writer ^^^Mr-^^.
appreciates the favorable tenor of the discussion which has been phen.
presented. Several points mentioned by Mr. Lamb are worthy of
note. The first deals with the question of the price of salt, which
no doubt was of great importance to the promoters of the Saline
Valley Salt Company, but was only of passing interest to the builders
of the tramway. Information as to the prices which can be obtained
for salt on the Pacific Coast shows that they range from $3.50 to
$40.00 per ton, depending on the grade and character. Ocean salt
sells for about $3.50 per ton, which is somewhat less than the computed
retail price of $26.70 per ton for salt, at the rate of TJ lb. for
10 cents. It is the writer's understanding that milled salt suitable
for table use sells wholesale at from $16 to $20 per ton, so that with
the ample demand of the fisheries and other users of salt on the
Pacific Coast and in the Northwest territories, the development of
the Saline Valley salt field was considered by its promoters to be
a worthy business enterprise.

Mention has been made of the length of the tramway built for
the American Copper Company, of Grand Encampment, Wyo. The
writer quotes from a report on file relative to this line:

* Carrollvllle, Wis.
t Trenton, N. J.



746 DISCUSSION ON AERIAL TRAMWAY

Mr. "The tram was built in four sections of about four miles to each

^ntfen'^' section. The first section from the smelter to Station 1 was approxi-
mately four miles in length, with a raise of perhaps 4% across an
almost level prairie. The buckets were transferred there from Section
1 to Section 2, etc. Section 2 was almost four miles, and the first
three miles above Station 1 was a gradual raise of probably 4 per cent.
For the last mile of Section 2 the raise was probably 12%, and crossed
one or two deep gulches. Station 2 to Station 3 was over a rough
broken country. It consisted of long spans and some very high towers.
From Station 3 to the loading station the tramway crossed the Con-
tinental Divide. Station 3 was in a canyon, and the mine was also
in a canyon. The tramway line raises probably 3 000 ft. between
the two terminals along Section 3.

"This tramway is of the old Leschen lug type; one of the first
four cable tramways built by that company. The lugs consist of a
piece of sheet steel bent around the cable and a cast-iron button
or lug riveted into this steel, and this button in turn entered into
channel irons on the buckets by means of triggers and slide bars.
There is one of the same type of tramways at the Sunnyside Mine,
Silverton, Colo.

"The cables on the tramway at Encampment were of the 6 by 7
lang lay type, and probably 11 or 1| in. in diameter. The traction ropes
were | in. in diameter.

"Tram was driven by power generated from boilers located at the
various stations along the line.

"Mr. Riblet was on the ground, and designed the structures and
figured all the towers, angles, and deflections of the cables. Equipment
was all furnished for this line by the A. Leschen and Sons Rope
Company, of St. Louis, Mo.

"The traction rope on these towers was supported by small sheaves
which hung on a cross-beam 21 in. from the top of the stationary cable.
These sheaves were grooved, and when the buckets passed over the
sheave the lug would raise the rope high enough to pass between the
rope and the sheave. One main difficulty was this : These channel
irons on the buckets were bolted to the frames with ^-in. carriage
bolts, two on each side, or four bolts altogether. The track ropes were
so slack that the buckets in passing over the long spans would hang
down so low that the traction rope would pull the lugs through these
irons, breaking oif the bolts and letting the buckets run away. The
lug, being riveted to the cable, would immediately whirl over a few
times and, as it passed, the next tower would hang on a rod that
supported the timber for the tower sheave. Towers were all set on
the ground without any anchorages, and consequently it dragged this
tower to the next one and then hooked onto that one and pulled it
to another one. Sometimes the writer would go up along the line
and find as many as four towers all piled vip in one bunch. The
engines were powerful, and the man in charge had no idea when
anything was hung up. They just kept pulling as long as they could
move the thing.

"The downward pressure on the traction rope in coming over the
Continental Divide, caused by the driving station and the loading
station being in the canyon below, and long spans leading to each



DISCUSSION ON AERIAL TRAMWAY 747

one of them, was so great that it would simply cut through a new Mr.
tower sheave in a very few hours. We experienced most of our diffi- ^phe^n."^^'
cvilties in the operation of this tramway on the three miles of country
adjacent to the Continental Divide."

The topography, due to the erosion of the Bridger sandstones, is
not comparable with the faulting and mountain-forming tendencies
which have developed the extreme slopes and elevations character-
izing the mountainous areas of California; and, therefore, the diffi-
culties of design of the two tramways are not of the same order.

No difficulties were experienced on the Saline Valley tramway
due to the faltering of the carriers in passing the saddles supporting
the track cables, on account of the traction rope not being parallel
with the bearing cable; nor is this tendency of any importance on
tramways of the Trenton-Bleichert construction, for it is eliminated
by the fundamental principles of tramway design. Reference to
Fig. 6, which represents loaded and empty carriers passing an 80%
grade, will show that the track cables and traction rope are practically
parallel.

In modern tramway design, it is customary to place the cable
supports so that the angle formed by the intersecting tangents
developed by the chord slope and the deflection of the empty and
loaded cable, is kept within a reasonable amount, depending on the
radius of the saddle and its capacity in angular magnitude.

The tensions used in tramway track cables have changed from
time to time. Twenty years ago track cables were erected with a
tension as low as 11 500 lb. per sq. in. Tensions were then increased



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