On a hot day, the rope sag means that cars approach-
ing a tower climb steeply as they enter the saddle and
descend similarly at the exit. This will produce very
high loadings on the rope at this point (Fig. 7). Con-
versely, if the rope is tensioned sufficiently to over-
come this, a drop in temperature can increase the rope
tension past the yield point of the rope.

Because of these problems and the necessity to stay
within the 3.3 safety factor, rope sizes are being in-
creased to 2.28 in. (58 mm) and 2 in. (51 mm) on the
top and bottom respectively (Fig. 7).

Approach and exit angles, wear on the rope as the
car comes out of the tower, rail wear within the tower
and terminals, and methods of solving these problems
are open to many theories. In an attempt to gather as
much information as possible, we have used a high-
speed movie of the tramline, slowed down to show the
rope and car movement. We are also embarking on a
test, together with help from Wire Rope Industries
Limited and Noranda Research, to place an instru-
mented tramcar in operation which will record car
wheel loadings at points along the route. It is hoped
that this information will help the company to design
saddle and tower configurations to increase the present
short rope life (Table 3) to at least 6,000,000 tons.

Apart from the increased rope diameters, we have
already tried or are in the design stages of other
modifications to better the original configurations.

On two towers on the top sections of the tramline,
20-ft (6.1-m) extension pivoting rails were fitted to
help support the car entering the tower and relieve
the rope of the strain. However, experience is showing
that rather than alleviate the problem of rope strand
breakages these are just being moved another 20 ft
(6.1 m) farther along the line. On two towers we are
now experimenting with a longer saddle of larger
radius, to give a more gradual change in rope-saddle-
rope transition.

Although these new saddle designs have only been
installed for a few months, they appear to be having
the desired effect, and more will shortly be fitted
(Fig. 8).

As mentioned earlier in the text, increases in am-
bient temperature can cause sagging. This, in fact,
caused a derailment on the 1060-ft (323-m) long top
span of the tramline, when the line became unstable.
A tie-down system was then installed to increase the
stability, but on hot days it is still sometimes necessary
to shut down the tramline due to sway in this section.

The permanent solution will be to install an ad-
ditional tower to reduce the length of the span. This
has now been designed and will be installed during the
summer of 1978. While the extra tower was being
designed, alternative designs were also produced for
the other towers in the top section, changing the
profile to a more gentle one and embodying the new
saddle design (Fig. 9). If put into practice this change
should further extend rope life.

Discharge Terminal

The discharge terminal is an enclosed steel structure
providing a steel framework for the 10-ft-diameter
urethane-lined floating tail sheave and the discharge
hopper (Fig. 10). The hopper is designed to receive
ore from any location of the tail sheave. Below the
hopper is a 60-in. reversible belt which directs the
ore either via belt to the concentrator or via a radial
stacking conveyor onto a wet-rock stockpile. An ultra-
sonic level detector within the hopper signals the bin
high-low levels.

Electrical

As described under the drive system, two 300-hp
575-volt induction motors drive through a Falk reduc-
tion gear box. Under full load, the motors regenerate,
about 400 kw/hr. The hydraulic pony drive is powered
by two 100-hp motors, the variable-rate pumps being
controlled by a ‘Moog’-type controller. ;

Safety systems on the tramline, consisting of over-
speed, underspeed and axle limit switches, all originate
shutdown and braking through an undervoltage relay.
Speed read-outs are provided by an ‘Airpax’ system.

Now in the design stages is a derailment alarm and

NEW RAILS, 60’ RADIUS-20' LONG
Track rope
t 3 == 3
= 5 ° ° ° 5
. = g e
a 2 TRACK ROPE SUPPORTED BY FULL LENGTH SADDLE - 60' RADIUS Y °
SECTION THRU
NEW SADDLE AND RAIL COMBINATION
.
OLD RAILS, COMBINATION 25' AND 40’ RADII - 12’ LONG

Track rope

« = = ————

le } SROMS :
I Se Ete
TRACK ROPE SUPPORTED BY TWO SHORT SADDLES-I2' RADIUS

FIGURE 8 — Old and new tower saddles and rails.

=e