Introduction
β
h0
h1
h2
Figure 5
Here,
I. Initial potential energy of downward moving
trolley (PE0) = m1gh0, where h0 is the
elevation difference between the upper and
lower saddles;
II. Potential energy of downward moving trolley
at the point of consideration (PE1) = m1gh1
where h1 is the height of the first trolley from
lower saddle at the time of consideration;
III. Potential energy of upward moving trolley at
the time of consideration (PE2) = m2gh2, h2
is the height of m2 from lower saddle at the
time of consideration;
IV. Combined work done by the masses against
the friction (W1)= 0.25(m1+m2) cosβS
where S is the rope length covered by the
trolleys at the time;
V. Combined Rotational Energy of sheaves
(W2) = I ω2, where ω= v/r, I = ½ mr2 where
r and m are the radius and mass of the
sheave respectively.
Now, as per the principle of conservation of
energy,
0.5 (m1+m2+mh) v2 = PE0-PE1-PE2 -W1-W2
Here, mh is the mass of the hauling rope.
From this relationship, the velocity of moving
trolleys at specified time and point along the
route can be calculated. The actual velocity for
a given loading condition is usually less than
the velocity obtained from this relationship. As
the track rope and hauling rope are not parallel
to each other in vertical plane, the hauling
rope is pulled towards the track rope while the
gravity ropeway is in operation. This leads to the
excessive friction between the hauling rope and
the sheave which leads to the loss of velocity.
Nevertheless, the idea of tentative approaching
velocity of the trolley helps to calculate the
maximum possible impact load which is very
important for the rope design.
1.4 Features of Gravity Ropeway
The followings are the features of gravity ropeway
which makes it suitable in the hills and mountains
of Nepal.
Cost effectiveness: Construction and installation
cost of gravity ropeway is lesser than other
conventional means of transport like roads
and railways. The approximate cost of the
gravity ropeway is Rs. 1,400,000 where as
per kilometre construction cost of a four metre
wide earthen road in the hills is approximately
Rs. 3,000,000.
Time saving: As goods can be transported
through gravity ropeway within few minutes,
it is efficient and time saving.
Short route: In the case of roads or railways,
alignments are usually winding to acquire
required gradient which makes the route
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