The intricate mechanisms that keep the clock tower running.
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The clock tower of BITS-Pilani is an engineering marvel.
Its intricate clockworks ensure the clock ticks with precision. The clockworks can be split into three “gear trains” sitting on a metal frame and its peripheral attachments. It is called a ‘flatbed turret clock’ because of the arrangement of these trains. They are:
The Going train
1. The Going train
It is designed to drive the clock and keep time. The rate at which the gears rotate is regulated by a special gear called the escapement gear. The clock uses what is known as a Graham Escapement. The escapement gear is connected to the pendulum, whose regular swing and time period is the heart of its timekeeping.
The Graham Escapement
The Tune Barrel
2. The Chiming Train
Four times an hour, the ‘going train’ lifts a lever that actuates the ‘Chiming train’. This section consists of a tune barrel and actuates all 10 bells to ring the quarterly and half hourly musical chimes.
The Hourly gong
3. The Striking Train
At the end of the tune for the hour, the chiming train lifts another lever that actuates the ‘Striking Train’. This section is connected to a single bell – the hourly gong. The striking train rings the gong bell according to the hour of the time. (i.e.- 4 strikes at 4’O clock, 12 Strikes at noon, etc.)
The bells are connected to both the Striking and Chiming trains through control cables (similar to the accelerator and brake pedals in a car) and when the mechanism pulls the levers, the hammer is raised. As the levers are released, gravity pulls the hammers back down and they strike the bell.
The four bevel gears linked to the clock faces
The going train also drives the four faces of the clock tower through bevel gears that transmit the torque needed to turn the arms, using a single shaft for each face. The interface at each face has a gear system to regulate the minute and the hour hand.
The entire mechanism is powered by the potential energy stored in large driving weights of 300-400kg each, that are raised through the entire height of the tower to store energy. As the weights fall to drive the three trains, the escapement gear functions as a regulator of the rate at which the gears turn, which in turn regulates the rate at which the weights descend.
The weights are raised once every few days when we ‘wind the clock’. To ensure that the clock continues to run uninterrupted even during the is winding process, a temporary system is available with a short distance travel weight to drive the clock while the main barrel is disconnected from the main gears and the weights are being raised.
Each design in the mechanism is well thought out and an attention to detail has been made to such perfection that this piece of engineering is indistinguishable from art.