This 22-metre-high Energy Machine is the Science Museum's tallest and biggest exhibit. Occupying four storeys of space, it stands prominently in the centre of various exhibition halls. This exhibit enables visitors to discover the relationship between energy conversion and movement of balls. At present, it is the largest Energy Machine of its kind in the world. When set in motion, a continuous stream of balls will roll along tracks within and between two towers like a roller coaster, producing dramatic sounds and visual effects.

The machine has three sections: Tower A, Tower B and a Connecting Gallery.

Tower A rises up from the centre of the Motion Hall on the ground floor where the Ball Elevator (A2) and the Archimedean Screws (A1) are used to lift all the balls to the top of the Energy Machine. After that, the balls will begin their downward journey by converting their own potential energy into kinetic energy.

While in transit, the balls are systematically directed to various tracks by a series of computer controlled gates. Some of the balls in Tower A will slide down the Cylindrical Spiral (A4) via the Loop (A7) before returning to the Ball Reservoir (A8) below. Some balls will enter a Free Falling (A6) path, or an Acceleration (A5) path triggering a series of resonating boxes to sound in shorter and shorter intervals.

Meanwhile, the other balls will enter separate tracks passing the Connecting Gallery. One is a Wavy Track (C1) and the others are straight. Sitting in the centre of the Electricity and Magnetism Gallery, Tower B rises up from the first floor of the museum. There is a Ball Counter (B1) at the end of the wavy track where five balls will assemble. Only the combined weight of all five balls can activate a mechanical device to send the balls towards a Zig-zag (B7) track sounding the buffers at six turnings as they roll along.

While this is going on, some balls on the other tracks will hit the Drums (B4), strike the Gong (B6), sound the Chimes (B5), "play" the Xylophone (B8), and "ring" the Bell (B12) in an action-packed energy symphony to entertain the visitors.

Some of the other balls will go on the Seesaw (B3), some will become Flying Balls (B2), and some will activate the Compound Pendulum (B9). Those balls which enter the Curve (B11) will swing to the left and to the right, triggering a sensor in the centre to switch on the multi-colour lights of the Neon Wall (B13) below.

Before they leave Tower B, most of the balls will enter a gigantic funnel-shaped Collector (B10). They will spin round the centre and move faster and faster. However, unless they collide with each other, it will take them a little while spinning before falling down. They will then leave Tower B and go through the Conical Spiral (A3) in Tower A to return to the starting point to wait for the next trip to begin.

Some fact about the Energy Machine

Each one of the synthetic fibre balls has a diameter of 19 cm and weighs 2.3 kg. The total length of all the tracks is more than 1.6 kilometres. It takes about 1.5 minutes for a ball to travel from Tower A along the longest route before returning to the starting point.