The Time Wheel ( Hungarian Időkerék ) is one of the largest, possibly the largest The world's hourglass . It has a lifespan of one year and stood not far from Heroes' Square , on the edge of the City Park in Hungary's capital, Budapest . Hungary used it to celebrate its accession to the European Union on May 1, 2004. It was dismantled in the summer of 2021 as part of a park renovation; when and where it will be reinstalled remains to be seen.

The Time Wheel is a wheel with a diameter of 8 meters and a width of 2.5 meters. The materials used are stainless steel , laminated safety glass , and red granite . The total weight of the clock is 60 tons. A comparable hourglass, 6 meters high, is located in the Sand Museum in the Japanese city of Nima. Each hourglass runs for one year. ^{[ 1 ]}

It is framed by a blue stainless steel ring, which was designed to absorb the forces generated during transport and protect the granite. It also ensures the stability of the wheel, which is composed of various stone elements with a thickness of 22 cm. A total of 30 tons of Indian granite were used for the monument.

The two containers containing the 4.5 cubic meters of glass granules were made of laminated glass. The advantage of this granule over regular sand is that the uniformly sized grains do not damage the surface of the containers and have a precisely defined flow rate . This uniformly sized, pure, absolutely dry, and impact-resistant granule moves in pressurized nitrogen . Approximately 137 mm³ of granules flow per second from the upper container into the lower one.

To regulate the flow, a control mechanism is located at the center of the time wheel. This allows for weather influences to be compensated and the clock to be adjusted for leap years .

Every year on New Year's Eve, after the last grain of sand has trickled through the clock at midnight, two people turn the clock 180° using a lever, thus setting it in motion again.

Cultural historian and inventor János Herner had the idea for a time wheel as early as 1983. He described his design as follows: "Originally, it was even supposed to move." "The goal was to depict time vividly, from a distance, so the 60-ton hourglass wasn't just supposed to be set up, but would also roll slowly—hence its shape. Within 87 years, the time wheel would have traveled from the Kunsthalle to the Ajtósi Dürer fasor."

In 1998, he finally received permission from the Budapest City Council to erect the clock in this form. However, it soon became apparent that an underground parking garage was planned to be built beneath the street. This project meant that the road's asphalt surface was no longer guaranteed to support the clock's weight. It was decided to relocate the Time Wheel behind the Art Gallery and anchor it firmly in the ground.

The Üröm- based stonemasonry company "Renaissance" was commissioned to build the monument, having already gained experience with large-scale projects through restoration work on St. Stephen's Basilica and the Parliament Building in Budapest. Combining stone and steel was particularly challenging. It was also difficult to develop a mechanism that would allow the enormous hourglass, weighing the size of a diesel locomotive, to be rotated once a year using human power alone.

The filling of the clock was celebrated at the edge of the artificial ice rink near Heroes' Square. A large funnel decorated with European Union flags was set up, into which everyone could pour a spoonful of "sand." János Herner described it as follows: "Here, interested parties can pour in a spoonful of sand and thus a spoonful of their own time."

In the first week, around 30,000 people took advantage of this opportunity, including many politicians and diplomats from various national embassies. Everyone who filled the hourglass with a spoonful of sand received a certificate containing a code and the exact time they had filled the container. After the inauguration, everyone could use their code to see "their time in the hourglass" online.

Other countries, such as Germany and China, also expressed interest in the Wheel of Time. The Chinese government, for example, inquired about obtaining a license to install its own clock in Beijing .