Shani Yantra should be installed and worshipped in order to appease planet Saturn. As per Ancient Vedic Texts, Saturn is a merciless planet. Saturn is the Lord of Zodiac sign Capricorn and Aquarius in Astrological terms. It is Exalted in zodiac sign Libra and Debilitated in zodiac sign Aries. It is said that planet Saturn acts as a judge for our past deeds. The planet Saturn is a natural grantor of jobs and services, metals, industries, age, poverty, hardships, diseases, all kinds of obstacles and selfishness. A person having weak or an evil Saturn in his horoscope has to undergo sufferings in all his life and his progress is retarded in spite of very hard work. However, if the planet Saturn is favourable in a person's horoscope then he can achieve very good Success, Name and Fame in his Business / Career especially in those areas that are governed by Saturn like industries. When Saturn is not favourable, it causes many problems, accidents, conflicts, poor financial position, sorrow, sadness, depression, poverty etc. Under such circumstances, a Shani yantra can deliver peace and comfort.
If the planet Saturn is in combination with planet Rahu, then it forms a bad yoga known as "Shani Rahu Shrapit Dosha" which adversely affects almost all the zones of life and the person's life is full of hardships. Similarly, if the planet Saturn is in combination with planet Moon, then it forms another bad yoga known as "Shani Chandra Vish Yoga". Such a person is very intelligent, still at times he can fall prey to extreme negativity and depression. In all such cases, worshipping a Shani Yantra can be extremely helpful.
A person is said to be under the major affliction of Saturn known as "Saturn Sade Sati" when the planet Saturn is transiting through the 12th, 1st and 2nd house from the Natal Chart Moon, each transition is of approximately two and a half years. A person has to undergo all kinds of hardships during this period including stress, anxiety, tensions, loss of mental peace as well as financial losses. These problems are more profound and severely affect if the planet Saturn is malefic in his horoscope.
Similarly, a person is said to be under the minor affliction of Saturn known as "Small Panoti" when the planet Saturn is transiting through the 4th or 8th house from his Natal Chart Moon. The adverse effects of Small Panoti are also very much like those of Saturn Sade Sati. In both these afflictions also, establishing and worshipping a Shani Yantra can bring immense relaxation by the blessings of Lord Saturn.