Drums used solely for orchestra were well known in the 18th century. These had fixed iron legs, although drums on loose iron stands can still be found, often in early instrument consorts. Haydn wrote for timpani more often after he left the service of Prince Esterhazy and they are usually used with the brass instruments. They played the same rhythm as the melody, an inner voice, or with a rhythm of their own. He especially like using them to keep an even beat and this may have helped keep the ensemble together.
Timpani are ideal for pedal tones.
He used quick changes of pitch between movements but still only used 4ths and 5ths. Mozart used 4 drums in two of his divertimenti but never again, possibly because of lack of instruments. Mozart used rolls and a fp attack. He was very rhythmic in his use of the timpani. He also called for muffled drums.