"ケッタ" is derived from "けったくる". It means "蹴(け)る" in standard Japanese. Why "蹴る"? Because we pump the pedals of a bicycle. In Nagoya, people use "蹴る" instead of "pump".
ペダルを蹴る機械 --> ペダルを蹴ったくるマシーン --> ケッタマシーン
But in standard Japanese, "pump the pedals of a bicycle" is 「自転車のペダルを漕ぐ」 but not 「自転車のペダルを蹴る」 .
Yeah, there were a number of ketta machine web sites related to bicycles -- but I was thinking of kick more than pump. Isn't there also a ketta machine band or music group?