There is absolutely no evidence of this. The Nazis did for example beat many people to death but no machines were involved. The only mechanized killing which was done during the Holocaust was through the use of gas chambers. Of course many millions were also shot, beaten, or starved to death. Unfortunately I think this rumor you heard may come from a bit of propaganda often used by Holocaust deniers. People who wish to deny or minimize the Holocaust in order to further modern antisemitism will often create rumors about highly elaborate methods of killing such as this which are meant to spread disinformation about the Holocaust and make it seem less real.