Infinitrack Brutal Dozer and Infinitrack Trencher can’t be special summoned from the hand by tributing an earth machine monster. Instead the simulator reads their effect as a tribute summon.
Summon an earth machine monster such as Infinitrack Harvester while you have either Infinitrack Brutal Dozer, Infinitrack Trencher, or both in your hand and the effect to special summon will not activate. In addition, because Infinitrack Brutal Dozer is not being special summoned from the hand but instead normal summoned, it does not receive its effect to special summon an infinitrack monster from the deck.
Both monsters should be capable of being special summoned from the hand provided there is an earth machine monster on the field as tribute. In addition, Infinitrack Brutal Dozer’s effect to special summon an infinitrack monster from the deck should activate if it is special summoned from the hand.