A tractor for feeding perforated paper forms as in a printer, to and around a platen where a print head impresses characters or other symbols on the paper. The tractor has an endless belt with pins engageable in the paper before, during and after engagement with a drive sprocket which drives the belt in such a manner that the load on the paper is polarized to one side of the drive sprocket, preferably the side between the drive sprocket and the platen. The tractor has guide members (idler sprockets or shoes) on opposite sides of the drive sprocket which define a generally triangular path for the belt with the belt engaging the sprocket only on one reach of the belt so that the load on the belt is relieved where the paper enters the tractor; the belt there being in an unstressed, relatively slack condition so that the pitch (spacing) between the pins can vary as by flexure of the belt or tilting of the pins, allowing the pins to enter the perforations in the paper without damaging the perforations or walking out of the perforations after entry.