▁Model ▁ 7 5 , ▁we igh ing ▁ ▁with ▁a ▁ ▁engine . ▁Pl iny ▁was ▁also ▁tre as urer ▁of ▁another ▁subs idi ary , ▁the ▁Hou ser ▁and ▁H aines ▁Man ufact uring ▁Company ▁of ▁Stock ton , ▁from ▁ 1 9 0 5 – 0 9 . ▁ ▁As ▁well ▁as ▁having ▁a ▁better ▁power - to - weight ▁ratio , ▁a ▁gas oline - eng ined ▁tra ctor ▁required ▁fewer ▁men ▁to ▁operate ▁it . ▁Comp eting ▁steam ▁engines ▁typically ▁required ▁a ▁crew ▁of ▁seven , ▁including ▁one ▁highly ▁sk illed ▁and ▁well - pa id , ▁lic ensed ▁" f arm ▁engineer ". ▁He ▁was ▁responsible ▁for ▁rising ▁in ▁the ▁middle ▁of ▁the ▁night ▁to ▁start ▁the ▁bo iler ▁fire ▁to ▁get ▁up ▁steam ▁by ▁first ▁light . ▁Ste am ▁tra ction ▁bo ilers ▁had ▁a ▁huge ▁need ▁for ▁water ▁and ▁fuel , ▁either ▁coal ▁or ▁wood . ▁Much ▁of ▁the ▁seven - man ▁crew ' s ▁time ▁was ▁spent ▁keeping ▁it ▁fue led . ▁ ▁T iller ▁wheel ▁▁ ▁C .   L .   Best ▁introduced ▁a ▁craw ler ▁tra ctor ▁in ▁ 1 9 1 3 ▁that ▁was ▁virt ually ▁a ▁carbon ▁copy ▁of ▁Hol t ' s ▁design . ▁Hol t ' s ▁tra ctors ▁had ▁a ▁conventional ▁wheel ▁on ▁the ▁front , ▁which ▁was ▁used ▁to ▁ste er , ▁and ▁craw ling - type ▁whe els ▁on ▁the ▁back , ▁but ▁otherwise ▁looked ▁very ▁similar ▁to ▁a ▁tra ction ▁engine . ▁During