. ▁ ▁The ▁more ▁a ▁tr uck ▁moves ▁to ▁the ▁side , ▁the ▁greater ▁the ▁lift ▁to ▁the ▁outside ▁of ▁the ▁locomot ive , ▁cant ing ▁it ▁slightly ▁into ▁the ▁curve . ▁Though ▁the ▁system ▁was ▁effective , ▁casting ▁and ▁mach ining ▁its ▁s lop ing ▁surfaces ▁was ▁expensive . ▁▁ ▁A ▁ref in ement , ▁the ▁Hudson - B iss ell ▁tr uck , ▁delivered ▁the ▁same ▁result ▁using ▁less ▁cost ly ▁components . ▁ ▁Instead ▁of ▁rest ing ▁upon ▁oppos ing ▁plan es , ▁the ▁engine ▁frame ▁is ▁joined ▁to ▁the ▁tr uck ▁by ▁two ▁swing ▁links . ▁As ▁the ▁tr uck ▁p iv ots ▁side ways ▁the ▁outside ▁of ▁the ▁locomot ive ▁is ▁elev ated , ▁a ▁practical ▁modification ▁used ▁right ▁to ▁the ▁end ▁of ▁the ▁steam ▁era . ▁ ▁Equ al izing ▁Part ly ▁because ▁load ▁was ▁not ▁equal ized ▁between ▁the ▁B iss ell ▁p ony ▁tr uck ▁and ▁the ▁leading ▁drivers , ▁the ▁p ony ▁tr uck ▁did ▁not ▁become ▁instantly ▁popular ▁in ▁the ▁US . ▁ ▁Lo comot ives ▁in ▁the ▁UK ▁were ▁generally ▁not ▁equal ized , ▁so ▁it ▁was ▁not ▁considered ▁a ▁problem ▁there . ▁ ▁John ▁P . ▁La ird ▁was ▁the ▁first ▁to ▁attempt ▁to ▁equal ize ▁the ▁p ony ▁tr uck ▁with ▁the ▁drivers ▁in ▁ 1 8 5 7 ; ▁he ▁received ▁a ▁pat ent ▁on ▁the ▁concept ▁in ▁ 1 8 6 6 . ▁ ▁La ird ' s ▁design ▁was ▁complex ▁and ▁did ▁not ▁find ▁favor , ▁although