Lift steering systems and methods

Abstract

A lift device includes a base, a retractable lift mechanism having a first end coupled to the base, a platform coupled to and supported by a second end of the retractable lift mechanism, and a steering system. The base includes a first wheel and a second wheel laterally spaced from the first wheel, and a third wheel and a fourth wheel laterally spaced from the third wheel. The third wheel and the fourth wheel are both pivotally fixed. The steering system includes a first electric actuator coupled to the first wheel and configured to independently control a steering direction of the first wheel, and a second electric actuator coupled to the second wheel and configured to independently control a steering direction of the second wheel.

What is claimed is: 
     
         1 . A lift device, comprising:
 a base including:
 a first wheel and a second wheel laterally spaced from the first wheel; and 
 a third wheel and a fourth wheel laterally spaced from the third wheel, wherein the third wheel and the fourth wheel are both in a fixed steering orientation; 
   a retractable lift mechanism having a first end coupled to the base;   a platform coupled to and supported by a second end of the retractable lift mechanism; and   a steering system including:
 a first electric actuator coupled to the first wheel and configured to independently control a steering direction of the first wheel; and 
 a second electric actuator coupled to the second wheel and configured to independently control a steering direction of the second wheel. 
   
     
     
         2 . The lift device of  claim 1 , wherein the first electric actuator is coupled to a first end of a first tie rod and a second end of the first tie rod is coupled to a first flange, and wherein the first flange is coupled to the first wheel. 
     
     
         3 . The lift device of  claim 2 , wherein the second electric actuator is coupled to a first end of a second tie rod and a second end of the second tie rod is coupled to a second flange, and wherein the second flange is coupled to the second wheel. 
     
     
         4 . The lift device of  claim 3 , wherein the first tie rod and the second tie rod both define an arcuate shape. 
     
     
         5 . The lift device of  claim 1 , wherein the retractable lift mechanism includes a linear actuator configured to transition the retractable lift mechanism between a stowed position and a deployed position. 
     
     
         6 . The lift device of  claim 5 , wherein the retractable lift mechanism is a scissor lift mechanism. 
     
     
         7 . The lift device of  claim 1 , wherein a battery is mounted to the base and supplies electrical power to the first electric actuator and the second electric actuator. 
     
     
         8 . A lift device, comprising:
 a base including two front wheels and two rear wheels, the two rear wheels being in a fixed orientation relative to the base, and the two front wheels being spaced from the two rear wheels in a longitudinal direction;   a retractable lift mechanism having a first end coupled to the base;   a platform coupled to and supported by a second end of the retractable lift mechanism; and   a steering system including:
 a first electric actuator coupled to a first front wheel of the two front wheels and configured to independently control a steering direction of the first front wheel; and 
 a second electric actuator coupled to a second front wheel of the two front wheels and configured to independently control a steering direction of the second front wheel, wherein the first electric actuator and the second electric actuator extend generally along the longitudinal direction. 
   
     
     
         9 . The lift device of  claim 8 , wherein the first electric actuator is coupled to a first end of a first tie rod and a second end of the first tie rod is coupled to a first flange, and wherein the first flange is coupled to the first front wheel. 
     
     
         10 . The lift device of  claim 9 , wherein the second electric actuator is coupled to a first end of a second tie rod and a second end of the second tie rod is coupled to a second flange, and wherein the second flange is coupled to the second front wheel. 
     
     
         11 . The lift device of  claim 10 , wherein the first tie rod and the second tie rod both define an arcuate shape. 
     
     
         12 . The lift device of  claim 8 , wherein the retractable lift mechanism includes a linear actuator configured to transition the retractable lift mechanism between a stowed position and a deployed position. 
     
     
         13 . The lift device of  claim 8 , wherein the retractable lift mechanism is a scissor lift mechanism. 
     
     
         14 . The lift device of  claim 8 , wherein a battery is mounted to the base and supplies electrical power to the first electric actuator and the second electric actuator. 
     
     
         15 . A lift device, comprising:
 a base including two steerable wheels and two fixed wheels held in a forward-aligned orientation;   a retractable lift mechanism having a first end coupled to the base;   a platform coupled to and supported by a second end of the retractable lift mechanism; and   a steering system including:
 a first independent steering subsystem including a first linear actuator coupled to a first wheel of the two steerable wheels and configured to control a steering direction of the first wheel; and 
 a second independent steering subsystem including a second linear actuator coupled to a second wheel of the two steerable wheels and configured to control a steering direction of the second wheel. 
   
     
     
         16 . The lift device of  claim 15 , wherein the first linear actuator is coupled to a first end of a first tie rod and a second end of the first tie rod is coupled to a first flange, and wherein the first flange is coupled to the first wheel. 
     
     
         17 . The lift device of  claim 16 , wherein the second linear actuator is coupled to a first end of a second tie rod and a second end of the second tie rod is coupled to a second flange, and wherein the second flange is coupled to the second wheel. 
     
     
         18 . The lift device of  claim 15 , wherein the retractable lift mechanism includes a third linear actuator configured to transition the retractable lift mechanism between a stowed position and a deployed position. 
     
     
         19 . The lift device of  claim 15 , wherein the retractable lift mechanism is a scissor lift mechanism. 
     
     
         20 . The lift device of  claim 15 , wherein a battery is mounted to the base and supplies electrical power to the first linear actuator and the second linear actuator.