Hydraulic actuator control apparatus for a stretcher

Abstract

A patient support apparatus includes a frame, a plurality of casters coupled to the frame and supporting the frame above a floor, a wheel, a push handle that is coupled to the frame and that is gripable to maneuver the patient support apparatus along the floor, and a brake handle coupled to the push handle and movable to move a brake to impede rotation of the wheel.

1 . A patient support apparatus comprising
 a lower frame,   an upper frame, and   an elevation adjustment mechanism supporting the upper frame relative to the lower frame, the elevation adjustment mechanism including
 a first jack having an reciprocating input movable between an extended and contracted position, 
 a first spring urging the reciprocating input of the first jack to an extended position, 
 a manually actuable user input, and 
 linkage coupled to the manually actuable user input, the linkage transferring motion from the manually actuable user input to the reciprocating input of the first jack, the linkage including a first contact member that engages the reciprocating input of the first jack. 
   
     
     
         2 . The patient support apparatus of  claim 1 , wherein the first jack includes a body and retainer coupled to the reciprocating input and the first spring is positioned between the body of the first jack and the retainer. 
     
     
         3 . The patient support apparatus of  claim 2 , wherein the first contact member engages the reciprocating input of the first jack such that motion from the manually actuable user input is transferred to the reciprocating input without the use of a fastener to secure the first contact member with the reciprocating input. 
     
     
         4 . The patient support apparatus of  claim 1 , wherein the first contact member engages the reciprocating input of the first jack such that motion from the manually actuable user input is transferred to the reciprocating input without the use of a fastener to secure the first contact member with the reciprocating input. 
     
     
         5 . The patient support apparatus of  claim 4 , wherein the patient support apparatus further comprises a second jack having a reciprocating input movable between an extended and contracted position and a second spring urging the reciprocating input of the second jack to an extended position. 
     
     
         6 . The patient support apparatus of  claim 5 , wherein the linkage includes a second contact member that engages the reciprocating input of the second jack. 
     
     
         7 . The patient support apparatus of  claim 6 , wherein the second contact member engages the reciprocating input of the second jack such that motion from the manually actuable user input is transferred to the reciprocating input without the use of a fastener to secure the second contact member with the reciprocating input of the second jack. 
     
     
         8 . The patient support apparatus of  claim 7 , wherein the manually actuable user input is a pedal that is biased to a raised position and application of a force to the pedal causes the pedal to move downwardly and the force is transferred through the linkage to the reciprocating inputs of the first and second jack. 
     
     
         9 . The patient support apparatus of  claim 5 , wherein the first and second jacks each comprise a hydraulic cylinder and a pump. 
     
     
         10 . A patient support apparatus comprising
 first and second jacks, each of the jacks including a body and a reciprocating input movable relative to the body, each reciprocating input including a retainer formed on the reciprocating input, and a spring positioned between the body and the retainer, the spring urging the reciprocating input to an extended position, and   an input mechanism acting on the reciprocating inputs of each of the first and second jacks, the input mechanism movable independently of the reciprocating inputs of the first and second jack, the springs of the first and second jacks urging the reciprocating inputs into contact with the input mechanism.   
     
     
         11 . The patient support apparatus of  claim 10 , wherein the input mechanism comprises a pedal and a linkage coupled to the pedal for movement therewith. 
     
     
         12 . The patient support apparatus of  claim 11 , wherein the linkage includes a first contact member engageable with the reciprocating input of the first jack and a second contact member engageable with the reciprocating input of the second jack. 
     
     
         13 . The patient support apparatus of  claim 12 , wherein the first and second contact members are not secured to the reciprocating inputs of the first and second jacks. 
     
     
         14 . The patient support apparatus of  claim 13 , wherein the patient support apparatus further comprises an upper frame and a lower frame, the upper frame movable vertically relative to the lower frame, wherein the upper frame is supported on the first and second jacks. 
     
     
         15 . The patient support apparatus of  claim 14 , wherein the patient support apparatus further comprises a plurality of casters having wheels supporting the lower frame, at least one of the casters including brake. 
     
     
         16 . The patient support apparatus of  claim 15 , wherein the patient support apparatus includes a brake handle movable between first and second positions and means for applying a variable force between the brake and the wheel that varies the brake handle moves from the first to second position. 
     
     
         17 . The patient support apparatus of  claim 14 , wherein the patient support apparatus further comprises a plurality of casters supporting the lower frame for movement over the surface of a floor and an auxiliary wheel supported from the lower frame, the auxiliary wheel including a brake and movable between a first position engaging a surface of the floor and a second position disengaged from the floor. 
     
     
         18 . The patient support apparatus of  claim 15 , wherein the patient support apparatus includes a brake handle movable between first and second positions and means for applying a variable force between the brake and the auxiliary wheel that varies in proportion to the magnitude of movement as the brake handle moves from the first to the second position. 
     
     
         19 . A patient support apparatus comprising
 a lower frame,   a plurality of casters supporting the lower frame for movement over the surface of a floor,   an upper frame movable relative to the lower frame,   a first hydraulic cylinder,   a first pump including a reciprocating pump rod, the first pump operable to extend and retract the first hydraulic cylinder,   a first spring urging the reciprocating pump rod of the first pump to an extended position,   a second hydraulic cylinder,   a second pump including a reciprocating pump rod, the second pump operable to extend and retract the second hydraulic cylinder,   a second spring urging the reciprocating pump rod of the second pump to an extended position,   a linkage engaged with the reciprocating pump rods of the first and second pumps such that movement of the linkage in a first direction acts simultaneously on both of the reciprocating inputs to cause the first and second hydraulic cylinders to extend, the linkage movable independently of the reciprocating pump rods of the first and second pumps, and   a pedal secured to the linkage for movement therewith, such that a force applied to the pedal causes to the linkage to move in the first direction to transfer the force from the pedal to the first pump rod and second pump rod.   
     
     
         20 . The patient support apparatus of  claim 19 , wherein the patient support apparatus includes at least one wheel in contact with a floor surface supporting the patient support apparatus and a brake handle movable between first and second positions and means for applying a variable braking force that that varies in proportion to the magnitude of movement as the brake handle moves from the first to the second position.