Patent ID: 8172255

Claim:
A height-adjustable cart apparatus comprising: a base comprising at least a plurality of wheel assemblies rotatably attached to an underside surface; a tray comprising an upper surface movably attached to a topside surface of said base; a pair of scissor lift assemblies connected between outside edge regions of opposing sides of said base and said tray for vertically moving said tray relative to said base, each further comprising: an upper support member having rollers rotatably attached to an upper end and slidably coupled within an upper track disposed on an underside surface of said tray and a lower end; a lower support member having an upper end pivotably fastened to said upper support member lower end and rollers rotatably attached to a lower end and slidably coupled within a lower track disposed on said base topside surface; an upper central member having an upper end pivotably attached to said tray underside surface and a lower end; and, a lower central member having an upper end pivotably fastened to said upper central member lower end and a lower end pivotably attached to said base topside surface; a pair of hydraulic actuators each having an end affixed to said base topside surface and an opposing end pivotably attached to one of said pair of scissor lift assemblies; a hydraulic pump for producing hydraulic pressure comprising a vent cap located along an upper surface for allowing a user to fill said hydraulic pump with hydraulic fluid and to vent said hydraulic pump; a pair of hydraulic lines connected between and in fluid communication with said hydraulic pump and each of said pair of hydraulic actuators; and, a pair of foot pedals affixed to said base topside surface and in fluid communication between said hydraulic pump and said pair of hydraulic actuators such that said hydraulic actuators extend and retract in response to actuation of said foot pedals; wherein said upper support member and said upper central member are pivotably fastened at a longitudinally intermediate location and said lower support member and said lower central member are pivotably fastened at a longitudinally intermediate location; and, wherein said hydraulic actuator opposing end is pivotably attached to said lower central member, such that extension of said hydraulic actuator rotates said lower central member outwardly thus raising said tray relative to said base and retraction of said hydraulic actuator rotates said lower central member inwardly thus lowering said tray relative to said base.