Transport vehicle

A transport vehicle comprising:

• an automotive vehicle body;
• a vessel which tilts up and down provided on said vehicle body and on which objects to be transported are loaded;
• a hoist cylinder which is provided between said vessel and said vehicle body and tilts said vessel upward or downward with expansion or contraction of a rod;
• a hydraulic source comprising a hydraulic oil tank for reserving hydraulic oil therein and a hydraulic pump for delivering hydraulic oil under pressure;
• a control valve device for controlling supply and discharge of the hydraulic oil to and from said hoist cylinder;
• a pump line for establishing connection between said hydraulic pump and said control valve device;
• actuator lines for establishing connection between said control valve device and said hoist cylinder;
• and
• a return line for returning the hydraulic oil which is delivered from said hydraulic pump and passes through said control valve device back to said hydraulic oil tank, wherein
• said control valve device has a plurality of switching positions composed of a raising position of expanding said hoist cylinder with supply and discharge of the hydraulic oil to under pressure to tilt said vessel upward, a lowering position of contracting said hoist cylinder with supply and discharge of the hydraulic oil to lower down said vessel, a floating position of contracting said hoist cylinder to allow for self-weight fall of said vessel, and a neutral position of stopping movement of said hoist cylinder by stopping supply and discharge of the hydraulic oil to hold said vessel,
• a flow rate limiting section is provided in said floating position of said control valve device to limit a flow rate of the hydraulic oil flowing in said return line from said hydraulic pump, wherein
• when said control valve device is in said floating position, an upstream side of said flow rate limiting section is connected to said pump line, a downstream side of said flow rate limiting section is connected to said return line, and a rod-side actuator line communicated with rod-side oil chambers in said hoist cylinder among said actuator lines is connected to said pump line,
• a pressure generated in said pump line upstream of said flow rate limiting section acts on said rod-said oil chambers through said rod-said actuator line, and
• a thrust force which restricts floating-up of said vessel that is generated in said hoist cylinder at the time said vehicle body travels.