Vibrator for dumping vehicle

A method for dumping particulate material from an hydraulically actuated dumping body of a semi trailer dump vehicle having an expansible hydraulic cylinder means for raising the body toward a dumping angle;

• an hydraulic pump for delivering hydraulic fluid under pressure to said cylinder means and a vibrating means affixed to said body and adapted to produce vibrations in said body to facilitate the dumping of the material comprising the steps of:
• determining the natural dumping angle of the material being dumped;
• determining the pressure of said hydraulic fluid in said cylinder means at a point where said cylinder means has raised said body to the natural dumping angle of the material being dumped;
• delivering hydraulic fluid under pressure to said cylinder means to raise said dumping body toward the natural dumping angle for said material;
• diverting a portion of said hydraulic fluid to a hydraulic control circuit for said vibrator;
• sensing the pressure of said hydraulic fluid in said circuit;
• applying said sensed pressure to open a valve means in said hydraulic circuit at a predetermined pressure level corresponding to a dump body angle between said natural dumping angle and a body angle such that actuating the vibrator will not significantly compact the material being dumped;
• directing hydraulic fluid through said opened valve means to an hydraulic motor adapted to drive said vibrator when said valve opens;
• and
• closing said valve means when the pressure of said hydraulic fluid in said cylinder means drops below said predetermined pressure level to stop said motor and vibrator.