dump truck

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A heavy-duty truck having a bed that tilts backward to dump loose material.

from the GNU version of the Collaborative International Dictionary of English.

• noun a truck, usually with an open top, the carrying bopdy of which can be tilted so as to emptied its contents without handling.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun a heavy truck, for carrying loose, bulk cargo, having a hinged bed that allows the contents to be unloaded onto the ground

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun truck whose contents can be emptied without handling; the front end of the platform can be pneumatically raised so that the load is discharged by gravity