We claim the ornamental design for a bed for a dump trailer, as shown and described.
FIG. 1 is a perspective view of a bed for a dump trailer according to an embodiment of the invention with the trailer depicted in phantom.
FIG. 2 is a top plan form view of a bed for a dump trailer according to an embodiment of the invention.
FIG. 3 is a bottom plan form view of a bed for a dump trailer according to an embodiment of the invention.
FIG. 4 is a first side elevational view of a bed for a dump trailer according to an embodiment of the invention.
FIG. 5 is a second side elevational view of a bed for a dump trailer according to an embodiment of the invention.
FIG. 6 is a front end elevational view of a bed for a dump trailer according to an embodiment of the invention; and,
FIG. 7 is a rear end elevational view of a bed for a dump trailer according to an embodiment of the invention.
The broken line showing of the wheeled base of the trailer is included for the purpose of illustrating environment and forms no part of the claimed design.