Title: Wireless Communications: Principles And Practice (2nd Edition)
A surface maintenance machine that includes a powered vehicle having a rotary tool in a tool enclosure to direct debris from the surface through an enclosure outlet, a debris hopper having a debris inlet locatable adjacent the enclosure outlet, and a discharge opening remote from the hopper inlet, a hingedly mounted door for closing the discharge opening, lift arms mounted on the vehicle for mounting the hopper for pivotable movement relative thereto, supporting the hopper in a debris collecting position, and selectively elevating the hopper from a street level position to a high dump position, control arms and piston cylinder combinations to control the pivoting of the hopper as it is moved between its street level and high dump positions, the piston cylinder combinations being operated from a retracted condition to an extended condition for pivoting the hopper to a dumping position in either the street level position or the high dump position, latches mounted on the hopper that are operated through the hopper pivoting to a dumping position to release their latching engagement with the door, and a door holder assembly which upon the door swinging open as the hopper is moved to a dumping position is resiliently operated to maintain a sufficient minimum spacing of the door from the discharge opening and that upon the piston cylinder combinations being substantially fully retracted is operated to release the door and permit the door swinging under gravity to a closed position with sufficient force to insure the door is latched in a closed position, the door holder assembly being operated to permit the door swinging closed by a cam surface on the adjacent control arm.