Advanceable and retractable plug-on unit assembly for a motor control center

An assembly supporting a switch unit having a plurality of plug-on jaws within a slidably removable unit enclosure of an electrical control center having a plurality of bus bars extending along the rear portion of the control center, said assembly comprising:

• a housing secured to said unit enclosure;
• said housing having a side leg and a rear leg, said rear leg including a pair of tabs;
• a mounting pan having opposite side flanges, an upper portion and a lower portion, said upper portion including portions defining a cut-out section, said switch unit mounted to said mounting pan with said plug-on jaws extending through said cut-out section, said side flanges respectively pivotally connected to said tabs, said mounting pan movable between a first position wherein said plug-on jaws are connected to said bus bars and a second position wherein said plug-on jaws are spaced from said bus bars;
• a generally U-shaped handle having opposite side legs connected to the upper portion of said mounting pan;
• a handle operator adjacent a first side of said side leg;
• a cam operator adjacent an opposite side of said side leg, said handle operator and cam operator pivotally interconnected;
• drive means for mechanically connecting said cam operator to operate said switch unit between an "ON" condition and an "OFF" condition,
• said handle operator and cam operator movable between respective first positions corresponding to said "OFF" condition and respective second positions corresponding to said "ON" condition;
• a shelf positioned above said unit enclosure, said shelf having an opening for receiving a stop tab;
• a unit interlock having a stop tab, a notch ear and a lever, said unit interlock mounted to said side leg for reciprocal movement between a first position in which said stop tab extends into said space for preventing relative movement between said unit enclosure and said shelf and a second position in which said stop tab does not extend into said space for permitting relative movement between said unit enclosure and said shelf;
• and
• a spring biasing said unit interlock to said first position,
• said cam operator having portions defining a notch channel which is aligned with said notch ear in response to said handle operator assuming its first position, said cam operator preventing movement of said unit interlock from said first position to said second position unless said handle operator is in said first position.