Combination lock with override key

A locking device, comprising:

• a housing;
• knob assembly disposed at least partially in the housing, the knob assembly selectively rotatable relative to the housing about a knob axis between a latched position and an unlatched position;
• a lock bar operatively coupled to the knob assembly and disposed within the housing, the lock bar shiftable substantially parallel to the knob axis between an up position and a down position;
• a rotatable dial disposed on an axle, the axle being substantially perpendicular to the knob axis, the rotatable dial disposed at least partially within the housing and extending through an opening in the housing and being accessible from outside the housing, the rotatable dial including multiple indicia disposed thereon, at least one of the indicia being selectively visible from outside the housing;
• a toggle plate rotatably disposed on the axle and engagable with the rotatable dial, the toggle plate having an outer circumference, the outer circumference having a circular portion and a flat portion;
• a lock plate having a bearing surface upon which the outer circumference of the toggle plate rotates, the lock plate shiftable between an unlocked position when the flat portion bears on the bearing surface and a locked position when the circular portion bears on the bearing surface, the lock plate further including a blocking face;
• wherein when the lock plate is in the locked position, the knob assembly is in the latched position, and the lock bar is in the down position, the blocking face of the lock plate blocks the lock bar and prevents rotation of the knob assembly, wherein when the lock plate is in the unlocked position and the lock bar is in the down position, the blocking face does not block the lock bar and allows rotation of the knob assembly;
• and
• the knob assembly further including a mechanical pin tumbler lock, a port, and an actuator, the port configured to receive a mechanical key, the actuator including a ramp and being operatively coupled to the lock bar, wherein upon receipt of a predetermined credential from the mechanical key, the mechanical pin tumbler lock is configured to permit rotation of the ramp, and the ramp is configured to shift the lock bar to the up position;
• wherein when the lock plate is in the locked position and the lock bar is in the up position, the lock plate does not block the lock bar and permits rotation of the knob assembly.