Operation breaking apparatus for construction equipment

An operation prohibiting apparatus for construction equipment in which an operating box is located adjacent an operator's seat within an operator cab and an operating lever of the operating box operates a cylinder of a working member, and a cutoff bar is situated in an entryway to the operator's seat such that it can be positioned in a first position in which it protrudes across the entryway and in a second, withdrawn position, the cutoff bar being linked with a locking mechanism of a hydraulic driving system for driving the cylinder, the locking mechanism being unlocked when the cutoff bar is positioned in the first, protruding position, the operation prohibiting apparatus comprising:

• a cutoff bar means for blocking the entryway to the operator's seat;
• a base plate;
• operating knob means for positioning the cutoff bar means;
• a first lever means for supporting the operating knob means which is attached thereto, the first lever means being pivotally supported by the base plate;
• a second lever means for supporting the cutoff bar means which is fitted thereunto, the second lever means being pivotally support by the base plate;
• a connecting means for transmitting a rotating force from the first lever means to the second lever means;
• a displacement enlarging means for providing that a distance between a first supporting means for supporting the first lever means and the connecting means exceeds a distance between a second supporting means for supporting the second lever means and the connecting section;
• and
• a switch means for unlocking the locking mechanism when the cutoff bar means is positioned in the first, protruding position.

An operation prohibition device for precluding operation of operating elements of a piece of construction equipment, the prohibition device mounted at an entrance to an operator cab and comprising:

• a base plate;
• an L-shaped first lever pivotally mounted to the base plate;
• a second lever pivotally mounted to the base plate;
• an engagement mechanism movably linking one end of the first lever and one end of the second lever;
• a handle at the other end of the first lever;
• and
• a rod extending from an opposite end of the second lever, wherein the engagement mechanism is further from the pivotal mount of the first lever than it is from the pivotal mount of the second lever.