Fire escape – ladder – or scaffold – Ladder – Supporting surface compensating means
Reexamination Certificate
2001-10-17
2003-08-12
Stodola, Daniel P. (Department: 3634)
Fire escape, ladder, or scaffold
Ladder
Supporting surface compensating means
C182S209000
Reexamination Certificate
active
06604607
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
The invention is an improvement to an A-frame ladder, adding to an A-frame ladder independent extension means allowing the ladder to be placed on uneven surfaces, stairs or level surfaces in a stable and level configuration.
2. Description of Prior Art
The following United States patents are identified and disclosed herein. Several devices are disclosed relating to ladders having extending characteristics. In U.S. Pat. No. 4,299,306 to C Hawkins, and U.S. Pat. No. 5,429,207 to Frank, a secure catch is disclosed for extension ladders. In U.S. Pat. No. 5,273,133 to Thocher, an extension for each leg of a ladder is disclosed allowing the ladder to be placed on uneven surfaces, the means of extension using a locking gear and a drive rod. U.S. Pat. No. 5,542,497 to Macyszyn discloses a similar extension mechanism as in Thocher, but a cam self-locking mechanism is used to lock the legs into position. A similar A-frame extension ladder is disclosed in U.S. Pat. No. 4,926,964 to Herrin, but it does not include a pivoting spring loaded locking catch for a plurality of locking bars on the sliding ladder segments and the A-frame ladder segments.
More recently, in U.S. Pat. No. 6,073,726 to McCrystal, an adjustable step ladder is disclosed having four independent extendable legs locking with pins riding in a slot of the adjustable legs. In U.S. Pat. No. 6,237,718 to Schwarzel, an extendable legs means for a leveling a ladder is disclosed, the means including a cable and pulley style leveling system and a built in level indicator. An adjustable ladder having a screw type leg lock is disclosed in U.S. Pat. No. 6,234,273 to Moore.
SUMMARY OF THE INVENTION
The invention is an improvement to an A-frame ladder, the improvement providing additional sliding ladder segments to the A-frame ladder allowing these sliding ladder segments to independently extend the A-frame ladder segments allowing the ladder to be placed on stairs, uneven surfaces or level ground, the sliding ladder segments and the A-frame ladder segments to be slidably engaged and locked by pivoting spring-loaded locking catches engaging a plurality of locking bars on the inside portion of the sliding ladder segments and the A-frame ladder segments, away from the area of travel by the person using the ladder.
REFERENCES:
patent: 2223911 (1940-12-01), Garnette
patent: 3374860 (1968-03-01), Stewart
patent: 5000289 (1991-03-01), Sanchez, III
patent: 5027923 (1991-07-01), Derome
patent: 5908085 (1999-06-01), Lovelady
Homburg Randal D.
Stodola Daniel P.
Thompson Hugh B.
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