Fire escape – ladder – or scaffold – Ladder – Supporting surface compensating means
Reexamination Certificate
2002-10-23
2004-06-08
Chin-Shue, Alvin (Department: 3634)
Fire escape, ladder, or scaffold
Ladder
Supporting surface compensating means
C182S202000, C182S203000, C182S204000, C182S205000
Reexamination Certificate
active
06745870
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates generally to the field of ladder attachments. More specifically, the present invention is related to removable ladder attachments; to provide support for a ladder.
2. Discussion of Prior Art
Ladders are used extensively in a number of different situations such as construction, painting, building maintenance, etc. At times, the surface a ladder needs to be placed on is uneven or inclined. Yet, placement of a ladder on an uneven surface renders the ladder unstable, which increases the possibility of the ladder toppling over, resulting in injury to workers. Therefore, a number of devices have been developed to adjust the level of the ladder legs so that the ladder is firmly supported, even when placed on uneven surfaces.
U.S. Pat. No. 3,447,631 (Smith) describes a ladder level having an adapter unit and a length-adjusting unit. The adapter unit is capped over forward edge portion,of the ladder leg, while the length adjusting unit is capped over the rear edge portion of the ladder leg. The web of the adjusting unit has teeth on the exterior portion, which cooperate with a latch dog connected to the adjusting unit to provide for sliding and locking the length adjustment member.
U.S. Pat. No. 4,412,599 (McCrudden et al.) describes a ladder leg extender in which an extension piece is loosely fitted within a rectangular opening defined by the ladder leg and flanges of an attachment piece. Tightening of a handle bolt biases the ladder leg towards the flanges to secure the extension piece therein.
U.S. Pat. No. 4,607,726 (Davis et al.) describes a ladder leveler that includes an outer sleeve member and an extension member. At the lower end of the extension member is foot that provides a gripping action to prevent slipping. Two L-shaped brackets are mounted to the sleeve member to receive and support a ladder leg. Opposing lockscrews advance through threaded bores or locknuts in the L-shaped brackets to engage the ladder leg on opposing sides so that the ladder leveler is secured to the ladder.
U.S. Pat. No. 4,792,017 (Grove) describes an adjustable support for ladders that includes load-supporting units that are axially-aligned with bearing members on ladder. The bearing members are connected within channel-like legs of the ladder. The bearing members have axially-aligned holes to receive elongated, externally threaded members, which can be secured in different vertical positions to provide adjustability.
U.S. Pat. No. 5,551,529 (Molitor) describes a ladder stabilizer comprising main frames, legs configured to slidingly engage with the main frames, and feet attached to:legs. Each main frame has a L-shaped pin that extends through a horizontally extending hole in the main frame and another hole in leg to lock the leg to the main frame at a desired height.
U.S. Pat. No. 5,678,656 (Lanzafame) describes a ladder stabilizing and leveling device with an outer housing fixed to a ladder rail and an inner housing, movable within the outer housing. The inner housing is locked in place by a lock block attached thereto that rotates so that its lock tip engages lock nubs attached to the outer housing. The lock tip engages the lock nubs such that a greater force is applied between the locking tip and locking nub when greater downward force is applied to the ladder rail so as to ensure the inner housing does not move.
There is still a desire, however, for an adjustable ladder support that is easily and removably attached without the need for any tools, and that employs an attachment arrangement that acts to tighten the grip on the ladder leg during use, thereby insuring against slippage.
SUMMARY OF THE INVENTION
Generally, a ladder attachment that can be removably secured to a ladder leg is provided. The ladder attachment comprises a base unit and a clamping member. The base unit has a channel formed by a web and corresponding sidewalls substantially perpendicular to the web. The sidewalls are sufficiently spaced apart to accommodate the ladder leg and the interior surface of each sidewall has sloping splices formed thereon. The clamping member is generally rectangular and has sloping splices formed on its first and second side surfaces. The sloping splices on the clamping member are dimensioned and arranged so as to slidably engage with the sloping splices on the sidewalls. The clamping member also has a bore to adjustably and securely retain a support rod therein. The sloping splices on the clamping member and the sloping splices on the sidewalls are arranged such that, during use, the clamping member is biased towards the ladder leg.
REFERENCES:
patent: 6126122 (2000-10-01), Ismert
Chin-Shue Alvin
Lacasse Randy W.
Lacasse & Associates LLC
Schade Jaclyn A.
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