Fire escape – ladder – or scaffold – Horizontal traversing - actuation – control – or response – Occupant actuation or control
Reexamination Certificate
2000-03-06
2001-10-23
Lev, Bruce A. (Department: 3634)
Fire escape, ladder, or scaffold
Horizontal traversing - actuation, control, or response
Occupant actuation or control
C182S017000, C182S127000, C280S471000
Reexamination Certificate
active
06305496
ABSTRACT:
BACKGROUND OF THE INFORMATION
1. Field of the Invention
The present invention relates to a safety mobile ladder stand and more particularly, to a large ladder stand which can be used in small spaces where mobility of a larger ladder stand is restricted.
2. Description of the Prior Art
Mobile or safety ladder stands are generally known in the industry and are used by workers and persons who need to reach products or materials stored on shelves in stores and warehouses. Such safety ladder stands also generally incorporate a rolling/locking mechanism so that the ladder stand can be moved easily to different locations in the warehouse or building when such a mechanism is actuated. With such a construction, the rolling/locking mechanism is deactivated when the mobile ladder stand is to be used such as when a person climbs on it to reach overhead shelves or spaces. The deactivation of the rolling/locking mechanism stabilizes the ladder stand in a fixed position thereby allowing for a safer and steadier use of the stand.
Some large mobile ladder stands with rolling/locking mechanisms are difficult or awkward to maneuver in small spaces such as in the aisleways of stores or warehouses. This is due to the fact that the length of the base must be increased to accommodate a taller ladder stand. Since such ladder stands are generally supported by wheel sets at all four corners of the base, a longer base makes turning of the stand difficult.
The problem stated previously was addressed in part in U.S. Pat. No. 5,941,341 entitled “Mobile Ladder Stand” which issued on Aug. 24, 1999. This patent discloses a safety ladder stand having a generally rectangular base having a front and rear and a center beam, with a plurality of stair treads extending upwards from the front of the base and means for supporting the stair treads secured to the base. Front wheels are mounted at the front of the base and beneath the top of the stair treads, with center wheels mounted on the center beam of the base and rear wheels mounted at the rear of the base. A set of feet are mounted at the front of the base. The ladder stand has an activated position and a deactivated position. In the activated position, the front and center wheel sets are in contact with the ground to enable the ladder stand to roll and the rear wheels and front support feet are out of contact with the ground. In the deactivated position of the ladder stand, the front and center wheel sets are not in contact with the ground and the rear wheels and the front wheels are in contact with the ground to prevent the ladder stand from being rolled. It includes means for moving the ladder stand from the deactivated position to the activated position.
The assignee of the present invention has manufactured for many years relatively small ladder stands with five to nine steps which are provided with a base having wheel supports at the front and rear of the stand. Each wheel support is provided with a safe-lock mechanism and a pair of swivable casters or wheels rotatable throughout 360°. The use of the safe-lock mechanism and swivable caster wheels at the rear end of the base allows the ladder stand to be more readily maneuverable in confined spaces.
The assignee of the present invention has also manufactured for many years relatively large ladder stands with six to nineteen steps, as an example, having a base with a safety lock mechanism and a pair of swivable caster wheels at the front and a pair of rigid caster wheels at the rear of the base. It is difficult with such a construction to maneuver the large ladder stands in confined spaces.
While a great variety of mobile ladder stands have been heretofore been proposed, nevertheless there remains a need for improved relatively large mobile ladder stands which are simple in construction, are relatively inexpensive to manufacturer and are convenient to use.
SUMMARY OF THE INVENTION
It is a feature of the present invention to provide an improved relatively large ladder stand which is stable when the ladder stand is in use and is mobile when it is required to move the ladder stand in confined spaces or areas.
It is a further feature of the present invention to provide an improved relatively large mobile ladder stand which employs a pair of swivable caster wheels at the front of the ladder and a pair of swivable caster wheels at the rear of the ladder which are used in cooperation with a pair of closely located non-swivable caster wheels, thereby providing a structure which has three modes of operation, one mode for climbing, a second mode which permits the ladder to be pushed in a straight line with wide turns and a third mode of operation which permits the ladder stand to be first pushed laterally and to provide sharp turns.
In the broader aspects of this invention, there is provided a ladder stand comprising a unitary base having a front end and a rear end, with a plurality of stair treads extending upwardly from the base and supported thereon. A front wheel support is mounted on and located approximate to the front end of the base and a retractable first pair of swivable caster wheels is mounted on the front wheel support. The ladder stand further has a rear wheel support mounted on and located inwardly from the rear end of the base, with a retractable second pair of swivable caster wheels mounted on the rear wheel support. A third pair of non-swivable rigid caster wheels are mounted at the rear end of the base outwardly from the retractable second pair of caster wheels. A plurality of foot pads are mounted on the front end of the base forward of the retractable first pair of swivable caster wheels.
A pair of laterally spaced apart independently operated foot pedals are mounted on the base at the front end thereof. Front and rear linkages are respectively carried by the front and rear wheel supports. A trip bar is located at the front end of the bottom stair tread. A trip tube is connected on one end to the front linkage and on the other end to the rear linkage. A reset tube is connected on one end to the front linkage and on the other end to the rear linkage. With such a construction, the trip bar of the present invention, when actuated, causes the trip tube to raise the front and rear wheel supports and the corresponding first and second pairs of swivable caster wheels from the ground thereby permitting the base to drop onto the foot pads at the front end and onto the rigid caster wheels at the rear end of the base thereby placing the ladder stand in a first mode of operation intended for a person climbing the ladder.
One of the pedals of the present invention, when actuated, causes the reset tube to lower the front wheel support and to bring the first pair of swivable caster wheels into contact with the ground thereby raising the front end of the base and the foot pads off the ground while maintaining the rigid caster wheels on the ground thereby placing the ladder stand in a second mode of operation intended for the ladder stand to be pushed to a new location either forward, backward or diagonally with straight tracking of the wheels.
The other of the pedals of the present invention, when actuated, lowers the rear wheel support and brings the second pair of swivable caster wheels into contact with the ground and raises the third pair of rigid caster wheels off the ground while maintaining the front caster wheels in contact with the ground thereby providing a third mode of operation intended for the ladder stand to be pushed or turned in confined spaces, with the four swivel caster wheels allowing for forward, backward, diagonal and lateral movement.
Other objects and distinctive features of the present invention which have not been referred to previously will appear from the following specification and claims and from the accompanying drawings wherein is shown a preferred embodiment of the present invention as described in the specification. The showing so made is not intended to be either exhaustive or as limiting the scope of the subject invention. The purpose here is to illustrate the invention so tha
Dykema Gossett PLLC
Lev Bruce A.
Material Control, Inc.
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