US2398812A - Ladder assembly - Google Patents

Description

Apri1,z3, 1946.

w. B. sTElL.

LADDER ASSEMBLY Filed June '7, 1945 v INVENToR. WALLACE ETEN.

G\BY

' K ATTENEY Patented Apr. 23, 1946 :.'fi

LADDER ASSEMBLY Wallace B. Steil, San Francisco, Calif.

Application June 7, 1945, Serial No. 598,191

(Granted under .the act of March 3, 1883, as

amended April 30, 1928; .370 O. G. 757)y m 2 Claims.

`This invention relates to a ladder assembly and more `particularly to a portable ladder assembly of the type adapted to be used in stockrooms Aand which may be moved about -freely and yetsecured in a fixed location when an individual stands on the ladder.

It stockroom work, it is desirable to employ a ladder -of the step-ladder type which maybe moved about as desired to furnish access toregions normally out of reach of an individual. Heretofore, such ladders have been mounted on castors or Wheels Yto enable them to be moved easily, but the castors or wheels have had a tendency to move or slip when an individual stands onfthe ladder, with the result that the individual may sustain a serious injury from a fall. It is the principal object of the present invention to provide a ladder assembly suitable for stockroom work and which may be moved about freely on castors or wheels when unoccupied, but which is vautomatically secured in a Xed location when an individual stands thereon.

It is a further object of the invention to provide for carrying out the foregoing object in a facile, economical, and efficient manner.

In accomplishing these and other objects of the present invention, I have provided improved details of structure, the preferred form of which is illustrated in the accompanying drawing, wherein:

Fig. l is a perspective view of a ladder assembly embodying my invention.

Fig. 2 is an enlarged detail elevational view of a portion of the ladder assembly showing the position of certain of the parts when the ladder is unoccupied.

Fig. 3 is a view similar to Fig. 2, but showing the position of the parts when the ladder is occupied.

Referring more in detail to the drawing:

The ladder assembly embodying my invention comprises a frame structure, designated generally as I, on which is supported the ladder, 'designated generally as 2.

The frame structure I preferably comprises an angle iron base 3 substantially rectangular in outline and formed by welding together suitable lengths of angle iron. Suitably secured to the base 3, as by welding, are a pair of rearwardly sloping front frame members 4 and a pair of forwardly sloping rear frame members 5. The respective frame members 4 and 5 are secured together by a pair of substantially horizontal connecting members 6 and the members 5 are further secured together by the substantially horizontal transverse cross member l. Preferably, the members 4, 5, '6, and `1 are formed from metal pipes or rods and are secured together by welding. It is thus seen that the iframe structure I is rmly constructed .to enable it to ysupport the weight of the ladder 2 and an individual standing thereon.

nThe ladder 2 preferably comprises a pair of side rails, 8 `and a plurality of steps v9 `suitably secured thereto. `The uppermost stepmay be extended over the side rails to form a shelf orlplatform, as indicated at III.

`A cross bar II is suitably secured between the front frame members 4. The side railsB of the ladder 2 Yare provided with elongated slots I2 through which the cross bar II passes to attach the ladder i2 to the frame I. The ladder is thus secured lto the frame in such a manner that it cannot readily be removed therefrom, but may be moved vertically with respect thereto to the limits permitted by engagement of the cross bar II with the upper .and lower bounding edges of the slots I 2,

The frame assembly is preferably supported on a plurality of castors or wheels I3 suitably secured tothe base 3. This manner of support enables Ythe assembly to bemoved easily about as desired over the surface on which it rests.

In order to prevent unintended movement of the assembly when an individual stands on the ladder, I provide a novel mechanism for holding the assembly in a fixed location at all times during which the ladder is occupied. The mechanism preferably comprises a pair of feet I4, one of which is preferably secured to each side rail adjacent the lower end thereof, as by means of the bolts I5 and nuts II.` The feet I4 each preferably have flange portions I1 adapted to engage the surface on which the assembly rests whenever the ladder is occupied. The frictional force between the feet and the surface substantially prevents movement of the assembly about the surface on the castors or wheels I3.

It is desirable that the feet I4 should automatically be forced into engagement with the supporting surface whenever an individual steps on the ladder and that these feet should automatically be removed from such engagement when the individual steps off the ladder, and I have provided a further novel mechanism for accomplishing this latter purpose.

A pair of brackets I8 are suitably secured to the side rails 8 of the ladder above the feet I4, as by means of th'e screws I9, one bracket I8 preferably being secured to each side rail 8. The side members of the base 3 preferably are prol0 The bolts 24 and nuts 25 retain the springs and flanges in the proper relationship and also act to I claim:

l. A ladder assembly comprising a frame having a substantially rectangular base, upwardly extending front and rear frame members secured to said base, connecting members securing said front and rear members together respectively, a crossmember securing said rear members to each other, and a cross bar connected between said front members, said base 'being mounted on castors, a ladder having a pair of side rails and a plurality of steps secured between said side rails,

j said side rails having elongated slots through limit relative upward movement of the ladder on y the frame.

Operation. Y -Y When the ladder is unoccupied, the assembly Y may be freely rolled about on the castors or wheels I3 to any desired location. The springs 23, acting between the brackets I8 and 2I, support the weight of the unoccupied ladder on the frame and maintain the feet I4 out of contact with the supporting surface, Fig. 2.

When an individual steps on the ladder, his weight is transmitted to the springs 23 and the force thereof compresses these springs. The ladder is thus moved downwardly relative to the frame I against the action of the springs 23 until the feetIli engage the surface on which the assembly rests, `Fig.' 3. Friction between the flanges I1 of Vthe'feet I4 and the surface is sufficient to prevent undesired movement of the assembly as long as the ladder is occupied.v When the individual steps off th'e ladder, the springs 23, acting'between the brackets, automatically raise the ladder to :the position shownV in Fig. 2 in which condition the assembly may again be moved about freely.

While I have shown but one embodiment of my invention, it is apparent that the structure is susceptible to modification without departing from the spirit of the invention. I do not wish, therefore, to be limited by the disclosure s'et forth, but only by the scope of the appended claims.

The invention described herein may be manu-V factured and used by or for the Government .of the United States' of America for governmental purposes without the payment ofany royalties thereon or therefor.

which said front cross bar passes to join the ladder kto the frame and permit relative vertical movement therebetween, feet on said side rails adapted to engage a surface on which the assembly rests in the lowered position of the ladder on the frame to prevent unintended movement of the assembly on said surface, at least one bracket secured to a side rail of the ladder, at least one bracket secured to said base in cooperative relation to said rst named bracket, and means between saidbrackets tending to raise said ladder with respect to said frame and maintain said feet out of contact with the surface on which the assembly rests. i

2. A ladder assembly comprising a frame having a substantially rectangular base, front and rear frame members secured to said base, connecting members securing said front and rear members together respectively, a cross member securing said rear members to each other, and a cross bar connected between said front members, said frame being mounted on castors, a ladder having a pair of side rails and a plurality of steps secured between said side rails, said side rails having elongated slots through which said cross bar passes to join the ladder t0 the frame and permit relative vertical movement therebetween, means on said side rails adapted to engage a surface on which the assembly rests in the lowered position of the ladder on the frame to prevent unintended movement of the assembly on such surface, and means arranged between portions of said ladder and said base tending to raise said ladder with respect to said frame.

WALLACE B. STEIL. l

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