US2237688A

US2237688A - Tractionally operated ladder

Info

Publication number: US2237688A
Application number: US294693A
Authority: US
Inventors: Phillips Jacob Harvey
Original assignee: CARL A MAYER; LAWRENCE E EICHEL
Current assignee: CARL A MAYER; LAWRENCE E EICHEL
Priority date: 1939-09-13
Filing date: 1939-09-13
Publication date: 1941-04-08
Anticipated expiration: 1958-04-08

Description

TRACT IONALLY OPERATED LADDER Filed Se t. 13, 19:59

INVENTOR Jacob Harvey P/izi/zpa BYWM . place by an operator while patented Apr. 8, 1941 TRACTIONALLY OPERATED LADDER Jacob Harvey Phillips, Cincinnati, Ohio, assignor of ten per cent to Lawrence E. Eichel, and fortyfive per cent to nati, Qhio Carl A. Mayer, both of Cincin- Application September 13, 1939, Serial No. 294,693

4 Claims.

This invention relates to a step ladder, and more particularly to a tractionally operated ladder structure.

An object of the invention is to provide a tractionally operated and supported ladder structure which is adapted to be propelled from place to occupying the upper portion of the ladder.

A further object of the invention is to provide steering means for a tractionally operated and supported ladder which steering means may be under the control of an operator occupying the ladder.

Still a further object of the invention is to provide an improved driving means for a tractionally operated and supported ladder which permits the ladder structure to be negotiated around sharp corners without toppling over.

Another object of the invention is to provide a ladder of the character be collapsed when not in use.

Still a further object of the invention is to provide a ladder of the character referred to which is sturdy when opened to a fully extended position and which is nevertheless light enough in weight to be easily carried by an operator, when in a closed position.

These and other objects are attained by the means described herein and disclosed in the accompanying drawing, in which:

Fig. 1 is a side elevational view of a tractionally operated ladder embodying the present invention.

Fig: 2 is a perspective view of the improved bucket holder comprising a detail of the invention.

Fig. 3 is an elevational view taken on line 3-3 of Fig. 1, showing the driving mechanism, comprising a detail of the present invention.

Fig. 4 is a perspective view of the steering mechanism comprising a detail of the invention.

Fig. 5 is a plan view taken on line E5 of Fig. 2 showing the combination bucket holder and steering shaft bearing support comprising a detail of the invention.

The present invention is directed, among other things, to the provision of a tractionally operated and supported ladder structure which is particularly adapted for use in buildings having long corridors and the like, the ceilings and upper portions of the walls of which are cleaned, from time to time, by hand. The ladder structure comprising the present invention permits the person cleaning the ceilings and walls to move the ladder from place to place, as the cleanreferred to which may fit over andengage a rung T'fof spaced front legs 0 the rungs bar ill.

ing job progresses, without the operator-occupant being required to descend from the ladder.

Such a ladder structure should be light enough in weight to permit it to be carried by a janitor, from one floor to another when in a closed or collapsed condition, and at the same time be sturdy in construction so as to be rigid when in a fully opened condition. Likewise, it is desirable that the ladder be of such a height as to 3 permit it to pass through doorways while in a fully extended position.

A ladder embodying the present invention may comprise a rear frame and front frame interconnected at their upper ends by a pair of said rails. The rear frame may comprise a pair of spaced rear legs or props .ll maintained in spaced relationship by reason of plurality of spaced transverse rungs l4 and narrow head piece Iii. The front frame may comprise a pair I6 which are connected at intervals by steps H.

A pair of side links l3 disposed one at each side of the ladder, join the upper ends of the adjacent front and rear legs of the front and rear frame structures, as disclosed in Fig. 2.

In the preferred embodiment of the invention the front legs are fixedly secured one to the front portion of each side link by means of rivets IE, or the like. The rear legs are pivotally mounted one to the rear end of each side link, 'as at I2.

It should be understood that the present invention is not directed to nor limited by the particular structural details or manner of securing I4 and steps I! to their respective leg members.

The front and rear leg structures may be properly secured relative to one another when the device is in an open or fully extended condition, as disclosed in Fig. 1, by means of a brace The front end of said brace bar may be secured to step I! by means of a suitable hinge member IS. The opposite end of said brace may be provided with a rung engaging device such as a hook member 20 which is adapted to M as shown in Figs. 1 and 4. The free end of the brace bar is adapted to be swung upwardly in a counterclockwise direction about hinge 19 when it is desired to collapse the ladder.

It should be observed that the uppermost step ii is disposed an appreciable distance below side links IS in order-to provide room for a platform 2| upon which the person using the ladder may stand. When disposed in a horizontal position,

Figs. 1 and ,2, latform 2! is surrounded on three sides by a safety railing comprising side links l3 and head piece it). By reason of said railing, an operator may brace himself while standing upon the platform. The front end of the platform is adapted for a pivotal or swinging movement relative to front legs ifi about a suitable pivotal connection 22. The platform may be constructed from any material capable of withstanding the stresses and strains induced by the weight of a person standing thereon. The opposite or free end of the platform is adapted to engage a rung M, as shown in Figs. 1 and 2.

It should be noted that by reason of providing a narrow head piece it! between the upper portions of the rear legs ll there are no structural elements disposed above the front portion of the platform which would interfere with a persons standing upon said platform while using the ladder structure.

In the preferred embodiment of the invention, each of the front legs I6 are supported on a drive wheel 23. Each drive wheel may be secured to the lower end of a front leg by means of a sleeve portion 24 into which the leg fits, as

show. Each sleeve and its associated front leg may be secured together by means of rivets 25, or the like. The lower portion of each sleeve terminates in a U-shaped bearing member 26 through which the drive wheel axle 21 extends, see Fig. 3.

Each drive wheel is provided with a drive pulley 23 suitably keyed to an axle 21 so as to be fixed relative to drive wheel 23 whereby a drive wheel 23, drive shaft 21 and drive pulley 28 will rotate as a unit. As shown in Fig. 3, each drive pulley is preferably located on the outer side of its respective front leg l6.

Each drive pulley is individually connected to a common or master drive shaft 30 by means of a continuous length of elastic or yieldable material denoted generally by the numeral 23. The opposite ends of the master drive shaft are each provided with a pulley 3! keyed thereto and preferably disposed in vertical alignment, one with each drive wheel pulley 28. Shaft 30 may be disposed beneath a step II, as shown. In the preferred embodiment of the invention I prefer to utilize a continuous V belt as the flexible elastic drive means, in which

case pulleys

28 and 3| are provided with suitable V-shaped grooves to accommodate the belt. Master drive shaft 30 is adapted to be remotely controlled by propelling hand wheel 32 which is mounted near the upper end of one of the front legs, as shown. The propelling hand wheel may be secured to shaft 33 which in turn may be revolubly secured to a front leg by means of a suitable bearing, not shown. A sprocket wheel 34 carried by and keyed to shaft 33 is connected to a second sprocket wheel 35 carried by and keyed to master drive shaft 30 by means of an endless sprocket chain 36.

It should be observed that by reason of providing each of the drive wheel axles in transverse alignment, the driving force from the master drive shaft 33 is normally divided equally between each drive wheel, and each of the drive wheels will normally rotate at the same speed. However, such construction permits one drive wheel to revolve faster than the other when required, as when the driving wheels are moving in an arc while the ladder structure is being turned. It is believed that the individual drive belts 29 act like a differential gear by reason of their inherent characteristics, viz., ability to stretch and/or slip to accommodate the relative travel of the drive wheels when the ladder is being turned.

In this manner the tendency of the ladder to topple over while being turned, as would occur in the event that the drive wheels were secured to a common drive shaft, is effectively minimized. The ability of the drive wheels to move at different speeds is of particular importance in those instances where rubber tired drive wheels are used which frictionally engage the supporting floor surface.

Experiment has disclosed that the most satisfactory results are gotten when power is transmitted from the end wheel sprocket 34 to the master drive shaft sprocket 35 by means of a nonextensible drive means, such as sprocket chain 36, and thence from the master drive shaft to the drive wheels 23 by means of individual, yieldable belts 29. It has been noted that when the master drive shaft 30 is located within three or four feet from the lower ends of the front legs l6 that each of the drive wheels 23 will be simultaneously and equally, though independent- 1y, powered. during those periods of time when the structure is being propelled along a relatively straight line of travel. However, such construction likewise permits the drive wheels 23 to be simultaneously rotated at different rates of speed during those periods of time when the structure is being turned by reason of the slipping action between the slower or inner drive wheel and its individual elastic belt 29.

In this manner I have provided simple yet highly effective means for propelling a tractionally supported ladder structure around curves and corners or in a straight line without danger of the structure toppling over.

The lower end of each rear leg ll terminates in a steerable caster or wheel 31 which may be suitably secured to the lower portion of a turnable plate 38 by means of a U-shaped bearing member 39 which carries an axle 40, as shown in Figs. 1 and 4. Turnable plate 38 is free to swivel about bearing plate M which may form an integral part of leg-sleeve 42, as known to the art.

The turnable plate 38 of each caster is interconnected by a cross bar 43 which may be provided with downwardly turned ends 44 which engage the turnable plates, as shown. Cross bar 43 interconnects the turnable plates 38 of the caster of each rear leg whereby each of the steerable wheels 31 may be simultaneously turned the same amount relative to their respective legs ll.

Suitable steering control means may be provided comprising a steering shaft 45, the upper end of which terminates in an outwardly turned hand grip portion 46, and the lower end of which terminates in an out-turned foot 41. The hand grip portion 46 is preferably located above head piece H] in order to be easily accessible to an operator standing on platform 2|.

Foot 41 may be pivotally secured to cross bar 43, as at 48, as shown.

Steering shaft 45 is shown secured at intervals throughout its length to rungs M by means of suitable bearing brackets 49, as shown in Fig. 4.

In the preferred form of the invention, I prefer to provide two water containers which are located intermediate platform 2| and head piece I0 and which extend outwardly over the rear legs, as shown in Figs. 1 and 2. Said water containers may comprise a pair of square buckets placed within the holder spaced relationship by adapted to be secured in bucket holder 49.

The bucket holder may comprise a central base member 50 suitably secured intermediate rear legs II. A bucket retaining strap may be provided in the form of a double U-shaped member comprising a pair of parallel outer elements and a pair of parallel inner elements 52 and a pair of rear elements 53 which interconnect adjacent inner and outer elements, as shown. The

free end of each outer element 5| may be an-v chored to a rear leg H by means of bolts 54 or the like. A pair of L-shaped straps each comprising a vertical element 55 and a horizontal element 56 which are secured to rear elements 53 and basemember 5|], respectively, are provided to support the rear and bottom portions of the buckets, which are shown by the broken lines in Figs. 1 and 2.

The front, or step side, of the bucket holder open in order to permit a bucket to be easily by an operator standing on steps H. In some instances, it may be desirable to provide a front bucket bottom retaining bar 51 to prevent accidental forward displacement of a bucket from holder 49. The retaining bar may comprise a suitable rod, the opposite ends of which are secured to suitable arms 58. The arms may be pivotally secured to rear legs II as at 59, and a stop pin 60 may be provided to limit the downward swing of said arm. Arms 58 and associated rod 51 are adapted to be swung upwardly in a clockwise direction about pivot 59 when platform 2| is lifted about pivots 22 in a counterclockwise direction preparatory to collapsing the ladder structure.

As shown in Fig. 5, a suitable steering shaft bearing BI is disposed between adjacent inner elements 52 of bucket holder 49 by means of rivets B2 or the like. In this manner the steering shaft and the central portion of the upper bucket strap are given added rigidity whereby a highly stable device is provided.

From the foregoing it is apparent that I have provided a collapsible, tractionally operated and supported, movable ladder structure which may be safely propelled and accurately steered from place to place by an operator disposed on the upper portion thereof.

I have provided a tractionally operated ladder which will not topple over while being turned even when loaded and carrying an operator. It is possible and practicable to effect sharp right angle turns for the purpose of following a wall, or the like, in perfect safety with the hereinabove disclosed device.

It should be understood that when not in use the ladder may be collapsed into a closed condition by swinging the rear leg structure toward the front legs about pivots 12, after brace bar l8 and platform 2| have been properly disengaged from the rear leg rungs.

I claim:

1. A movable ladder structure comprising side link members, a pair of step carrying front legs and a pair of prop members, the upper end of each of said front legs being anchored to opposite sides of the front portion of the side link members, the upper end of each of said props being pivotally secured to opposite sides of the rear portion of the side link members, a drive wheel disposed on the lower end of each front leg, and a steerable wheel disposed on the lower end of each prop member, means for simultaneously driving each drive wheel from the upper portion 3 of the ladder structure, said driving means comprising a pair of drive pulleys, one operably associated with each drive Wheel, a master drive shaft extending transversely of the front legs, the opposite ends of said master drive shaft projecting beyond the sides of each front leg, a pair of'pulleys, one disposed on each end of said master drive shaft in vertical alignment with one of said drive wheel pulleys, yieldable drive means interconnecting each pair of vertically aligned pulleys, and means to actuate said master drive shaft, each of said drive wheels being adapted to rotate at different speeds during those periods of time when the ladder structure is being turned and the drive wheels are being moved in an arc, whereby the tendency for the structure to topple over while being turned is overcome.

2. The combination with a tractionally operated and supported ladder structure comprising a pair of linkage members, a pair of step carrying front legs and a pair of transversely braced-rear legs, the upper end of each front leg being anchored to the front end of a linkage member, the upper end of each rear leg being pivotally secured to the rear end of a linkage member, a head piece extending transversely between the upper ends of the rear legs, and a steerable wheel disposed on the lower end of each rear leg, of a drive wheel assembly disposed on the lower end of each front leg, each drive wheel assembly comprising a drive wheel, an axle and a drive wheel pulley, said drive wheel and drive wheel pulley being fixed relative to the axle, a master drive shaft extending transversely of the front legs, the opposite ends of which overhang said front legs, a pair of pulleys one secured to each end of said master drive shaft and in vertical alignment with one of said drive wheel pulleys, yieldable drive means interconnecting each pair of vertically aligned pulleys, and means for actuating said master drive shaft from the upper portion of the ladder structure, said means comprising a hand crank and a non-extensible chain drive interconnecting said master drive shaft with said hand crank, said yieldable drive means independently interconnecting the master drive shaft with each drive wheel pulley for permitting said drive wheels to rotate at different speeds during those periods of time when said drive wheels are being moved in an arc,

3. The combination with a tractionally operated and supported ladder structure comprising a pair'of lin'kage members, a pair of step carrying front legs and a pair of transversely braced rear legs, the upper end of each front leg being anchored to the front end of a linkage member, the upper end of each rear leg being pivotally secured to the rear end of a linkage member, a head piece extending transversely between the upper ends of the rear legs, a platform, one end of which is pivotally secured to the front legs, the opposite end of which is adapted to engage a transverse brace interconnecting the rear legs, a bucket holder mounted to the rear legs intermediate said platform and the head piece, a steerable wheel mounted on the lower end of each rear leg, a cross bar interconnecting each steerable wheel, a drive wheel mounted on the lower end of each front leg, a steering shaft extending longitudinally of the structure intermediate the rear legs, the upper end of said steering shaft terminating in a forwardly disposed handle member, the lower end of said steering shaft terminating in an outturned foot the outer end of which is pivotally secured to said cross bar, said steering shaft extending through the central portion of said bucket holder, a steering shaft bearing provided in said bucket holder for providing anchorage means for the central portion of said bucket holder, and means for actuating said drive wheels from a location adjacent the top of the ladder structure, and for permitting each of the drive wheels to rotate at different speeds when the ladder structure is being propelled in an are by an operator standing upon said platform.

4. The combination with a tractionally supported ladder structure comprising a pair of props, a pair of step carrying front legs and a pair of side links, the upper end of each front leg being permanently secured to the front portion of a side link, the upper end of each prop pivotally secured to the rear portion of a side link, a head piece secured to and spacing the upper ends of said props, a steerable wheel disposed on the lower end of each prop, of a drive wheel assembly disposed on the lower end of and supporting each front leg, each drive wheel assprockets, a pair of sembly comprising a drive wheel, an axle, and a drive wheel pulley operatively connected to said drive wheel, and means for individually driving each drive wheel from the upper portion of said ladder, said means comprising a hand crank rotatably secured to the upper portion of a front leg, a sprocket operatively associated with said hand Wheel, a master drive shaft extending transversely of and having its opposite ends overhanging said front legs, a pair of pulleys fixedly secured one to each end of said master shaft, a sprocket carried by and secured to said master drive shaft, an endless chain drive interconnecting the hand wheel and master drive shaft endless elastic belts each connecting a master drive shaft pulley to a drive wheel pulley for permitting said drive wheels to normally rotate at the same speeds, and for permitting said drive wheels to rotate at different speed during those periods of time when said drive wheels are being moved in an arc.

JACOB HARVEY PHILLIPS.