US3237719A - Power lift for ladders - Google Patents

Description

March 1, 1966 w, RUSSELL 4 3,237,719

POWER LIFT FOR LADDERS Filed Jan. 5, 1962 3 Sheets-Sheet l INVENTOR.

@MPLJ ATTORNEYS 4. WILLIAM G. RUSSELL March 1966 w. G. RUSSELL POWER LIFT FOR LADDERS 3 SheetsSheet 2 Filed Jan. 5, 1962 m mnHH nH INVENTOR. WILLIAM G. RUSSELL A TTORNE Y5 March 1, 1966 Filed Jan. 5, 1962 W- G. RUSSELL POWER LIFT FOR LADDERS 3 Sheets-Sheet 3 "6/ no no l ne H2 '0 IIO- H4 H2 I14 H4 H2 H4 E I I3- 7 INVENTOR. WILLIAM G. RUSSELL A TTORNE vs 3,237,719 POWER LIFT FOR LADDERS William G. Russell, San Francisco, Calif., assignor of thirty percent to Donald Marsh, San Francisco, and twenty percent to Michael A. Grappo, Oakland, Calif.

Filed Jan. 5, 1962, Ser. No. 164,554 Claims. (Cl. 182103) This application is a continuation in part of my copending application Serial No. 72,635 filed November 30, 1960, for Power Lift for Ladders and now abandoned.

This invention relates to extension ladders and more particularly to improvements in load lifting apparatus having an extension ladder as an integral part thereof where the apparatus may be used both as an extension ladder and as a power hoist.

It is an object of the invention to provide an extension ladder with power lift means for lifting loads along the length of the ladder where the length of the ladder is adjustable and the length of the lifting path of the power hoist is changed as the length of the ladder is changed.

It is another object of the invention to provide an extension ladder with power lift means where the ladder may be used conveniently as a ladder while it is in condition for use as a power hoist.

It is another object of the invention to provide such a load lifting extension ladder of substantial strength which can support and lift heavy loads with the ladder erected vertically horizontally or inclined to both the vertical and horizontal.

It is another object of the invention to provide an extension ladder with a load carrying rack movably mounted thereon where the rack is supported on the ladder by dependable guide means which guide the rack along the length of each ladder section and across the area where the ladder sections overlap.

It is another object of the invention to provide such an extension ladder power lift with which heavy loads may be placed on a lifting platform at ground level and removed therefrom very easily at selected upper floors of a building without interfering with the ladder or attachments thereto.

It is another object of the invention to provide such an extension ladder having movable rack and guide means thereon where the apparatus is compact and light in weight so that it may be stored efliciently and handled easily by one man.

It is a more specific object of the invention in this regard to provide such an extension ladder which may be rolled on and off of a horizontal frame on a pickup truck by one man where the apparatus includes a power unit which may be removed from the ladder for separate handling by one man.

It is another object of the invention to provide such a telescopic extension ladder with power lift means which may be built easily and which is particularly well suited for use where the extension ladder portion of the apparatus has three or four or even more extension sections.

It is another object of the invention to provide such an extension ladder power lift structure which is particularly well suited for installation on existing extension ladders on fire trucks where the extension ladder has three or more extension sections.

It is another object of the invention to provide such a power lift structure on the extension ladders of fire trucks where the guide means on the extension ladder sections may take the place of or be mounted on handrails normally used on such ladders.

It is another object of the invention to provide a power lift for extension ladders having a load carrying rack and guide means for guiding the rack along the length of the ladder whereby the rack is aligned in an etlicient manner United States Patent 0 "ice with each new ladder section which it approaches even where the ladder may be deformed slightly due to loadmg.

It is another object of the invention to provide such guide means which align the rack with each new ladder section which it approaches and which insure smooth movement of the rack over the length of each ladder section.

It is another object of the invention to provide a power lift extension ladder having an electric motor for lifting loads along the length of the ladder and where the operation of the electric motor may be controlled automatically from selected points along the length of the ladder without having any electrical conductors extending along the ladder.

Other objects and advantages of the invention will become apparent from the following description read in conjunction with the attached drawings in which:

FIG. 1 is a perspective view of apparatus constructed in accordance with this invention with the apparatus illustrated in position for use adjacent to the wall of a building;

FIG. 2 is a similarly oriented perspective view of a portion of a platform forming a part of the apparatus of FIG. 1 where the platform is omitted from FIG. 1 for the sake of clarity of illustration;

FIG. 3 is a plan view of the movable rack which is shown on the apparatus of FIG. 1;

FIG. 4 is an edge view of the rack of FIG. 3;

FIG. 5 is a cross sectional view of a slightly modified form of the ladder shown in FIG. 1 with this view being taken along the plane indicated at 5-5 in FIG. 1;

FIG. 6 is an enlarged view illustrating the entry of one of the guide members on the rack into the lower end of one of the guiding tracks on the upper ladder section of the ladder shown in FIG. 1;

FIG. 7 is a perspective view of a four section fire truck ladder carrying the power lift apparatus of this invention, and

FIG. 8 is a sectional view of the ladder of FIG. 7 taken along the plane 8-S in FIG. 7.

Referring now in detail FIGS. 1-6 of the drawings, the extension ladder illustrated therein has a lower section 10 and an upper section 12 with the lower section having side rails 14 and rungs 16 and with the upper section having side rails 18 and rungs 20. As illustrated in FIG. 5, the side rails 14 of the lower ladder section carry inturned flanges 22 which define with the rungs 16 a channel for receipt of outturned flanges on the upper ladder section for telescopically supporting the ladder sections together. The side rails 18 of the upper ladder section carry suitable hooks 24 for latching upon rungs 16 of the lower ladder section to support the two sections at selected telescopic positions.

A- U-shaped channel 26 is provided on each of the side rails 14 of the lower ladder section and a similar U-shaped channel 28 is provided on each of the side rails 18 of the upper ladder section. The channel members 26 and 28 may be attached to the side rails 14 and 18 by rivets, but the side rails and channel members are preferably formed integrally with each other by extruding them simultaneously from suitable dies. Thus it will be noted that the channel members 26 and 28 are illustrated as being separate elements attached to the rails of the ladder sections in FIG. 1, but they are illustrated as being integrally formed with the ladder rails in FIG. 5. The lower ends of the channel members 28 and the upper ends of the channel members 26 are flared outwardly as seen in FIG. 1 and as illustrated in greater detail in FIG. 6 to facilitate entry of guide members into the channel members 26 and 28 as a load carrying rack moves into the .ladder section.

area of the ladder where the upper and lower ladder sections overlap.

As best seen in FIG. 1, a load carrying rack is mounted on the ladder for movement along the length of the ladder, the rack being made of side members 38 and 32 and a central brace member 34 connected to the side members and 32 by bolts 36. A plurality of roller units 38 are mounted on the underside of the members 30 and 32 of the rack to guide the rack along the length of the ladder with the roller units received in channel members 26 and 28. As best seen in FIG. 3, four of these roller units are provided for engagement with the channels on each Thus, an upper pair of roller units 40 and a lower pair of units 42 are mounted on the rack with one unit of each pair on each of the side members 30 and 32 of the rack. The units of each pair 40 and 42 are spaced apart by the proper distance to permit them to be received simultaneously in the two channel members 28. Similarly, four outer roller units 44 are provided on the rack for engagement with the channel members 26 on the lower ladder section.

As indicated in FIGS. 4 and 6, each of the roller units 4044 comprises a central strut 46 carrying two parallel axles 48 with a pair of wheels 58 mounted on each axle 48 on opposite sides of the strut 46. The strut 46 also carries a pair of axles 52 which are arranged perpendicular to the axles 48 and carry single rollers 54 thereon. The rollers engage opposed cam surfaces 56 and 58 (see FIG. 5) on the channel members, and the rollers 54 engage the side surfaces 60 (see FIG. 5) of the channel members 26 and 28 to guide each roller unit into the mouth of the channel member and insure smooth alignment of the roller units throughout the length of the channel member. As indicated in FIG. 4, the roller units 40-44 are mounted on the movable racks by means of flanges 62 on the struts 46 and bolts 64.

As illustrated in FIG. 5, the side rails 18 of the upper ladder section are made smaller in a direction perpendicular to the plane of the ladder than the side rails 14 of the lower ladder section so that the channel members 26 and 28 on the two ladder sections lie in the same plane parallel to the plane of the ladder. Also, the roller units 40- 44 are mounted on the movable rack in a common plane. This arrangement of elements reduces the bulkiness and weight of the apparatus to a considerable extent.

A pair of load carrying forks 66 are mounted on the rack members 31) and 32. As indicated in FIGS. 1 and 4, the load supporting forks 66 are made of square tubing and receive telescopic extensions 7 0.

The load carrying rack is lifted along the length of the ladder by a hoist unit 72 (see FIG. 1) attached to the lower ladder section by U-shaped brackets 74 which receive a rung of the ladder. The hoist unit 72 may include any suitable power means such as a hand winch, gas engine, etc. and is shown herein as including a con ventional electric motor and cable winding means for pulling a cable 76 which is entrained over a pulley 78 at the top of the ladder with the lower end of the cable 76 being attached to the movable rack. As indicated in FIGS. 3 and 4, the cable '76 is attached to the rack by means of a cable receiving spool 80 attached to the central brace member 34 of the rack with the spool 80 being locked in position by suitable means such as an eccentric bolt 82. The spool 80 is provided to hold a suitable reserve length of the cable 76 when the extension ladder is contracted to permit additional cable 76 to be played out when the equipment is to be adjusted for use with the ladder sections extended.

Operation of the electric motor in the power hoist unit 72 is controlled by a rotary switch 84 (see FIG. 1) mounted on a bracket 86 at the foot of the ladder and connected by a wire 88 to the power unit. The rotary switch element of the switch 84 is connected to a square tube 88 which is rotatably mounted in the bracket 86. The tube 88 telescopically receives a square rod 90 which is rotatably supported in a bracket 92 on the side rail 18 of the upper ladder section. The telescopic fit between the rod 90 and tube 88 permits the switch 84 to be operated by rotation of either the rod 90 or tube 88 regardless of the extension position of the ladder sections. The switch 84 is of conventional construction having three positions for forward, stop, and reverse. Actuation of the switch 84 may be accomplished automatically by a pair of fingers 94 which are adjustable secured to the rod 90 and tubes 88 by suitable means such as set screws. A double ended cam 96 is attached to the load carrying rack for engagement with the fingers 94 to stop operation of the power hoist 72 automatically as the rack approaches the positions on the ladder where the fingers 94 are secured.

As illustrated in FIG. 1, the ladder is supported in a vertical position with the plane of the ladder (that is a plane parallel to all of the rungs of the ladder) extending perpendicular to a wall 98 of a building. The ladder is supported in this condition by a triangular brace member 180 attached to the wall 98 by bolts 102 and attached to a ladder rung by U-bolts 104. A suitable load supporting platform 186 (see FIG. 2) is positioned on the fork 66 of the load carrying rack so that heavy loads may be rolled onto the platform 106 at ground level and rolled off of the platform 106 at the top of the wall 98 or at intermediate floors of the building selected by proper positioning of the upper switch finger 94.

Referring to FIGS. 7 and 8, the apparatus illustrated the-rein includes a four section extension ladder of the type customarily mounted on a turn table 188 on a fire truck of the hook and ladder type. Each ladder section includes side rail members 110 connected by rungs 112 with the side rail of each upper ladder section being supported on rollers 114 which are mounted on the rungs of the adjacent lower ladder section. A plurality of support bars 116 are rigidly mounted on each side rail 110 of each ladder section with the support bars 116 normally sup porting hand rails on their upper free ends. Aerial lad= clers of this type are shown in US. Patent No. 2,069,514, an the ladder may be operated by a suitable hoisting mech anism such as that shown in US. Patent No. 2,114,262. As illustrated in FIGS. 7 and 8, the normal hand rails on this ladder are replaced by channel members 118 which are substantially identical to the channel members 26 and 28 shown on the apparatus of FIG. 1. For purposes of use on existing ladders, the channel members 118 may be added on top of the existing hand rails by suitable at tachment means without removing the hand rails or the channel members 118 may replace the hand rails. The channel members 118 are all mounted in a common plane as are the channel members 26 and 28 in FIG. 1 so that men using the ladder can slide articles such as stretchers up and down the side rails of the ladder. A load carrying rack 120 is mounted on the ladder with four sets of roller units positioned for engagement with channel members 118 on the four ladder sections. The load carrying rack 120 is pulled upwardly along the length of the ladder by a cable 122 which may be connected to suitable power hoist means on the fire truck.

While two specific embodiments of the apparatus of this invention have been illustrated and described in detail herein it is obvious that many modifications of the apparatus shown may be made without departing from the spirit and scope of the invention.

I claim:

1. In a load lifting apparatus comprising a ladder having upper and lower sections each constructed of a pair of edge struts interconnected together by ladder rungs, means telescopically mounting said sections together with said upper section positioned on one side of said lower section, a load supporting rack positioned adjacent to the ladder for movement along the ladder, and hoist means for moving said rack along said ladder, the improved guide means for mounting said rack on said ladder which comprises a generally linear trackway provided on each of:

said struts and having opposed cam surfaces generally parallel to the plane of said ladder, said trackways being generally parallel to each other with the trackways on the upper section positioned between the trackways on the lower section and overlapping the trackways of the lower section where said upper and lower ladder sections are telescopically mounted together, and two sets of antifriction means mounted on said rack and positioned for each set thereof to engage the trackways on one of said sections while contacting the opposed cam surfaces thereof at longitudinally spaced points thereon characterized further by the inclusion of means for supporting said ladder in an erect position adjacent to the wall of a building with the plane of said ladder perpendicular to said wall.

2. In a load lifting apparatus comprising a ladder having upper and lower sections each constructed of a pair of edge struts interconnected together by ladder rungs, means telescopically mounting said sections together with said upper section positioned on one side of said lower section, a load supporting rack positioned adjacent to the ladder for movement along the ladder, and hoist means for moving said rack along said ladder, the improved guide means for mounting said rack on said ladder which comprises a generally linear trackway provided on each of said struts and having opposed cam surfaces generally parallel to the plane of said ladder, said trackways being generally parallel to each other with the trackways on the upper section positioned between the trackways on the lower section and overlapping the trackways of the lower section where said upper and lower ladder sections are telescopically mounted together, and two sets of antifriction means mounted on said rack and positioned for each set thereof to engage the traokways on one of said sections while contacting the opposed cam surfaces thereof at longitudinally spaced points thereon, said load lifting apparatus characterized further in that said hoist means includes electrically operated cable pulling means, a cable extending between said rack and said cable pulling means for lifting said rack upwardly on said ladder and control means are provided for said hoist means comprising: a pair of elongated elements telescopically and non-rotatably connected together with one of said elements rotatably connected to each of said ladder sections, a rotary switch mounted on said lower ladder section and connected to one of said elongated elements to be operated responsive to rotation of said element with said switch being connected to said cable pulling means to control the operation thereof, a finger member adjustably mounted on one of said elongated elements, and cam means on said rack for engaging said finger member and rotating said elongated elements responsive to movement of said rack with respect to said finger.

3. A load lifting apparatus comprising a ladder having upper and lower sections each constructed of a pair of edge struts interconnected by ladder rungs, means telescopically mounting said sections together with said struts of said upper section positioned between the struts of said lower section and on one side of the rungs of said lower section, an elongated generally U-shaped channel member mounted on each of the struts of said sections with the open sides thereof facing away from the side of said lower section on which said upper section is mounted, said channel members having inturned lips on the open side thereof whereby the bottoms of said channel members and the undersides of said lips provide longitudinal opposed cam surfaces generally parallel to the plane of the ladder, said channel members being generally parallel to each other with the channel members on said inner struts positioned between the channel members on said outer struts and overlapping where said upper and lower ladder sections are telescopically mounted together, a load supporting rack positioned adjacent to said ladder and having two sets of rollers mounted thereon with one set received in said channels on one ladder section and the other set positioned in alignment with the channel members on the other ladder section, each of said sets of rollers having at least four support rollers divided into two pairs with the support rollers of each pair positioned to engage a single channel member at points spaced apart longitudinally of the channel member with at least one support roller of each pair positioned to roll on each of said opposed cam surfaces, hoist means for moving said rack longitudinally of said ladder, and means for supporting said ladder in an erect position adjacent to the wall of a building with the plane of the ladder perpendicular to said wall.

4. A load lifting apparatus comprising a ladder having upper and lower sections each constructed of a pair of edge struts interconnected by ladder rungs, means telescopically mounting said sections together with said struts of said upper section positioned between the struts of said lower section and on one side of the rungs of said lower section, an elongated generally U-shaped channel member mounted on each of the struts of said sections with the open sides thereof facing away from the side of said lower section on which said upper section is mounted, said channel members having inturned lips on the open side thereof whereby the bottoms of said channel members and the undersides of said lips provide longitudinal opposed cam surfaces generally parallel to the plane of the ladder, said channel members being generally parallel to each other with the channel members on said inner struts positioned between the channel members on said outer struts and overlapping where said upper and lower ladder sections are telescopically mounted together, a load supporting rack positioned adjacent to said ladder and having two sets of rollers mounted thereon with one set received in said channels on one ladder section and the other set positioned in alignment with the channel members on the other ladder section, each of said sets of rollers having at least four support rollers divided into two pairs with the support rollers of each pair positioned to engage a single channel member at points spaced apart longitudinally of the channel member with at least one support roller of each pair positioned to roll on each of said opposed cam surfaces, hoist means for moving said rack longitudinally of said ladder in which the said generally U-shaped channel members have side walls which provide lateral opposed cam surfaces on the inside of said channel members perpendicular to said longitudinal cam surfacesand each of said sets of rollers contains four roller units with two of said units received in each of the channel members on one of said ladder sections and with each of said roller units having a first pair of spaced apart rollers engaging said lateral cam surfaces and a second pair of spaced apart rollers engaging said longitudinal cam surfaces between said first pair of rollers.

5. A load lifting apparatus comprising a ladder having upper and lower sections each constructed of a pair of edge struts interconnected by ladder rungs, means telescopically mounting said sections together with said struts of said upper section positioned between the struts of said lower section and on one side of the rungs of said lower section, an elongated generally U-shaped channel member mounted on each of the struts of said sections with the open sides thereof facing away from the side of said lower section on which said upper section is mounted, said channel members having inturned lips on the open side thereof whereby the bottoms of said channel members and the undersides of said lips provide longitudinal opposed cam surfaces generally parallel to the plane of the ladder, said channel members being generally parallel to each other with the channel members on said inner struts positioned between the channel members on said outer struts and overlapping where said upper and lower ladder sections are telescopically mounted together, a

load supporting rack positioned adjacent to said ladder and having two sets of rollers mounted thereon with one set received in said channels on one ladder section and the other set positioned in alignment with the channel members on the other ladder section, each of said sets of rollers having at least four support rollers divided into two pairs with the support rollers of each pair positioned to engage a single channel member at points spaced apart longitudinally of the channel member with at least one support roller of each pair positioned to roll on each of said opposed cam surfaces, and hoist means for moving said rack longitudinally of said ladder, said hoist means comprising a sheave mounted on said ladder adjacent to the top thereof, power operated cable pulling means detachably connected to said ladder adjacent to the bottom thereof, and a cable detachably secured to said rack and extending over said sheave to said cable pulling means, and means for facilitating the extension and retraction of said ladder comprising a drum mounted on said rack with said cable secured thereto, and means latching said drum against rotation.

References Cited by the Examiner UNITED STATES PATENTS 1,429,012 9/1922 Andrews 187-95 2,037,860 4/1936 Hummel 182207 2,338,833 1/1944 Bailey 182103 2,438,791 3/1948 Russell 182-403 2,569,653 10/1951 Boedecker 182145 3,026,963 3/1962 Wilkie 182-93 FOREIGN PATENTS 362,028 12/1931 Great Britain.

HARRISON R. MOSELEY, Primary Examiner.

GEORGE LEO BREHM, Examiner.

Claims (1)

1. IN A LOAD LIFTING APPARATUS COMPRISING A LADDER HAVING UPPER AND LOWER SECTIONS EACH CONSTRUCTED OF A PAIR OF EDGE STRUTS INTERCONNECTED TOGETHER BY LADDER RUNGS, MEANS TELESCOPICALLY MOUNTING SAID SECTIONS TOGETHER WITH SAID UPPER SECTION POSITIONED ON ONE SIDE OF SAID LOWER SECTION, A LOAD SUPPORTING RACK POSITIONED ADJACENT TO THE LADDER FOR MOVEMENT ALONG THE LADDER, AND HOIST MEANS FOR MOVING SAID RACK ALONG SAID LADDER, THE IMPROVED GUIDE MEANS FOR MOUNTING SAID RACK ON SAID LADDER WHICH COMPRISES A GENERALLY LINEAR TRACKWAY PROVIDED ON EACH OF SAID STRUTS AND HAVING OPPOSED CAM SURFACES GENERALLY PARALLEL TO THE PLANE OF SAID LADDER, SAID TRACKWAYS BEING GENERALLY PARALLEL TO EACH OTHER WITH THE TRACKWAYS ON THE UPPER SECTION POSITIONED BETWEEN THE TRACKWAYS ON

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