US2970016A - Guide rail structure for lift platform - Google Patents

Description

Jan. 31, 196i E. WOLDRING GUIDE RAIL STRUCTURE FORLIFT PLATFO Filed April 18, 1958 2 Sheets-Sheet 1 INVENTQR.

BY WM A7TORA/EYS Jan. 31, 1961 E. woLDRlNG GUIDI: RAIL STRUCTURE FUR LIFT PLATFORM 2 Sheets-Sheet 2 Filed April 18, 1958 TUT INVENTOR. 7 cr/ /o/o/r//y BY /0 f @m 7M 2,? ld Patented Jan.. 3i, llSl GUIDE RAR STRUCTURE FOR LIFT PLATFRM Egbert Woldring, Grand Rapids, Mich., assignor to The Rapids-Standard Company, Inc., Grand Rapids, Mich., a corporation of Michigan Filed Apr. 18, 1953, Ser. No. 729,412'

1 Claim. (Ci. 30S- 6) This invention relates to lift platforms in general, and more particularly to means for guiding lift platforms in the course of their vertical movement.

Most lift platforms are provided with guide wheels which are mounted on the sides of the liftv platform itself. These guide wheels usually cooperate with stationary vertical tracks or guide rails. The wheels on the lift pltaform are mounted near the side ends of the platform members and usually near the top and bottom limits of the lift carriage member.

Such guide mounting of lift carriages causes the full load of the lift platform to be concentrated on the guide wheels and, through them, on the guide rails where engaged by the guide wheels. Accordingly, the guide rails are required to be of heavy, durable, construction throughout their length and the guide wheel construction must also be exceptionally serviceable because of the load concentration thereon. Such factors increase costs of manufacturing, maintenance, and repair.

As a rule, the guide wheels and rails are required to be protected or shielded from possible damage. Any damage or interference with the function of either the guide wheels or guide rails will disrupt the operation of the lift carriage member. Each of the guide wheels must be freely rotatable at all times and any misalignment relative to the guide rails may prove quite serious.

Any eccentric loading of the lift platform, towards one end thereof, produces a binding end thrust on the guide wheels of most lift carriages. Such loading must be taken by the guide flanges of the guide wheels. This is another reason that the guide wheels are required to be of a massive and durable construction. Obviously, such ange loading of the guide wheels is most undesirable. However, thus far all means which have been proposed to relieve this situation have proven generally unsatisfactory. Such means have included a double set of guide wheels provided on the guide carriage, or equally expensive and impractical construction.

it is an object of this invention to teach a new and improved guide structure for lift platforms. Such guide structure includes having a plurality of rotatable guide wheels mounted on a stationary guide member and eliminates having guide wheels provided on the carriage member.

Itis an object of this invention to disclose a guide rail structure for lift platforms that is highly serviceable and which has numerous advantages over previously known guide rail structures for lift platforms. The use of a multiplicity of guide wheels mounted on a stationary guide rail does not require that the guide wheels be continuously in service. Further, when they are in service the frictional load thereon is divided between numerous of them. Accordingly the guide wheels can be of lighter construction which is far less expensive to make.

Another object of this invention is to teach the use of standardly available guide Wheel construction for use with lift platforms. The guide rail structure of this invention makes use of commonly known conveyor wheeled track sections. Such track sections are mounted within a channel guide for wheel engagement with a guide flange of the lift platform. f v

The conveyor wheel track sections are relatively inexpensive because of the standardized mass production methods used in their manufacture. The track sections and the wheels of such track sections are readily replaced if damaged. `However, in view of the use of multiple wheels, the chance of wheel damage is minimal. Further, damage of one wheel will not interfere with the operation of the lift carriage which is guided thereby.

The conveyor wheel guide rails ofthe disclosed guide' rail structure are arranged for radial loading and are free'A of any thrust loading due to off center loading of the lift platform or otherwise. The lift carriage includes a simple guide tlange which is engaged on opposite sides and on its end face by the multiple wheels of the guide means. TheV side wall engaging wheels are required to take no end thrust loading. The end wall engaging wheels, on the other hand, are disposed to take such forces radially.

A further object and advantage in the practice of thisy invention is to simplify the construction of the lift plattrackr sections is commonly usable as a structural mem-v ber in forming the lift platform and elsewhere. Conse-V quently, such members may be kept in stock for numerous diiferent purposes and will be available to extend,

revise, repair or otherwise change the guide rail struc-v ture disclosed herein. Such track sections are readily adapted to include the yconveyor wheels when and where required. Thus the track Vsections may be cut to length, as required, and be adapted to include conveyor wheels, as desired, right on the erection site.

These and other objects and advantages will be more apparent in the illustration and description of a working embodiment of this invention, as hereinafter set forth.

In the drawings:

Fig. l is a front view of a lift platform and guide rail structure.

Fig. 2 is a side view of the same lift platform and guide rail structure.

Fig. 3 is a cross sectional and enlarged view through one of the guide rails of the structure shown by Figs. 1 and 2.

Fig. 4 is a perspective view of a part of the guide rail structure of this invention.

The lift platform and guide rail structure shown in the drawings, and later described in further detail, includes a housing of a semi-portable nature having a lift platform exposed on one side thereof. The housing has structural guide rails framing its open side and which are adapted to receive and guide the lift platform in the course of its vertical travel. by an endless drive chain and chain drive mechanism mounted in the housing member.

Referring to the drawings; the housing l2 is formed as a shield or shroud which has a back wall 14 and side walls 16 and 18. A cover plate 20 closes the top of the housing 12. A pair of stabilizing legs 22 are secured near the bottom front face of the housing.

A pair of channel members 24 are secured to the hous-v ing side walls 16 and 1 8' near their front edges. The channel members 24"extend the full height of the hous sides exposed inwardly across the housing'.

The lift platform is raised and lowered 34. The shaft 34 is disposed near the bottom of the housing structure and is journaled within spaced bearing plates 36 and 3S. The bearing plate 38 extends across the front face of the housing 12 and also serves as a structural brace for the housing structure.

A similar bearing plate and shaft assembly is disposed at the top of housing 12. Such assembly includes spaced bearing plates 40 and 42 having a shaft 44 rotatably journaled therein. The bearing plate 42 extends across the front face of the housing structure 12 and serves to frame the opening in the housing and to provide a further structural cross support.

A sprocket wheel 46 is mounted on the driven shaft 34 and a sprocket wheel 48 is mounted on the other shaft 44. An endless chain 50 is engaged with both sprocket wheels 46 and 48 and serves as the drive means for the lift platform S2.

The lift platform S2 includes a mounting plate 54 which serves as a supporting back wall. The mounting plate 54 is part of the lift carriage 56 which carries a short run gravity conveyor structure 58.

The lift carriage 56 includes horizontally disposed arms 60 and 62 which extend from the face of the mounting plate S4 and are supported by braces 64 and 66 secured to brackets 68 and 70 on the mounting plate. The arm members 60 and 62 are disposed in parallel spaced relation to each other inboard of the side edges of the mounting plate 54. They are secured together by a cross brace The gravity conveyor 58 includes a pair of parallel spaced wheeled tracks 74 and 76 which are mounted on the lift carriage 56 in a horizontally inclined disposition. The conveyor structure includes the track sections or rails 74 and 76 which each have a plurality of wheels 78 r0- tatably mounted thereon. Side guide rails 80 and 82 are secured to the wheeled rails.

The conveyor tracks or rails 74 and 76 are secured to a tubular cross member 84. Y A shaft 86 extends through the tubular member 84 and is iournaled in lugs 88 and 90 secured to arm 60 of the lift carriage. This makes the conveyor structure 58 pivotal on the lift carriage. The other end of the conveyor structure 58 rests on supports 92 and 94 provided on arm 62 of the lift carriage.

The mounting plate S4 of the lift carriage structure is received for guided vertical travel within the open face of the housing 12. The mounting plate is engaged to the endless drive chain 50 by suitable hoist connectors 96 and 98. The upper edge of the mounting plate serves as an upper travel limiting stop upon engagement with the sprocket wheel shaft 44. The plate is cut out at 100 to permit lower travel prior to stop engagement with the other sprocket wheel shaft 34. l

. The mounting plate 54 is of sutiicient width to have its side edges received within the channel members 24 and within the guide means mounted therein. Such side edges thus serve as guide rails for the lift carriage member.

Channel members 24 are of sufficient size to receive lengths of Wheeled conveyor track 102, 104 and 106 therein. The conveyor tracks are mounted on the side anges 108 and 110, and the back web 112, of the channel members. They are disposed in parallel spaced relation to each other and are of sufficient length to extend the full height of the channel members.

Each of the wheeled conveyor tracks 102, 104 and 106' are of the same construction. Such track members are commonly known and are readily obtainable. The track members each include a channel shaped structural rail having a plurality of wheels 116 mounted between 1111;

side flanges 118 and 120 thereof. The web 122 of the rail is periodically slotted to expose the wheels therethrough. The wheels 116 are mounted 0n bolt shafts 124 which extend through the rail anges 118 and 120. Spacers 126 center the wheels between the side flanges and a nut 123 is threaded on the exposed end of the bolt shaft to complete the Wheel assembly.

The rail members of the wheeled conveyor tracks 102, 104 and 106 have the side walls 118 and 120 formed into the open face, near their ends. This provides strengthening ribs for the rail members. .It also provides a bearing surface for a bolt head which can be used to secure the guide rail members 102, 104, and 106 to the channel member. This is a commonly known means of attachment for this type of wheeled conveyor track and therefore has not been illustrated.

The load bearing surfaces of the wheels 116, of tracks 102 and 104, are on opposite sides of the guide edge of the mounting plate 54, as received therebetween. Accordingly, the mounting plate 54 is engaged with several wheels 116 of each of the guide tracks. Such engagement imposes a radial load on the wheels 116 but does not subject the wheels to any end thrust load. Any movement of the mounting plate 54 in its own plane, that is normal to the wheels of guides 102 and 104, is taken by the Wheels 116 of guide track 106.

The load bearing surfaces of the wheels of guide tracks 106 are disposed for end face engagement with the mounting plate 54. Accordingly the mounting plate is restrained against lateral movement in its own plane. The wheels of rails 106 thus are disposed to take the thrust loading of the lift platform but to receive such load radially of the wheels 116 thereof.

The lift platform may be signalled for a certain vertical travel. A limit stop switch actuator 11S is mounted on the lift carriage 56. Such actuator is intended to engage a limit switch connected to the drive motor 26. The limit switch might be mounted on a table or the edge of a storage bin.

Operation The guide rail and lift platform structure shown is semi-portable in nature. It may be moved from one location to another. A particularly good use for such a device is in the loading and unloading of heavy dies on and off of work tables, or the like.

The housing 12 and the structure thereof is located beside the die-work table. A heavy die is disposed upon the conveyor section 58 of the lift platform structure. The die is prevented from running oft the conveyor rails 74 and 76 by a suitable stop at their lower end.

The drive motor 26 is energized to raise the lift platform 52, via the chain drive connection thereto.

At the lift carriage 56 is actuated the mounting plate 54 is guided over the many wheels 116 of the track sections 102, 104 and 106. The track sections 102 and 104 are engaged with both side edges of the mounting plate. Accordingly there are a plurality of wheels to take the load of the extended carir-age. Similarly, the wheels of -track sections 106, in the spaced guide channels 24, are engaged with both side end faces of the mounting plate 54 to take any load force due to eccentric loading on the carriage. The mounting plate is of suicient height to be in engagement with several of the different wheels 116 at the same time. Accordingly the load of the carriage is distributed between the different wheels.

The lift carriage moves freely within the guiding track sections 102, 104 and 106 at each side thereof. The wheels 116 are of sufficiently light construction to have a low inertia factor and can be readily rotated into service. Such light construction is permissible due to the load distribution between the different wheels and the fact that they are not continuously in service.

None of the wheels of the different guide track sections 102, 104 and 106 are subjected to any end loading. The side and end face engaging disposition of the Wheels enables each set of wheels to cooperate with each other set to receive all bearing loads radially of the wheels.

The close spaced alignment of the side guide tracks 102 and 104 may be adjusted by shimming the track sections relative to the side walls of the housing channel member. The end face engaging tracks 106 may be similarly adjusted and set.

Any injury to the guide rails, or damage to any of the wheels, is readily corrected. Whole new sections of guide track may be replaced, or individual wheel assemblies may be changed with little effort.

When the lift carriage 56 is signalled as having reached the required vertical height, as by the limit switch actuator 118, the drive motor 26 is automatically inactivated. The tiltable conveyor section 58 may then be pivoted to raise its lower end higher than the other end Iand cause the die to move olf the conveyor bed and onto the work table. This tilting operation may be by power operated means, if desired, but such means are not shown here since they are quite well known and form no particular part of this invention.

This structure is used in the reverse order to that described, in unloading work from a table area, storage bin, or the like.

While a preferred embodiment of this invention has been described it will be understood that other modications and improvements may be made thereto. Such of these modications and improvements as incorporate the principles of this invention are to be considered as included in the hereinafter appended claim unless these claim by their language expressly state otherwise.

I claim:

A guide structure for -a lift platform comprising: a supporting channel member having a web and a pair of flanges, channel-shaped rail means mounted on said web and on each of said flanges, spaced wheels protruding through said rail means and mounted on said rail means throughout the extent thereof, each wheel being rotatable about an axis parallel to the portion of said channel member on which its rail is mounted, and an elongated plate member ixedly attached to said lift platform, said plate member having three plane surfaces formed thereon for engagement with said wheels, each of said surfaces being simultaneously engageable with no less than four of said wheels throughout the travel of said lift platform so as to limit its movement toward any portion of said channel member.

References Cited in the le of this patent UNITED STATES PATENTS 1,713,165 Bridge May 14, 1929 2,561,163 Wolters July 17, 1951 2,635,771 Black Apr. 21, 1953 2,786,578 De Graaf Mar. 25, 1957

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