US3040675A

US3040675A - Assembly line apparatus

Info

Publication number: US3040675A
Application number: US642075A
Authority: US
Inventors: Gino A Rudolfi
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-02-25
Filing date: 1957-02-25
Publication date: 1962-06-26
Anticipated expiration: 1979-06-26

Description

June 26, 1952 G. A. RUDOLFI 3,040,675

ASSEMBLY LINE APPARATUS Filed Feb. 25. 1957 5 Sheets-Sheet 1 June 26, 1962 G. A. RUDOLFI 3,040,675

ASSEMBLY LINE APPARATUS v Filed Feb. 25. 1957 5 Sheets-Sheet 2 HMM June 26, 1962 i G. A. RuDoLFl 3,040,675

ASSEMBLY LINE APPARATUS Filed Feb. 25. 1957 5 Sheets-Sheet 5 June 26, 1962 G. A. RUDOLF! ASSEMBLY LINE APPARATUS 5 sheds-sheet 4 Filed Feb. 25. 1957 June 26, 1962 G. A. RuDoLr-I 3,040,675

ASSEMBLY LINE APPARATUS Filed Feb. 25. 1957 5 sheets-sheet 5 tats arent Il c t 3,040,675 ASSEMBLY LiNE APPARATUS Gino A. Rndolfi, 7Stl1 Anise Ave., Los Angeles, Calif.

'Filed Feb. 25, 1957, Ser. No. 642,675 f 6 Claims. (Cl. lim- 118) This invention relates to an assembly-line structure for use by seated workers for the progressive assembly of work pieces.

A prevalent type of assembly structure comprises a long workbench for a row of workers seated on relatively high stools. The work pieces that are moved from worker to worker along the workbench either rest on the top surface of the workbench or are mounted on carriages that roll lalong the top surface of the bench. A high rack structure extending upward from the floor adjacent the workbench on the side opposite from the seated workers provides tiers of inclined trays or baskets holding components to be assembled to the work pieces. Instruction sheets for guidance in the assembly procedure are customarily either mounted on the rack structure or positioned face up in the inclined trays. assembly line structure has numerous disadvantages.

Several of these disadvantages have a serious cumulative fatigue effect. The bench top is at a relatively high level requiring relatively high stools and, since the stools Such a prior art are so high it is necessary to incorporate Afoot rests in the v bench construction. Such an arrangement is not conducive to comfort for the workers and induces unnecessary fatigue. Another fatigue factor is that the elevated bench top requires the seated workers to work with their hands at relatively high levels, the forearms of the workers normally extending upward as much as 45 degrees or more. A third fatigue factor is that the position of the workbench relative to the seated Workers -tends to cause the workers to hunch over the work pieces, and this j factor is aggravated too often by the failure of the workers to move their stools suiiiciently close to the Work- Abench. Another factor contributing to fatigue is the necessity for the workers to `lean forward repeatedly to reach for components in the trays on the opposite side of the bench. It is also necessary lfor the Workers to lean over in the same manner to read the instruction sheets.

Another disadvantage of the described prior art structure is that the top of the bench is the only convenient place for miscellaneous items. It is natural for workers to lay tools and assembly components on the bench top and occasionally the workers also place the instruction sheets on the bench top. Consequently, it is normal for the bench top to be in disarray with a consequent unfavorable psychological effect on the workers. If a soldering iron is used in an assembly operation, it is commonly placed on the bench top where it becomes a hazard. Whenever it is necessary to shift a work piece from station to station by moving a carriage along the bench top, time is lost in moving these various obstacles to clear a path for the carriage.

Another disadvantage is that confusion may arise as to the relation of the instruction sheets to the different assembly runs. Reference by a worker to the wrong instruction sheet -may cause serious and expensive errors.

lt has lbeen further found that there is a psychological handicap on .the part of the workers in facing the high rack structure across Athe workbench. The workers have a sense of being hemmed in which increases the monotony of the work.

A still further disadvantage of the described assembly line structure is that it requires a relatively large amount of valuable floor space per worker.

The present invention provid an assembly line construction that avoids all of these disadvantages. The

2 workers are seated in comfortable chairs of convenient height permitting their feet to rest flat on the floor. Instead of a relatively high workbench extending along the assembly line, a relatively low base structure runs longitudinally of the assembly line and is provided with track means for conveying work pieces. Carriages on the track means extend upward and outward from the base structure to hold the work pieces in positions for optimum comfort of the workers and optimum efficiency in the assembly operations. In the preferred practice of the invention, the top of the base structure is approximately at the level of the knees or the laps of the seated workers and the work pieces are held in positions immediately above the workers laps. There is no tendency for the workers to sit away `from their work and the workers' ture from the seated workers, special component racks are positioned between successive workers in the row of workers. Thus, each worker may reach to one side 'for component parts without any necessity of change in body posture. component racks are releasably mounted on the base structure itself leaving the oor space clear under the component racks.

A special feature of the invention is the concept of including trucks to move the component racks bodily from the assembly lline to a supply room where the racks are stocked with component parts. 'Ilhe usual procedure is to deliver the component parts to the assembly line in bags, trays or other containers for distribution to the trays in the upright rack structure. The new procedure provided by the invention makes it possible to distribute the parts directly to the racks at the point of supply, the parts being arranged on each component racks in an order convenient for the worker that is to carry out the corresponding assembly operation. An important advantage of this arrangement is that while one set of the component racks is in use at the assembly line structure for an assembly run, a second set of racks may be in the process of being stocked in the supply room in preparation for a succeeding assembly run.

With the base structure at approximately 'lap height and with elimination of the necessity for a high bank of trays facing the seated Workers, the workers do not feel` hemmed in but rather are given a sense of spaciousness.

Preferably, there are two rows of workers facing each other across the low base structure with two corresponding tracks for carriages and with component racks on both sides of the base structure. The fact that the rows of workers face each other lessens the tendency for the assembly operations to become monotonous.

A special feature of the preferred practice of the invention is the maximum convenience afforded the seated workers with respect to space for tools and miscellaneous objects. One provision in this respect ycomprises a pair of lockers in the base structure at each assembly station, a lefthand locker for use by a worker of one shift and a righthand locker for a worker of another shift. These lockers are provided with doors which may be swung open to make the inner sides of the doors accessible to The work pieces are relatively -low In the preferred practice of the invention, the' are mounted on the sides ofthe base structure. Inasmuch as it is more convenient to return tools to the rack on the locker door and to place miscellaneous objects on the component rack, the new structure induces'an orderly appearance along the assembly line with a favorable effect on the workers.

An important feature of the preferredV practice of the invention is the provision of special holders for soldering irons that may be detachably mounted on the base structure. As will be explained, the holders provide for conv venient storageof the soldering irons and completely eliminate the possibility of the workers being accidentally burned by the soldering irons.v

The placing of the component racks in a row with the seated Workers results in a substantial reduction in floor space; The saving in iioor lspace per worker if only one Vrow of workers is employed amounts to approximately 1/3. If two rows of workers are employed on vopposite sides of the assembly base structure, there is an additional reduction of 25 percent in the iloor space per worker. Thus, the combined reduction in floor space per worker may amount to approximately 50 percent.

y The assembly line structure of the invention is highly ilexible in a number of respects. For example, the base structure is wiredy to permit various devices to be plugged in at will, including soldering irons and buzzer test circuits. Further ilexibility in another sense is provided by making the assembly line structure in short units that may be positioned end to end to form a composite assembly line structure of any desired length. Where several such composite assembly line structures are used, they may be individually varied in length to meet changing production requirements. The assembly line structure is further ilexible in that the carriages for the work pieces may be added or removed at any point. Thus, carriages may be removed at one station'along an assembly line where the assembly of one run of work pieces is completed and carriages may be added at the next station for the initiation of another-run. Y t

The various features and advantages of the invention may be understood from the following detailed description, considered with the accompanying drawings.

In the drawings which are to be regarded as merely illustrative: Y

FIGURE l is a perspective view of the presently prekferred,embodirnent'of the assembly line structure;

Y FIGURE 2 is a perspective view on an enlarged scale of one of the component racks of the assembly line struc- Y ture; f

showing how a component rack is supportal by an arm that is releasably mounted ture; K p Y 1 FIGURES 5 and 6 are simplified sectional views showin a socket in the base strucing two stages in the movement of the support arm'of theV component rack into a 'mounting socket; v

FIGURE 7 is a view similar to FIGURES 5 and 6,

on a somewhat larger scale showing the ,support arm of the component rack in its mounted position i-n a socket;

FIGURE 8 is a perspective view of a soldering iron holder that is provided by the invention;

FIGURE 9 is a longitudinal section of the soldering iron holder taken as indicated by the line 9 9 of FIG- URE 8;

FIGURE l0 is a perspective view, partly broken away, showing a carriage mounted on a track for movement of work pieces along the assembly line;

`assembly line procedure since the tracks for the carriages mounted on the component v FIGURE 11 is a transverse sectional view of the track showing the carriage in its normal engagement therewith;

FIGURE l2 is a Viewv similar to FIGURE ll showing how the carriage may be disengaged from the track; and

FIGURE 13 is a perspective view from below showing how the support arm of a panel for instruction sheets may be releasably mounted on the carriage.

FIGURE l shows one unit or section of an assembly line structure, which is generally designated by numeral 20, and which may be combined with other similar units positioned end to end to form a composite assembly line structure of any desired length. Thus, a second assembly line structure unit 20a: shown in phantom abuts one end of the unit 20.

The assembly line structure unit 20 is intended for use with two rows of seated workers and is of a length to provide two work stations on eachside of the structure. Each of the four work stations of the unit is provided with a comfortable chair 22 of conventional height to seat a worker. Only Aone of the four chairs is shown in the drawing, the rest being omitted for sake of clarity of illustration.

The base structure of the unit includes a pair of spaced pedestals or stanchions 24 and a top assembly supported thereby. In the construction shown, the top assembly comprises atop plate 25 and a lower plate 26 interconnected by transverse members 28 to form a double wall.

An electric conduit 30 in this top assembly supplies current to pairs of electrical outlets 32 into which various electrical devices may be plugged, such as soldering irons and buzzer test devices. In the construction shown, there are three pairs of the jacks 32 on each side of the support structure.

The top plate 25 and the lower plate 26 of the top assembly are additionally interconnected by a metal track member 34 on each side of the base structure. The two track members 34 are special channel members and serve as structural beams of the base structure. Each end of each of the two track'rnembers 34 is provided with a U-shaped bracket 35 so that short guide bars 36 may be inserted in the brackets at the adjacent ends of the abutting assembly line structure units to hold the units in accurate longitudinal alignment with each other.

At each vof the four sta-tions where a chair 22 is provided to seat a worker, there is a clear space for ample leg room under the topV assembly and there are two lockers 38 and 40 on opposite sides of this clear space for use by workers of two dierent shifts. The lefthand locker 38 at each station has a door 42 that opens to the left and the righthand locker 40 has a door 44 that opens to the right, both doors Opening in a direction away from the worker seated at the station. As shown in FIGURE l, each of these doors 42 and 44 is provided on its inner side with a suitable tool rack 4S to hold a set of tools. When a locker door is in open position, the tool rack 45 on'the inner side thereof is within convenient reach of the seated worker.

As heretofore indicated, the assembly line structure includes a number ofV component racks, each generally designated by numeral 46, which are positioned between successive workers in a row of the seated workers. These component racks 46 may either stand on the floor or be supported by the base structure. A feature of this particular embodiment of the invention is that the component racks 46 are detachably supported by the base structure.

Preferably, as best shown in FIGURE 2, each of the component racks 46 comprises an upright metal frame 48 and a horizontal metal frame i) ,that extends in opposite directions from the lower edge of the upright frame. There are two spaced rows of cross rods 52 on the opposite sides, respectively, of the upright frame 48 to receive receptacles 54 of a well known type for holding supplies of assembly components. This arrangement permits receptacles 54 to -be arranged on the opposite sides of the upright frame 48 for use, respectively, by the seated workers at the two adjacent stations. As best shown in FIGURE 3, each of the receptacles 54 has a downwardly extending back tongue 55 for supporting engagement with a pair of the cross rods 52 to permit the receptacle to be releasably mounted on the upright frame 4S.

The horizontal frame 5i? of .the component rack has spaced cross rods 56 from which various objects may be suspended, if desired, such as a component S8 `shown in FIGURE 1. The horizontal frame 50 is also provided with low guard rails 66 at its opposite ends to keep objects from rolling oft the frame.

In the preferred practice of the invention, shelf panels 62 are provided for use on the bottom frame 56 of the component rack 46 on opposite sides of the upright frame Each of these removable shelf panels 62 comprises a piece of sheet metal formed with downwardly extending end flanges 64 to engage the opposite ends of the metal frame 50 and formed with an upright ilange 65 for abutment against the inner side or the corresponding guard rail 60 to keep the shelf panel securely in position. The addition of a shelf panel 62, when desired, provides a convenient space for small objects as may be seen in FIGURE 1.

Each of the component racks 46 may be adapted in any suitable manner for detachable mounting on the base structure. In this instance, each of the component racks t6 is united with a cantilever support arm 66 that has a tongue 68 at its end for insertion into a complementary socket 76 in the side of the base structure.

As best shown in FIGURE 4, each of the sockets 70 may be formed by attaching a U-shaped bracket 72 of appropriate dimensions to the under side of one of the track members 34, the track member forming the upper wall of the socket and the bracket forming the side and bottom walls. In the construction shown, the U-shaped bracket 72 has a downwardly extending front webb 7 d on the back of which is mounted an electrical outlet box 75l to provide one of the previously mentioned pairs of jacks 32. Preferably, the socket 7n provides greater vertical clearance than the thickness of the tongue 63 so that the inserted tongue takes an inclined position as shown in FIGURE 7. The tongue is correspondingly inclined relative to the support arm 66 to hold the support arm substantially horizontal.

Preferably, means is provided to lock the tongue 68 against withdrawal from the socket 70. For this purpose, the tongue 68 may be provided with a downwardly extending lug 76 to seat in a corresponding recess in the form of an aperture 7S in the bottom wall of the socket 7i. Obviously, the lug may be carried by the socket instead of the tongue, with the tongue recessed to receiv the lug.

The described arrangement makes it a simple matter to mount or dismount a component rack 46 in a rapid manner. Thus, FIGURES 5 and 6 show how the tongue 68 may be inserted into the socket 7d with the trailing end of the tongue inclined upward to permit the lug 76 to enter the socket. Once the lug 76 is linside the socket, the support arm 66 may be lowered to position the various parts relative to each other as shown in FIGURE 7.

FIGURE l shows a hand truck 8i) that may be used to convey a number of the racks 46 to and from a supply room where the component racks may be stocked with assembly parts. Preferably, the assembly parts are arranged on the rack in whatever sequence is to be followed at the particular assembly station and the upright frame its of the rack makes it convenient to place the receptacles 5'4 in any desired arrangement for this purpose.

The preferred practice of the invention further includes soldering iron holders 82 which may be constructed as best shown in FIGURES 8 and 9. The holder 82 is designed for a conventional soldering iron having a handle 84, a handle guard 85 and a shank S6 that incorporates a heating element .to heat the usual copper tip 8S. An electric cord 9i? for energizing the soldering iron extends through the handle 84 and terminates in a jack plug 92 to tit into any one of the previously mentioned jacks 32 onthe base structure.

The holder 82, which preferably is slightly inclined downward, has an inner metal tube 94 to receive the shank 86 of the 4soldering iron and has. a substantially larger outer guard tube 95 that is formed with numerous perforations 96. The outer guard tube 95 is connected to the inner tube 94 solely by an annular end wall 98 at the lower end of the holder. Both ends of the inner metal tube 9d arer open and the free end Mtl of the tube terminates short of the corresponding end of the outer guard tube 95. In the construction shown, this corresponding end of the outer guard tube 94 has an inclined disc 162 united therewith and this disc has a central aperture 104 to receive the soldering iron 'shank 86. The inclination` of the disc 102 causes the disc to make contact with only one point of the handle guard 85 when the soldering iron is inserted into the holder. v

The soldering iron holder may be mounted permanently on the assembly line base structure or may be adapted for such mounting in any suitable manner. In the constructions shown, a support arm 10S in the form of an upright metal plate is rigidly united with the outer tube 95. This plate is provided at its lower end with a leaf spring bracket 1% by means of which the soldering iron holder may be removably mounted, for example, on a cantilever support arm 66 of a component rack 46. Preferably, the support arm 105 is provided with a brush 108 having metal bristles for the convenience of the worker in cleaning the tip of the soldering iron.

The described construction of the soldering iron holder 82 keeps the outer guard tube 95 relatively cool. In fact, the guard tube may be grasped yby the hand without undue discomfort even when -the soldering iron has been stored in the holder for several hours at maximum temperature.

A number of factors account for the relatively low temperature of the guard tube 95, Thus, the inner tube 9d that is directly heated by the soldering iron is cooled by radiation through the perforations 96 of the outer tube as Well as by convection. Preferably, cool air enters the perforations 96 on the under side of the holder and the heated air ilows out of the perforations on the upper side of lthe guard tube. The fact that the soldering iron holder is nearly horizontal is important, the upwardly traveling heated air flowing away from the outer guard tube 95 instead of along the guard tube. The remaining heatof the inner tube 94 is conducted by the annular end wall 9S to the outer guard tube 95 but its residual heat is of low magnitude and is rapidly dissipated by the guard tube. Since the inclined disclZ of the holder makes only point contact with the handle guard 85 of the soldering iron and since the free end lltll of the inner tube 94 is spaced from this inclined disc, all the heat that travels by conduction from the inserted soldering iron to the outer guard tube 95 must follow the relatively Along path to the fixed end of the inner tube at the annular end wall 92.

As best shown in FIGURE l0, each of the track member 34 has a longitudinal bottom web llt), an upright web M2 along its inner longitudinal side, and an overhanging longitudinal web 114 that is a continuation of the upright web. Either the bottom web il@ which is one rail element of the track or the overhanging web 114 is anged to retain carriages on the track. In the 'Z construction shown, the bottom web 11i? is formed with a relatively low upright flange 11S along theouter longitudinal side ofthe track member.

FIGURES 1G, l1 and l2 show how a suitable carriage, generally designated by theY letter C, is constructed for releasable engagement with a track member 34. The carriage C has a base plate V116 that is stirened by a downwardly extending ange 118 along one Vside and an upwardly extending flange 1253 along the other side. As indicated in FIGURE 1l, two axles 124 and 125 at each end or' the carriage are bonded to each other by welding 126 and are bonded to the under side of the base plate 116 by weldingY 123. The two lower axles 124 journal corresponding wheels 130 at the outer edge of the base plate 116 to ride on the lower rail element 11d of the track member, and the two upper axles 125 journal wheels 132 at the inner edge of the base plate to ride on the underside Vof the overhanging rail element 114.

Each carriage C further includes a tubular member or pedestal 13d that is united with the base plate 116 centrally thereof and extends upwardly from the base plate in an outwardly inclined direction. The upper end of this tubular member ldis suitably adapted to hold work pieces forconveyance along the track member. For this purpose the upper end of thetubular member 134 may be provided with a horizontal disc 135 to carry a well known device commonly termed a power4 arm. Such a power arm has a socket member 136 which may be ilxedly attached to the horizontal disc 135 by suitable screws 138.

The socket member 136 forms a socket 1411 having a vertical slot 142, the socket Vengaging a ball element 144 at the end of a support arm 14S with the support arm extending through the slot. A short handle 146 may be operated to tighten or release the ball element 144 in the socket. The outer end of the support arm carries ra support plate 14g (FGURE l) which has numerous apertures 1S@ therein to receive screws or bolts by means of which work pieces may be mounted on the supportl arm for assembly operations.

In the preferred practice ofv the invention, a panel 152 for an instruction sheet is carried by the carriage C in a position facing the 'worker from across the work piece. ln the construction shown, the panel 152 is made of Vsheet metal and is provided with flanges 154 on the sides and bottom to retain anV instruction sheet. The panel 152 is carried'by an angular support arm 155 which is detachably mounted on the carriage C in a suitable manner. For this purpose, the undersideV of the carriage disc 135 may be provided with a U-shaped bracket 156, as shown in FGURE 13. The bracket o has a slot 158 to receive a downwardly extending stud 160 carried by the support arm 155. When the end of the support arm 15S is fully inserted into the socket formed by the bracket 156, the stud 169 extends through the slot 15S and a wing nut 162 may be tightened on the stud 169 to secure the support arm lin a releasable manner.

it may be readily appreciated by reference to FIGURE ll that with the carriage structure extending upward and outward from the track member 34 towards the seated worker, the center of gravity ofthe carriage together with a work piece thereon is positioned outward from the track member so that the carriage tends to tilt about the near wheels 130 as a fulcrum in a manner that presses the near wheels downward against the bottom rail element 11b and presses the far wheels 132 upward against the overhanging rail element 114. As a result, the carriage rides along the rack member .in a highly stable manner.

FGURE l2 shows how a carriage may be easily and quickly disengaged from the track member 34. The

carriage is rst swung upward sufficiently to lift the two near wheels 130 above the track flange 115 and then the carriage is shifted outward to the position shown in solid lines in FIGURE 12 where the near wheels 13G are out- Clt 8 side the flange 15. The carriage is then swung back to its normal angle and shifted outward still further to the position shown in broken lines in FIGURE 12 where the far wheels 32 are clear of the overhang-ing rail element 114. The carriage may then be lifted from the track member. rlhe reverse procedure is followed to place a carriage in running engagement with the track member. Thus, a carriage may be engaged with or disengaged frorn a track member 34 at any intermediate point of the track member.

My description in specific detail of the selected ernbodiment of the invention will suggest to those skilled in the art various changes, substitutions and other departures 4from my disclosure within the spirit and scope of the appended claims.

l claim:

l. in an assembly line construction for the progressive fabrication of work pieces by a row of seated workers, the combination of a base structure having a rst support portion extending along the assembly line construction in the direction of the row of seated workers, the base structure alsohaving rst and second side portions extending from the support portion at opposite lateral extremities of the support portion, the extent of the rst side portion along the first support portion being less than the extent of the second side portion along the first support portion, the base structure further having a second support portion extending partially from the second side portion toward the rst side portion in a direction having a major component parallel to the tirst support portion, and a carriage movable along the base structure in 4the direction of the row of seated workers, the carriage including a iirst wheel rotatable on the trst support portion at a position near the first side portion and including a second wheel rotatable-on the second support portion at a-position near the second side portion, the carriage also including means coupling the irst and second wheels to the carriage for respective rotation on the iirst and second support portions of the base structure.

2. The combination set forth in claim l in which a pedestal is included in the carriage and is disposed in a direction extending away from the first support portion of the base structure at an'inclination to the rst and second portions of the base structure to facilitate the disposition of the rst wheel against the rst portion and the disposition of the second wheel against 'the second support portion of the base structure and in which means are included on the pedestal to hold the work pieces.

, 3. In an assembly line construction for the progressive fabrication of Work pieces by a row of seated workers, the combination of a. base structure extending along the row of workers and having a support portion, the base structure having a ange portion extending from the support portionat a first lateral side of the support portion, the base structure having a side portion extending from the support portion at a second lateral side of the support portion opposite to the rst lateral side and extending in substantially the same direction as the liange portion and through a distance greater than that of the iiange portion, the base structure having a second support portion extending from the side portion at a position removed from the rst support portion and extending in a direction appreaching the flange portion, and a carriage movable on the base structure along the row of Workers, the carriage including a rst pair of wheels displaced from each other along the row of workers and movable on the iirst support portion at a lateral position adjacent to the ilange portion of the base structure and further including a second pair of wheels displaced from each other along YVthe row of workers and movable on the second support portion of the base structure at a lateral position adjacent to the side portion of the base structure, the carriage further including axlemeans for supporting the iirst and second pairs of wheels to obtain a rotary movement of the rst pair of Wheels on the iirst support portion of the base structure and a rotary movement of the second pair of wheels on the second support portion of the base structure, the carriage further including means for obtaining a tilt of the carriage in a direction to dispose the iirst pair of Wheels against the rst support portion of the base structure and to dispose the second pair of wheels against the second support portion of the base structure.

4. In an assembly line construction for the progressive fabrication of work pieces by a row of seated workers, the combination of a base structure having a tirst support portion extending along the base structur. in the direction of the row of Workers, the base structure having a ange portion extending for a -limited distance from the iirst support portion at a iirst lateral side of the support portion, the base structure having a side portion extending from the support portion at a second lateral side opposite to the rst lateral side, the base structure having a second support portion extending for a limited distancey from the side portion in a direction having a major cornponent parallel to the iirst support portion and approaching the ange portion, the second support portion extending for a distance to dene an opening between the ange portion and the second support portion, a carriage movable along the base structure in the direction of the row of workers, the carriage including a iirst pair of Wheels disposed in the direction of the workers at the rst lateral side of the support portion and including a second pair of Wheels disposed in the direction of the Workers at the second lateral side of the support portion, the second pair of wheels having a diameter slightly less than the distance l'between the iirst and second support portions of the base structure, the carriage further in cluding axle means for respectively supporting the irst and second pairs of wheels on the first and secondV support portions of the base structure, the carriage further including means for applying a torque to one of the pair of wheels with the other pair lof Wheels as a pivot to maintain the first pair vof wheels on the tirst support portion of the base structure and to maintain the second pair and to x the support plate relative to the pedestal in anyV pivotal position.

6. The combination set forth in claim 5 in which a panel is attached to the pedestal Ito carry instruction sheets for the seated workers.

References Cited in the tile of this patent UNITED STATES PATENTS `1,383,065 Biggert .Tune 28, 1.921 11,408,047 Upp Feb. 2s, 1922 .1,801,141 `Connors Apr. 14, 1931 1,816,031 Willis July 28, 1931 `1,986,413 Ruernelin Ian. 1, 1935 2,002,427 Bacon May 21, 1935 2,190,919 Hampton Feb. 20, 1940 2,308,098 Neal a Jan. l2, 1943 2,327,068 Rylander Aug. 17, 1943 2,355,883 Mathews Aug. 15, 1944 2,439,790 Becker Apr. 20, 1948 2,481,421 Hayes Sept. 6, 1949 2,633,810 Freeman Apr. 7, 1953 2,636,591 Galper Apr. 28, 1953 `2,678,489 Ratzlaff et al May 18, 1954 2,690,136 Freeman Sept. 28, 1954