US2574045A

US2574045A - Fork lift truck

Info

Publication number: US2574045A
Application number: US5752A
Authority: US
Inventors: Sidney D Lapham
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-02-02
Filing date: 1948-02-02
Publication date: 1951-11-06
Anticipated expiration: 1968-11-06

Description

NOV- 6, 1951 s. D. LAPHAM 2,574,045

FORK LIFT TRUCK Filed Feb. 2, 1948 2 SHEETS-SHEET l I il Y Y v F/ .j JNVENTOR.

/a/vir EAW/MM NOV. 6, 1951 S, D, LAPHAM 2,574,045

f FORK LIFT TRUCK Filed Feb. 2, 1948 2 SI'XEETS-.SHEET 2 Patented Nov. 6, 1951 11 Y UNITllIe STATES OFFICE n v FORKLIFT TRUCK i lSidney DLLapham, MartineaCalif. f, nppliatian February' 2, 1942s,;sria1 No. 5,752

' "10vClaims. if (Cl. 214-113)v u This -invention relatesA toyand in general has Y for its object the provision of ai forklifttruck and a retractable fork `therefor. i

space, some of which could otherwise be valuable storage space. x

More speciiically then, i'vheobjectA of this invention is the provision in an industrial truck of a retractable articulated fork mounted inafork carrier supported by said truck forv vertical and tilting movement with respectthereto.

A further object ofA thisinventionis the pro-'j vision of a new and* novel link, 'a*number of which can be pivoted together in staggered relation toforma belt capable of sustaining a load cantilever fashionfv Y Y l The invention possesses other advantageous features, some of iwhich,-`with theforegoing, will be set forth at ylength in the following description where that form of the invention which hasfbeen selected for illustration the drawings accompanying and forming a part of the present specif' mation is outlined in fu11..`-1n said-drawings, one

form of the.invention'isshowm but it is to be understood that it is'j'n't limited' to such form,

be embodied 'ina'plurali'ty of forms.v

Referring to the drawings: l Fig. 1 is an isometric projection of an industrial since the invention as set forth in the claims'may lift truck embodying the'objects of myinvention.'

Fig. 2 is an enlarged-fragmentary sectiontaken through one of the fork'carriers immediatelyjadg jacent and parallel to one of its articulated rei tractable forks.

Fig. 3 is a' vertical section taken through one of the fork carriers along" the longitudinal axis of its associated fork' retracting screw. v Y Fig. 4 is a horizontal section takenvthrough the fork carrier on the section line 4`-j4 vjof Fig; 3. 'Y

Fig. 5 is a fragmentary vertical section taken on the section line '5m-'5 of Fig. 3.

Fig. 6 'is an enlargedside elevation y,of oneof v, Y f50 Fig. 7 is a vertical 'section taken 'onthepline the fork links.

1-1 of Fig. 6.y `As shown in 'theevriious figures/*fthe @biens-T 0f Ymy invention hare been embodied inferi dustrial lift truck generally' *designated 'by' the' reference numeral I, of conventional construe? tionandonrwhich a mast, generally designated by thel re'f'erencenumeral `2, is mounted-for tilt-'ff ing movement'with respectl thereto; Y-

The mast'2` includes a pair of laterally opposed'` guide-channels 3 and 4 fastened at their upper" ends 1toa-icross-channel 5. '@Slidably disposed' within the'guide channels 3 and 4 is a rectanguiY lar frame E including an upper cross arm 6a, and' l secured intermediate the ends thereof is a piston rod `I- provided at its lower end'with a piston '(vnotv" shown) arranged to slide in a cylinder; vThe" cylinder Il is mounted on the mast 2 between the guide -channels 3 and 4V so as tomove bodily therewith. Formed integral with the upperjend ofthe piston rod l'I and forming a lT therewith a transverse sleeve A9, and'mounted therein is a shaft '(not shown). `Journaled on each :end of this shaft is a sprocket'wheel II, and passing 1 over each of these sprocket wheels inV mesh there?" with' isa chain I2.' The forward lower end of* each chain I2 is anchored to a crossarm I3' arranged to slide over the forward faces of the] guide Ychannels 3 and 4 and'which maybe con`1 sideredas a mounting for supporting the tines of ga lift fork.Y vIn accordance withstandard prac-lf tice, the cylinder 8 communicates with arsourcef of iiuidy under pressure such as a pump for low' ering and raising its pistonv and the associated pistonA rod l, suitable valves being mountedV oni' the truck cab for controlling the ow of fluid in the desired'direction. Since ther lower rear endsl of the chains" I2 are anchored tothe lower ends, of the guide channels 3 and 4, the elevationof the frame 6 'in response to the upward movement ofthe piston rod'l over a, predetermined distance,

d, will result in the elevation of` the cross arm I3 through a distance equal to 2d;

They lift truck thus far described, is of morei or less standard construction and operation; andff isfnormally provided with vvrigid, forwardly" extending forks,l these forks being mountedr on the cross arm kI3 orl some equivalentrstructure.

,Howeven in carrying out the objects of lmyin'- vention, 'a' fork carrier generally designated by ,v the reference numeralfI4; is bolted to each endl. of ,the cross arm I3 on thejforward face thereof`. Eachof'these carriers includes a rectangular back',`V plate" I5, opposed side plates I6' and I1, 'atop plate'I8 'and avblock'or foot I9.f Fastenedt'the inner face of'each of the side'plates-,IB and'I'I.

is a cleat 2l, vthese cleats and the back plates I5 formingvertically extending fork guide 'chanv Y nels` 22,1;Formed in'each foot I 9 is anlarcuate slot",v4

23v having an upper end 24 in alignmentwith' the` channels 22 of its carrier I4 and a forwardly extending end 25. Disposed over the front face of each foot I9 is a vertically adjustable wear plate 26 provided with a horizontally extending slot 21 forming a continuation of the forwardly extending end 25 of the arcuate slot 23. Each of the wear plates 26 is provided with vertically elongated slots 28 for the reception of bolts 29 threaded to the foot I9. Extending forwardly from each of the side plates I6 and I'I immediately above the wear plates 26 is an ear 3I and extending through each ear is a set screw 32 threaded to its associated wear plate for deter-- mining the vertical position of said plate.

Bolted to the back plate I on either side of the longitudinal center line, and extending substane tially the full length thereof is a cleat 33 andY bolted to the forward edges thereof is a plate 34 (see Fig. 4). Slidably disposed within each of the channels 22 is a block 35,-.these blocks being held in place by the cleats 2I and plate 34. Fastened to the lower portion of each of the blocksV 35 by a pin`- 36 i's an articulated andretractable Vfork generally 'designated by thereference numeral 37 and which is arranged to slide through one of the channels 22, through* one of the arcuate slots 23, and through one of the slots 2'I formed in its associated wear plate 26. Each of the retractable forks 3'I ismade up ofA a number of staggered or offset links 38 pivoted to eachother by pins 39. Formed on one side of each link 38 about each ofi't's pins 39 isa boss `4E), the oppositeside thereof being provided with concentric recesses 40a in which, the bosses of the laterally adjacent and staggered links are receivable. lower edge of'each link 3B is curved on a radius equal to the outer radius o-f the arcuate slot 23 but has substantiallysqllare corners, whereas .the

corners of the upper or outer v edges of each link are formed on a radius equal to one-half the distance between the axes of the pins 39. VIn this connection it shouldbe noted that the distance from either end of the link to the axis of the adjacent pin is equal to one-half the distance between the axes of thetwo pins passing through the link. By resorting to this construction, a fork is provided Vwhich will bend freely in one direction but which in the oppositeV direction will not bend beyond a common straight line or reference plane. In this connection it is` to be noted that the pins 39 are located above or forwfard of the longitudinal center lines of the links so that the major portion of their end edges form extended lever arms by which eachlink is supported cantilever fashion from the link immediately behind it in a straight line or plane. Secured to the forward ends of the front terminal links of each adjacent Vpair of` forksis a wedge shaped toe 4I, the rear edgt-lfof'eachv toe being provided with fingers 4,2 interdigitated with the terminal links and pivoted thereto by a pin 43.

Mounted respectively in the top plate I8 andn in the block or foot I9 are

bearings

44 and 45,V andjournalled therein is a screw 46. Threaded on the screw 46 is a cross bar 4'I formed on its rear face with a channel 48 for the accommodation of the plate 34 (see Fig.v 4), and secured at each end to slideblocks 35 by bolts 49. It will, therefore, be seen that rotation ofthe screw 46 willv produce a 'vertical movement of the cross The back or g .4.. including a drive shaft 53 aligned with one of the screws 46 and secured thereto by a coupling 54. Communicating with each of the motors 52 in accordance with standard practice are a pair through the motors 52, the screws 46 can be rotated in either direction to thereby selectively Y extend or retract either or both of the forks 37,

bar 41 and acorres'ponding movement of the rebracket 5I and mounted on each, of these brackets isa fluid motor 52 ofconventional construction it being contemplated that the motor 52 for each of the two forks shown, be controlled by its own and independent valve.

To pick up 'a load on the retractable forks above described, the truck with the forks in their retracted position is advanced to the load, its brakes set, and then the forks vare advanced to agposition lunderl the load.l Thisl having been done, the fork carrier is manipulted in the usual.

manner totip the load slightly backward and to elevate it clear vof the pallet on which it was resting. To deposit the load on a receiving pallet, the. fork carrier is simply lowered until the load rests on the pallet, and with the truck brakes set, the forks aref retracted away from the load and into Athe carrier.

I claim:

1. A lift truck comprisingz'a vertically movable fork carrier provided with aV fork-Way therein in- 1 cludingv a'.curver l forwardly extending lower portion; an articulated.fork movable within said fork-'way,'said. fork being bendable from a reference plane only'inf onel direction.; and power means mounted onsaid truck Vfor paying out and retracting said fork. A

2. A lifttruck comprisingLa vertically movable fork carrier; a fork-WayY includingV a curved lower `portion mounted on said fork carrier; an

s articulated fork mounted in saidv fork-way for movement therein, said fork being formed by-two sets of coplanar links, .theV links ofone set being offset with respect to the links ofthe other set andY said fork being bendableY from a reference plane only in one direction.

3. A lift-truck comprising: a vertically movable fork carrier provide'l. with a fork-way including an outwardlyy directed curved lower portion; a link belt fork mounted in said fork-way for movement therein, saidfork being bendable "from a reference planefonly. inY one direction; a

screw actuatedcross head mounted in said forkway above Saiifork andv attached thereto; and a IIOOI munted On'saidtruck for rotating said screw ineither direction,

4. A` lift truck comprising: al tiltable elevator; a vertically movable fork carrier mounted on said elevator, vsaid carrier, being provided with a forkway having a` forwardly, curved lower end; a link-chain'fork mounted ,inr said. fork-way for movement-therein inV either direction, said. fork beine bendable from.. areference plane only in one direction; andi means,rnourited on, said truck for. moving said`r fork throuehsaid forkfway in either direction. Y f

5,.,1A lift truck including, a vertically movable fork'carrier provided vwith a curved arcuate fork retainer; a linkedfork accommodated insaid retanerzand.movabletherethroueh. said fork-being constrained bynhQfr-ination, of. links frein bending in one direction beyond a straight line but being free to bend in the opposite direction in conformation with said curved fork retainer and means mounted on said truck for moving said fork through said retainer in either direction.

6. A lift truck such as defined in claim 1 wherein said articulated fork includes a rst set of links aligned in rows and columns interdigitated with a second set of coplanar links likewise aligned in rows and columns and forming therewith a staggered, symmetrical pattern, the rear ends of the links in each row of each set of links being pivoted to the forward ends of the links in each row of the other set of links, the corners of each of said links on one side of said fork being curved and the corners of each of said links on the opposite side of said fork being substantially square.

7. An articulated load supporting member comprising: rst and second sets of links arranged in rows and columns, the links of said first set being staggered with respect to the links of said second set, the trailing ends of the links in each row of links being pivoted by a pin to the leading ends of the links in the next succeeding row of the links, the adjacent ends of links in each set meeting in a common line when said member is disposed in a common plane, and the corners of all of said links on one side of said member being curved so as to permit said member to bend in one direction with respect to said reference plane.

8. An articulated member for supporting a load cantilever fashion, comprising: a belt made up of identical links pivoted together by means of pins in columns andstaggered rows wherein each link is provided at each end thereof with a bore for receiving one of said pins, and the distance between the axes of said bores is substantially equal to twice the distance between the axis of each bore and the adjacent end of the link, and wherein the upper corners of said link lie within an arc formed on a radius equal to the distance between one vof said bores and the adjacent end of said link, and having its center on the axis of its adjacent bore.

9. A link forming a belt bendable only in one direction beyond a reference plane and capable of sustaining a load cantilever fashion comprising: a generally rectangular metal block having opposed faces, opposed ends and a top and bottom, and formed with a pair of parallel pin receiving bores extending through said faces on a common horizontal center line lying above the horizontal center line of said block, the distance d between the axis of either of said bores and the adjacent end of the block being equal to onehalf the distance between the axes of said bores, the upper corners of said block being cut off so as to lie completely within an arc having a center lying on the axis of the adjacent bore and formed on a radius equal to d.

10. A link such as dened in claim 8 wherein said bores are counter-bored on one face of said block, and wherein said block on its opposite face is provided with bosses surrounding each of said bores and arranged to mate with the counter-bores of other and identical links.

SIDNEY D. LAPHAM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 736,104 I-Iubartt Aug. 11, 1903 799,163 Hubbard Sept. 12, 1905 898,537 West Sept. 15, 1908 912,679 Hollander Feb. 16, 1909 1,457,639 Straight June 5, 1923 1,543,214 Luce June 23, 1925 1,578,072 Canning et a1. Mar. 23, 1926 1,693,074 Falco Nov. 27,1928 1,693,335 Damerell Nov. 27, 1928 1,900,569 Lederer Mar. 7, 1933 2,165,283 MacChesney vJuly 11, 1939 2,246,810 Nicolai June 24, 1941 2,270,858 Gallamore Jan. 27, 1942 2,477,167 Bliss July 26, 1949 FOREIGN PATENTS Number Country Date 22,066 Great Britain Nov. 5, 1914