US3534664A

US3534664A - Lift truck mast and ram assembly

Info

Publication number: US3534664A
Application number: US817218*A
Authority: US
Inventors: Bronislous I Ulinski
Original assignee: Eaton Yale and Towne Inc
Current assignee: Yale Materials Handling Corp
Priority date: 1967-09-06
Filing date: 1969-03-07
Publication date: 1970-10-20
Anticipated expiration: 1987-10-20

Description

United States Patent [mentor Bronislous I. Uimki [72] 2.788.148 4 1957 Parcell 92146X Pa|mB3h,Fl0rld8 2,221.3]6 l 1958 Saints 9ll67X '[211 AppLNo. 817,218 3339.400 6 1962 Trent. 92,161 {22] Filed March v h 3,042,149 7.1962 Comfort 9252K A diigsinnnfse r. No. 665,826,5 p -6, 1967, 3,049,334 8/1962 Montague 251 367X now atent N0.3,485,323,Whih is 3,128,468 4/1964 Bade 92 161 continuation-impart ofSer. No. 601,638, 3,172,339 3,1965 Quayle. 92 5 Dec. 14,1966, now abandoned. 3212,6 1 10 1965 Garnett H 212/55 [45] Patented 061. 20, 1970 FOREIGN PATENTS i731 Awgn g g 418,560 231967 Switzerland a. 12 /17 Prl'muqv xaminer Martin P. Schwadron Assistant xaminerl.eslie Jv Pa ne [54] LIFT TRL'CK MAST AND RAM ASSEMBLY Almrne Teagno and Todd 9 Claims, 8 Drawing Figs. 152} Cl H 92/146,

. 92/]6492/165 187/9 187/17 ABSTRACT: A mast construction for a lift truck in which l5l Int. (J FUlb 1/00, each i h aswmbly is moved by a ram supported on a bts I 36Gb 9/20, B6613 1,1104 plate and acting against a thrust plate of an adjacent upright 1 1 Fleld 593mb 92/ 161 assembly. The rams are connected in series through a hydraul6 f 14551152, 53; 91/169, 167; I lie circuit including therespectixe base and thrust plates and 7 l 2/ by l rigid piping extending from the base plate to the thrust plate of I each upright assembly Further, the particular construction of i References voted the upright assemblies and the position of the rams provides L IT STATES PATE5T5 an extremely compact combination protecting the rams from 2,651 ,180 9/1953 Haller 92/ 1 46X lateral bending forces applied to the mast.

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LIFT TRUCK MAST AND RAM ASSEMBLY This application is a Division of my earlier application Ser. No. 665,826, filed Sept, 6, 1967, for Lift Truck Mast and Ram Assembly now U.S. Pat. No. 3,485,323, issued Dec. 23, 1969, which is a ContinuationIn-Part of application Ser. No. 601,638 filed Dec. 14, 1966 and now abandoned.

This invention relates to the assembly of a ram relatively to an upright assembly or load lifting mast. More particularly, my invention relates to means for assembling either one end of a hydraulic ram to an upright, or the opposed ends of a rum to two telescoping uprights, whereby the extension of the ram will lift either a second upright relatively to a first upright, or will lift a load carriage relatively to an upright.

As those skilled in the art well appreciate, it is extremely important to utilize a minimum of hose or piping for bringing fluid to a hydraulic ram. This is due to the fact that the fluid pressures used in industrial trucks are extremely high so that the longer the hose or other passage through which the fluid moves, the greater the risk of breakage and loss of fluid. Further, industrial trucks must be extremely compact and it is highly desirable, therefore, to limit the amount of hose or pipe required, and the resulting hydraulic friction.

Those skilled in the art are also fully aware of the fact that while it is desirable to obtain maximum throw or extension of a hydraulic ram, this maximum extension should be obtained through a ram having a minimum overall length. As a matter of interest, inventors have been attempting for many years to achieve maximum extension with minimum length of ram.

My invention contributes a ram for a mast having an extremely long throw in proportion to its overall length, all because of the manner in which it is assembled to one upright or to a pair of telescoping uprights in which one upright slides on another upright.

As a further feature of my invention, I contribute a mast assembly utilizing one ram for each movable upright of an extremely compact construction highly resistant to lateral bending forces applied to the mast, and thus prevents such forces from effecting the operation of the rams.

It is a further feature of my invention that through the ram mounting means I have conceived, it is possible to have a minimum of piping for the hydraulic fluid, with the further feature that none of this piping need be flexible, thereby making possible the use of rigid piping.

As still a further feature of my invention, I contribute a mast assembly utilizing more than one ram, in which all of the rams may be identical in construction and in which all of the mounting means for securing the rams in position may be identical.

As a particular feature of my invention, the ram thereof is formed with an open end adapted to fit against an open surface on the base plate that supports the ram. Actually, the open end of the ram is adapted to fit into a bore in the plate that supports it and to receive fluid from passage means carried by the plate and preferably internal of the plate.

Where the fluid is adapted to flow from one ram toward a second ram for sequential operation of the rams, that end of the ram opposite the support plate and operating against the thrust plate of the next upright, may have the same construction as that just described. Therefore, the thrust plate may be constructed as is the base plate with the relatively moving portion of the ram assembled thereto as is the relatively stationary portion assembled to the base plate.

Where a series of uprights are to be utilized, I am able to secure a series of rams for lifting the series of uprights. Each upright functioning in the assembly will have, where necessary, a base plate and a thrust plate, and preferably the base plates and thrust plates will have the same construction although that is not essential. The relatively movable portions of the ram, which are a cylinder and a piston, may be applied between the thrust plate and the base plate. Then, through suitable means such as will be described hereinafter, and which preferably take the form ofa hollow nut, the piston and cylinder may be secured to the thrust and base plates. Where the piston is secured to the thrust plate, it will supply fluid to the passage in the thrust plate, this fluid then moving through a rigid pipe downwardly to the base plate of the secondary upright and to a second ram, and so on as may be desired.

l have thus outlined rather broadly the more important features of my invention in order that the detailed description thereof that follows may be better understood. There are, of course, additional features of my invention that will be described hereinafter and which will form the subject of the claims appended hereto. Those skilled in the art will appreciate that the concept on which my disclosure is based may readily be utilized as a basis for the design of other structures for carrying out the several purposes of my invention. It is important, therefore, that the claims be regarded as including such equivalent constructions as do not depart from the spirit and scope of my invention in order to prevent the appropriation of my invention by those skilled in the art.

In the drawings:

FIG. I is a vertical side elevational view showing schematically the arrangement of my fork lift truck to which the mast assembly of the present invention is applied.

FIG. 2 is a plan view of FIG. 1.

FIG. 3 is a vertical side elevational view showing the truck of FIG. I in a full lift position.

FIG. 4 is a cross-sectional view through the mast taken along the lines 4-4 of FIG. 1.

FIG. 5 is a cross-sectional view similar to FIG. 4 but taken along the lines 5-5 of FIG. 1.

FIG. 6 is an enlarged fragmentary sectional view showing the lower end of the upright assembly and ram.

FIG. 7. is an enlarged fragmentary sectional view showing the upper end ofthe upright assembly and ram.

FIG. 8 is an enlarged elevational view partly in section and partly in parts broken away showing the hydraulic rams for each of the uprights and the hydraulic circuitry for supplying power to each of the rams.

Referring to the drawings and more particularly to FIG. 1, a fork lift truck 10 comprises a main frame 11 having rear wheels 12 and front wheels 13 controlled by means of steering wheel 14. A suitable power plant is enclosed within the housing 15.

Supported from the main frame 11 is a primary upright assembly l6 and one or more secondary or movable upright assemblies l7, l8 and 19 mounted for vertical movement relative to the primary or fixed upright assembly 16. The secondary upright assembly 17 is mounted for movement directly on the primary upright assembly 16 and the remaining secondary

upright assemblies

18 and 19 are mounted for relative vertical movement in telescoping relationship, as shown in FIG. 3.

A load carriage 20 is mounted for vertical movement on the forward secondary upright assembly 19 so that a load can be moved from a lower position to the top of the forward secondary upright 19, as shown in FIG. 3. The three secondary or movable upright assemblies can be moved relative to one another and relative to the primary upright assembly 16. The load carriage 20 includes a pair of horizontal forks 21 adapted to engage and lift a load such as a pallet, as shown in FIG. 2.

As best seen in FIGS. 4 and 5, the primary upright assembly 16 is constructed of a pair of channel uprights 22 of generally block-S cross-sectional configuration joined together by a vertical plate 23 which is welded or otherwise secured to the transverse web 24 of each upright. It is important to realize that the plate 23 extends through a very substantial part of the length of the channel uprights 22 and acts with those uprights to form an integral unit that has a very high degree or rigidity. Each of the channel uprights 22 has an outwardly facing channel 25 and an inwardly facing channel 26. I secure the primary upright assembly 16 to the truck body by bolts 27 which extend through the inwardly facing channel 26.

Each of the secondary or movable upright assemblies is of similar construction to the primary upright and each includes a pair of block-S cross-sectional channel uprights 28 having a web 29 with a vertical plate 30 welded to a transverse web 29 to form integral units that have a very high degree of rigidity.

The channel uprights of each of the upright assemblies are interdigitated as shown in FIGS. 4 and 5. I secure upper rollers 31 to the rear longitudinal web 32 of each of the uprights which bear against the forward face of the

transverse webs

24 or 29. A portion of the transverse flange 33 of each of the uprights adjacent to each of the upper rollers 31 is cut away to enable the rollers to engage the transverse webs. In like manner, each of the uprights is provided with a lower roller 34 rotatably mounted on the front longitudinal web 35 of each upright and mounted to engage the rear side of the

webs

24 or 29. A portion of the transverse flange 36 of each of the uprights is cut away adjacent each of the lower rollers 34 to permit the rollers to engage the transverse web 24. Thus, all of the upper rollers 31 and all of the lower rollers 34 respectively engage the forward and rear faces of the

transverse webs

24 or 29 of an adjacent upright. Additionally, each upper roller 31 is surrounded or bounded by the sides of adjacent uprights. Thus, the upper rollers 3| are surrounded by three surfaces or flanges of an adjacent upright as well as to the surface to which it is secured and the lower rollers 34 are likewise so surrounded or nested on all four sides. This novel upright construction provides a mast construction of exceptional rigidity. Moreover, I can achieve this rigid construction while actually arranging the primary channel uprights 22 in close relationship to one another with the channel uprights 28 of each of the movable uprights correspondingly close to one another. Therefore, l am able through my novel inventive concept to contribute an upright assembly that is very narrow and enables the truck driver to have a better view from his position on the truck when manipulating a load.

As best seen in FIG. 4, each of the pairs of

channel uprights

22 and 28 are connected near the bottom end thereof by the plate 38 which is welded or otherwise secured to the front longitudinal web 35 of each of the uprights and extends a slight distance rearwardly thereof beyond the

transverse webs

24 or 29 and the vertical plates 23 or 30 for purposes which I will explain hereinafter. At the upper end of each of the channel uprights 22 and 28, I mount a thrust plate 39 which is welded or otherwise secured to each of the forward webs 35 of the channel uprights with each of the thrust plates extending rearwardly of the vertical plates 23 or 30 into overlapping relationship with the bottom plate 38 of an adjacent upright,

Thus, it will be seen when considering FIGS. 4 and that I can utilize the space between the channel uprights and each of the vertical plates 23 and 30 for a ram cylinder 40 mounted on the bottom plate 38 of the primary upright with the piston 41 thereof engaging the thrust plate 39 of a movable upright assembly 17. In like manner, I mount ram cylinders 42, 43 on each of the bottom plates 38 of the movable upright assemblies l8 and 19 as well as a ram 44 for the load carriage 20. Each of the

ram cylinders

42, 43 and 44 have a

piston

45, 46 and 47 respectively connected to the thrust plate of the next adjacent upright assembly. The piston 47 of ram 44 is provided with a sprocket 48 about which a pair of chains 49 are reeved. The chain ends 50 are fixed to the ram 47 and the other end 51 is connected to the load carriage 20.

The hydraulic circuit for operating the rams includes a reservoir 52, connected by a pipe 54 to a pump 56. The pump 56 is driven by a suitable motor 58, and is connected to a twoway control valve 60 by a pipe 62. The two-way control valve 60 is connected by a pipe 64 to the bottom end of the first primary ram 40. A pipe 66 is also connected between the twoway control valve 60 and the reservoir 52.

By this arrangement, fluid is drawn from the reservoir 52 by the pump 56 and moved under system pressure to the two-way control valve 60. From the two-way control valve 60, the pressurized fluid can be moved to the ram system for lifting purposes. Also, the two-way control valve 60 is effective to dump fluid from the ram system back into the reservoir 52 for purposes of lowering the rams 40 and 42 through 44.

Referring particularly to FIGS. 6 through 8, the bottom end of each of the ram cylinders is closed by head member 67 having a threaded axial passage and a shoulder 69 that supports the cylinder and bears against the bottom plate 38. A portion 70 of the head member 67 projects part way into a bore formed in the bottom plate 38 which stabilizes the ram relatively to the bottom plate. The head member 67, and thus the ram. is secured to the bottom plate 38 by means ofa threaded cap 71 threaded into the axial passage 68. Suitable sealing means, such as O-rings, are provided between the bottom plate 38 and the flange of the cap 7], as well as between the shoulder 69 of the head member and the bottom plate 38. The cap 71 is provided with a bore 72 communicating with axial orifices 73, so that when the cap is in assembled position the orifices 73 communicate with a passage 74 extending through the bottom plate 38 and connected at 75 to a vertical pipe 76.

As seen in FIG. 7 of the drawings, each of the pistons for the rams is tubular and extends out through the top of the ram cylinder. The upper end of the ram cylinder is enlarged for receiving a packing seal 77 held in place by a threaded annular retainer 78. The upper end of the piston 4| is threaded to receive a threaded cap 79 having a counterbore 80 communicating with orifices 8] which in turn communicates with a passage 82 in the thrust plate 39. Suitable sealing means, such as O-

rings

83 and 84, seal the upper end of the piston to the thrust plate. The passage 82 is connected to the vertical pipe 76 which, of course, extends from the thrust plate 39 of one upright assembly to the base plate of the same upright assembly, as clearly shown in FIG. 8 of the drawings. It will be understood that the vertical pipe 76 of the primary or fixed upright assembly communicates with the control valve 60. Also, the ram 44 of the upright assembly 19 is provided with a solid rather than a tubular piston provided with the sprockets 48 which operates the load carriage through the lift chains 49.

In summary, the present invention provides a novel upright and ram construction in which the uprights are of very rigid and stable construction while at the same time being compact to increase the operator's visibility. Moreover, the upright assembly is actuated by rams which are hydraulically connected in series through a hydraulic circuit employing a minimum of piping with the further feature that none of the piping need to be flexible.

Iclaim:

1. A load lifting mast for a truck having an upright and a load carrier mounted in front of said upright and having a movable part adapted to impart lifting movement to said load carrier, the improvement that comprises fixing a base plate on the base of said upright with said base plate having a fluid passage connected at one end to a source of fluid pressure and terminating in an opening, a ram having an opening in its lower end adapted for coaction with the opening of said passage when the lower end of said ram is applied to said base plate, and means securing said ram to said base plate and effecting the closing of said openings to form a continuous sealed passage from said fluid source through said plate fluid passage to said ram.

2. The invention according to claim 1, wherein said base plate passage terminates at an opening terminating in the upper face of said base plate and into which the lower end of the ram fits so as to connect the opening of the lower end of the ram with said passage, and means extending into said base plate and coacting with said ram to secure said ram to said base plate whereby to form said continuous sealed passage.

3. The invention according to claim 2, wherein said means extending into said base plate i s a nut entering anopening in the underside of said base plate and threaded into the opening of the ram, said ram opening having threads formed on its surface for coaction with said nut, said nut thereby securing the ram to said base plate while closing the open end of said ram.

4. The invention according to claim 3, wherein said nut is itself formed with an internal opening whereby to establish a flow path from said fluid passage to said ram.

5. The invention according to claim 1, wherein said upright is a primary upright and said load carrier is a secondary upright, said secondary upright having a thrust plate fixed thereto and extending rearwardly above said ram and having a passage and an opening formed similarly to said passage and opening at said base plate, said ram having a hollow piston as its movable part with an open end adapted to lift said secondary upright through said thrust plate a nd means assembling said piston to said thrust plate, aha communicating with the opening and passage of said thrust plate whereby fluid may flow into said passage from said ram.

6. The invention according to claim 5, wherein a base plate assembly on said secondary upright like that on said primary upright, and a second ram supported on said base plate and asseml ledtheretoas is the first ram to the primary base plate.

7. The invention according to claim 6 wherein the base plate passage on said secondary upright is connected to a fluid passage terminating at the passage of the thrust plate of the secondary upright.

8. The invention according to claim I. wherein said upright is a primary upright and said load carrier is a secondary upright, said secondary upright having a thrust plate fixed thereto, said thrust plate being like said base plate on said primary upright but oppositely secured to said secondary upright, and means assembling the movable part of said ram to said thrust plate in the same manner as the lower end of the ram is secured to said base plate, said movable part being hollow and having an opening like the opening in the lower end of said ram.

9. The invention according to claim 5 wherein the base and thrust plates are the same but opposed to one another. and that the open ends of the two relatively movable parts of the rams are the same so that the rams may be assembled in either of opposed positions between said plates.