US2791292A - Ram guide for lift truck - Google Patents

Description

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May 7, 1957 Filed Aug. 31, 1953 G. F. QUAYLE RAM GUIDE FOR LIFT TRUCK 4 Sheets- Sheet 1 INVENTOR GP. Q /e ATTORNEY May 7, 1957 e. F. QUAYLE RAM GUIDE FOR LIFT TRUCK 4 Sheds-Sheet 2 Filed Aug. 31, 1953 INVENTOR 6P7 Qua BY E ATTORNEY May 7, 1957 e. F. QUAYLE RAM GUIDE FOR LIFT TRUCK 4 Sheets-Sheet 3 Filed Aug. 31, 1953 ATTORNEY May 7, 1957 Filed 18115.31, 1953 G. F. QUAYLE RAM GUIDE FOR LIFT TRUCK TiclE.

4 Sheets-Sheet 4 INVENTOR ATTORN EY RAM GUIDE FGR LIFT TRUCK George F; Quayle, Philadelphia, Pa., assignor to The Yale & Towne Manufacturing Company, Stamford, Conn, a corporation. of Connecticut Application August 3-1, 1953, Serial No. 377,604

3: Claims. (Cl. 187-9) This invention relates to industrial trucks of that class in which a hydraulic ram is used to move a load relatively to uprights carried by-the truck. More particularly, the invention relatesto that type of truck in which the uprights-are adapted to carry a secondary pair of uprights for movement relatively to the first orprimary uprights, a load-lifting carriage being then mounted for movement on the secondary upright-s. Thehydraulic ram lifts the carriagethrough chains secured at one end to the car'- riage and at the other end relatively to the primary uprights ofthe truck. The ram is adapted to lift the secondary uprights through physical engagement there'- with after the carriage has been moved a relatively short distanceon the secondary uprights, so that thereafter the ram lifts both the secondary uprights and the carriage.

In an arrangement of the particular class, it will be appreciated that very considerable stresses are transmit ted to the hydraulic ram by any force tending to move the piston of the ram laterally in any direction relatively to the cylinder of the ram. In other words, it is extremely important that the forces acting on the piston be transmitted along the center line-of the piston and the cylinder of'the ram:

*It is the purpose'ot'my invention to contribute means whereby all pressures applied to the piston will be axial thereof, in all positions of the secondary uprights rela tively to the ram.

To=understand fully the problem solved by my inven: tion, it must be 'considered' that the ram in trucks of this class is'mou'nted relatively to the primary uprights, but

that the'sec'ondaryuprights do not always remain perfectly Paiticularly' as the aligned with the primary uprights. secondary uprights are extended upwardly, these uprights lean somewhat under the weight of the'load, and may also tend' to-cock in a lateral direction relatively tothe primary uprights. Becausethe movement of the load carriageis parallel to the secondary uprights, this movement is at .an' angle to the primary uprights when the secondary uprights'lean or cock, and the chains through which the carriage is lifted then exert a pull that'is out of alignment with the primary uprights. By my invention, 1 cause the forces'that lift the carriage to be applied in the axis of'the ram without regard to the-leaning of'the secondary uprights or to the particular direction of i the pull exerted by the lifting chains.

As a particular'feature of my invention, 1 guide the of theram in. alignment with this point as the secondary" uprightsl'ean or cock relatively to the primary uprights. Thereby the ram is substantially aligned with the secondary. uprightsat' all times, and when the lifting-chains areout of alignment with the primary uprights, the stresses transmitted byrthese chains to the ram arein the axisoffthez-ram'... Asa; further part of this feature, I arrange the: ram pistonto enter into lifting engagement with the secondaryruprightstcoaarially with the. aforesaidzpoint rela nited States atent ice 2 tively to the upper end of these uprights. By this'arrangement I enable the rant to' lift the secondary uprights through forces that are maintained in the axis of the ram.

In order to appreciate further the considerable value of my invention, it should'be realized that frequently the secondary uprights in trucks of the particular class will not move downwardly freely when the ram is contracted incidental to the lowering of the carriage. This means that there is a tendency for the piston of the ram to move a considerable distance downwardly from the secondary uprights should these secondary uprights remain in an upward position as the piston moves downwardly with the carriage. To obviate the damagethat can result by the eventual freeing of the uprights for movement downwardly against the piston, .a lost'motion connection is applied between the secondary uprights and the piston to limit the free movement between the two. Should the uprights be prevented by" some obstacle from moving downwardly, very considerable pressure can be developed between the piston and the secondary uprights through this lost motion connection because of the heavy load that is imposed on the piston by the carriage and the chains during the lowering ofthe loaded carriage. It is a feature of my invention that the lost motion connection is applied axially of the piston so that n side thrusts are applied between the piston and the cylinder because of the operation of the lost motion connection.

As a detailed f'eature of my invention, 1 utilize a guide rod for guiding the ram piston relatively to the secondary uprights with this rod acting also as a lost motion connection between the piston and these uprights. I maintain the. rod in axiallalignment'with the ram at all times, and for this-purpose 1 mount the rod in the piston through heating means that are spaced a considerable distance along the length of the rod. More particularly, I prefer to utilize bearing meansfor the rod in the upper end of the piston, and also lower bearing means through which the lower end of the rod is held in an axial position in the piston. I attach-the upper 'end of the guide rod to the secondary uprights in such a waythat the rod is extended when the piston moves downwardly relatively to these uprights, but I limit theextension of the rod by providing on the rod a collar that is adapted to -engage the upper end of the piston. By so-limiting the extension of the rod, I maintain the lower bearing means always a considerable distance below the upper bearing means, and I' can therebyhold th'e rod'very effectively in axial relation to the piston. Becausethe ram then acts always in alignment with the point at which the guide rod is attached to the secondary uprights, the leaning or cocking of these uprights does not cause lateral stresses in the ram. It is, of course, thecollar on-the guide rod that enables me'to utilize the ram piston to move the secondary uprights downwardly:

Whiledshall describe my invention without regard to pivoting uprights, it should'be understood that my concept will operate insubstantially the same fashion whether ornotthe primaryuprightsare pivoted on the'main frame of the truclc or: are rigidly secured thereto.

1 have thus'outlinedrather broadly the more import-ant features of myinventionin order that the detailed descrip tion thereof that follows may be better understood, and

in order that my contribution to the artmay be better appreciated. T herezare, of course, additional featuresof my inventionthat will be described hereinafter and which will form the subject of the claims appended hereto. Those skilled in theart will appreciate that the conception on which my disclosure is based may readily be utilized as a basis-for the designing of other structures for carryingout the several'purposes of my invention. It is important, therefore, that the claims be'reg-arded'as' including such equivalent constructions as do not depart ram guide, with the ram piston extended to lift the secondary uprights.

(Fig. 5 is similar to Fig. 4, but with the ram guide limiting downward movement of the piston relatively to the secondary uprights.

Fig. 6 is a view taken on the line 6-6 of Fig. 1, showing the mounting of the ram cylinder.

In order that my invention may be fully appreciated, I show in Fig. -l of the drawings an industrial lift truck T of the class having -a pair of primary uprights '10, a pair of secondary uprights 1 1, and a load carriage 12 upon which are lifting forks 13. As may be best seen in Fig. 2, the uprights 10, 11 are formed as channel members, with rollers 14 engaged in the channels of the primary uprights to guide the secondary uprights 11 for vertical movement, and rollers 15 similarly guiding the carriage 12 (for vertical movement on the secondary uprights 11. The primary uprights 10 are integrally connected as a unit by upper cross member 116 shown best in Figs. 1-3, lower cross member 17 shown best in Figs. 1 and 6, and an intermediate cross member 18 also shown best in Figs. 1 and 6.

I show in Figs. 1, 2, and 3 a pair ofrollers 19 on the upper cross member 116 for guiding the secondary uprights 11 in a lateral sense relatively to the primary uprights 10. A pair of rollers 20 serve a similar purpose at the lower ends of the uprights "11, as shown in Figs. 2 and 6. Also, the carriage '12 has rollers 21, Fig. 2, for guiding it laterally -relatively to the secondary uprights 1 1.

The lower cross member 17 has upon it a hydraulic ram, indicated generally by the numeral 22, for lifting both the load carriage 12 and secondary uprights 11. Ram 22 has a cylinder 23 mounted relatively to the primary uprights 10 through the lower cross member 17 in position bet-ween the secondary uprights 11. In the cylinder 23 is a piston .24 adapted to be extended upwardly by fluid pressure, with a packing 25, shown in Figs. 3 and 4, applied between the piston and cylinder to prevent leakage of fluid. In the construction that I have chosen to illustrate, the packing 25 is retained in position between rings 25a, 25b, and the packing 25 together with the rings would of course accept considerable stress in the event that side thrust were to occur between the piston and cylinder.

:On the upper end of the piston 24 is a cross head 26 having a pair of wheels 27 over which lifting chains 28 are rceved, as seen in Figs. 1 and 3. I show the chains 28 secured at one end to the ram cylinder 23 through a bracket 29, and at the other end to the load carriage 12 through attachment members 30, shown in Fig. 6. The ram piston 24 when first extended from its positions of Figs. 1 and 5 to its position of Fig. 4 lifts the carriage 12 through the chains 28. With the cross head 26 engaging an upper cross member 31 on the secondary uprights 11, as shown in Fig. 4, further extension of the ram piston 24 moves the secondary uprights 1 1 up-wardlyas the carriage 12 continues its lifting movement. The carriage '12 moves at double the speed of the secondary uprights 11 because the movement of the ram piston 24 is multiplied by the chain arrangement. When the carriage 12 reaches its limit of upward movement relatively to the secondary uprights 1 1, the carriage engages the cross member 31 to lift these uprights whereby the carriage can move still further upwardly, with the member 31 then 4 moving away from the cross head 26. So far as I have described it, this construction is conventional.

I have already described the leaning or cocking action of the secondary uprights in trucks of the particular class. 5 Thus, in the truck that I illustrate, the weight of a load lifted on the forks 13 tends to cause the secondary uprights 11 to lean forwardly relatively to the primary uprights 10. Because of small clearances incidental to the construction of the rollers 14 on the secondary uprights l l, these uprights actually do lean, and the leaning action becomes more pronounced as the secondary uprights 11 are extended upwardly. In a somewhat similar way, the secondary uprights 11 tend to cock in a transverse direction when the forks 13 support a load that is offset relatively to the center line of the truck. Since the load carriage .12 is mounted on the secondary uprights 11, these uprights when in cooked or leaning position cause the load lifting chains 28 to exert a pull that is out of alignment with the primary uprights 10.

I shall now describe in detail the exceedingly novel construction whereby I maintain the pull of the lifting chains in alignment with the hydraulic ram, and so control the forces on the ram as to act in the axis of the ram when the secondary uprights lean or cock.

Thus, I mount the ram 22 for limited universal movement relatively to the primary uprights 10, utilizing preferably for this purpose a tubular member 32 on the cross member 17, as well shown in Figure 6. Somewhat above the lower end of the ram cylinder 23 is a flange 33 supporting the cylinder on the upper end of the tubular member 32. The lower end 34 of the cylinder is then positioned within the tubular member 32 to hold the ram 22 in position on the cross member 17. The lower end of the ram has a lateral clearance relatively to the member 32, whereby the ram 22 can lean relatively to the primary uprights 10.

At the upper end of the ram piston 24 I provide a novel guide rod 35, best seen in Figures 3, 4, and 5. I form the upper end of the piston 24 preferably as a screw plug 36, and this plug has a central opening 37 in which the guide rod 35 is adapted to slide in the axis of the piston 24. Packings 38 prevent the leakage of fluid from the upper end of the piston 24 around the rod 35. The screw plug 36 has a laterally extending flange 39, and it is through this flange, incidentally, that I mount the cross head 26 on the piston 24.

It is extremely important to note that I hold the lower end of the guide rod 35 in the axis of the piston 24, and I show for this purpose a bushing 40 retained on the lower end of the rod by snap rings 41. The bushing 40 is adapted to slide on the inner surface of the piston 24, and is formed to allow the passage of fluid around it so that its movement is not obstructed by fluid in the piston. Further, I mount a collar 42 integrally upon the guide rod 35 at an intermediate point in the length of the rod. By engaging the screw plug 36 in the position shown in Fig. 5, the collar 42 limits outward movement of the rod 35 relatively to the piston 24. Through this arrangement, the screw plug 36 and bushing 40 are maintained always in quite widely separated positions, and are effective therefore as bearing means at two ditferent points along the length of the guide rod 35 to hold the rod aligned in the axis of the ram piston 24.

To illustrate the attachment of the upper end of the guide rod 35 at a particular point relatively to the upper end of the secondary uprights 11, I show in Figs. 4 and 5 a reduced upper end portion 43 on the guide rod 35 positioned in an opening in the cross member 31, and retained in this opening by a snap ring 44. It will be apparent that the rod 35 guides the piston 24 relatively to the point at which the rod is attached to the cross member 31. When the secondary uprights 11 lean, therefore, the ram 22 also leans by movement of the lower end 34 of the ram cylinder 23 in the tubular mounting member 32. Because the guide rod 35 is held ayrsneea actually in the axis of the ram piston 24, the forces applied to the ram 22 by the lifting chains 28 are maintained in alignment with the ram. Also, the piston 24 when engaging the cross member 31 as shown in Fig. 4, lifts the secondary uprights 11 through forces applied in the axis of the ram.

It will be observed further that the collar 42 on the guide rod 35 enables me to utilize the rod as a lost motion connection for limiting downward movement of the ram piston 24 relatively to the secondary uprights 11. Thus, in the event that the secondary uprights 11 do not move freely downward, the downward movement of the piston will cause the screw plug 36 to engage the collar 42 as in Fig. 5, and the pull of the lifting chains 28 can then act through the piston 24 and rod 35 to pull the secondary uprights 11 downwardly. In this instance, as during the lifting action of the ram, the forces applied to the ram are aligned with the ram axis without regard to the leaning or cocking of the secondary uprights.

Through the novel construction that I have conceived, I enable the lift ram in a truck of the particular class to act without side thrust between the ram piston and cylinder, and I thereby enable the ram to operate efficiently and without the damaging effects that are a result of side thrust.

I believe that the construction and operation of my novel ram guide will now be clearly understood, and that its very considerable merit will be fully appreciated by those skilled in the art.

I now claim:

1. In a truck of the class described, a main frame having a pair of spaced uprights, a member mounted for vertical lifting and lowering movement on said uprights, a hydraulic ram including a cylinder and a piston in said cylinder for moving said member on said uprights, mounting means for said ram cylinder positioned between said uprights and fixed relatively thereto, said mounting means being formed to support said ram cylinder for limited universal movement whereby said ram cylinder may be maintained in predetermined alignment relatively to said member, a guide rod for said ram piston and cylinder mounted at its upper end on said member and carrying at its lower end within said ram piston a bushing coacting with the inner surface of said ram piston, and bearing means in which said guide rod slides mounted on said ram piston, the said bearing means and the bushing causing said guide rod to have contact with said ram piston at two linearly spaced surfaces whereby said guide rod is held in alignment with the axis of said ram piston for moving said ram piston and cylinder 50 relatively to said mounting means.

2. In a truck of the class described, a main frame having a pair of spaced uprights, a member mounted for vertical lifting and lowering movement on said uprights, a hydraulic ram including a cylinder and a piston in said cylinder for moving said member on said uprights, mounting means for said ram cylinder positioned between said uprights and fixed relatively thereto, said mounting means being formed to support said ram cylinder for limited universal movement whereby said ram cylinder may be maintained in predetermined alignment relatively to said member, a guide rod for said ram piston and cylinder mounted at its upper end on said member and extending downwardly into said ram piston, said guide rod carrying at its lower end within said ram piston bearing means coacting with the inner surface of said ram piston, and additional bearing means between said guide rod and piston linearly displaced from said first bearing means for guiding said guide rod relatively to said piston, the said two bearing means causing said guide rod to have guiding contact with said ram piston at two linearly spaced surfaces whereby said guide rod is held in alignment with the axis of said ram piston for moving said ram piston and cylinder relatively to said mounting means.

3. In a truck of the class described, a main frame having a pair of spaced uprights, a member mounted for vertical lifting and lowering movement on said uprights, a hydraulic ram including a cylinder and a piston in said cylinder for moving said member on said uprights, mounting means for said ram cylinder positioned between said uprights and fixed relatively thereto, said mounting means being formed to support said ram cylinder for limited universal movement whereby said ram cylinder may be maintained in predetermined alignment relatively to said member, a guide rod for said ram piston and cylinder mounted at its upper end on said member and carrying at its lower end within said ram piston a bushing coacting with the inner surface of said ram piston, bearing means in which said guide rod slides mounted on said ram piston, the said bearing means and the bushing causing said guide rod to have contact with said ram piston at two linearly spaced surfaces whereby said guide rod is held in alignment with the axis of said ram piston for moving said ram piston and cylinder relatively to said mounting means, and a collar fixed to said guide rod for limiting the outward movement of said guide rod with respect to said ram piston.

References Cited in the file of this patent UNITED STATES PATENTS 742,891 McCarroll Nov. 3, 1903 2,595,120 Barnes Apr. 29, 1952 2,625,285 Weaver Jan. 13, 1953

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