US2009970A - Variable fluid-operated elevating truck - Google Patents

Description

Juy 3,1935.. D. E. HENNEssY VARIABLE FLUID OPERATED ELEVATING TRUCK Filed sept. 9, 1932 l 3 Sheets-Sheet ll nvenTo'r.

Eli-ienness July 3Q), 1935 D. E. HENNEssY VARIABLE FLUID `OPERATED ELEVATING TRUCK Filed Sept. 9, 1932 3 Sheets-Sheet 2 lnvenTor.

7 ZIM ATTyS.

uly 30, 1935..

D. E. HENNESSY VARIABLE FLUID OPERATED ELEVATING TRUCK Filed Sept. 9, 1952 5 Sheets-Sheet 3 w V/ T S .S T T. OS A .l8r m mnn/ NSMHW v .EMM A @E 3 .www 6 n G Dm/ y w -l w Y. 9 Af 8 6 QV ..6 i. :,w 77 .5 CU /f .27 57 5 Patented July 30, 1935 UNI.TliD STATES PMENT oFFlca VARIABLE muratore-RATED ELEVAMNG TRUCK. Daniel E.; H ennessy,v Watertown, Mass., assigner to Lewis-Shepard Gompany, Watertown, Mass.,

a corporation ofv Massachusetts Amazon sentences, 1932., serai No. 652,358.

la claims.

meer-ticle t0 be raised-)such es e Platform. cr skidf.;

@md hal/'ing uPWaidlY. .movable .1Q-3.@ sullqrtg.. l. means with mechanism for raising thevsarnre to lift thearticle, skid, or platform,y and transport it from one place to another. l Y' i' Such trucks areQrdinaril-yused for transporting skids 0r platforms carrying light or ,heavy loads Y and in which the under 'clearance of the s lid or platform may vary from sevento eleven inches,` or

more.

It has heretofore beerfcustomary to'maketrucks for practically each heightl of platform under w clearance. Furthermore, if a truck 7 highwhen the load supporting means is in lowered position, having a 6 lift for the load supporting means, is employed to raise a platform having several vinches under clearance, with a vsuiiciently high me- 2 chanical lifting ratio required for. heavy duty,

considerable time would be consumed to raise 'the load supporting means into engagement with the.

platform before the lifting of the platform is loegun. t

One of the objects of the inventionY is to provide an elevating truck whichmavhe used efficiently with any .standard height skid or platform..

Another object of the vinvention is tu provide an elevating truck of this character with meansv for 3a@ elevating the load supporting means to .lift loads varying from licht to' very heavy loads in which the force required to be appliedr to the lifting lever does not exceed a reasonable iria-ni-V mun'l, while at the same time lthe total lifting op-V eration may be performed in a minimum time.

elevating truck comprising a vertical hydraulic jack provided with a single Vliftingranik operable by a plurality'of pumping elements .and having means selectively `operable to enable one .or more.

40 of the'pumps to be actuated to raise the itam.

A furtherobject of the invention is to provide an elevating truck Vhaving a hydraulic jack. pros.

vided 'with a single lifting or ram .element 010erable by a-plurality .of pumps .of different capacityJ4 with means selectively operable to actuatc .one or more of the pumps, and thereby to enable thcload supporting means to be raised rapidly or more slowly with increased effective pow-er applied through the same actuating mechanism. p

In elevating trucks having a hydraulic lifting jack heretofore constructed, the lifting jack has been located yin positions slightly inclined u pwardly from the horizontal and `the relatively move ing surfaces so arranged that a seepage takes place around them resulting in the loss of reserve Another object of the invention isto provide'anl uid, thereby greatly impairins the efficiency `of the lifting mechanism.- y

Another object of the invention is to provide an elevating truck having a hydraulic iacls for raisine the load supporting means in which 'less of s fluid will not coeur. This is accomplished by previding a construction in which the lifting jack is at all times 'in a vertical or substantially vertical position.

More specifically the object of the invention i l0.:A to provide an elevating truck with a hydraulic jack comprising a reservoir, aram cylinder andrarn' and a pump or pumps for drawing liquid from the reservoir and discharging it under pressure into the ram cylinder, so constructed as to avoid any 15 loss of liquid by seepage or otherwise.

A further object of the invention is to provide.

a lifting truck having a hydraulic lifting j acl; which the lifting force ofthe ram is directlyV er# plied to the load supportingmeans in a vertical 2Q direction. Y

Another object of the invention is to provide an elevating truck having a hydraulic lifting jack with means for preventing damage from overleeding. 2

Another object ofthe invention is to provid? @all elevating truck having a hydraulic lifting lachV with 'means for positivelyV arresting the upward movement of the load supporting means at a pre.- deterrnined height in combination with means rfor 39, preventing overload if actuation of the ypump or pumps is continued after the arrest of the lupward movement of the load ksupporting means'.

A further object of the invention is t9 Dr@- vide a graduated manually operablerelease for 3 the ,fluid pressure inthe ram cylinder to control the descent 0f the lead supporting means .to any desired rate of speed. Y t

Another .Object of the invention is te hrm/.leleY an elevating truck having a hydraulic jack .comprisme vertically movable ram'cperahle tc apply avertieel lifting frce te the 1trent endef the load supporting means, with novel v-and mechanism operable by the lifting .movement of the front end of .the lced .supporting ric Y raise the rear end of the lecci '.Sllppertirts in synchronism/ with the umlald nimmt? .Qf the frontend .of the load supporting means.

'Iheseand other objects and features .of the in.-l ven'tion will `more fully appear from the follows ing description'and the accompanying drawings andwill be ticularly pointed outlin the claims.

` Inthe drawings;A l Y 1 f vFig. -l` isa side elevation pf anelevatingtruck Q embodying my invention having a hydraulic jack for lifting the load supporting means operable by vertical swinging movement of the tongue;

Fig. 2 is a similar side elevation of a portion of a lifting truck embodying the invention in which the hydraulic jack is operated by a foot lever;

Fig. 3 is a plan view lof the lifting truck illustrated in Fig. l showing a lifting jack having a verticali-am cylinder and ram, and a plurality 0f pumps for supplying fluid under pressure thereto;

Fig. 4 is a detail View illustrating the selectively operable means employed for detachably connecting the actuating lever to one of the pump plungers, it being understood that such mechanism may be employed for connecting either pump plunger to the actuating lever or levers;

Fig. 5 is a horizontal sectionalview of the lifting jack on line 5-5 Fig. 6; and,

Fig. 5 is a view, partly in vertical section, upon the broken line' 8-l, Fig. '5, showing, also, pump cylinders and plungers therefor of different capacity.

The preferred form of elevating truck illust'rated in the drawings comprises a main frame having side bars I and2 connected at their front ends to 'ahead 3 and diverging rearwardly therefrom and provided at their rear ends with bearings 4 for arrear axle 5 having wheels 5 mounted upon it preferably outside of the side frames I and 2,

thereby providing a wire rear end support for the truck.

Suitable steering mechanism ris rotatably mounted in the head 3 of the'frame. As illustrated herein, the steering mechanism comprises a vertical steering post 'I rotatably mounted in the head 3 'and provided with 'an annular bearing 8 underlying and engaging the under face of the head, with a yoke 9 extending downwardly therefrom, the lower ends of the arms of which support a shaft 'I0 for the front steering wheel or wheels I I. The steering post 1 extends upwardly beyond the upper surface of the head 3 and has clamped upon it a split collar I2- provided with upwardly and forwardly extending ears I3 with a shaft I4 forming a fulcrum'for the tongue mounted in said earsadjacent the upper ends thereof. The. tongue preferably comprises a cylindrical tube or pipe I5 having at its upper end the usual transverse handles (not shown) and having its lower end extending into and secured to the bifurcated cylindrical upper end I6 of a tongue member which is fulcrumed upon the shaft I4 and provided with a bifurcated downward and rearward extension I1 having flat end surfaces I8 adapted to engage the collar upon the steering post in such manner as to limit the rearward swinging movement of the tongue and thereby enable it to be employed to push the truck rearwardly.

' The load supporting means preferably comprises parallel side bars I9 and 20 in the form of angle bars having their horizontal flanges overlying the frame and their vertical flangesV outside of the side bars of the frame and connected at their rear ends by a transverse girder 2l, preferably in the form of an angle bar, having its horizontal fflange flush with the upper surface of the side'bars of the load supporting The front ends of the side bars of the load supporting means are connected to an integral standard 22 having a transverse web 23 forming a dash board and upwardly extending members 24 curved forwardly at their upper ends forming a head overlying the lifting ram of the hydraulic jack, which will hereinafter be described. The head 22 of the platform is also provided with integral, downwardly extending bosses or brackets 25 which provide journals for the transverse shaft 26 upon one of which one end of a bell crank lever 21`is mounted. The bell crank lever 21 is fulcrumed upon a shaft 28 carried by suitable brackets 29 mounted upon the side bars I and 2. The other arms of the bell crank lever preferably comprise pairs of bosses 30 and 3I in each of which is mounted a shaft 32 upon which a T- shaped coupling 33 is pivotally mounted. Tension rods 34 desirably are adjustably connected to the couplings 33 by screw threaded unions and extend rearwardly therefrom longitudinally of the truck and are connected at their rear ends by reversely screw threaded couplings to T-shaped members35 which are mounted upon shafts 36 in pairs of webs 31 and 38 of a lifting lever 39 which is pivotally mounted upon the-rear axle and the rear end of which is provided with a cylindrical boss 40 having a shaft 4I mounted therein and provided at its end with anti-friction means, such as rollers 42 which underlie and engage the under faces of the horizontal flanges of the side bars of the load supporting means.

By reason of this construction the application of a vertical lifting force to the head of the load supporting means will cause upward movement thereof which in turn will raise the forwardly extending arm of the bell crank lever 21, thereby swinging the other arms or bosses 3U, 3I downwardly and forwardly, thus drawing the tension rods 34 forwardly, and in turn swinging the rear lifting lever which is pivoted upon the rear axle upwardly and forwardly, so that the rollers upon the end thereof will raise the rear end of the load supporting means. The relative dimensions of the parts thus described are so constructed that the rear end of the load supportingl means will` be lifted in substantial synchronism with the lifting movement of the front end of the load supporting means.

One of the principal objects of the invention, as above described, is to provide a hydraulic jack comprising a ram cylinder having a ram so constructed and positioned as to apply a lifting force to the load supporting means with a plurality of pumps,V preferably of different capacities, operable selectively or conjointly to supply fluid under pressureto the ram cylinder, so that by supplying the fluid under pressure at a rapid rate t0 the ram cylinder the load supporting means may be elevated quickly, or by supplying fluid under greater pressure from one of the pumps an increased lifting power will be effected to lift the load supporting means when carrying a heavy load, at a relatively low rate of speed, and without-requiring substantially greater application of force upon the mechanism for operating a single pump than would be required to operate a plurality of pumps witha lighter load.

,'In thepresent construction the ram cylinder, and preferably also the pump cylinders are in a vertical position with suitable valvevconnections between the reservoir and the pumps and between the. pumps and the ram cylinder. this construction there is no likelihood of loss of fluid by reason of seepage or in any other manner.-

By reason of Any suitable means may be employed for actuating the pump or pumps of a hydraulic jack. VAs illustrated in Fig. 1 the pump plungers are reciprocated by an actuating lever which in Yturn is oscillated by vertical swinging movements of the steering tongue, suitable connections between the actuating lever and the steering tongue being provided to permit disengagement of the steering tongue therefrom when it is to be used for steering purposes. Means are also provided for detachably connecting either or both of the pump plungers to the actuating lever, so that either pump may be operated singly `or both conjointly to force fluid under pressure into the ram cylinder.

p The invention furthermore includes an exhaust conduit leading from the ram cylinder to the reservoir oi the jack, with means manually operable toprovide a graduated 'releaseof the fluid under pressure from the ram cylinder, thereby enabling the operator to permit the load supporting means to descend at any desirable speed.

The invention further includes automatic means for preventing the production of excessive pressure in the ram cylinder which might damage or break the lifting mechanism.

In the particular embodiment of the` invention shown in the drawings the lifting jack comprises a vertical block 43, preferably of general rectangular cross section, having downwardly extending bosses which are mounted upon a shaft 44 journaled at its ends in the side frames and 2.

The block 43 desirably also is provided with a plurality of bosses 45 having bearings therein in alinement with like bearings in bosses 46 extending upwardly and rearwardly froml the head 3. The bosses 45 and 46 are connected by a shaft 47 extending through the alined bearings in said bosses.

By reason of this construction the block 43 is maintained rigidly in vertical position, as illustrated in Fig. l.

The block 43 of the jack is cored to provide.y

a reservoir 48 of ample capacity to contain suiiicient oil, or other fluid, to supply the pumps and the ram cylinder. The block 43 has centrally of its width an integral vertical ram cylinder 49Y in which a ram 50 is reciprocably mounted. Vertical pump cylinders 5| and 52 are arranged symmetrically upon opposite sides of the ram cylinder 49 and are respectively provided with plungers 53 and 54. The pumps 5| and 52 may be of the same diameter, or of different diameters, as illustrated in Figs. 5 and 6.`

vSuitable valved connections are provided for conducting liquid from the reservoir to the pump cylinders, and from the pump cylinders to the ram cylinder. In the particular construction illustrated the oil passes from the reservoir 48 through a conduit 55 to the pump cylinder 5|. The admission of oil to the conduit 55 is controlled by a poppet valve having a valve seat or casing 56 seated in an inlet leading to the conduit 55 and having screw threaded engagement with the wall of the inlet. The flow of oil through the inlet is controlled by'a spring actuated poppet valve 5l normally held against the under face of the valve seat 56 by a spring 58 interposed between the upper end of the valve seat member 55 and a suitable abutment securedtothe upper end of the valve stem. The upward movement of the plunger 53 will create a partial vacuum in the lower part of the pump cylinder 5 Ythereby causing the fluid in the reservoir to exert suiiicient pressure upon the valve 5l to depress it from itsseat, so that the liquid will i'low from the reservoir throughthe vconduit 55 into the pump cylinder 5|. When the upward movement of the `plunger has ceased, .the spring 58 of the poppet valve will return it to its seat, thereby closing the inlet and upon downward movement of the plunger 53 liquid will be forced through the conduit into the chamber 59 beneath the poppet valve 57 from which it is forced through an outlet 60 into a conduit 6 which communicates with the lower end of the ram cylinder 49.V A

.valve 62, having a valve stem `of small diameter extending into the outlet 60, is normally held in engagement with the lower walls of the outlet orifices 60 by a helical spring 63, the upper end of which engages the valve 62 and the lower end of which desirably is seated in a depression in a plug 64 suitably secured to the block. Downward movement of the plunger 53 therefore forces the liquid from the lower portion of the pump cylinder 5| through the conduit 55, thence through the outlet 60, displacing the valve 62so kthat liquid under pressure is caused to iiow through the conduit 6| into the lower end of the ram cylinder 49. When the downward movement of the plunger 53 ceases, the valve 62 is seated by. the action of the spring 63, thereby preventing liquid from iiowing backwardly from lthe ram cylinder into the. pump. t

Similar conduit 65 having a like poppet valve 66 in the inlet, therefore, establishes communication between the reservoir and the other pump cylinder 52, and upon depression of the plunger 54 in said cylinder the liquid is caused to flow through the outlet 6l into-a conduit 6B, the end of which communicates with the lower portion of the ram cylinder. A spring-pressed valve 69, similar to the spring-pressed valve62, is arranged to prevent backward flow from the ram cylinder into the pump in the manner lheretofore described.

Inasmuch as the iiuid pressure transmitted from a pump cylinder to the ram cylinder, when a predetermined force isapplied to the pump cylinder, is inversely proportional to the respective crossv sectional areas of the pump cylinder and ram cylinder, the provision of a plurality of pumps selectively operable to force iiuid under pressure from the reservoir into the ram cylinder enables the operator, while exerting substantially the same force upon an actuating lever, to exert different forces upon the ram of the ram cylinder. When4 two or more pumps'are reciprocated conjointly by the actuating means, the force exerted upon the ram approximates the relative inverse proportion of the sum of the cross sectional areas of the pump cylinders to that of the ram cylinder.' The amount of iluid, however, which is forced from the pump cylinder to the ram cylinder, when the plunger is given a predetermined stroke, varies in amount in direct proportion'to the relative cross sectional areas of the pump cylinder and ram cylinder. Consequently, with a smaller pump actuated by the same force, a greater number of reciprocations is necessary to raise the ram cylinder a predetermined distance. As a consequence, the selective operation of a .plurality of pumps of diierent diameters, either singly or conjointly, enables the operator employing substantially the same force upon the actuating means to raise the ram cylinder rapidly when alight load is to be lifted, less rapidly when an intermediate load isto be lifted, and

Ystill more slowly when a maximum load is to be lifted.

Means for preventing the generation-oi an excessive fluid pressure in the ram'cylinder is provided. As illustrated, the mechanism for accomplishing this purpose comprises a'npple 10 having a screw threaded hollow stem which engages a complementary internal thread in the walls of a boss 1l which is bored to communicate with the conduit 68. A cylindrical valve casing 12 is externally threaded upon the nipple 10 and encloses a valve 13 which when seated engages the upper face of the nipple. The valve 13 is provided with a stem 14 which extends axially through the casing 12 and a heavy spring 15 interposed `between the upper end of the valve casing and the valve 13 serves to hold the valve normally in seated position unless sufficient pressure is built up to raise the valve. The valve casing is provided with a plurality of ports 16 through which the liquid may escape into the reservoir when the valve 13 is raised from its seat by such excessive pressure. I

Any suitable manually operable means for permitting graduated-release of the liquid from the ram cylinder maybe provided. In the preferred construction the conduit 68 is provided with aV vertical branch: 11 which communicates with an venlarged chamber in a boss 18 extending upwardly from the lower wall of the reservoir. rIhe ball valve 19 is seated at the upper end of the conduit 11 and is adapted to be held in seated position by a rod 80, the lower end of'which has screw threaded engagement with the internal wall of the boss 18. The lower end of the rod V8) desirably is slotted crosswise to a distance slightly above the upper end of the boss when the ball is held in seated position to provide a delicately adjustable outlet 8i which, when the rod is raised suiciently to vrelease the ball from its seat, will permitliquid to ow from the conduit 11 through the enlarged chamber in the boss 18 and thence through the adjustable outlet 8| into the reservoir. By reason of this construction the release ofiiuid under pressure from the ram cylinder can be very accurately controlled as the effective area of the outlet 8i is determined by the distance between the wall forming the end of the rslot and the upper end of the boss 18. The screw threaded connection between the lower end of the rod 88 and the boss 18 also enables delicate adjustment of the ball valve 19 relatively to' its seat, and the sinuous course followed by the uid under pressure passing around the ball, thence upwardly through the slot in the lower end oi the rod, and nally through the outlet, provides a delicate control which will enable the load supporting means to be lowered at any desired rate irrespective of the weight of theA load upon it. The rod 88 desirably extends through a suitable b'earing in the-cover 82 for the reservoir and is provided with ahandlel 83.,by which it can be conveniently rotated by the operator. In the constructions illustrated in Figs. 1 to:3 the upwardly extending curved members 24 of the standards 22 are provided at their outer ends with bosses 84 in which a shaft 85 ismounted and an anti-friction roller 85 engages the upper end of the ram 58, whereby it exerts'a vertical pressure upon the lunder side of the overhanging end of the standard 22 and consequently upon the load supporting means.

Any suitable means may be providedy for selectively actuating the pump plungers vsingly or ccniointly. In the construction illustrated in Figs.Y l, 3, ande, the actuating mechanism comprises levers fulcrumed upon the shaft 41 which is mounted in thebosses 45 Vand 46, withmeans for detachably connecting the levers at one end to the tongue extension and with means for detachably connectingthe opposite ends selectively to one or both of the pump plungers 53 and 54.

In the preferred construction illustrated each levercomprises an arm 81 having a boss 88 which -is Xedly secured to the shaft 41 and another arm 89 having a similar boss also secured to the shaft 41. The front ends of the arms 89 are pivotally connected to vertical legs 90 o'f` a. yoke having a horizontal portion 9| adapted to be swung over the lower end of the tongue extensions I1. The horizontal member 9i of the yoke is provided with a central downwardly extending boss or arm 92 having a recess 93 adapted to engage a pin 94 mounted in the rearward extensions l1Y of the tongue. By reason of the pivotal connection of the yoke arms 98 to the arm 89 of the actuating lever, the yoke may be swung forwardly to cause engagement of the recess 93 with the pin 94 ort may be swung rearwardly therefrom, into engagement with the block 43, out vof engagement with the tongue extension, thereby permitting the tongue to have a free steering movement.

The other arms 81 of the actuating levers are provided with outwardly extending studs 95, (see Figs. l and 4) adapted to be engaged by recesses in the lower ends of links 95 the upper ends of which are connected to pins 91 which extend through across head 98 enclosing the upper end or the plunger 53 and reciprocably mounted in a cylindrical guide 99 of larger bore than that of the pump cylinder, the walls of the guiding cylinder 99 being provided with suitable slots 98 to permit vertical Ymovement of the pin91 therein.

Means desirably are provided for selectively retaining the links 96 respectively in such position .that the recesses therein will engage the pins 95, or for holding the links in a position inA which such engagement cannot take place. A convenient device of this character comprises an arm lill pivotally mounted upon the pin 91 upon which the link 96 is mounted, the arm IGI being pro-vided with a counterweight #G2 yand with oppositely disposed lugs 103 and |94 adapted respectively to be swung into engagement with the link 96, so that when the lug |83 engages the link 96 the counterweight 182 will hold the lower recessed end of the link in engagement with the pin 95, and conversely when the counterweighted arm i8! is swung forwardly to cause the lug E84 to engage the opposite side of the link, it will hold the lower end of the link rearwardly so Ythat its recess cannot engage the pin 95. Similar constructions areprovided for detachably connecting the plunger 54 to a like actuating lever. By reason of this construction, therefore, the actuating levers can be selectively connected toV either or both of the pump plungers 53 and 54 and the opposite end of the actuating levers may be connected to or disengaged from the rearward extension of the tongue.

Where in the operation of the device it is desirable to raise the load supporting means rapidly, as from its lowest position, to engage the under face of a platform having high underclearance, or to raise the relatively light load rapidly, the counterweighted arms IUI may be swung backwardly to vcause engagement of the recesses at the lower ends of the links 95 with the pins 95 upon the arms 85 of the actuating levers. The yoke at the opposite ends of the additional time for the skid or `platform to be` actuating levers may then be swung forwardly to cause engagement of the recesses' 93 in the downwardly extending boss l92 of the yoke, thereby connecting the tongue extensionto the actuating levers. Vertical swinging movements of tlieV tongue will, therefore, cause the actuating levers to reciprocate the plungers of both pumps in unison, thereby drawing a maximum amount of liquid from the reservoir and forcing it into the ram cylinder under relatively low pressure, but at a rate sufficient to raise the ram and con-Y sequently the load supporting means rapidly. If a load of moderate weight is to be raised which, however, would necessitate a considerable exertion upon the tongue by the operator, the counterweighted lever I 0I which connects the plunger of the smaller pump to the actuating len ver, may be swung forwardly to disengage the link 96 from the pin 91 of the pump plunger.

- Vertical swinging movement of the tongue will 2k than where both pumps are actuated simultaneously. Consequently, -a greater number of reciprocations of the tongue will be required toY raise the ram, and if substantially the same force is n exerted upon the tongue byv the operator tlie fluid under pressure will be forced by'the pump into the ram cylinder underl greater pressure. thereby enabling the heavier load to be raised with eoual exertion upon the part of the operator, with the exception that he will be required to swing the tongue downwardlyand upwardly a greater number of times to raise the load the same distance.

If a much heavier load is to be raised by the load supporting' means, the counterweighted arm IIlI of the larger pump may be rotated forwardly to detach the link 96 from the pin 95 of the actuating leverand the counterweighted arm IBI whichcontrols thelever ,9B ofthe smaller pump may be rotated rearwardly to cause engagement of the lower end 96 of thelink with the pin 95 upon the actuating lever for the smaller pump, A greater number ofrreciproc'ationsI of the plungerof the smaller pump will be required to raise the ram of the ram cylinder through the same distance',l but the liquid will be supplied to the ram cylinder under still higher pressure as will be readily understood, thus enabling a maximum load to be lifted without undue exertion upon the part of the operator. When the load has been lifted, either by a single pump or by the action of the pumps conjointly, the load supporting means will be retained in elevated position so long as the rod 8U is intheV position in which it holds the ball valve 'mfirmly upon its seat. When it isdesired to lower the load. the operator may grasp the handley 83 of the rod BIJ and rotate it in a reverse direction to such an extent as will enable the load Vto' descend at the desired rate of speed which is controlled by the escape of liquid from the outlet 8l inthe slotted lower end of the rod 80 into thereservoir. l .1

In lifting loads for transportation, 4and par,-

A ticularly the usual skids or platforms, it is neces sary to raise the same a sufficient distance 4to avoid possible contact with the floor, but is un` desirable to lift the skid or platform to any considerably-greater height as such additional elevation of the platform not only requires addi-` tional time during Athe lifting operatiom. but-also,

deposited upon the floor. Ilurthermore',A the raising of the load to an unnecessary and unde? sirable height decreases the stability of "thetry ck if a high load is being transported..

The present invention contemplates the pro'v vision of preferably adjustable means for limiting the maximum height to which the load support.`A ing means can be raised. Thisv is accomplished in the preferred construction illustrated by providing adjustable stops, suchas nuts Ill5, uponl one or both of the tension rods134 to engage a transverse girder |06, secured, Apreferably `by welding, to the side frames Iv and 2, Vwhen the.A

including a vertical swinging` tongue, as hereto-l fore described, and mechanism `operable by the" lifting of the front end of the load supporting-l' means to raise the rear end ofthe load support.-

ing means in synchronism therewith in the man-v ner heretofore described,` but which differs fromj the mechanismpreviously described in that the. block 43, which contains the reservoin.tliejfrai'n'v and'pump cylinders, is pivotally mounted .upon the transverse shaft 4,4,- and Yin that tliejfor-M` wardly curved lexter'ision. 24 of the standard 22 is pivotally connected by Vtlfiegshaftftlito lugs Ill'Iintegral with and extending upwardly from the upper end of the ram 5B.` I i By reason of these pivotal-connections the block 43 is adapted `tofoscillateslightlyabout the pivot 44 during the raisingand lowering'move'fk ments of the load supporting means caused by the movement of the bell crank lever 2T which supports'ithe front end of theload's'upporting means. i f 'A The contruction illustrated in Fig. 2 also differs from that previously described in that links v|08, which are pivotally mounted at their upper ends upon the pins 91 which extend through thepump plungers 53 and 54 and their cross hea`ds,'- are of greater lengthand are providedwith recesses IDS adapted detachably to engage suitable pins or studsV II!) which areactuated by a footlever or pedal I I I'. Inv the construction illustrated the pedal III is xedly secured to a transverse shaft I I2 mounted in suitable bearings in thesideV frames I and 2, and a spring II3, coiled'upon the shaft IIZ and having one end attachedthereto and the other end engaging a suitableabutmenh. normally holds the vfoot pedal in elevated'positio'n,V as illustrated. One ofthe links IGS may beides tachably secured to the pin IIil' upon the 'lever llvlg'while "the other `link lIIN! may be similarly detachably secured to `a like pin projecting from another lever arm which is xedly secured to the shaft II2 and extends forwardly in parallelism with the pedal III.

It will, therefore, be obvious thatinfeither 'of' x70 the constructionsV above ldescribed the rpump plungers are adapted tok be selectively reciprocatedY either singly orconjointly to raise the ram and thereby to raise the load supportingmeans,

when carrying different loads, with a forc'evlD-l plied to the pumpeactuating means which does If the pumps are .actuated -YIt will be understoodthat the-particular embodiments of the invention disclosed herein are of an f illustrative character and not restrictive and that various changes'in form, construction and arrangement of parts may be made Within the spirit and scope of the following claims.

Having thus described the invention, what is claimed as new, and desired to be secured by Letters Patent, is:

1. elevating truck comprising a wheelsupportedframe, load supporting means mounted thereon and movable upwardly relative thereto, a Yfluid-ope'rate'd "jaclfrY mounted in said main frame comprisinga vertical ram cylinder, a ram 'reciprocably mounted therein and means operable` by said ramto lift SaidlOad-SuppOrting means, a plurality ofV pump cylinders of diierent diameters each having an independently valved connection with said ram cylinder, a plunger for each pumpv cylinder, a lifting lever and selectivelybperable means for connecting either of said pump plungers to said lifting lever or for connecting all of said plungers to said lift-r ing lever for simultaneous operation.

2. An elevating truck comprising a main frame having rear wheels, a-head, Steering mechanism rotatively mounted in said head having a tongue mounted to swing vertically, load supporting means mounted upon saidframe and movable upwardly relative thereto, a fluid-operated jack mounted in said frame comprising a vertical ram` cylinder, a ram reciprocably mounted therein and means operable by said ram to lift said load supporting means, a plurality Aof pump cylinders of different diameters each Vhaving an Yindependent valved connection with said ram cylinder, a plunger for eachV pump cylinder and means selectively operable ,for connecting either of said' pump cylinders to said tongue or for connecting all of said pump cylinders to said tongue for simultaneous operation. n

3. An elevating truck comprising a frame having rear Wheels, a head and steering mechanism rotatively mounted therein having a tongue mountedto swing vertically, a fluid-operated lifting jack mounted on said frame comprising a vertical ram cylinder vand a ram reciprocably mounted therein, a platform supported upon said main frame by parallel links and having a headv overlying said ram, a plurality of pump cylinders of different diameters each having valved con'- nection with said ram cylinder, a` plunger for voir and an independent valved connection withY said ram cylinder, a ram'reciprocably mounted in Said ram cylinder, plungers reciprocably mounted in the respective pump cylinders, load supporting means mounted on said frame, means operable by the vertical movement of said ram to raise said load supporting means, an actuating lever, and means for releasably connecting one end of said actuating lever to each of the plungers for the respective pump Vcylinders selectively to 1 cause individual or conjoint simultaneous actuation thereof, and means for releasably connecting the other arm of said actuating lever to said tongue whereby vertical swinging movement of the tongue will actuate the selected plunger or plungers. f j

5. An elevatingftruck comprising a frame having rear wheels, a head and steering mechanism rotatably mounted therein and having a tongue mounted to swing vertically, a jack comprising a cylinder block located in proximity to saidhead' having a reservoir for liquid, a central vertical ram cylinder, and vertical pump cylinders located on opposite sides'of said ram cylinder each having a valved connection with'said reservoir and an independent valved connection with said ram cylinder, a ram reciprocably mounted in said ram the tongue will actuate the selected plunger or plungers.

6. An elevating truck comprising a frame having rear wheels, a headand steering mechanism rotatably mounted therein, a jack comprising a cylinder block located in proximity to said head having a reservoir for liquid, a central vertical ram cylinder, and a plurality of pump cylinders each having a valved connection with-said reservoir and an independent-valved connection with said ram cylinder, a ram reciprocably mounted in said ram cylinder, plungers reciprocably mounted inthe respective pump cylinders, load supporting means mounted on said frame having a head Voverlying said ram operable by the vertical movement of said ram to raise said load supporting meansyan actuating lever, means for releasably connecting one end of said actuating lever to the plungers for the respective pump cylinders selectively to cause individual or conjoint' actuation of said plungers,^means for` releasing fluid under pressure from said ram cylinder including a. valve and a member having screw` threaded connection with Vsaid head operable to control said valve andthereby to regulatewith accuracy the rate of descent of the load 'supporting means.

'7. An elevating truck comprising a frame having rear wheels, a head and steering mechanismrotatably mounted therein, a jack comprising a cylinder block located in proximity to said head having a reservoir for liquid, a central vertical ram cylinder, and a plurality of pump cylinders each having a valved connection with saidreser- Voir and an independent valved connection wif-h said ram cylinder, a ram reciprocably mounted in said ram cylinder, plungers reciprocably mounted in the respective pump cylinders, load supporting means mounted on said frame having a head overlying said ram operable by the vertical movement of said ram to raise said load supporting means, an actuating lever, means for releasably connecting one end of said actuating lever to the plungersY for the respective pump cylinders selectively to causev individual or conjoint actuation ofv said plungers, an exhaust conduit leading from said ram cylinder to said reservoir having therein a ball valve, and a manually operable rod having screw threaded engagement with said head operable to force saidloall valve upon its seat or to release said valve gradually therefrom and thereby to determine the rate of escape of fluid from said ram cylinder.

8. An elevating truck comprising a frame having rear wheels, a head and steering mechanism rotatably mounted therein having a tongue mounted to swing vertically, a cylinder block mounted upon said frame in proximity to said head having a reservoir for liquid, a central vertical ram cylinder, vertical pump cylinders of different diameters located on opposite sides of said ram cylinder each having a valved connection With said reservoir and an independent valved connection with said ram cylinder, a ram reciprocably mounted in said ram cylinder, plungers reciprocably mountedV in said pump cylinders, load supporting means mounted on said frame having a head rigid therewith extending over said ram, an actuating lever pivotally mounted on the head of said frame, independent means releasably connecting said actuating lever to the respective pump plungers, and means releasably connecting said lever to the tongue, whereby said actuating lever may be operated by the vertical swinging movement of said tongue or released from said tongue to permit free `steering movement of said tongue, an exhaust conduit leading from said ram cylinder to said reservoir, and manually operable means for controlling the escape of fluid from said ram cylinder thereby to regulate the rate of descent of said load supporting means.

9. An elevating truck comprising a frame having rear wheels, a head and steering mechanism rotatably mounted therein having a tongue mounted to swing vertically, a cylinder block mounted upon said frame in proximity to said head having a reservoir for liquid, a central vertical ram cylinder, vertical pump cylinders of different diameters located on opposite sides of said ram cylinder each having a valved connection, and an independent valved connection with said reservoir and said ram cylinder, respectively, a ram reciprocably mounted in' said ram cylinder, plungers reciprocably mounted in said pump cylinders, load supporting means mounted on said frame having a head rigid therewith extending over said ram, an actuating lever pivotally mounted on the head of said frame,'independent means releasably connecting said actuating lever to the respective pump plungers, and means releasably connecting said actuating lever to the tongue, whereby said actuating lever may be operated by the vertical swinging movement of said tongue or released from said tongue to permit free steering movement of said tongue, an exhaust conduit leading from .said ram cylinder to said reservoir, a valve in said conduit, manually operable means for adjusting said valve to control the escape of fluid from said ram cylinder and thereby to regulate the rate of descent of said load supporting means, a relief conduit leading from said ram cylinder to said reservoir, and a spring-actuated relief valve for said conduit adapted to release fluid from said ram cylinder in response to pressure exceeding a predetermined amount.

l0. An elevating truck comprising a frame having a rear axle and wheels thereupon, a head, steering mechanism rotatably mounted therein, a cylinder block located in proximity to said head'havi'ng a'reservoir 'for aliquid, a centralvertical ram cylinder, a plurality of pump cylinders havingv valved connections respectively with said reservoir and said rain cylinder, aram reciprocably mounted in said ram cylinder,'plungers reciprocably'mounted in said pump cylinders, an actuating lever, means releasably connecting said actuating lever to the respective plungers, load supporting means having a` head'rigidf therewith extending over-saidram cylinder having antifrictionmeans to engage said ram whereby the upward movement oi said ram will apply continuously avertical lifting 'force directly-'to the' front end of said load supportingv means, a bell crank lever mounted on said frame having one arm pivotally connected to said load supporting means, a link connecting the otherarm of said bell crank lever to a lifting member pivotally mounted upon said rear axle having at its end anti-friction means engaging the under face of said load supporting means and acting upon upward swinging movement of said lifting member to apply a lifting force vertically to said load supporting means.

1l. An elevating truck comprising a frame having a rear axle and wheels thereupon, a head, steering mechanism rotatably mounted therein, a cylinder block located in proximity to said head having a reservoir for a liquid, a central Vvertical ram cylinder, a plurality of pumps having valved connections respectively with said reservoir and said ram cylinder, a ram reciprocably mounted in said ram cylinder, plungers reciprocably mounted in said pump cylinders, an

actuating lever, means realeasably connecting said actuating lever to the respective plungers, load supporting means having a head rigid therewith extending over said ram cylinder, a bell crank lever mounted on said frame having one arm pivotally connected to said load supporting means, a link connecting the other arm of said bell crank lever to a lifting member pivotally mounted upon said rear axle having at its end anti-friction means engaging the under face of member to limit the upward movement of said Y load supporting means, and a conduit leading from said ram cylinder to said reservoir having therein a yieldable valve operable to relieve fluid pressure in said ram cylinder in excess of a predetermined amount upon continued action of said pumps after the arrest of the upward movement of said load supporting means by the engagement of said stop with said abutment.

12. An elevating truck comprising a main frame having a rear axle and Wheels thereupon, a head and steering mechanism rotatably mounted therein, a hydraulic jack comprising a block located in proximity to said head having a reservoir for liquid, a vertical ram `cylinder and a pump cylinder having valved communication with said ram cylinder, and means for actuating said pump, load supporting means having an integral head extending over said ram having an anti-` kconnected to said load supporting means and another arm connected by a link to a member pivotally mounted on said axle and having its free end provided with anti-friction means engaging the under face'of said load supporting means whereby upward movement of said ram will cause the load supporting means to be lifted vertically withoutrsubstantial longitudinal movenient relatively to the main frame. i

13, An elevating truck comprising a frame having a rear axle and wheels thereupon, a head, steering mechanism rotatably mounted therein, a cylinder block mounted on said frame and located in proximity to and rearwardly of said head having a reservoir for a liquid, and a central vertical ram cylinder, a pump having a valved connection respectively with the reservoir and said ram cylinder, a-ram reciprocably mounted in said ram cylinder, means for actuating said pump to raise said ram, load supporting means having a head rigid therewith extending over said ram provided with anti-friction means to engage said ram, whereby the upward movement of said ram will apply a vertical lifting force directly to the front end of said load supporting means, and means operable by the upward movement of the front end of said load supporting means having anti-friction means to engage the under face of the rear end of said load supporting means and to raise the same substantially vertically.

DANIEL E. HENNESSY.

Images