US2940767A - Light duty hydraulic truck - Google Patents

Description

June 14, 1960 G. F. QUAYLE LIGHT DUTY HYDRAULIC TRUCK 5 Sheets-Sheet 1 Filed Oct. 4, 1955 INVENTOR. 6. F. Cpway i ATTORNEY June 14, 1960 e. F. QUAYLE LIGHT DUTY HYDRAULIC TRUCK 5 Sheets-Sheet 2 Filed 001'... 4, 1955 2 3% O Y M m F. -A 6 June 14, 1960 e. F. QUAYLE 2,940,767

LIGHT DUTY HYDRAULIC TRUCK Filed Oct. 4, 1955 5 Sheets-Sheet 5 IN V EN TOR.

ATTORNEY June 14, 1960 G. F. QUAYLE LIGHT DUTY H YDRAULIC TRUCK Filed Oct. 4, 1955 5 Sheets-Sheet 4 INVENTOR.

Wake

ATTORNEY June 14, 1960 G. F. QUAYLE 2,940,767

LIGHT DUTY HYDRAULIC TRUCK Filed Oct. 4. 1955 5 Sheets-Sheet 5 INVEN TOR.

ATTORNFY United States Patent LIGHT DUTY HYDRAULIC TRUCK George F. Quayle, Philadelphia, Pa., assignor to The Yale & Towne Manufacturing. Company, Stamford, Conn, a corporation of Connecticut Filed'Oct. 4; 1955, Ser; No: 538 360 11.Claims. (Cl'..280-43l12)' Thisinvention' relates to a hydraulicntruck in; which therlifting: operation is performed. the. actuation afa -lever that in turn operates a pump; Tracks of the particular classfarewell known inthe art and: numerous patentsshave issued onvarious types: of 'constrnctions. The truck of this application forms atconsiderablevcontrihution overthe prior art since it makes possible the applicatiomof lifting forces in a most ingenious and novel manner. Further, my truck makes possible the utilizatiorc of. extremely simple hydraulicv control means.

Asa very important. feature of the invention; a minimumhofpartsare utilized between thelifting mechanism and the elevating platform in order to eliminate, as fully as. possible; the occurrence of. flexing and deflection'of the several parts incidental to the lifting of the load. As a2featureofimy invention,v I utilize a-ram cylinder that. accepts substantially directly" the. lifting r stresses applied; in.one. direction: to; the 1 cylinder :through. the lifting of'the. elevating platfonmtherampiston moving :in the ram cylinder accepting directly'theapplicatiorr ofllie forces in a reverse direction. As a-moreparticular fea: tureof part, of theinvention, the-ramicylindenisasuhstantiallyan integral part-of the liftingheadrof thettruck, with the steering and rotating wheel supporting the lifthead through. forces .appiiedzaxially of the cylinder. Asa; further detailedfeature, of this part ofthe invention, the ram. cylinder is; formed as;a; partpof': one pprtionof therliftinghead,this.;portion;ofi:the liftingchead resting'iagainst the-remainder of the lifting:l1ead;with:ithe supportv wheel. for the: lifting. head: mounted. forfrota= tionabout the'ram cylinder and inrbearingrelation to the. liftinghefld. The. ram cylinder has; moving; therein a-ram piston. that bears directly against theelevating platform so that allstresses arev axially of the cylinder and piston with a-minimum'of intermediate parts, and with said intermediate parts indirect bearing relation to one another. Those skilled in ,the* art will fully appreciate aiter. reading the specification, theqnature oflhe. contribution inherent in the construction, I have set forth.

The elevating platform. of the truckis-adapted to bear directly against theram piston as. has been set forth, meansbeing'provided whereby the elevating movement ofithe platform through theoperation. of the ram piston efiectslifting movement of..wheels atthe'r'ear end-of theelevating platform. Thesemeans alsoare arranged to.apply directly to theram those-forces incidental to:the movement of the rear wheels.

Asa feature .of the invention, the elevating platform of my truck utilizes. fabricated tubular'sections, and within those sections. are mounted compression. members extending from. the forward end of, the'elevatingplatformz to thereanload supporting wheels; for moving the rear: supporting wheels. between liftingandlowering positions. It issan important feature ofthe invention that thecompressionmembers are. mounted within the tubular, portions of the elevating platformand move Within said tubular' portions at all times, therebyeprotecting the lifting mechanism through maintaining it completely unexposed in. all operating positionsof the elevating; platform. So far as I know; no truck ofthe particularclass has fully enclosed lifting-members extending; between the forward end of the truck-and the rear lifting wheels.-

As a further feature of the invention, I utilize ae single valve mechanism for controlling the hydraulic liftingand lowering mechanism, while simultaneouslyacting as" a relief valve-for preventing-the application ofundue forces through --thehydraulic lifting mechanism; Asa'fe'ature of the-invention! "employa foot treadle forefiectingthe positioning of the valvemechanism' so thatfluid will'flow from below-theram piston -to allow the downward move ment'ofthe-ram piston'and the lowering of theload. a novel feature of-thisportion of the invention; I utilize wgravitydevice for normally holding-a valve against its seat, the'fo'ottreadle pressing againsti the-gravity'device to hold the valve= seated when lifting-of. the elevatingzplatform isv required; The movement-ofi the treadleto:- a lowering position-merely: withdraws pressure from the gravity device: so -thatithe load may be. lowered.

Asafurther feature of. therinvention, whenthe treadle is not depressed toeffect lowering-.- of theiload its :pressure against the gravity device maintainsispring. pressure againstca: valve-that: in. turn prevents the flowrofcfiuid from, beneath the ram piston. However, upon .thez-ap plication ofundue forces, thesprin'g. will yield; allowing the+movementof .the'valve away frornitsseat; so that there may bea. bypassing -of theram cylinder, aszthose skilled in: the art will fuilyappreciate.

As; a further, featureof my invention, .1; apply.- within the;-.=hydraulic:system of .imy truck a: turbulence. creating device that. is extremely efiective; to; prevent unduly fast flow of fluidincidental to-the-lowering operation; thereby preventing; too. swift a: lowering. movement of, the-opera;- tionof, the truck;

I have thus outlined rather :broadly the:moredmportant features: of'my; invention, in orderthat the detailed description; thereof, that follows. may bebetter under. stood and in orderthat my'contribution-to the; artmay bebetter appreciated; 'Ihererare, of course, additional features ofimy; invention; that. will: be described herein,- afteriand whichrwill form the subject .of the-.clairnssap pended hereto: Tse 1skilled;in;the;,art.wil1; appreciate that the conception ,orl which my disclosure is based'may readily; be utilized; ,as-arbasis Q F? e: desigilingtof ti structures -for carrying;;out;,the several; purposes of my invention, It. is important, therefore thatthe claims .be regarded as inoluding sl 1(;h. equivalent constructions as do not depart ;from,the;spirit: and. scope. of myinvention, in. order to;:preventthe appropriation of:myinventionby those skilledlin thelarta Referring now tothedrawihgs Fig. 1 is a side view of my novel hydraulic truck.

Fig. 2.; is like,.F,ig.. l .butrshqwsltheteleyating platform liftediontheloadwheelsand liitinghead. V

Fig. 31shows a plan view of the. frontend of. the truck,

Fig. 4 is a verticalgsection on the line 44.ir' 1 Fig.,.3I.

Fig. Sis a section .on'the line-.5 5 in Fig; 4.

Fig; 6 is'a section showing'my novel hydraulic valve.

Fig; 7'is a, section on the line 7-'7"in' Fig. 4 showing the pump cylinder:

Fig. 8 is a section on the -line-8-'8-in-Fig.- 2.

Fig; 9 is-a-section on -theline 99*of Fig: 1.

Fig: 10. showsin perspective a=- rear.- load wheel and its actuatingmechanism;

Refe ringrnowmoreeparticularlv-tos Figs. 1 andrZgQf the drawings .my novel; truckthasram elevating rplatfomr 10; that is supported late.v its; roan end; on loadi wheelsen and at. its front. end onsa. Thedifting head is supported in turn on wheels 13 that have steerging movement for steering the truck. As is usual in p a ly tively to the king post.

"retains a packing 33in ,theupper end, of king post cyltaneously to move the load wheels 11 for lifting the I shall describe the platform '10 and load wheels 11 n further detail, 'but my invention rear end of the platform.

,will be more readily, understood if I describe first the novel structure of theglifting head 12 and the means through which'it acts. j I p f As is best seen in Fig. 4, =1 utilize as parts of the lifting head 12 a casing 14, and a king post 15 that I form as a hydraulic ram cylinder. In theconstructionthat I prefer, and that I show in the drawings, the'lifting head casing '14 has an upper portion 16 that forms a reservoir for hydrauliefluid. In the bottom of the casing 14is a vertical opening 17 for the king post cylinder 15, and a medial part of the cylinder. fits in .this opening 17 with thelower end of the cylinder positioned below the casing 14. The upper part ofking post cylinder 15 has upon itan integral portion 18, formed preferably as a plate welded to the cylinder, that bears upon the sides of the upper Therebythe' king post cylinder. 15 is in' direct bearing relation to the lifting head 12, with the 7 portion 16 of the lifting head casing.

plate 18 acting'further as a cover for the fluid reservoir. For holding the plate 18 in assembled position, I utilize screws 19 that are shown in Fig. 3.

I mount the steering wheels 13' for steering movement through a mounting bracket 20,'Figs. 4 and 5, that encircles the lower end portion of the king post cylinder '15. The cylinder 15 has at its lower end a stub shaft 21, and the wheel mounting bracket 20 has a bearing 22 coacting with stub shaft 21 whereby to rotate in the king post axis. Further, the upper portion of mounting bracket 20 rotates on ball bearings 24 that are seated in a circular recess on the lower side of the lifting head casing 14. Thus, the mounting bracket 20 rotates on the stub shaft 21 in' the axis of king post cylinder 15 for ;steering the truck, while in direct bearing relation'to the lifting head through the ball bearings 24. For rotating the mounting bracket'20 on its bearings, I' show a steering'handle H pivoted to an arm 23 on the bracket. 1 Ifurther form the mounting bracket 20 with integral portions 24 that are in spaced relation at opposed sides 'of the king post ads below the bearing 22. 1 Between these portions 241 pivot an axle 25 through a pin 26.

7 a 4 I construct the front end of the elevating platform 10 with a rigid neck 34. The forward end of neck 34 is pivoted to the upper end of ram piston through a pin 35, thus placing the front end of the platform and the piston 30 in direct bearing relation to one another, It

. will be realized, therefore, that the king post cylinder The axle 25 has opposed end portions 27, Fig. 5, that are in the plane of the king post axis, and-that are offset to lie in substantially aligned relation to the bearing 22 on which the wheel mounting member rotates rela- Bearings 28 mount the steering wheels 13 to rotate on the axle ends 27. Through the particular construction, the forces incidental to the move.

ment ofthe truck will be applied in aligned relation to the bearing 22 on the king'post, but with axle 25 rotating on pivot 26 when the truck moves over uneven ground. 7

It will be understood that the construction I have thus far described enables me to utilize a relatively long ram cylinder, since that cylinder lies in a position extending from an upper part of the lifting head to a point that is between the steering-wheels 13. I am, therefore, able to utilize in the king post cylinder 15 a relatively long ram piston 30, well shown in Fig. 4. Thepiston 30 in itself is rather conventional, but it may be observed at thispoint thatthe piston is somewhat smaller than the bore of king post cylinder 15 whereby to. leave a space around the piston, and that the piston has at its lower end a bearing sleeve 31 on which it slides. Passages 31a in the lower end of-piston 30 enables fluid to flow past the sleeve 31 between hte sides and end of the piston. Piston 30 slides also on a packinginut 32 that inder 15g;

movements of platform 10, levers 78 rotate on a shaft 79 on the front of theplatform, with this rotating movement utilized for moving the rear load wheels 11 as I shall later describe. It is important here to observethat I pivot the front ends of levers 78 to opposed sides of the lifting head 12 through pivots that I arrange particularly in the plane of the axis of king post cylinder 15. Thisarrangernent enables the cylinder15 to accept directly through-the lifting head casing '14 the forces that are incidental to the lifting of the rear end of platform 10 on the load Wheels 11, with those forces applied always on the ram center.

I shall now describe in detail the particular features of the lifting head whereby i apply fluid pressure to the king post cylinder 15'and piston 39. It'will be remembered that a medial portion ofthe king post cylinder 15 is assembled in the opening 17 in the lower part of the lifting head casing 14, as shown in Fig. 4. In this medial part of cylinder 15, I form a series of ports 36, with an outer peripheral channel 37 in communication with those ports. Packing rings 38"at opposed sides 'of' channel 37 prevent the seepage of fluid between the channel and the opposed ends-of opening 17 in the easing. Communicating with the channel 37 at'opposed sides of the cylinder 15 is a bore 40 formed in the lower past of casing 14, this bore being well shown in Figs. 4 an '7. a

Further, I equip the lifting head casing 14 with a pump piston 41, Figs. 7 and ll, that is adapted to move in a cylinder 42 formed integrally in the casing. The cylinder 42 extends through casing 14, but is formed at its right hand end, as viewed in Fig. 7, with a chamber39 closed by a cap 42a. Chamber 39 communicates with the right hand portion of bore 40-through-a passage '43, 'Fig. 7', this passage having a spring pressed check valve 44 that will permit. fluid to flow'only a direction toward the rain cylinder 15. For supplying fluid from the reservoir 16 to the pump cylinder 42, I show in Fig'll a passage 45 that is equipped with a check valve 46. It will naturally be understood that the piston 41 will have power and return strokes in the cylinder 42.. During the power stroke, the right hand end of piston 41 will act against fluid in the chamber 39 for directing fluid pressure past check'valve 44 toward the ram cylinder 15; I' prefer, incidentally, so to form the casing 14 that the fluid reservoir has a portion 16a communicating with a medial part of the pump cylinder 42, as well shown in Figs. 7 and 11, so that any high pressure fluid seeping around piston 41 will be directed to the reservoir and will not leak out at the left hand end of the-piston. i

I utilize a rather novel construction for the pump piston 41 and its operating means. Referring to Figs/7 and ll, I make the piston 41 tubular whereby to have hollow end portions, but with a medial wall 47 that closes the piston to fluid flow. This enables meto utilize within the piston a relatively long coil spring 48 that acts 'between the medial .wall 47 and the cylinder cap 42a for effecting the return stroke of the piston. The piston'41 can itself be relatively long since it can move in thebpcn cylinder end at the left in Fig. 7.

Forthe purpose of effecting the pumping stroke of piston-a 41, I utilize a pedal lever 49, Figs. 3, 4, and 11, onzazshaft 50 that rotates on a pair of bearin'gportions 51. atthe rear side of lifting head casing 14. As best seenzin. Fig. 11, the shaft 50 is quite close to the open endof pump cylinder 42 and has fixed upon it an arm 52i.'l1aving.a crank pivot 53 that movesin substantially aligned; relation to the pump piston 41. Pivoted at one end to the crank 53 is a rod 54, this rod extending into the hollow-piston 41 and having a curved surface 55 that isrin bearing: relation to a complementary surface 5-5 on the-.medial wall 47 ofpump piston 41. Thus, the pedal lever 49 when depressed will efiect a pumping stroke of piston 41, with the pump rod 54 coacting with the piston 41 at amedial point on the piston While moving angularly inzthe outer: hollow end of the piston. The particular arrangement enables meto utilize a-relatively longpiston forrthe pump while arranging the pump and its operating meansrin a relatively small space on the lifting head 12.

Fort-rotating the pedal: lever 49. in a return direction, thiscrotationbeing upward, I equip the shaft 50 with a lug 57 to which I pivot a rod 58, with a coil spring 59 acting. between this rod and a portion 60 on the reservoir cover 18. The rod 58 isguided in an opening in the cover position 69, and acts in turn to guide spring 59. Duringthe return rotation of pedal 49, the piston spring 48willact to press the piston bearing surface 56 toward contact with the surface 55 on rod 54.

It'will be understood from the foregoing description that the pump piston 41 will apply fluid pressure through the. passages 43. and 40 to the ports 36 in the king post cylinder 15.. for'moving the ram piston 30 upwardly in the; cylinder. It will. be obvious further that the fluid pressure will be applied through the peripheral channel 37 on cylinder fto the left hand portion of the bore 40, as'viewed inFig. 4; Onthe left hand portion of bore 40, Iutilize a valve 61. positioned in the fluid reservoir, as best seen in Fig; 6, that is adapted to coact with a valvebody 62. having a bore 63" communicating with the. bore 40. I controlvalve 61 through a gravity member 64 that is adaptedto slide vertically in a bracket portion 65 on fluid reservoir 16. This gravity member 64 has a hollow lower. end portion 64a positioned about valve 61 and arranged in guide relation to the valve body 62, but with clearance whereby fluid can flow from valve 61 into the reservoir 16. In the hollow end portion 64a I utilize a coil spring 66 that presses a sliding plunger 67' toward the valve 61 forpressing the valve to seated position on valve body 62. For reasons'that will appear, I equip the upper end of the plunger 67 with a stop portion. 67a for limiting the movement of the plunger 67 and so arranged that spring 66 will not press the plunger substantially beyondthe point thatis necessary to seat the valve 61.

The pressure of spring 66 is such that it can hold the valve 61 seated until the fluid pressure inpassage 40 develops to a predetermined point, and will yield when the pressure rises beyond that point. Thus, through the operation of pedal 49 and pump piston 41, the fluid pressure will move the ram piston upwardly for lifting the truck platform, but, should the truck be overloaded, the fluid pressure will move the valve 61 from its seat whereby to relieve the pressure applied to the ram.

I effect a further control of the valve61 through the gravity member 64, and I prefer to utilize for the purpose atreadle 70, shown in Figs. 4 and 6. This treadle 70- is pivoted tothe reservoir cover 18 through a pivot 71, and has at one end a screw 72 that is aligned with the upper end of the gravity member 64. A coil spring 73- acts against the treadle 70 for pressing the screw 72 against the gravity member 64. The spring pressure that is thus applied to the gravity member 64 is sufi'icient to hold the member in a depressed position even when. the pressure relief spring 66-yields. However, by moving the treadle 79, the truck operator can relieve the gravity member 64- from the spring pressure; that is applied through screw 72. This will relieve also the pressure of spring 66,; since the plunger. 67 limits the extensionof that spring, The fluidpressure actingonvalve 61 can then lift the valve,.together with the gravity. member 64. Thus, the treadle 7 0 Whendepressed will effect a-discharge of fluid from the ram cylinder 15. to the fluid reservoir and will thereby'eifect a lowering movement of the. truck platform 10.

I control automatically the speed at which the plat form 13 is lowered, utilizing for that purpose an extremely novel. flow limiting member 75, well shown in. Fig, 6,

that I prefer to position in the bore 63 of valve. body 62..

This member 75 is formed as a rod with its outer peripheral surface 76 maintaining a substantial clearancezrelatively to the inside of bore 63. Along-the rod 75, I form the outer. surface 76 with a series of angular grooves 77. When the truck platform is lowered with no load or a load that is. relatively light, the fluid will' be discharged rather freely through the clearance around rod surface 76, but the rate of flow will be moderate since, the. fluid will have relatively low pressure. If we assume, on the other. hand, that the load is heavy, the rate ofzflow will increase somewhat and the grooves 77 will. then cause the flow to be more-turbulent, therebyabsorbinga very considerable amount of energy and restrictinggthe rate at which fluid will discharge from the mm. This arrangement will act when -a heavy load. is on, the platform to prevent a lowering. movement that is too fast, yet will not make the lowering movement. unduly slow when the platform has little or no load.

To describe more particularly-the platform 10 of my novel truck, I utilize as the load carrying. part of the platform a pair of rearwardly extending tubular sections 81, Figs. 1, 2, and 8. These. tubular. sections 81 may, of course, form parts of:a continuous wide load surface when that is desired, but for apallet truck ofthe particular type the sections 81 extend separately from the front of the platform. in spaced relation to one another, as shown in Fig. 3. At the front of the platform 10, the tubular sections 81 are welded to opposed ends; of a transverse tubular section. 82, Figs. 1 to 4, andto a reinforcing cap member 83 on each end of' section 82. The neck 34 on platform 10 has a relatively wide lower end 84, Fig. 3, that is formed with a notch 85 and a seat 36 for the transverse section 82,.as best seen in.Fig. 4, and section 82 is welded to said notch and seat.. Thereby the neck 34 is secured in very rigid relation to the rearwardly extending platform sections 81.

Referring particularlyto Fig. 3, I mount the. shaft 79, on which the levers 78 rotate, on the sides of the lower neck portion 84 and on the ends of reinforcing members 83. Rotating. integrally with each lever 78 on shaft 79 is an arm 87 that is in aligned relation to a corresponding platform section 81, and through which the leverv acts for moving a load wheelll. I assemble each lever 78 to its arm 87 through a welded tubular portion 88 that has a relativelylarge diameter, so that the lever and arm will be very rigid and will not deflect under load.

To the rear end of each tubular platform section 81 I weld a hollow end section 89, Figs. 1, 2, and 9, that is open at its lower side. Each end section 89 is rearwardly tapered and has inclined guide portions .90 whereby these sections will more readily enter a pallet. One of the loadwheels 11 is mounted for lifting andlowering movement on each end section 89 through a mounting member 91, this member having at one end a shaft. 92 for the wheel and being pivoted to the section 89 through a shaft 93. The mounting member 91 further is equipped with a pivot 94 in offset relation to the shaft 93.

To enable the liftinglevers 87 to move thewheel mounting members 91 for lifting the rear end of the platform, I utilize particularly an operating rod 95 that acts in compression and that extends through the interior of. each tubular platform section 81, as showninv Figs.

i lar,

:the elevating platform of the ram can accept substantially small number of parts.

8 and 9. I prefer to make these operating rods 95 tubu- M and the rods are therefore quite rigid. The front end of each rod 95 is equipped with an integral clevis 96, Fig.110, that is pivoted to the corresponding lifting lever 87 through a pin 97. For connecting the rear end of each rod 95 to the pivot 94 on wheel mounting 9i, I prefer to utilize a connector 93 that is threaded into the rod for purposes of adjustment. By this novel construction, I enable the lifting mechanism to move the load Wheels through rods that extend rearwardly from the front end of the elevating platform, but with those rods enclosed by parts'of the elevating platform; Thus,

in all operating positions of the platform, the rods are "completely protected against damage.

I believe that those skilled in the art will now understand that I have contributed anextremely novel hydraulic truck having very considerable advantages over the prior art: cylinder, 1 am able to place the lifting ram in rather idirect'bearing relation between" the steering wheels and duck. Thus, the lifting directly those forces that ,arei incidental to the lifting and steering of the truck platform. -The platform itself'is very rigid, and the lifting head can-liftthe platform with practically no flexing and deflection of any parts'of the truck. This naturally is a very considerable advantage'in a truck of the particular itype, since it enables the truck operator to lift a load with'less effort. In additioml'utilize for the hydraulic system of my truck a novel pump, together with a valve that acts as both 'a relief valve and a lowering valve while automatically controlling the lowering speed'of the platform under different loads. Thereby I contribute a hydraulic system that is very efiicient, but that enables me nevertheless to make the lifting head of the truck All of these things I accomplish through simple and that has .a relatively v I believe, therefore, that those skilled in the art will appreciate value of my invention.

1 nowclaim:

l. 'In a truck of the class described, an elevating platform, a lifting head having a king post and including quite compact. a construction that is tion ofsaidking post, means pivoting said elevating plat- ;form to and lifting head for lifting movement relatively thereto, said king post forming a part of a hydraulic "ram, an opposed part of the hydraulic ram in direct bearing engagement with the elevating platforrnand' --moving relatively to'the king post for lifting the platform, a support wheel for the lifting head mounted for "bearing engagement with the elevating platform and moving relatively to the king post cylinder for lifting the platform relatively to said king post, a support wheel for the lifting head, means mounting said wheel for steering rotation about said king post, and, a bea'ring'between said wheel mounting means and a lower portion of said lifting head through which the support'wheel 7 supports the l fting head. 7

- 3; In a truck'of the class deseribedhaving an elevating platform, a liftinghead, means pivoting said elevating platform to said lifting head for lifting movement relatively thereto,'a kingpost'having' an upper portion bear ing vertically on said lifting headgsaid post forming the 'very considerable a part of a hydraulic ram,

an opposed part of'said hydraulic ram in direct bearing relation to the elevating platform and moving relatively to the king post for lifting the platform rela vely. to said king post, a support wheel for the lifting head, means mounting said wheel 7 for steering rotation about said king post, and abearing moving relatively tothe cylinder for lifting the plat- By utilizing aking post that forms a ram means in direct bearing engagement with an upper por "hearing relation to the elevating relatively to the king post for lifting the platform, levers form, a support wheel for the lifting head, means mounting said wheel for steering rotation on the king post cylinder, and a bearing between said wheel mounting means and said lifting head through which the support 7 wheel supports the lifting head.

S. In a truck of theclass described having an elevating platform, a lifting head forming a fiuid'reservoir, a king post forming a hydraulic ram cylinder, a cover for said fluid reservoir integral with the king post cylinder, said cylinder positioned 'in the reservoir and bearing vertically on the lifting head through said cover, a ram piston for said king post cylinder in direct bearing relation to the elevating, platformv and moving relatively to the cylinder for lifting the platform, a part of the king post positioned in an opening in'the bottom of the fluid reservoir and extending below the reservoir, a supportwheel for the lifting head, and means mounting said wheel for steering rotation on the said part of the king post.

6. In a truck of the class described, a lifting head, lifting means on the lifting head, an elevating platform having a frontend portion adapted to be lifted on said lifting means, tubular platform sections extending rearwardly from the front end portion of the platform, a load wheel pivoted to each tubular platform section at its rear end, the tubular form of the platform sections rigidly support ing those sections between said wheels and the front end portion of the platform, an operating member for each load wheel lying within the corresponding tubular section whereby 'to be enclosed and protected at the top and bottom of the platform, levers pivoted at one end to the front portion of the platform and coacting at their opposed ends with the lifting head whereby torotate upon lifting movement of the platform, and means through which said levers when rotating move the wheel operating members whereby to lift the rear end of the 'platform on the load wheels.

7. In a truck of the class described having'an elevating platform, load wheels pivoted to the platform'at its rear end, a lifting head having a vertical king post and including means in direct bearing engagement with an upper portion of said king post, said king post forming the cylinder of a hydraulic ram, a piston in said cylinder in direct pivoted at their rear ends to the elevating platform and at their front ends to the lifting head, for moving the rear load wheels when the ram piston lifts the" platform, the pivots between the levers and the lifting head lying with their centers substantially in the plane of the vertical axis of the king post'cylinder, a support wheel for the lifting head mounted for steering rotation about said king post, and a bearing arranged on alower portion ofthe lifting head and through which saidwheel supports .the lifting head and king post. I

8. In a truck of the class described having an elevating platform, a lifting head for said platform, a king poston the lifting head, a mounting member encircling the lower end portion of the king post, a pair of steering wheels at platform and moving opposed sides of the king post, an axle having opposed end portions on which said wheels rotate, a bearing between the mounting member and king post whereby said member has steering rotation in the king post axis, a part of the mounting member extending downwardly beyond the king post and lying in spaced relation to the king post axis, and pivot means supporting the axle on the said part of the mounting member with the axle ends substantially in the plane of the king post axis and aligned relatively to the bearing between the member and king post.

9. In a truck of the class described having an elevating platform, a lifting head for said platform, a king post mounted vertically on the lifting head with a part thereof below the lifting head, a mounting member encircling the said part of the king post, a pair of steering wheels, an axle having end portions on which the wheels rotate at opposed sides of the king post, a bearing whereby the mounting member rotates on the king post, said mounting member bifurcated at its lower end to form portions spaced from one another at opposed sides of said king post bearing, and pivot means supporting said axle intermediate the bifurcated portions of the mounting member with the axle ends substantially aligned relatively to the king post bearing.

10. =In a truck of the class described having an elevating platform, a lifting head forming a fluid reservoir, a king post forming a hydraulic ram cylinder bearing vertically on said lifting head, said king post and cylinder positioned in the reservoir with a part of said cylinder arranged in an opening in the bottom of the reservoir and extending below said lifting head, a ram piston in said cylinder in lifting relation to said elevating platform, a support wheel for the lifting head, means mounting said wheel for steering rotation on said king'post, a pump cylinder and piston on said lifting head, and means through which said pump piston when moving in its cylinder applies fluid pressure to the part of said ram cylinder that is below the lifting head for lifting said elevating platform on the ram piston.

11. In a trucklof the class described having an elevating platform, a lifting head, a king post forming a hydraulic ram cylinder, said cylinder bearing vertically on said lifting head and having a part arranged below said lifting head, a ram piston in said cylinder in direct bearing relation to the elevating platform, a support wheel for said lifting head, means mounting said support wheel for steering rotation on the said part of the king post cylinder that is below the lifting head, a bearing between said wheel mounting means and said lifting head through which the wheel supports the lifting head, a pump cylinder on said lifting head and having a piston therein, and means through which said pump piston when moving in its cylinder applies fluid pressure to the said part of the king post cylinder that is below the lifting head whereby to actuate the ram piston.

References Cited in the file of this patent UNITED STATES PATENTS Boylan Feb. 14, 1956

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