US2915137A - Mobile aerial tower - Google Patents

Description

Dec. 1, 1959 H. J. TROCHE MOBILE AERIAL TOWER 8 Sheets-Sheet 1 Filed May 5. 1958 INVENTOR.

HERMAN J. TRocHE ATTOR NE [5 Dec. 1, 1959 H. J. TROCHE MOBILE AERIAL TOWER 8 Sheets-Sheet 2 Filed May 5, 1958 INVENTOR. HERMAN J. Tnocua 3 1 Team. 41 3M A'rroRNEYs Dec. 1, 1959 H. J. TROCHE 2,915,137

MOBILE AERIAL TOWER Filed May 5. 1958 8 Sheets-Sheet 3 INVENTOR. HERMAN J.TROCHE A TTORNEYS Dec. 1, 1959 H. J. TROCHE ,915,137

MOBILE AERIAL TOWER Filed May 5, 1958 8 Sheets-Sheet 4 INVENTOR.

BY HERMAN J. TROCHE.

Bu Tau. i

ATTORNEYS Dec. 1, 1959 H. J. TROCHE 2,915,137

MOBILE AERIAL TOWER Filed May 5, 1958 8 Sheets-Sheet 5 INVENTOR.

BY HERMAN J TROCHE.

Bales, 75mg 4 A11 B ATT RNEYS Dec. 1, 1959 H. J. TROCHE MOBILE AERIAL TOWER 8 Sheets-Sheet 6 Filed May 5, 1958 m RE mw mm a m mm vT P fm T M s, m% HZ w \E A rTo/uvEys Dec. 1, 1959 H. J. TROCHE 2,915,137

MOBILE AERIAL TOWER Filed ma 5, 195a a Sheets-Sheet '1 i 5 a Q INVENTOR. HERMAN J. Twcwa BY ATT ys Dec. 1, 1959 H. J. TROCHE MOBILE AERIAL TOWER Filed May 5, 1958 8 Sheets-Sheet 8 ATTORNEY United States Patent 1,915,131 MOBILEAERIAL TOWER Herman J. Troche, Fairview Park, Ohio, assignor to J. H. Holan Corporation, Cleveland, Ohio, a corporation of Ohio r Application May 5, 1958, Serial No. 732,893

'4 Claims. (Cl. 182-2) This invention relates in general to a mobile aerial tower of thearticulated type and to control mechanism therefor which can be operated to cause actuation of fluid powered motor units for positioning the mobile aerial tower and associated work platformstructur-e on the outer end thereof, to any selected longitudinal or vertical angle and at various extended distances, to provide acess to overhead traflic lights, street lamps, and similar objects for installation, maintenance and repair. The invention relates more particularly to a mechanical control system which extends up through the movable portions of the tower and includes a pilot control unit mounted adjacent the work platform-structure for selective and ready actuation by workmen on the platform, thus permitting such workmen to control the movement of the work platform and associated aerial tower to any desired position.

=In recent years, control systems for movable aerial towers of the type with which the present invention is concerned have often incorporated hydraulic or electrical compounds for initiating the actuation of power devices which provide for the various positional movements of the aerial tower and the associated work platform structure. However, since the desirable design of such a tower is of the foldable or articulated type, comprising relatively movable sections, and since various componnts of the control system therefor (i.e. fluid lines or electrical lines)- are supported on the relatively movable tower sections, such components of the control system are relatively easily susceptible to breakage and fracture, resulting in increased maintenance costs and possible disablement of the tower for use, and accordingly such prior art control arrangements have not always been completely satisfactory.

The present invention provides a mechanical control system including a plurality of flexible members which extend through the sections of the aerial tower and which are expeditiously mounted thereon in an operative manner, which obviates their interference with movements of the tower sections with respect to one another and to the support structure for the tower, and which may be eifectively actuated by pilot control mechanism located on the work platform structure of the aerial tower, for the selective and effective positioning of the aerial tower by a Workman disposed on the work platform.

Accordingly, an object of the invention is to provide mechanical control mechanism for an aerial tower including a pilot control unit mounted in conjunction with the work'platform structure of the tower, for selective and positive actuation and control of a fluid power system for controlled movement of the aerial tower to a variety of positions.

Another object of the invention is to provide a control mechanism of the latter mentioned type which can be effectively mounted and supported on relatively movable sections of the aerial tower without interference with the positional movements of the tower, and which is not readily subject to breakage and failure in operation.

A more specific object of the invention is to provide an articulatedaerial tower which is movable to a variety of positions by a plurality of fluid actuated powerxdevic'es and including valve means for controlling the flow of actuating fluid to said power devices, and wherein there is provided a mechanical control system for operating. said valve means with said control system including a pilot control unit mountedadjacent the work platform structure of the aerial tower and operatively connectedto the valve means located on the aerial tower supportingstructure by means including flexible elements extending through the various tower sections and operatively mounted thereon by a novel drum or sheave system.

Other features and advantages of the invention will be apparent from a consideration of the following description taken in conjunction with the accompanying drawings wherein:

Fig. 1 is a top plan view of a utility vehicle carrying an aerial tower in accordance with the instant invention.

Fig. 2 is a side elevational view of the utility vehicle and aerial tower illustrated in Fig. 1.

Fig. 3 is-a perspectiveview of the utility vehicle and mobile aerial tower of Fig. 1, illustrating in dot-dash lines various positions of the tower and .associated work platform structure.

Fig. 4 is a side elevational view of the utility vehicleand aerial tower of the invention showing further positional movement of 1 the articulated aerial tower mechamsm.

Figs. 5 and 5a represent an enlarged, partially sectio'ned, fragmentary plan view taken substantially along line 55a of Fig. 2, and illustrating more or less in detail the pilot control unit mounted on the work platform portion of the aerial tower and associated chain and sprocket connectingmechanism to the cable system of the control mechanism, which operates to actuate the fluid powered motor unitsin the aerial towerdrivingmechanism. I

Figs. 6 and 6a illustrate a partially sectioned, side elevational view of the Figs. 5 and 5a mechanism, taken substantially along lines 6-6a of Figs. 5-511, looking in the direction of the arrows.

Fig. 7 is an enlarged, fragmentary, side elevational view of the aerial tower pedestal or mast structure, and illustrating the connection of the cable control system to the valve mechanism which controls the flow of actuating. fluid to the various fluid motor units of the aerial tower apparatus.

Fig. 8 is a partially broken, end elevational view taken operating the distributing valve mechanism of the fluid powered aerial tower apparatus.

Fig. 12 is a diagrammatic representation illustrating Y the stringing of one-half of the sheave and cable control system of Fig. 11.

Fig. 13 is a diagrammatic representation illustrating the stringing of the other half of the sheave and cable:

system of Fig. 11.

Referring again to the ,drawings, there is shown a wheeled utility vehicle 10, having a truck-body 11 which carries a vertical mast or pedestal 12, the upper portion 14 of which is rotatable through 360, and supports a collapsible or articulated'tower assembly at its upper extremity. The collapsible tower assembly includesa pair of tower sections 15 and 16 pivotally interconnected (Figs. 1 and 2).

at one .of their adjacent ends through the saddle member I.

17, and carries, in the embodiment of the invention shown, a plurality of work'platforms 20 and 20a at its upper, extremity. 'While' a pair of work platforms are illustrated in the drawings, it will be understood that only onerworkplatform could be utilized if so desired. The work platform structure 20, 20a is maintained in a level condition with respect to the vehicle body 11 by means of a leveling cable and drumsystem generally referred to by number 21 and including a fixed drum 21a (Figs. and 7) secured to the upper end of rotatabie portion 14 of the mast 12. The latter arrangement maintains the work platform structure level irrespective of the pivotal movements of the tower sections 15 and 16 with respect to the vehicle body, such a leveling arrangement being known to those skilled in the art and accordingly will not bedescribed here in greater detail.

The lower tower section 15 is pivotally connected as at 18 to the upper extremity of the rotatable portion 14 of the mast 12 for tilting movement in a vertical plane. The pivotal interconnection by means of saddle member 17 between the upper and lower tower sections it; and 15 respectively is such that the upper section 16 is pivotal in a vertical plane relative to the lower section 15. In this connection and referring in particular to Figs. 2, 4 and 10, in the embodiment of the invention shown, the outer end of lower tower section 15 has a pair of transversely spaced, double section sheaves 22 and 22a rotatably mounted by means of shaft 24, on opposite outer sides thereof and secured to the downwardly and outwardly extending ends 1711 of bifurcated saddle member 17. Saddle member 17 is secured to the adjacent end of upper mast section 16 and upon rotation of sheaves 22 and 22a, saddle member 17 is pivoted in a vertical plane, thereby pivoting upper tower section 16 with respect to the lower tower section 15. Another pair of single section sheaves 26 and 26a are rotatably mounted on opposite outer sides of lower tower section 15 in generally longitudinally spaced relation to sheaves 22-, 22a and are connected to the latter by flexible elements or cables 28, 280: One end of cable 28a is anchored as at 30 to the associated sheave 22 or 22a and the cable 28:: is then reeved in a counterclockwise direction (as viewed in Fig. 2) about one section of the associated sheave 22, 22a, and the other end of the cable is then anchored as at 32 to bracket structure 34. One. end of cable 28 is anchored as at 35 to the upper portion of the other section of the associated double sheave 22, 22a, is strung rearwardly with respect to the utility vehicle, around the associated sheave 26, 26a and then is tautly anchored at the other end 37 to the respective side of the aforementioned bracket structure 34. Bracket 34 is of the adjustable length type comprising adjusting bolt and nut elements 37a. The piston rod 38 of a fluid actuated, double acting piston motor 40 is connected as at 39 (Fig. 2) to the bracket structure 34, intermediate cable strands 28 on either side of the tower structure, and upon retraction or inward movement of the piston rod from the Fig. 2 position, cable elements 28a are tensioned, thereby causing rotation of sheaves'22, 22a and pivoting of saddle member 17 and attached upper tower section 16 about the axis of shaft 24. Upon pivoting of upper tower section 16 in a counter-clockwise direction (as viewed in Fig. 4) beyond a vertically upright position with respect to the horizontal, it will be seen that gravity will cause the upper tower section 16 to pivot further with respect to the lower tower section 15 and therefore the cable elements 28a will slacken. The cable elements 28 will then take over and prevent the upper tower section 16 from free pivoting movement throughout the remainder of its pivotal range in a counter-clockwise direction, such tower section 16 with respect to the lower tower section in a clockwise direction (as viewed in Fig. 3), cable members 28 will be the actuating elements up to a vertically upright position of upper tower section 16, after which cable members 28a will serve as the braking elements of the arrangement, when gravity takes over as aforediscussed. It will be seen therefore that with such a sheave and cable arrangement, the pivotal movement of the upper tower section 16 with respect to the lower tower section 15 can be effectively and selectively con-- trolled throughout the pivotal range of the upper tower section.

The lower tower section 15 is tilted by means of a fluid actuated, double acting, piston motor 42 whose cylinder 44 is anchored to a bracket 46 carried by the rotatable portion 14 of the mast 12 and whose piston rod 48 is pivotally connected at its external extremity to a bracket 50 mounted intermediate the ends of the lower tower cables (28) being tensioned by the holding action of the pistonrod 38 of motor unit 40 with respect to the attached bracketstructure 34. .For pivotal movement of the upper section 15. The upper portion 14of the --mast 12' is rotated by means of two-way, fluid actuated motor 52 (Fig. 2) which is provided with a driving connection with the upper portion 14 of the mast in any suitable manner such as by means of the gearing arrangement 53 illustrated.

Retractable fluid actuated jacks 54 extend outwardly from the sides of the vehicle body 11 to engage the ground surface and thereby anchor the vehicle body in a stationary position to insure stability during movement of the tower sections and the mast. The jacks 54 may be extended and retracted in any suitable manner'as for example by fluid actuated motor units which may be coupled to a source of operating fluid in a conventional manner. The universality of movement of the work platform structure 20, 20a relative to the supporting vehicle body 11 provides virtually unlimited access to any point relative to the vehicle and within the dimensional limits of the structural members of the tower.

Controlled operation of the collapsible tower assembly to present the work platform structure 20, 20a to any desired work location is accomplished by selectively supplying operating fluid to each of the fluid motors 40, 42 and 52 through a conventional fluid piping system including fluid supply and fluid return lines. The supply of operating fluid to each of the fluid powered motor units 49, 42 and 52 is selectively controlled by means of a main, multi-stage, distributor valve 54 which is of the open center type including a pressure relief valvewellknown in the artthe more or less detailed construction of which may be seen in Fig. 9.

Distributor valve 54 is mounted on the rotatable portion 14 of the mast 12 adjacent the pivoted connection 18 of the tower section 15 to the mast structure. Operating fluid for the system is supplied by the variable output pump (not shown) of conventional well-known design mounted on the vehicle body and which may be independently engine driven or may be coupled to a power take-off on the drive shaft of the vehicle transmission, to pump operating fluid from a reservoir supported on the truck body and in a manner Well-known in the art. The valve spools 54a, 54b and 54s of the distributor valve 54 are adapted to be positioned axially by the mechanical control system to be hereinafter described in detail to direct operating fluid from the inlet port of the distributor valve to the proper feed lines of the respective fluid powered motor units 40, 42 and 5'2, for actuation of the latter, thereby causing movement of the associated aerial tower apparatus to the desired position. All of the valve spools 54a, 54b and 540 may be independently actuated or they may be actuated to gether in various combinations to' accomplish a compound movement of the aerial tower apparatus by multipleenergization of the corresponding portions of the mechanical control system to be hereinafter described. In accordance with the invention, a mechanical conanew? trol system is. provided includingflexible elements or cables extending up through the hollow-interiors of the articulated tower apparatus and mountedinq operative relationship thereon by plurality of rotatable sheave or drum elements, and with a pilot controlmechanism located adjacent the upper end of the tower structure and within ready accessibility by workmen standing, on-the work platform structure 20 and 20a.

As aforementioned, each ofthe work platforms are supported in cantilever fashion from the-upper extremity of the upper tower section 16=by means of shaft member 58 (Figs. 1- and 5a) which in-theembodiment illustrated, is of hollow or tubular construction. Rotatably mounted on shaft 58 are a plurality of ,telescoped sleeve elements 60, 62 and 64 whichare rotatable with respect one another and include grease fittings '66 for facilitating such relative rotary movement. Retainer members 67 detachablysecured to the associated of the sleeve members prevent relative axialmovementbetween the sleeve members. Secured to each of the sleeves60, 62 and 64 is a handle element 68, 70. and 72- respectively, for manually rotating the respective, sleeve element. The inner end of the sleeves are disposed -in the .;sarne stepped relationship asjthe outer-ends thereof, and secured to each of such stepped, inner ends of the sleeve elements are'drive sprocket members 74, 76-and 78 respectively.

Rotatably mounted on one side ofupper. tower section 16 are a plurality laterally stepped follower sprocket members 80, 82 and 84 (Figs; 5 and-6 Each of the latter sprocket members is securedito a shaft'member 86 which is rotatably mounted by meansfof bearing and mounting structure 88 to the confronting. wall of the upper tower section 16. Structure 88 is adjustably mounted on tower section: 16 by means of fastener elements, such as bolts 89, andassociated elongated slots 89a in the side wall of the upper tower section'16. Each of shaft members 86 has a drive sheave element 90, 92 or 94 secured to the respective inner endthereof, such sheave elements being disposed within the hollow interior of the upper-tower section 16. Thus upon rotation of sprocket members 80, 82 or- 84, a respective sheave member 90,92 or 94 is rotated therewith. Sprocket members 841, 8-2 and 84 are disposed in generally longitudinally aligned relation with sprocket members 78, 76 and 74 respectively, as can be best seen in Figs. 5 and 5a, and an endless chain 96 is entrained around each of the aligned pairs of sprocket members. 1 Each'of the drive sheaves 90, 92 and 94 is connected ;by a flexible cable system to one of the control spools of themain distributor valve 54, such fieXible-- elements or cables being mounted on the articulated tower sections by means of a sheave system to be hereinafter described in detail, for controlling the positioning of the spools of the distributor valve 54, and thus controlling the powered positional movements of the aerial tower apparatus. 7 V

The aforementioned pilot control sprockets 74,76, 78, 80, 82 and 84 and associated driving chains 96, are preferably enclosed by a housing guard 100 since such sprocket and chain mechanism is disposed exteriorly of the tower sections.

The cable system and related sheave and linkage apparatus for connecting the pilot control mechanism disposed adjacent the work platform structure and above described, with the valve spools of the main distributor valve 54 will now be described. Referring in particular to Figs. 11 and 13 inclusive, which diagrammatically illustrate the stringing of one sheave and cable system located on the articulated aerial tower sections, and which provides for the remote fcontrol mounting of the pilot control mechanism on the upperend of the-tower structure, it will be seen from Fig. 12,, which illustrates one-half of the stringing arrangement for eachof three 6 separate cable systems (one cable systembeing utilized to actuate one'of the main distributor valve spools) that one end of a cable 102 is anchored as at'104 to' one of the drive sheaves 90, 92 or 94 disposed adjacent the upper end of the tower, is wrapped in a clockwise direction (as viewed in Fig. 12) about the associated sheave, is extended through the interior of the upper tower section 16,.and looped over an idler sheave 106 rotatably mounted on a shaft 108 (Fig. 10) on the pivoted end of upper towersection 16. The cable 102 is then trained downwardly through the open face of the saddle member 17 and is looped in ,aclockwise direction (as viewed in Fig. l2),fabout another idler. sheave 1'10 rotatably mounted on the aforementioned shaft 24 on the outer end of lower tower section 15. From sheave 110 the cable 102 is'extended, r'earw'ardly with respect to the truck chassis through the hollow interior-of lower tower section 15 to be looped over one, of a set of valve spool control sheaves 112,114 and 116, rotatably mounted on a shaft 118 which is securedto the upper portion of rotatable section 14. ofthefm'ast structure 12. 'The end of the cable element 102 is then anchored as at 120 to the respective one of the spool. control sheaves 112,114 or 116. The other half of themounting forfeach of the valve spool remote control systems isfldiagrammatically illustrated in Fig. 13 wherein oneend of a flexible element or cable 122 is anchored as at 124 to the associated sheave '90, 9'2 or 94, is looped. in a counter-clockwise direction (as viewed in Fig. 13) thereover, is extended through the interior of the upper tower section 16 and looped over a respective idler sheave member 106a mounted on shaft 108 adjacent the pivoted end of upper tower section 16, is extended downwardly along the open face ofsaddle member 17 and is entrained (in a counterclockwise.direction, as viewedin Fig. 13) about a respective idler sheave vmember 1-10a, rotatably mounted on shaft 24 on lower. tower section 15, and'then is extended rearwardly with respect to the truck chassis through theinte'rio'r of lower tower section 15 to be anchored as at' 126 to the respective valve spool control sheave 112, 114 or 116. 1 The combined cable mounting arrangement for each of the remotelycontrolled valve spool systems is diagrammatically illustrated in Fig. 11, orin other words Fig. 11 is merely a combination of the elements of Figs. 12' 'and,.-13'.' Turn buckle members 128 of conventional well-known type are-associated with each of the cable elements 102iand 122 for adjusting the tension of the latter during service operations of the tower apparatus, and covered access openings 129 (Fig. l) are provided in the defining'walls of .upper tower section 16 to provide ready access to turn buckle elements 128. i

Each of the spool control sheavesll2, 114 and 116 is connected to a respective oneof the main distributor valve spools 54a, 54b and 54c by a bracket 130 (Fig. 7) suitably secured as by means offastening elements 132 to the respective one of the control sheaves, an adjustable length driver link element .134, a rocker member 136 pivotally mounted as by means of a pin 138 to bracket structure 140 secured to portion 14 of the mast, and follower link 142 which is pivoted as at 144to the respective rocker element 136and as-at 146 to the upper end of a respective valve spool. Se cured'to each of rocker members136 is a handle element 150 which'provides for independent manual control for positioning the distributor valve spools from the vehicle body in case of special circumstances or in the event of an emergency. The main distributor valve 54 is mounted on the aforementioned bracket structure 140 below rocker members 136 and is connected in a Well-known manner by distributor port 152, 154 and conventional associated feed and return lines, to the respective fluid powered motor units 411,- 42 and 52, which move the aerial tower mechanism to'any desired position.

As hereinbefore indicated, the distributor valve spools 54a, 54b and 540 may b e 'p'ositioned individually or in various combinations to .ac complish individual or compound movements of the various operative components of the tower assembly by manual positioning of the handle elements 68, 70 and 72 of the pilot control mechanism remotely located with respect to the main distributor valve 54, adjacent the work platform structure located atthe upper end of the tower structure. The valve spools can also be manually actuated as aforediscussed 'by the hand operated levers 150 on the rocker elements 136 disposed just above the main distributor valve unit which fion i i A suitable material for the control cables 102 and 122 of the remote control cable systems has been found to be one-eighth inch diameter steel aircraft cable which possesses the necessary strength and flexibility for the purposes described.

With such a remote control system and mechanism as aforedescribed, the remote pilot control levers 68, 70 and 72 remain in level position relative to the work platform structure mounted on the upper end of the movable aerial tower apparatus regardless of the amount of movement of the various components of the tower. The drive chain and sprocket arrangement readily translates control of the main distributor valve from the hollow interior of the upper tower section to the exterior thereof, in an uncomplicated yet positive manner, and permits the remote control levers to be mounted on the work platform support shaft 58 in an expeditious manner which prevents interference between the movable tower sections and the control levers, and wherein the latter are readily accessible to a workman positioned on the work platform structure. The direct mechanical connection of the control levers to the valve spools of the main distributor valve provides a good feel at the control levers for effective starting and stopping of the movement of the tower apparatus. The mechanism is easily and readily maintained, and adjustments may be made thereto without the need for special tools and the like. Another advantageto the mechanical .cable control system is that electrical insulation may be readily provided by inserting sections of non-conducting material in the control cable assemblies 102, 122. It will be understood that while only one set of pilot controls is illustrated in the drawings with the paired work platform structure, dual controls could readily be provided on the aerial tower with one set being associated with each of the work platform structures 20, 20a. v

From the foregoing description and the accompanying drawings it will be seen that the invention provides an improved collapsible aerial tower apparatus embodying a mechanical remote control system and mechanism for readily and positively controlling the application ,of fluid pressure to various fluid motor units which actuate the various components of the tower apparatus.

The terms and expressions which have beenemployed are used as terms of description and not of limitation and there is no intention in the use of such terms and expressions of excluding any equivalents of any of the features shown or described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.

Iclaim:

1. An aerial tower comprising in combination, a base, a tower section having one end pivotally mounted on the base for tilting movement in a vertical plane, a second tower section having one end pivotally coupled to the other end of the first tower section for relative tilting movement in a vertical plane, said tower being operatively supported on the base for unitary rotation in a horizontal plane, work platform structure carried adjacent the upper end of said second tower section, a plurality is mounted on the rotatable mast sec.

of fluid actuated motor-"units for independently rotating and movingjsaid'tow'e'r sections to selectively locate the work platform structure in any selected horizontal and vertically angled-piston anddistance relative to the base, fluid distributingvalve means located adjacent the base for-selectively controlling the application of operating fluid to each of said motor units, pilot control mechanism including a pluralityof manually manipulatable levers located on 'said work platform structure, a drive sheave element rotatably'mounted on said second tower section and operatively connected to said pilot control mechanism, a sheave 'element rotatably mounted on said one en'dof said second'tower section, another sheave element rotatablymounted on said other end of said first tower section, afurther sheave element rotatably mounted on said one end of said first tower section, means connecting said further sheave element to said fluid distributing valve means for actuation of the latter, and flexible means interconnecting said sheave elements and coacting therewith in response to movement of said levers to operate said fluid distributing valve means.

2; An aerial tower in accordance with claim 1 wherein said pilot control mechanism includes means for transferring the movement of said levers to said driver sheave element, said last mentioned means comprising a rotatable member mountedon said tower and operatively connected to said levers, another rotatable member mounted on said tower in 'longitudinally'spaced relation to said first mentioned rotatable member, and flexible means connectingsaid rotatable members, said second mentioned rotatable member beingoperatively connected to said driver sheave element.

3. In a control system for multiple element aerial tower having a plurality of fluid actuated motors for independently moving the tower elements relative to each other, a multispooled distributing valve for selectively supplying operating fluid to each of said motors, pilot control mechanism mounted on said tower remote from said distributing valve, said pilot control mechanism comprising a plurality of manually operable pivotal levers, a;drivesprocket member operably connected to each of said levers, a follower sprocket member rotatably mounted on said tower in generally longitudinally spaced relation to each of said drive sprocket members, an endless chain entrained about each of said longitudinally spaced pairs of sprocket members, a drive sheave member operatively connected to each of said follower sprocket members, a system of idler sheave members mounted on said tower along the vdirection of extension thereof, flexible cable elements entrained about said sheave members and coacting with the latter to rotate the same ,upon pivotal movement of said levers, and linkage means connecting said idler sheave system to the spools of said distributing valve for translating the rotary motion of the sheave members into axial movement of the valve spools for controlling the flow of operating fluid to said motors.

4. In a multi-element aerial tower having a plurality of fluidactuated motors for independently moving the tower elements relative to each other, a control system comprising a multi-stage distributing valve for selectively supplying operating fluid to each of said motors and means .for selectively actuating said distributing valve to-eontrol the flow through each stage thereof, said means comprising a pilot control mechanism mounted on said tower remote from said distributing valve and connecting means. disposed along saidtower elements and operatively connecting said pilot control mechanism to said distributing valve, said pilot control mechanism including a plurality of manually operable control levers each of which controls the flow of fluid through a corresponding stage of said distributing valve, means independently coupling. each of said. control levers to said connecting means for actuating the latter, said connecting means comprising a plurality of sheave members mounted on said tower sections and flexible elements entrained about References Cited in the file of this patent said sheave members and c oacting with the 1atter to UNITED STATES PATENTS transfer the movement of s a1d levers to sa1d d1str1but1ng valve to thereby control the application of fluid pressure 2,578,897 Oliver 1951 to said motor units from said remotely located pilot 5 2,616,768 Stemm N 2 control mechanism, 7 We e Mar. 16, 1954

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