US2428163A - Crane - Google Patents

Description

Sept.30,1 947. I .G, HUBBARD AL 2,428,163

CRANE Filed Oct. 31, 1944 8 Sheets-Sheet 1 l'lllill |||l||lllllllllllllllllllllllllllllllllifl INVENTORS.

Sept. 1947- G. H. HUBBARD EI'AL 2,428,163

CRANE Filed ot. 31, 1944 a sheets-sheet 2 Sept. 30, 1947.

G. H. HUBBARD ET AL CRANE Filed Oct. 31, 1944 8 Sheets-Sheet 5 INVENTORJ. uard iii Sept. 30, 1947.

e. H. HUBBARD ETAL Filed-Oct. 31, 1944 CRANE 8 Sheets-Sheet 4 uvmvrozes: I Georye f/uard We?! y G. H. HUBBARD El AL Sept. 30; 1947.

CRANE Filed Oct. 31, 1944 8 Sheets-Sheet 4 INVENTORS:

69 or, h. #:16601 0 Sept. 30, 1947. G. H. HUBBARD ET'AL CRANE Filed 001:. 51, 1944 8 Sheets-Sheet 6 INVENTORS. g e orye fffi ubard P 1947- e. H. HUBBARD EI'AL CRANE Filed Oct. 31, 1944 8 Sheets-Sheet 7 Sept. 30, 1947.

G. H. HUBBARD ErA'L I cRAfiE Filed Oct. 31,1944

8 Sh ets-sheet s Wm? FOOT 152M411 TOFPIHG FOOT BZAKY:

v V roles. Georye b. A f/Egan? -flarry urney I- CL AN! MI. ggg tvow.

COM'PElSS R Patented Sept 30,1947

UNITED STATES PATENT' OFFICE CRANE Application October 31, 1944, Serial No. 561,228

Claims. 1

This invention relates to cranes. The general object is to engineer a crane in which recourse is had, as the powering agency responsible for accomplishing slewing movements, to the same engine which customarily is applied only to the hoist, topping and whip drums in the heavy-duty work of spooling the load-handling cables. In order that this end may be attained, it becomes a particular object to so modify the power output of the engine, as applied to slewing, as will assure complete safety against destructively intense forces being transmitted from the engine to the load-carrying and, in consequence, motion-resisting boom.

The invention further aims to provide a perfected system of controls employing the force of pressure air as the instrument responsible for activating normally inoperative and ostensibly independent means associated with the spooling drums and with the slewing mechanism, and which is particularized in that the said condition of inoperative normalcy is brought about by force of spring pressure in order that-given a failure in the source of pressure-air supplythe crane will be rendered inoperative.

The foregoing with other and more particular features of the invention, and the advantages arising from their use, conjointly or otherwise, will be made clear in course of the following description taken in connection with the accompanying drawings, in which- Figure l is a fragmentary front elevational view portraying a crane constructed to embody the teachings of the present invention, the view being confined to a showing of only those parts of the crane related to the instant advance, namely the non-rotary bull gear and the rotative deck, to the exclusion of the boom.

Fig. 2 is a, top plan view thereof,

Fi 3 is a fragmentary top plan View taken to an enlarged scale to detail the lay-out of the manual controls which customarily are located within an operators cab (not shown) movable with the machinery platform or, as previously termed, the rotative deck of the crane.

Fig. 4 is a. longitudinal vertical section on line 44 of Fig. 3.

Fig. 5 is a fragmentary transverse vertical section employing a still larger scale and detailing one of the three spooling drums shown in Figs. 1 and 2.

Figs. 6 and 7 are longitudinal vertical sectional views taken to a reduced scale on jogged lines 6-6 and 1-1, respectively, of Fig. 5. Fig. 8 is a transverse vertical section taken to a some- 2 what larger scale than that of Fig. 5 and detailing structure which we apply as a braking assembly for the slewing control.

Fig. 9 is a fragmentary vertical sectional view detailing one of a number of dumping valves which are applied at various points within the pressure-air system of the inventions control hook-up.

Fig, 10 is a diagrammatic lay-out of that part of the control hook-up which overns the cranes slewing movements; and

Fig. 11 is a diagrammatic lay-out of that part of the control hook-up which governs the cablewinding drums;

Referring to said drawings, the numeral 20 designates the usual rotative table or platform swingable about pivot-pin 2| and having supporting wheels 22 which travel on a circular track 23 laid upon a stationary bed 24, motion being communicated to move the platform by a spur-pinion 25 meshing bull-wheel 26 and, by vertical shaft 27, driven from a horizontal stub shaft 28 through bevel gearing Z930. J ournaled .in suitable boxes, as 3|, to occupy an exposed position upon the platform, said stub shaft 28 to be hereinafter termed the slew-shaft carries upon its opposite end a bevel gear 32 and in mesh therewith are two bevel gears 33-3 3 occupying positionsat diametrically opposite sides of the slew-shafts axis. 'Said gears last mentioned are mounted normally loose upon an engine-driven cross-shaft 35, and by a permitted selective cou pling of gears 33-34 thereto oppositely directed rotational movements are selectively imparted to the slew-shaft. Clutches employed to perform this work, and the manner of their operation, will be hereinafter described.

The engine, denoted at 43, is desirably of the Diesel-powered typesay a 200 H. P. plant-and acts through chain 36 to drive a cross-shaft 3T journalled in suitable boxes 38 and occupying a position longitudinally removed from and paralleling the power-shaft 35. Upon this shaft 31 is a driving pinion 40 and driven off this pinion is a train of spur gears 4445-46-M.

The last-named gear in this train is made fast to the power-shaft 35, and the other three gearsnamely the gears 44, 45 and 46-are each associated, through an intervening and normally disengaged clutch, with a related one of the customary three cable-winding drums ordinary to crane practice, namely a drum 48 carrying the topping line 49, a drum 59 carrying the hoist line 5|, and a drum 52 carrying the whip line 53. In addition to said clutches, there is provided for each said drum a normally active brake and a normally inactive pawl, each made subject to a spring for maintaining a condition of normalcy and, as with the spring-released clutch, operated in opposition to the respective spring by'force of pressure air derived from a receiving tank 54 fed by compressor '55,, the compressor being powered off the engine 43. A detailed, description of any one of the illustrated three drums will sufiice for the other two, the parts being functionally alike, and the structural nature of these parts will be best understood by inspection of Figs. through 7, inclusive.

Referring, therefor, to these views in which we have selected the topping drum 48 for the purposes of the illustration, it will be seen that the drum and its powering spur gear 4.4 are co.- axially supported upon a shaft 56', with spring 5? adjustable as to pressure being introduced therebetween and acting to urge the annular clutching nose 58 out. of friction-gripping engagement with a mating recess presented in the facing outer end of the drum. The said nose, and which is comprised of a severalty of blockelements spaced at intervals of the circumference, is, in more particularity, fixedly associated with the shaft 56, and the drum proper is arranged for relative endwise movement thereon. An air-head 69 is carried upon an exposed end of this shaft remote from the gear 44 and findsconnection, through pipe 61 and flexible hose 62, with the receiver tank 5 3,, and received: within the head is a piston 63. Return springs 64 are applied to oppose the force of the pressure air. A pin 55 extends as an axial prolongation of the hub part 63' of the. piston, and extends freely through a center-bore 66 of the shaft into a cross-slot 61 cut diametrically of the latter,

pressing within the slot against a key 68 which} in turn, operates upon a thrust collar 69 bearing upon the drum.

Describing the brake which, as stated,- isprovided for respective said cable-winding drums, there is employed a flexible band made functional to a brake-drum II and having its dead end 72 anchored to a fixed shaft, as 13, much in. the manner of the usual brake of this type, the other or live end, also as is customary, carrying. a terminal fitting I4 presenting. a wrist-pin 1.5 to admit of the adjustable attachment of an eye-bolt 16. A lever-arm 18 connects by pin H with this eye-bolt, and movable with said arm 18 about connecting shaft 19 as a fulcrum is a lever arm 80. Arms 18-88 constitute, in effect, short and long arms of a substantial bell-crank, and the long arm is linked to a second bell-crank structure, as by rod 8!, similarly composed of' compounding short and long arms 82-83, respectively, connected for unitary movement by fulcrum-pin 8A. A clevis 85 carried upon the end of a spring-mounting rod 86 subjects the arm 83 to the pressure of a spring 81 shouldering against a frame-rest 88, and there is applied. to said arm a second clevis 89 carried upon a rod- 90 made subject to the movement of a piston 9t received within an air cylinder 92. The pressure air, introduced to the cylinder through. flexible hose 93, is arranged to act in opposition to the spring, the latter being relied upon to contract the brake band and the pressure air in consequenceby its overpowering of the springacting to expand the band.

Proceeding with a description of the pawl. as sembly, and denoting the pawl proper by 94 andits ratchet by 95', there is here again-appliedsprings and air pressure working in opposition, with the spring, as 96, operating directly upon the pawl to normally hold the latter in an inoperative position, and the pressure air being fed by flexible hose 9'! into an air cylinder 98 for operation of a contained piston, connecting rod H19 imparting responsive movement to the pawl by its. engagement with crank [ill fixedl'y'associated with the pawl.

Reverting now to the slewing function of the crane, and here, as with the drum structures, first describing only the apparatus which is made responsive to control impulses, and which is tosay excluding a detailed recitation of the controls proper which, for the slewing mechanism and for the: drums, will be hereinafter set forth, there is applied to each end of the continuously driven cross-shaft an air-head, as l02-IB3, formed similar to and operating in much the same manner as the air-head 60 previously described, the one saidv head being pressure-ted by an air-line Hi4 and the other by an air-line W5, see Fig. 10-. The. pistons (not shown) related. to these air-heads. actv through the complements of a friction clutch to cause either of thetwogearsH-Sito be brought selectively into couple with thepower-shaft 35'. This is to say that an activation of the piston related to one said head works-through a. clutch assembly I06 tobring the bevel-gear 33 into a connecting couple with the shaft, and an operation or the other said piston activates clutch assembly I01 to bring the other bevel-gear 34- into a connecting couple, thus to drive, coincidently with. the powering shaft 35, one said gear by delivery o-f pressure air through. one air-line and. the other said' gear by delivery of pressure air through the other air-line, and through these gears rotating the. slew-shaft 28 in opposite directions. Any suitable clutch. device capable of obtaining an engagement as between shaft 35 and either of the two bevel-gears 3334 independently may be used in imparting the desired converse directional rotation from the uni-directional and continuously driven. shaft 35 to the shaft 28, and which, for example, might desirably comprise a sleeve splined to the former shaft so as to integrally rotate therewith while being movable axially thereon, and provided with a conical-shaped nose movable against spring opposition into amating recess. presented inthe meeting face of a. second "member fixedly secured to a. respective bevel-gear, very much along. the line of the structure detailed in Fig. 5 with this departure, namely, that the drive. carries. through. the shaft- Upon the slew-shaft 28. is. a brake drum. L08 to which are applied. brake shoes till-4.1 l. supported by backing arms. LIZ-H3, these arms being given a pivotal mounting at one. end, as at H4, and connecting. by their other ends with. means for accomplishing. the expansion. andv contraction oflice of. the shoes, the particular structure. which.

we have elected to illustrate comprising a lever N5 of the bell-crank order connected by pin .6 to. work about the. end. of one said. backing arm as a floating fulcrum and finding connection by rod H1 from. its short arm to the free end of the other saidbacking arm, the long. arm of the. lever, by action of a spring H8, being. normally urged in a direction causing braking contraction of the shoes. For overpowering the spring, pressure. air is here again used, being fed. from the source 54' through flexible hose. I26- intoa cylinder i24 re.-

ceiving a pivotal. mounting, as at L25, and within the cylinder actuating a piston I23 which connects by rod l 22 with a perch I2 I, the perch finding pivotal connection, as at I20, with said lever I I5. We have detailed the arrangement in Fig. 8, selecting for the purpose a spring set air release brake produced by Wagner Electric Corporation, and illustrating a hydraulic snubbing unit I2'I as being also applied to the brake. This snubbing unit derives its hydraulic energy through line I29 from a foot-operated pump 53!] (Fig. It may be here stated, while the snubber characterizes the Wagner brake and may, if desired, be employed in the present system, the nature of the latter obviates any need for its usage and the snubber can be deleted without destroying the systems operating efficiency.

Now to consider the pressure-air controls, it is to be expressly pointed out that the invention lies in the application rather than in any peculiarity of construction of the component parts of the system, and no need exists, therefor, for a detailing of these parts, our illustration being limited to elevational views of the several control valves (Figs. 3 and 4:) and to symbolic indication of these and other elements where they occur in the diagrammed complete systems (Figs. 10 and 11). These parts are, or they may be, standard equipment, selected in the open market according to the particular ofiice each is to perform.

First having reference to Fig. 11 wherein are shown the clutch, the brake, and the pawl related to each of the three cable-winding drums, it will be seen that two valves are provided for each of these clutch-brake-pawl sets, designated l3I and 32 for the topping drum, I33 and I34 for the hoist drum, and I35 and I35 for the whip drum. It becomes the oihce of the firstnamed of each of these paired control valves to govern the delivery of pressure air fed from the air reservoir 54 through supply line 93 to the cylinder for the brake-releasing piston ill. The second-named Valve of each said pair has the twofold function of governing both the clutch and the pawl, being a two-way valve fed from the air reservoir and connecting by one of its outlet sides with the supply line 52 for the clutch and by its other outlet side with the supply line 97 leading to the cylinder for the pawl-activating piston 33. A dumping valve I3? is applied to each of the lines 93, 62 and 31 to lie in intervening relation between the said control valve and the responding piston, this dumping valve being detailed in Fig. 9 and serving the self-evident end, as line pressure is cut oif, of exhausting pressure air to the atmosphere from the cylinder of the activated piston, thus to permit assertion by the related spring of its counteracting power. It is found that the Flexair line of valves produced by Westinghouse Air Brake Company present control units exactly suited to our purpose, the Flexair valve #A-2-F. being especially adapted for use in the first-mentioned of the said control capacities while Flexair valve #B-l-L serves as the two-way unit. For operating these valves and which will be best seen from inspection of Fig. 4, We resort to the use of a hand lever I38 (Fig. 3) in respect of the two-=way valve,-while utilizing foot power to work the shifting lever I39 of the one-way valve, linking the latter to a treadle I40 with which is associated a ratchet-and-pawl catch and effectuating restoration to normal upon the release of this catch by a spring I4I.

Proceeding, now, to a consideration of the cranes swing control diagrammed in Fig. 10, a three-way valve denoted I43 is here used, and we again finda Flexair valve, #D-l-L in this in-- stance, is ideal for our purpose. Fed as with the other Flexair valves from the air reservoir 54 but with this difference, namely, that a reducing valve I44 is applied inthe line I45, two of the valves three outlet sides lead one by the supply line I04 to the clutch assembly I36 and the other by the supply line I05 to the clutch assembly I01, and there is introduced to each supply line a check valve, as I50, metered such as will develop a predetermined choking of the supplied air.

At this point, and in order that the significance of the reducing valve I44 and the metering check valves I50 will be fully understood, it should be expressly pointed out that a cranes swinging movements can be safely carried out only where the power applied is held Within a range well under the force which can, and should, be applied to operate the cable-winding drums. Moreover, the speed with which the crane is permitted to picl: up the full power of the available slewing force is of very real moment to safe operation of the machine. Therefor, if the power of an engine developing, say, the 200 H. P. of the engine 43 is to be applied through spur gear 41 to the shaft 35 which powers the bevel gears 33-34, it becomes necessary, for practical operation, that a modifying influence be introduced, and as our means of modifying the power of the engine and also the time interval for completing a, driving couple between the shaft 35 and an elected said gear, we utilize the relatively light air pressure of 60# to maintain a friction-couple between complementary elements of the clutch I06 or Illl, as the case may be, and permit access of thispressure air to the elected clutch only by way of a. choked aperture. The reducing valve I44 constitutes the means responsible for placing the clutch assemblies under a head pressure of, say, 60# as compared with a 1504i" reservoir setting, while the metering check valves I59 perform the office of choking the volumetric flow.

Reverting to the remaining, or third, outlet side of the valve I43, connection is made therefrom by air line I5I to the face of a spring-opposed piston (not shown) working as the governor element of a relay air valve I52. This relay valve (Westinghouse #512905) we apply to lie in intervening relation between the air reservoir 54 and the cylinder I24 of the Wagner brake assembly previously described, connecting with the latter by the air line 126 and with the reservoir by a delivery line I53. Describing such relay valve in more particularity, the same is fittedin addition to the governor piston--with two spring-loaded check valves. One check valve serves as a supply valve and the other as an exhaust valve, and the operation is as follows: Assuming that the governor piston has been relieved of air pressure upon its face, and which follows a shifting of the lever I54 of the three-way Flexair valve I43 from brake position to the neutral location in which shown, the said piston will then be influenced by the spring therefor into its normal position. So

disposed, the exhaust check valve of the relay.

assembly is caused to close while the supply valve becomes unseated, and incoming pressure air from line I53 is admitted to the air line I26. Piston I23 is responsively caused to overpower the brakesetting spring H8, and the brake released. Thus, slew-shaft 28 is free to rotate and the shift lever I54 may, if desired, be intro.- duced to either of its two swing positions. Given a shifting of the lever from said neutral to the brake position, pressure air is given access is accordingly from line 1'45 to the line I51, and this pressure applied to the face of the relay valves governor piston overpowers the latters spring. Responsive movement of the said governor piston seats the supply valve and by such seating isolates the deliveryline 153 from line 126, coincidently opening'thc exhaust check valve and causing the pressure air contained within cylinder I24 and connecting airline I25 to be dumped to the atmosphere. Spring H8 thus being permitted to assert its influence, the brake becomes set and the crane is locked against rotative action.

A clear understanding of the invention should be had from the foregoing description taken in connection with the drawings, and it is believed unnecessary to make express reference to gauges and the like applied, as is customary, to fill their customary oflice. lhe two elements denoted I66 and lfil in Figs. 3 and 4 serve as clutch and throttle controls for the engine.

It will be apparent that we have made it possible 'to apply-with full safetyto the cranea single power plant to perform the slewing as well as the cable-spoofing function. The answer perforce lies in having engineered a practical mode of paring down the power-output of the engine insofar as its drive is made efiective upon the slewing mechanism and, perhaps the more salient, effectuating first a gradual increase and, thereafter, a gradual decrease in the force moment of the power-couple between engine and slewing mechanism through the two critical periods of acceleration and deceleration during which resisting forces of destructive intensity are created by the unwieldy nature of a cranes boomsupported load.

Departures from the embodiment of the invention which has been illustrated and to which express reference has been made in the "foregoing description will suggest themselves; It is our intention that no limitations be implied as we consider all forms of construction and variation in detail coming within the scope of the hereto annexed claims to be comprehended by the invention.

What we claim is:

1. In combination with the rotative machinery platform of a crane, the relatively stationary bull gear, and with a normally idle slew-shaft, and the powering engine therefor, said shaft being journaled upon the platform and having operative interconnection with the bull gear whereby to reve'rsely swing the platform by conversely directed rotational movements of the shaft: a bevel gear and a brake drum fixedly secured upon the shaft; 3, spring-set brake mechanism for the brake drum; a cross-shaft powered from the engine and lying at right angles to the slew-shaft; a pair of oppositely disposed bevel gears loosely mounted upon the cross-shaft and continuously in mesh with the bevel gear of the slew-shaft; independent spring-released clutch devices for the paired gears arranged by activation to couple the cross-shaft to either of the two ears, selectively; units made responsive to pressure air and applied to each of said clutch devices and the brake mechanism to work in opposition to the springs therefor; an air compressor; an air receiver; and valved connections from the receiver to each of said pressureair units.

2. In a crane, in combination with the rotative machinery platform, and with the relatively sta tionary bull gear to which recourse is 'had'in swinging the platform: a slew-shaft icurnaled upon the platform and having operative interconnection with the bull gear whereby to reversely swing the platform by conversely directed rota tional movements of the shaft; a bevel gear and a brake drum fixedly secured upon the shaft; a spring-set brake mechanism for the brake drum; 2. power shaft driven from the engine and disposed to occupy a position at right angles to the slew-shaft; a pair of oppositely disposed bevel gears loosely mounted upon the power shaft and continuously in mesh with the bevel gear of the slew-shaft; independent spring-released clutch devices for the paired gears arranged by activation to couple the power shaft to either of the two gears, selectively; units made responsive to pressure air and applied to each of said clutch devices and to the brake mechanism to work in opposition to the springs therefor; an air compressor; an air receiver; air-flow connections from the receiver to each of said pressure-air units; a normally open valve for the air-flow connection which leads to the pressure-air unit for the brake mechanism; control valves for the other twoair-fiow connections arranged for manual operation and adapted to be selectively operated alternatively; a manual control for said normally open valve'to effectuate a closing of the latter and interrelated to the other two controls such that an operation of either of the latter bars a valveclosin-g operation of the former; and valves for each of said air-flow connections located proximate to the delivery ends of the latter and acting automatically upon an isolation from the air receiver to exhaust pressure air from within the line to the atmosphere.

3. Means associated with a rotatively mounted shaft for either holding the same stationary or selectively powering the shaft in opposite directions of rotation and comprising, in combination with'the shaft, and with a source of rotary power therefor: a brake drum fixedly secured upon the shaft; a spring-set brake mechanism for the brake drum; connection including a spring-released clutch device from the power source to the shaft and acting, when the clutch is engaged, to drive theshaft in one direction of rotation; a second connection likewise including a spring-released clutch device independent of the first-named clutch device leading from the power source to the shaft and acting, when the last-named clutch is engaged, to drive the shaft in the opposite direction of rotation; separate units made responsive to pressure air and applied to each of said clutch devices and to the brake mechanism to work in opposition to the springs therefor; a source of pressure air; an air valve having an inlet made subject to the pressure of the source and provi'ding three outlets, and characterized in that connection is made from the inlet to a selected one of the three outlets; air-flow connections from two of said three outlets one to one and the other to the other of the two said pressure-air units related to theclutch devices; a means operating automatically upon an isolation of a respective said pressure-air unit from the source of .pressure air for relieving pressure upon the unit; a normally open air-flow connection leading from the pressure-air source to the pressure-air unit of the brake and lay-passing said air valve; a normally inactive control element for said last-named connection operating by application of pressure air thereto to isolate the source of pressure air from the pressure-air unit of the brake and coincidentally exhaust pressure air from the latter to the atmosphere; and an air-flow connection from the third of the three outlets of the air valve made 9'- functional upon the element last recited to transmit activating lpressure thereto.

-' 4. In a crane having a rotative machinery platform, providing an engine, and having normally "inactive spooling drums arranged and adapted to be driven from the engine, and normally inactive mechanism for slewing the platform and likewise arranged and adapted to be driven from the engine, all of which are carried upon the platfrm,the combination with said platform, the engine, the spooling drums, and the slewing mechanism: means functionally associated with manually-controlled clutches for said spooling drums and for the slewing mechanism acting automatically to cut out the spooling drums only upon the development of a resistant force exceeding a given major ceiling pressure and to cut out the slewing mechanism upon the development of a lesser resistant force exceeding a given minor celing pressure.

5. -In a crane having a rotative machinery platform,- and providing an engine, and spooling drums, and having a supply of pressure air, said engine and the spooling drums being carried upon the platform, the combination with said platform, and with the engine, drums, and pressure air supply: driving connections including respective spring-released clutches between the engine and the spooling drums; a normally idle slew-shaft journaled on the platform and arranged and adapted to reversely swing the platform by conversely directed rotational movements of the shaft; a pair of driving connections including respective and alternatively acting spring-released clutches between the engine and the slew-shaft and operating by activation of one said clutch to cause the slew-shaft to be driven in one direction and by activation of the other said clutch to. cause the slew-shaft to be driven 'in the other direction; units made responsive to pressure air and applied to each of said several clutches to work in opposition to the springs therefor; connections including separate control valves from the single pressure air supply to each of said pressure-air units; and means applied to the connections which lead to the pressure-air units for said clutches of the two driving connections for the slew-shaft functioning to reduce the pressure and choke the fiow by comparison with the pressure and flow applied to the other pressure-air units.

6. In a crane having a rotative machinery platform, providing an engine, and having an air compressor driven from the engine, an air receiver associated with the compressor, and spooling drums, said engine, compressor, receiver, and drums being carried upon the platform, the combination with said platform and its said supported machinery, and with a relatively stationary bull-gear: driving connections including respective spring-released clutches between the engine and the spooling drums; a normally idle slew-shaft journaled on the platform and operatively interconnected with the bull-gear whereby to reversely swing the platform by conversely directed rotational movements of the shaft; a pair of driving connections including respective and alternatively acting spring-released clutches between the engine and the slewshaft and operating by activation of one said clutch to drive the slew-shaft in one direction and by activation of the other said clutch to drive the slew-shaft in the other direction; units made responsive to pressure air and applied to each of said several clutches to work in opposition to the 10 springs therefor; connections including separate control valves from the receiver to each of said '-pressure-air units; and means applied to the connections which lead to the pressure-air units for said clutches of the two driving connections for the slew-shaft functioning to reduce the prespressure and flow applied to the other pressureair units.

7. In a crane having a rotative machinery platform, and providing an engine, and having an air compressor driven from the engine, an air receiver associated with the compressor, and spooling drums, said engine, compressor, receiver, and drums being carried upon the platform, the combination with said platform, and with the engine, compressor, receiver, and drums: driving connections including respective spring-released clutches between the engine and the spooling drums; a normally idle slew-shaft journaled on the platform and arranged and adapted to reversely swing the platform by conversely directed rotational movements of the shaft; a pair of driving connections including respective and'alternatively acting spring-released clutches between the engine and the slew-shaft and operating by activation of one said clutch to cause the slewshaft to be driven in one direction and by activation of the other said clutch to cause the slewshaft to be driven in the other direction; units made responsive to pressure air and applied to each of said several clutches to work in opposition to the springs therefor; connections including separate control valves from the receiver to each of said pressure-air units; and means applied to the connections which lead to the pressure-air units for said clutches of the slew shafts two driving. connections functioning to reduce the pressure and choke the flow by comparison with the pressure and flow applied to the other pressure-air units.

8. In a crane having a rotative machinery platform, an engine, an air compressor, an air receiver associated with the compressor, and spooling drums, said engine, compressor, receiver, and drums being each carried upon the platform, the combination with said platform, and with said engine, compressor, receiver, and drums: driving connections including respective spring-released clutches between the engine and the spooling drums; a slew-shaft journaled on the platform and arranged and adapted to reversely swing the platform by conversely directed rotational movements of the shaft; a spring-set brake functional to the slew-shaft; a pair of driving connections including respective spring-released clutches between the engine and the slew-shaft and operating upon a release of said brake and by activation of one said clutch to cause the slew-shaft to be driven in one direction and by activation of the other said clutch to cause the slew-shaft to be driven in the other direction; units made responsive to pressure air and applied to each of said several clutches and to the brake to work in opposition to the springs therefor; connections including respective control valves from the receiver to' each of said pressure-air units for the clutches; means applied to the connections which lead to said pressure-air units for the clutches of the slew-shafts two driving connections functioning to reduce the pressure and choke the flow by comparison with the pressure and flow applied to the other clutchactivating pressure-air units; a connection from the receiver to the brakes pressure-air unit; a

1,1 governor valve in said connection: and a second connection including both a control valve and .a. reducing valve and leading .from the :receiver to the governor valveand acting, when open,

to cooperate the governor valve .as 1'10 isolate the ,5

hrakes pressure-air unit from the said receiver while simultaneously exposing the'unit to the atmosphere :for dumping the pressure air and thus permitting the spring to assert its power for setting the brake. 9. The structure of claim .8 having a, single control lever functional to the control valve lastnamed and also to the two control valves of the connections which lead to the pressure-air units for the clutches .of the slew-shafts two driving 5 connections and so arranged .as to permit the related two pressure-air units-(and, the governor valve to be subjected to said operating air pressure alternatively only.

1.0. In a crane having -a i'otative machinery no platform, on engine, an air compressor, an air receiver associated the compressor, and spooling drums, said engine, compressor, receiver, and drums being each carried upon the platter-m, the combination with said platform, 25

and with said engine, compressor, receiver, and drums: driving connections including respective spring-released clutches between theeng-ine and the spooling .drums; .a slew-shaft .journaled on the platform and .arranged and adapted to ,30 reversely swing the platform by conversely -directed rotational movements of the shaft; a spring-set :brake tunct-ional to the slew-shaft; a pair of driving connections including respective spring-released clutches between the engine and .85 Number the slew-shait and operating upon a release of said loralce and by activation of one said clutch to :cause the slew-shaft to be driven in one direction ,and by activation of the other said clutch to-cause the slew-shaftto Joe driven in the other 40 direction; units made responsive to pressure air and applied to each of said several clutches and to the brake to work in opposition to the springs therefor; connections including separate control valves item the receiver to each of said pressure- 45 air units ,for the clutches; mesm connections which lead to said prese s for the clutches of the .slew-shafts twist, 8 connections functioning to reduce the presse and choke the .flow by comparison with the pressure and how applied to the other clutch-activating pressure-air units; a relay valve providing tour openings one of which is a pressure-dumping discharge; connection from one of the other three openings to the pressure-air unit .for the F brake; and separate connections leading from the receiver one to one and the other to the other of the remaining two openings and, in the instance of one said connection, including a control valve and :a means for reducing the pressure below the pressure which obtains in the receiver, the working of said relay valve being such that the pressure-air unit for the brake is made subject to the high pressure of the high-pressure connection and with the-low pressure of the lowpressure connection serving .as -13: means for isolating said pressure-air unit from said pressure of the high-pressure connection while .simultaneously connecting :the related pressure-air unit with the pressure-dumping discharge.

GEORGE H. HUBBARD. HARRY L. TURNEY.

REFERENCES CITED The iollowing references are of record in the file of this patent:

UNITED STATES PATENTS .Name :Date 1,260,780 Latshaw Mar. 26, 1918 1,298,056 King et :al Mar. 25, 1919 1,255,909 Bernard Apr. 22, 19.30 2,071,135 McGifiert et al. Feb. 16, 1937 12,094,278 Morin et'a-l Sept.,28, 1937 2,129,267 Miller Nov. .5, 1939 2,180,469 J aeger .et 'al Nov. 21, 1939 2,254,083 Nickles :etal. Aug. 2 6, 1941 2,363,860 Gentry Nov.128,1944 2,375,255 Snader eta-l. May 8, 19,45

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