US2696016A

US2696016A - Retractable soot blower

Info

Publication number: US2696016A
Application number: US155304A
Authority: US
Inventors: Mart Le Roy S De
Original assignee: Diamond Power Specialty Corp
Current assignee: Diamond Power Specialty Corp
Priority date: 1950-04-11
Filing date: 1950-04-11
Publication date: 1954-12-07
Anticipated expiration: 1971-12-07

Description

Dec. 7, 1954 LE ROY 5. DE MART RETRACTABLE SOOT BLOWER 8 Sheets-Sheet 1 Filed April 11, 1950 QWM HQ INVENTOR. X6 Fag 5 J6 fifk/Z.

Dec. 7, 1954 LE ROY 8. DE MART I RETRACTABLE SOOT BLOWER 8 Sheets$heet 2 Filed April 11, 1950 Dec. 7, 1954 LE ROY s. DE MART RETRACTABLE SOOT BLOWER 8 Sheets-Sheet 3 Filed April 11, 1950 IN V EN TOR.

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Dec. 7, 1954 LE ROY 5. DE MART 2,696,016

RETRACTABLE SOOT BLOWER Filed April 11, 1950 8 Sheets-Sheet 4 Dec. 7, 1954 LE ROY 5. DE MART 2,696,016

RETRACTABLE SOOT BLOWER Filed April 11, 1950. 8 Sheets-Sheet 5 1N VEN TOR. Fag 5. Zf/Vk/Z? 8 Sheets-Sheet 6 7 5. .H x a W a %E e m 5% 1 2 M W, 5 fl v 5 i w M w 2 ,6 1 Z LE. 4 k 9 0 J W a; V a Z 4 W, W fi Dec. 7, 1954 Filed April 11, 1950 if m Dec. 7, 1954 LE ROY 5. DE MART 2,696,016-

RETRACTABLE SOOT BLOWER Filed April 11, 1950 8 Sheets-Sheet '7 INVENTOR.

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' RETRACTABLE SOOT BLOWER Filed April 11. 1950 8 Sheets-Sheet 8 u INVENTOR.

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United States Patent RETRACTABLE soor BLOWER Le Roy S. De Mart, Detroit, MiClL, assignor to Diamond Power Specialty Corporation, a corporation of Ohio Application April 11, 195th Serial No. 155,304

17 Claims. (Cl. -317) This invention relates to cleaning devices of the class employed in cleaning the heat exchanging surfaces of boilers and the like, and which are commonly known in the trade as soot blowers.

The primary object of the present invention is to provide an improved rotary retracting soot blower which employs only a single extensible and retractable blower tube, having a blower nozzle at its end, and which is capable of relatively long travel, being operable through the agency of projecting and retracting mechanism of a unique, simple and reliable character, and which achieves advantages not heretofore obtainable in a single structure of this class.

Among important advantages of my invention may be mentioned the fact that my improved soot blower is operable by extremely compact driving mechanism which may be located close to the wall of the furnace or boiler, while the retractable and extensible portions of the blower which project rearwardly from such driving mechanism are fully enclosed, due to the inherent construction of the blower, so that if desired, such projecting portions may extend outwardly from the building containing the boiler and into the open air, a great saving being thereby effected in that the building need not be large enough to enclose all portions of such soot blower assemblies, even though they be of the long-retracting type. Soot blowers constructed in accordance with my present invention incorporate a stationary threaded driving element which also serves as a support for the blower tube, and a feed conduit through which the blowing fluid is supplied to the blower tube and'nozzle, novel means being incorporated for rotating the blower tube and for simultaneously rotating a traveling driving nut secured to the blower tube to project and retract the blower tube.

Another object is to provide such a traveling blower wherein all of the parts which are subjected to high temperatures are of smooth, circular concentric cross section, with no angular contours such as keyways or splines in the areas exposed to the products of combustion. Due to the smooth contour of such parts of my improved blower, warpage is reduced to a minimum, fouling is minimized, and the improper functioning which is sometimes caused by the tendency of foreign matter to accumulate in key- Ways and the like is obviated.

it is an important object of this invention also to provide improved driving means for a smooth surfaced telescopic or sliding tube such as a blower tube.

Still another object is to provide an improved soot blower of the indicated character, wherein all of the driving components, and most of the controlling elements which activate and regulate the action of the blower are located close to the boiler or furnace wall, in a compact assembly which is conveniently accessible for servicing and adjustment.

A further object is to provide an improved control system for blowers of the indicated class arranged in such manner that although each individual blower is sequentially operable under the supervisory control of a central automatic control station remote from the blower, a subordinate control system located appurtenant to the blower itself takes over important aspects of the controlling function during each operating cycle of the blower, and prevents the operation of the blower from being interrupted priorto complete retraction of the blower, even if a failure should occur at the central automatic control station during the operation of the blower.

Another object of the invention is to provide improved sealing means for preventing unwanted leakage, which sealing means is readily accessible for servicing.

Still another object is to provide improved subordinate control mechanism at the blower station which will immediately cause retraction of the blower in event the supply of blowing medium fails during operation of the blower.

Other objects and advantages of the invention will become apparent upon consideration of the present disclosure in its entirety.

In the drawings:

Figure l is a side elevational view of the forward portion of a retractable soot blower constructed in accordance with the present invention, partly broken away and with the control panel cover removed;

Fig. 2 is a similar view, partly broken away, of the rear portion of the blower;

Fig. 3 is a longitudinal sectional view upon a larger scale showing the principal components of the driving mechanism;

Fig. 4 is a longitudinal sectional view of the blower tube and blowing fluid supply means;

Fig. 5 is a cross-sectional view taken substantially on the line 5-5 of Fig. 3, and looking in the direction of the arrows;

Fig. 6 is a sectional detail partly broken away, taken substantially on the line 6-6 of Fig. 5, and looking in the direction of the arrows;

Fig. 7 is a cross-sectional view taken substantially on the line 77 of Fig. 1 and looking in the direction of the arrows, but with the control box removed;

Fig. 8 is a fragmentary elevational detailed view, taken substantially as indicated by the line and arrows 8-8 of Fig. 7;

Fig. 9 is a sectional detail taken substantially on line 99 of Fig. 3 and looking in the direction of the arrows, on a larger scale;

Fig. 10 is a cross-sectional view taken substantially on the line 101tl of Fig. 1, and looking in the direction of the arrows;

Fig. 11 is a rear elevational view of the control panel, taken substantially on line 1111 of Fig. 10, and looking in the direction of the arrows;

Figs. l2, l3, l4, l5 and 16 are sectional views taken substantially on the lines 12-42, 1313, 1414, 15-15, and 1616, respectively, of Fig. 2, and looking in the direction of the arrows;

Fig. 17 is a sectional elevational view, partly broken away, of a main blower control valve;

Fig. 18 is a sectional detail of a three-way valve forming a part of the control system;

Fig. 19 is a schematic diagram;

Fig. 20 is a longitudinal sectional elevational view showing a somewhat modified driving construction;

Fig. 21 is a cross-sectional view taken substantially on the line 2121 of Fig. 20, and looking in the direction of the arrows;

Fig. 22 is a crosssectional view similar to Fig. 20, showing a further modification; and

Fig. 23 is a longitudinal sectional view of the principal mechanical components of a blower of somewhat modified construction.

Referring now to the drawings, my improved soot blower construction includes a slidable blower tube as 20, which is projectable through an opening as 22 in a boiler-wall or the like, the wall being fragmentarily, diagrammatically indicated at 24. The blower tube is of smooth cylindrical form and carries a blower nozzle as 25, through which steam, air, or a combination of these, or other desired cleaning fluid, may be projected against boiler tubes or other heat exchanging surfaces to be cleaned. When retracted, the blower tube 20 lies entirely outside the high temperature zones within the boiler or furnace. A relatively heavy main casing 27 surrounds the slidable blower tube outside the supporting wall 24 and may be directly attached to and carried by the wall, through the agency of a wall box as 29, to which the substantially circular front wall 30 of the casing is bolted.

Rotatably mounted in the casing 27, as in front and rear "ball bearings '32, 33, and coaxial'ly surrounding the blower tube 20, is a driving and supporting sleeve 35. At its forward end, the sleeve 35 is substantially sealed-with respect to the front opening inthe wall of the casing as by a sealing ring '36. The blower tube 20 is fitted to slide easilywithin the sleeve 35. A worm wheel'37 is keyed to the 'sleeve 315 within the casingand drivable by a worm 39, which is in turn rotatable by a suitable driving motor such as the air motor 40. Atits rear end, the sleeve is also sealed externally with respect to the casing as by means of the sealing rings 42, 43, which coact with a flange 46 on sleeve 35 to divide the casing-into two compartments. One compartment, designated 44, contains the worm and worm wheel 39, 37, and the other, designated 45, serves to house arotatable cage '47 secured as by screws -48 to the rearface of -flange 46 of sleeve "35. "Cage-47 surrounds and is rotatable concentrically with the'blower tube 20.

The cage 47 carries threerollers 50, 52, 54, the first two of which constitute driving rollers, white roller-54 serves as a reaction element. Each of the "rollers is positioned approximatelytangentially and journaled on a supporting shaft as '55, 56, 57, perpendicular to the blower tube, the rollers being formed of hardened material, engaging the surface of the blower tube and rotatable therealong during projection and retraction of the tube.

Each of the rollers-is provided with peripheral serrations, as indicated at 58, to increase the unit pressure between'the rollers and the'blower tube and reduce any tendency of the rollers toslip when they are performing their function of driving the tube rotatably. Each of' the rollers is carried bya'gimbal-type mounting consisting of a floating'ring as 60, supporting the roller shaft- (55 in Fig. 6) and trunnioned as by means of

trunnion studs

62, 64, for rocking movementabout an axis perpendicu lar to'the axis of theroller shaft. As best shown in Fig. 6, the gimbal rings may be of generally rectangular form,'although this is ofcourse subjectto variation,-an to-reduce wear, a bearing sleeve'65 is interposed between each roller and its shaft, and thrust bearing washers as 66,:67 are arranged upon the'shaft at each end of the roller, between the roller and the sides of the gimbal ring.

The gimbal rings of the driving rollers 50, 52 are urged in opposite angular directions about the axes of their

gimbal studs

62, 64, by means of a tension spring 70 secured as by screws 72 to the adjacent ends of such gimbal rings andreacting in opposite angular directions thereupon. roller52 clockwise, as the parts are'viewed in Fig.5, and tends to rock the gimbal ring of the roller 50 counterclockwise. The gimbal ring of the reaction roller 54 floats freely upon its supporting studs62, 6'4,'no spring means beingprovided to urge'it in either direction.

To the rear of the compartment '45, the casing 27 is necked inwardly and provided-with a reduced tubular flangeportion 75,'in which is tightly fitted a casing tube 77 extending rearwardly therefrom to serve as an enclosure for the slidable blower tube and other parts. At its-rear extremity, the casing tube 77 supports "an externally threaded tube 79 which projects forwardly withinthe blower tube to a'position near the plane of the boiler wall 24, as shown in 'Fig. 3, although the length of the tube 79, like the length of the blower tube itself. is subject to variation, as will be appreciated. The tube 79 is provided throughout thevmajor proportion of its length with external screw threads, as indicated at '80, and near its forward extremity carries a packing assembly, generally designated 82 and indicated as of the herringbone-type. The packing assembly issupported by a sleeve 83 threaded upon the tube 79 and locked in position with respect thereto by setscrews 84. The sleeve is sea ed with respect to the guide tube bv'plastic'packing 85 injected throughaplugged opening86 into an annular chamber 87 formed in an enlargedrear flange portion 88 of the sleeve-83. Flange -88 forms a retainer-for the rear end of the packing and also forms an abutment to limit theextent .of projection of the blower tube. Setscrews 84 retain upon the front peripheral portion of sleeve 83 a front retainer ring 89 which also serves, with the front end of the sieve, to limit theretracting travel of the blower tube. It will be noted thatthe blower tube '20 is somewhat shorter than the guide tube 79. In order to gain access to the packing assembly 82 for Spring'7tl tends to'rock the gimbal ring of elements.

the'top section 29 ofthe'wall"box,remove'the blower nozzle 25, and back the blower tube off the packing assembly. The packing can thus be easily serviced without disturbing or disassembling any of the major components of the blower actuating or controlling mechanism.

At its rear end. the screw tube 79 is rigidly held by means of a clamping ring '90,'having a neck 'portion 91 which projects into and is snugly fitted with respect to the rear end 'of the casing tube'77, to which it is attached by means of setscrews 92 projected through apertures (undesignated) in the wall of the casing tube.

A blowing-fluid supply pipe 93 is so coupled with respect to the rear end of the screw tube 79 as to permit feeding of blowing fluid into the rear end of the screw tube, and it will be noted that the forward end of the screw tube is open to the interior of the blower tube 20, so-that the screw tube'serves as means for delivering the blowing fluid to the blower tube. The means .for coupling the supply pipe is shown as -comprising a-coupling ring 94 with which the supply pipe is threadedly engaged, the coupling'ring beingsecured as'by means of screws 95 to the terminal ring90 carried 'by'the rear'endof the casing tube 77. A sealing gasket'as 96 may be interposed between the rings 90, '94. It will be observed that the external threads 'stl of the screw tube extend into the conformably internally threaded ring portions'90, '91 to provide additional holding means between these elernents.

A seal is preferably provided between the casing tube 77 and screw tube 79, and may comprise injected'plastictype'sealing material, designated 97, retained under compression in an annular space between the inner end of the neck'91 and a spaced backing retainer ring 99 threaded onto the external threaded surface of the screw tube 79 and snugly fitting the interior of the casing tube '77, and held inspaced relation with respect to the neck 91 as by meanso'f locating'p'ins 100 extending through the retainer ring 99 and into the forward end ofthe neck 91. :Theplastic "sealing material may be injected and replenished through a normally closed orifice sealed by a removable screw :plug 102.

A tubulardriving nut is fast upon the rear end of the blower tube 20 andinternally threadedly interen- .gaged with the external threads '80 of the screw tube 79.

It will be noted upon reference to Figs. 5 and 6 that the (common) axis of the gimbalstuds'62, 64 is spaced outwardly from the axis of the blower tube 20 a greater radial distance than is the rolling axis of therollerSt) (the latter axis being defined by the 'axis of spindle 55). This is also true in the case of each of the other two 'gimbal-mounted rollers 52, 54. When the cage is rotatably driventhrough the driving means, previously described, comprising the worm 39, worm wheel 37 and sleeve 35,'the rollers are moved in a'planetary path and the teeth'ofthe rollers ten'dto rotate the blower tube about-its axis. Referring to Fig. 5, assuming'that the drive is such as to turn the cage 47 in a clockwise direction, the drive is transmitted to the 'gimbal ring 60 of'the roller '52 through to the

gimbal studs

62, 64. Due to the tendency of the roller to'drag upon the blower tube, the gimbal ring is urged'clockwise about the axis of the

gimbal studs

62, 64. This rocking influence upon the gimbal ring is assisted by the spring 70. The roller 52, like'the other rollers 50. 54 of the assembly, is of hourglass-shape. The external hourglass curvature of the rollers is on a radius somewhat exceeding the radius of the blower tube,'so that such rocking of the gimbal about the axis of the gimbal studs tends to force portions of the roller 52 of increasing radius into tighter peripheral engagement with the blower tube, and the'serrated surface of the roller is thereby driven into tight wedging engagement with the blower tube. Since the blower tube possesses a certain amount of inherent lateral flexibility, the wedging action of the driving roller 50, urging the tube in adirection radially inwardly from the roller 52, drives spaced portions of the tube 20 tightly against the rollers 50, 54, both of which then serve as reaction The blower tube is thereby tightly located and held upon three sides through the interaction of the rollers in the manner described, and the rollers, in response to the rotation of the cage, exert a tangential drag upon the blower tube in the direction of rotation. The grip of the rollers is so effective as'to turn the blower tube at'the full speed of thecage, and thedrivings nut portion 105, (Fig. 4) being thereby turned=upon the threaded portion 80' of the screw tube 79,. drives. the blower'tubelongitudinally With respect to the screwtube in: response to such rotation.

to extend it: farther into the interior'of' the boiler.

tion will cause the principal wedging'eif'ect tobe exerted through: the roller. 50, which is preliminarily biased in a counterclockwise direction, as:viewed in Fig; 5, about the axis of its girnbal studs by the counterclockwise-acting end ofspring 70. The rollers 52', 54 then serve as the reaction elementsand the blower tube is reversely rotated and resultantly axially reversely driven to rotate it-' in the opposite direction and retract it to the protected withdrawnposition in: which it is shown in Fig. 3.

The driving air mtor40' is mounted upon a flat top surface portion 113 ofthe casing 27 in a position to-the rear of the plane of the worm andthewo'rm wheel 39,

37; onlya fragment ofthe air. motor being illustrated in- Fig. 7. Since the details of'construction of the air motor parent that the rate at which the blower tube is driven can be changed by substituting gears of different proportions.

The compartment 44 containing the Worm and Worm wheel is substantially sealed by the sealing rings 36', 42, at its opposite ends and may be charged with lubricant. Any pressure developed between the

tubes

20, 79 behind the packing 82 is communicated to the space 124 between the'casing tube 77 and the blower tube 20 through orifices 122, formed in the wall of the blower-tube 29 near its rear end. The space 124 communicates with the compartment 45 within the casing 2'7, as'best' shown in Fig. 3, and as also shown in that view, the internal diameter of the sleeve 35 is enlarged throughout a portion of its length by countcrboring the same from its rear end, as indicated at 126, for approximately two-thirds of its length. The counterbored enlargement 1.26 communicates with the interior of' the wall box 29 through a helical groove 69, which is also formedin the interior wall of the sleeve 35, and which extends forwardly to provide fluid connection between the enlargement 126' and the interior of the wall box, and thus with the space within the furnace. Although axial grooving could" be employed in place of the helical groove 69, I prefer the helical groove formation for the reason that there is less tendency toclogging, inasmuch as the realtive rotation of' the parts and the flow through the helical passage 69'- tend to carry any fouling material out of such helical passage. I preferably also deliver the exhaust of the air motor 40 to the chamber 45within the casing 27, so

that the discharged air from the motor also passes throughv the counterbored' portion 126 and passage 69 to the interior of the boiler, thereby assisting in maintaining positive pressure within the boiler and also in preventing clogging of the passages 69, 126, while the motor exhaust'may be connected at any point to the portion of the casing 27 which defines chamber 45 or to the casing tube 77, such connection is indicated as effected by means of: a conduit 117 which extends rearwardly along the sideof the casing tube 77' to the housing 171 for the rear actuating lug 160.

As shown in Fig. 2, the conduit 117 may besupported by the same bracket elements 316 which carry the

rods

152, 315. The actuating lug housing 171 is provided with a port 395 to which the conduit 117 is coupledto provide communication between such conduit and the interior of the housing 171. Conduit 117 communicates interiorly with the casing tube 77 through the slot 162 (Fig. 15).

Thus the exhaust from the motor passesthroughout theentire length of the casing tube and is discharged into the furnace through the counterbored chamber 126 andhelical slot 69, inthe manner previously described. This arrangement: is such that the motor exhaust is in con- If: right-hand threads are provided upon the screw tube-and: driving nut 105; such rotation of the cage and rollers in a clockwise direction, as'viewediin Fig. will project the blower: tube outwardly. Con-- versely, rotationof the cage in a counterclockwise:direc-- motor air serves to lubricate the working parts of the blower as well as-the motor and the motor control valving mechanism.

It Will be observed-that in the preferred construction illustrated in Figs. 1-19, the portion of the fixed. screw.

tube-79, which carries the packing assembly 82', projects.

beyond the front wall plate 30 of the casing 27. In event it becomes necessary to service the front packing 82', therefore, his only necessary to pull the blower tube back clear of such packing, Withthe nozzle element 25 removed. This will be-seen to' expose the packing for convenient servicing. As shown in Fig; 1, the wall box is formed in separable sections,.which facilitates such access.

Although the means for automatically controlling the projection and retraction of the blower is subject to variation, my preferred arrangement, shown schematically in Fig. 19, employs a reversing valve assembly corresponding to the disclosure of my copending application Serial No. 60,435,- filed November 17, 1948, now patent No. 2,623,534. The reversing valve assembly is generally designated 121 (Fig. l) and is mountedon a control'panel 123: secured as by means of screws 12?; to a pad 125 formed on the side of the collar'fiange 75 of casing 27. The-details of construction of the control valve 121 form no part of my present invention and may be derived from my previously mentioned copending application.

The valving components actuatable by such stems are incorporated in a controlling system'which is so arranged that when the. stem 127 is projected outwardly with respect'to the valve body 121, as by the helical compression, spring 130, the valving components provide connections between the air supply and

exhaust conduits

133, 117 and the air motor 40, of' such character that motor power air is delivered to the motor in a-direction to'driver it forwardly, that is, in, a direction to project theblower unit.. When the stern 127 is pressed inwardly against the resistance of the spring 130, while stem 129 is in the projected position (under the influence of the spring 132) the air connections to and from the motor are reversed, to cau'se'themotor'to reverse its direction ofrotationand'retract the blower. During such reverse rotation and retracting movement of the blower, the stem 127 is held depressedby the biasing effect of air pressure uponavalvecomponent 372 carried by such-stem. Upon completion of theretracting movement of the blower, the stem 129-is depressed, and in the system disclosed in my aforementioned copending application such actuation of stem 129 acts to cause the supply of motivating air l to the blower motor to be cut off, so that the blower improved further upon these control features in certain respects which will presently'be discussed.

The stems 127, 129 of the motor control valve are mechanically actuatableby the blower tube as it completes its forward and reverse travel. The stems are actuatabl'e by a lever 14h rockably mounted on a stud 135 carried by the-panel123; A blade-like arm 1371s independently pivoted on stud 1 35 and extends down- Wardlyin a position overlying the lower arm 138 of the lever; Arm 13'2" extends across the end of the stem 127. AnupWardly extending arm 139 of lever 14%? overlies the stem 1 29". Adjustable abutment screws 141, 143' are carried by the arms 138, 139, respectively. Abutment screw 141 is engageable' with the lower extremity of arm 137 to limit independent relative movement of the arms 137, 138 inone direction, the arrangement being such that arm 137' can move away from the abutment screw 141 to the left or clockwise, as viewed in Fig. l, to actuate plunger 127 independently of the lever 1411, al-' though=movementof the'main lever arm 1355 in the same direction is also effective to depress the plunger 127, since: the arm 137 is thereby moved through the agency of the abutment screw. Near its lower end arm 133-is provideda slot -like opcning142 forming a driving yoke in which: a driving roller 144 actuatable by the: blower tube is fitted. By rocking the lever 140, the stems 127;

129 may be depressed or released in the manner previously mentioned. The action of the lever is modified by detent means including a roller 146 acting against a specially contoured upper end formed upon lever 140. The roller is urged against the upper extremity of the lever by a helical tension spring 147 acting through a pivoted arm 149 which carries the roller 146.

Near the center of the upper end of the arm 139, in a position such that the roller when engaged therewith tends to hold the lever in a centered position, substantially perpendicular to and free of both of the stems 127, 129, so that neither of such stems is depressed, is an angular re-entrant notch-like depression 280 positioned to be engageable by the roller 146 and so proportioned that when the roller is engaged therein, the lever is yieldably held in such centered position. To the left of the depression 280, as the parts are viewed in Fig. 1, the end of the lever is formed with a downwardly inclined face 282, so that when the lever is moved in a clockwise direction far enough to carry the depression 280 to the right until the roller is forced out of the notch and the left end of the depressed portion moves to the right of the vertical radius of the roller, the roller thereafter, acting through the inclined surface 282, urges the lever clockwise to impart a snap-action thereto and quickly depresses the stem 127. Extending to the right from the deepest part of the depression 280, as the parts are viewed in Fig. 1, and forming the right-hand wall of the depression is an upwardly inclined camming surface 284. The roller must roll up surface 284 when the lever 140 is rocked counterclockwise from the centered position shown in Fig. 1. The reaction of the inclined portion 284 with the roller is thus such as to oppose counterclockwise movement of the lever and to return it to the centered position after the stem 129 has been depressed.

The arm 137 is independently actuatable in a clockwise direction, to depress the stern 127, by means of an actuating plunger 285 which is secured to and actuatable by a piston 286 slidable in a cylinder 288 secured to the face of the panel 123. The cylinder, piston and plunger, 288, 286, 285, constitute part of an emergency reverse mechanism, the action of which will presently be described.

The lever 140 is actuatable by means of a rod assembly 152, which is in its effect a unitary rod, although for convenience, constructed in sections. The rod assembly extends longitudinally beside the casing tube 77. At its forward end, the rod assembly is secured to a slide member 300, slidably supported upon the back of the panel 123 for horizontal movement in unison with the rod assembly. Slide 300 carries a pair of studs 154, 155, which project through and are guided in a horizontal slot 150 in the panel. Stud 155 carries roller 144, so that movement of the rod assembly will actuate the lever 140.

At a position corresponding to the desired limit of forward travel of the blower driving nut 105, and which accordingly bears a fixed relation to the degree of projection of the blower, a lug 157 rigidly secured with respect to the rod assembly 152 projects through a slot 159 into the interior of the casing tube 77, while at a position near the rear extremity of the casing tube and corresponding to the desired limit of rearward travel of the actuating nut 105, a similar lug portion 160, rigidly secured with respect to the rod assembly 152 near its rear end, extends through a slot 162 into the interior of the casing tube. The

lugs

157, 160 lie in the path of movement of the actuating nut 105 and are actuated by the nut as the blower completes its forward and rearward travel, respectively. While the details of the mounting and actuation of the

lugs

157, 160 may be varied widely, in the preferred construction illustrated each such lug is housed in a casing as 170, 171, which covers the slot (159, 162) in the casing tube. Each such casing is open upon the side thereof which covers the slot, being tightly secured and sealed with respect to the side of the casing tube 77 in an area entirely surrounding the slot. In each case, a lug-supporting section of the rod assembly 152 projects slidably through both ends of the housing, being sealed with respect to both end walls of such housing as by sealing rings 174. The forming of the rod assembly in sections promotes ease of assembly and adjustment, the sections which project through the

housings

170, 171 being separably and adjustably secured to the adjacent sections, as indicated at 172, although normally rigidly secured, so that the rod assembly functions as a unit.

8 The

lugs

157, 160 and the actuating rod assembly 152 are so proportioned and positioned that as the blower completes its forward travel, a bearing collar 250 carried by nut strikes the lug 157, moving the rod assembly forwardly and thereby also carrying the rear lug 160 forwardly to a position forward of the rear limit of travel of the nut 105. Such forward movement of the rod assembly rocks the lever in a direction to cause the arm 138 to depress the stem 127, causing the air motor to reverse and so initiating the retracting travel of the blower tube. As the blower tube approaches the rearward limit of its travel, it strikes the lug and in completing its rearward movement moves such lug, and resultantly the rod assembly 152, to rock the lever 140 in the opposite direction and so cause the arm 139 to depress the stern 129, and also causing an arm 434 carried by slide 300 to open a valve 406, stopping the air motor and interrupting the drive of the blower with the blower fully retracted. The action of these parts will presently be considered in greater detail. After the blower motor stops, the air supply to the motor control valve assembly 121 is interrupted and the stem 127 is accordingly no longer biased by such air pressure. Stem 127 is therefore again projected outwardly by the spring 130.

Where steam is used as the blowing medium, the flow of blowing steam may be controlled by an air operated valve assembly constructed as indicated in Fig. 17, although it will be appreciated that the details of the blow valve are subject to variation. The blow valve assembly consists of a hollow valve body 180, having an inlet opening 184 and coupling portion 182 positioned at right angles to the valve outlet pipe 93, which may comprise the supply pipe for the blower as previously mentioned and as indicated in Figs. 2 and 4. The inlet opening comprises an enlarged chamber 184 within which is a poppet valve assembly 185 opening against steam pressure and biased to closed position by a spring 187 mounted above the valve body upon the valve stem 188, which extends above the body as shown. The stem is slidable and substantially sealed with respect to the top wall of the valve body 180, extending through a guide 190 tightly secured in such top wall, the guide being externally threaded and extending downwardly to a position close to the valve port. The valve port is defined by a hardened valve seat ring 192, to and from engagement with the lower end of which the valve is movable when the stem 188 is actuated. The effective port area through which steam can flow when the valve is open is adjustable by means of a blocking element 194, which may be of circular cross section, somewhat greater in diameter than the port in the ring 192, and mounted on the guide 190 in such manner that it may be adjustably moved to, and fixed in, any of various positions with respect to the ring 192, wherein it may block to a greater or lesser extent the flow of steam through such ring. The blocking member 194 is internally threaded to fit upon the threads of the guide 190, so that by rotating such blocking member, it may be moved to and from the upper face of the ring. The periphery of the blocking member is provided with a plurality of radial slots as 195 engageable by a locking pin 196 formed as a rigid axial extension of a plug 198 fitted in a threaded aperture 200 in the side of the valve body 180. When the plug is removed, the blocking member may be rotated by means of a drift, screw driver or other suitable instrument thrust through the opening 200, and when the blocking element is thereby located in a desired position, with one of the slots 195 in radial alignment with the axis of the plug hole 200, the blocking member may be locked in position merely by reinserting the plug 198 and simultaneously projecting the pin 196 into the slot to hold the blocking member against turning on the guide.

The valve 185 is actuatable by means of a servomotor comprising a cylinder 202 supported by lower and

upper cylinder heads

204, 205, held together by clamping bolts 206 and rigidly mounted in axial alignment with the stem 188 upon the upper ends of struts 189 extending upwardly from casing 180. A piston 208 in the cylinder 202 has an axial rod 210 extending downwardly through an opening 211 in the head 204, rod 210 being engageable with the upper end of the stern 188 to open the valve 185 when the piston 208 is actuated downwardly by air delivered to the upper end of the cylinder through a conduit 212. When the air pressure in the cylinder is relieved, the piston is moved upwardly by the biasing spring187.

The conduit 212 leads to a coupling 214 connected to '9 -a.,port 215 formed .in one :side \of 1:he body ,portion .217 of ta :three-way valve assembly mountedon the back of panel .123. The three-way alve 217 serves to-establish and interrupta connection between the actuating cylinder v202 for the blow'valve and a source of air supply (motor .power air) under pressureas the blower tube commences its forward travel, so that as such forward travel commences,-the blow valve element 185 is moved downwardly off its seatandblowing steamcanflow 'intoand through the screw-tube 79, blower tube 29, and from the nozzle 25 during substantially the entire projecting and retracting movement .of theblower tube andlnozzle. The threeway valve #217 also functions .to shut off such air supply to allow the blow valve element to reseat as vthe blower tube and nozzle complete their retracting movement. The construction of the-three-way valve is subject to variation, butit is shown in Fig. 18 as comprising .a pair-of coaxial cylindrical chambers-220, 222 formed .in opposite ends of the valve body 217, such chambers having seat portions .224, v225 at their-inner extremities, and being connected by a reduced axial passage 227. Valve element 229 is mounted in'the chamber 220 to move to andfrom the seat 224, and a valve element 230 "in the chamber 222 is mounted for movement to and from the seat 225, the valve elements 229, 230 being carried by opposite ends :of a stem 232 whichextends through .the passage227, but is materially smaller than such passage, so that it does not substantiallyi interfere with air flow therethrough. The double valvelassembly is biased to the right, as the parts are viewed in Fig. 1 8, by a helical compression spring'233 arranged in the chamber 22'0'behind the valve element v2'29. The side port 15 to which the conduit 212 3 is connected communicates with the-central passage I227. The'left end of the chamber 22%) is enlarged and tapped to receive a coupling element 234, adapted to be connected'to aisuitable source of air under pressure or-other appropriatemotivating fluid. Actuating plunger235 is slidable in the chamber 222 and adapted-to bear at its inner end against valve element 23d, plunger 235 being provided with an extension .237 which projects from the end .of the body 217. The plunger 235 is substantially smaller than the chamber222, sothat air mayflowfreely around .the plunger and the valve elements 229, 230 are also substantially smaller than their

respective Chambers

220, 222.

The three-way valve .assemblyis actuated through the agency of mechanisrncontained ina casing 219 and carried by a bracket 24!) attached to the top of the casing tube 77. A lever 24-2 is rockably supported by a shaft .2- i3'journaled inbracket 2 50 withinthe casing 219. The lever'2d2 isinthe'forni of aroc'ker arm and extends generally parallel'to the'blower tube, vbeing'fast upon theshaft 243. A lever actuating plunger 255 is vertically 'slidable in a guide nipple 256 extending through the top wall of the casing tube '77, the upper end of'the plunger 255 being formed as an enlarged head 257' engageable withan adjustable abutment screw 2'44- carried'by one end of the lever 242 forward of the'fulcrum pini2 -l3. At its lower end, the plunger'255 is provided with arounded tip259 extending into the path of a bearing retaining'collarfitl carried by'the'actuating nut 165. An antrifriction bearing assembly252 isinterposed between the nut and collar25t).

The 'collar250 slides in the casing tube 77. Aplunger 260 similar to plunger255, but spaced longitudinally therefrom,

:ha's ahead 262 engageablewith an abutmentscrew 2-2-5 carriedby lever 242 .to the rear of the fulcrum pin 243, and is vertically .slidable to actuate the same. Plunger "260 is provided with a rounded lower end portion 264 which also projects into the path of the actuating nut bearingcollarZSti. The plungers 255, 266 are spaced from one another'a distance greater thanthe axial length of the collarl250,"the rearmostplunger 260beinglocated a short :distance forwardly rtf the position occupied by the traveler nutwhen thelBlOWBr is fully retracted.

.As best'shown in'Fig. '12, the'shaft 243 exten'clshorizontally to t a position where it overhangs .oneside of the casingtube 77, such overhangingportion projecting laterally beyond the supporting bracket .240. A downwardly extending arm 254is fast .upon such projecting end .of'ithe shaft 243 and carriesa vertically adjustable ball joint element.310,.the ball.portion-31 1-of which coacts with a socket.3'12 which .is secured to the rear end of a forwardly extending rod 315slidably supported in suitable guide brackets 3'16 .attaChed at suitable spaced points to theside of .the casing tube 77. The-brackets 10 316 may also serve to slidably support the rod assembly 152, previously mentioned. Rod 315 extends forwardly to a position just behind the housing 17%), where it is coupled by means of a couping member 318 toa rod 320 which is upwardly offset a slight distance from the rod 315, but serves as a continuation thereof, the

rods

315, 320 being connected in such manner as to move as a unit. The rod 320 extends through a suitable bearing guide portion 322 formed integrally with the casing 170 and projects behind the control panel 123, where it is coupled by means of a ball and socket connection, generally designated 324, to the lower end of a lever 325 pivoted on a stud 126 mounted on the panel and projecting from the rear face thereof. The upper end of the lever 325 is provided with a wedge-shaped top 32% adapted to coact with a roller 33% carried by an arm 332 pivoted as on pin 333 upon the rear face of the panel, and urged downwardly in such manner as to urge the roller 339 against the .wedge-shaped top 328 of-the lever 325 by means of a helical tension spring 334-, the lower endof which is hooked upon a pin 335 carried by the panel, while the upper end of the spring is secured to anadjustableabutment and coupling element 336 carried by the arm 332. The lower end of the lever 325, upon its side opposite to that coupled to the rod 320, is engageable with a stem 237, which forms the actuating plunger of the three-way valve 217, previously described. The plunger 237 is surrounded by a helical compression spring 338, which tends to rock the lever 325 clockwise, as viewed in Fig. 11, but is not strong enough to overcome the resistance .of the spring 334.

When the blower tube is fully retracted so that the nut and collar 250 lie behind the rearmost plunger 260, the plunger .260 is elevated and the plunger 255 is depressed, as shown in Pig. 4, the rocker arm 242 being tilted correspondingly, as shown in that view. The rod 329 is accordingly drawn rearwardly, that is, to the left as viewed in Fig. 11, so that valve portion 229 (Fig. 18) is seated, the air supply through the conduit 212 leading to the blow valve actuating cylinder 202 is cut off, and the blow valve actuating cylinder 202 is connected toatmosphere through port 215, passage 227, and chamber 222. Blow valve element 185 is thereby closed under the influence of the spring 187.

When the traveler nut moves forwardly during the first part of the forward travel of the blower, the collar 250 passes under plunger 260 and then engages and lifts the plunger 255, throwing the lever 242 clockwise, as viewed in Fig. 2, andby virtue of the overcenter means previously described, thereby causing the lever 325 to snap counterclockwise, as viewed in Fig. l1, to the other of the two extreme positions it occupies. The vent'valve element 230 is thereby closed and the air supply valve element 229 opened, allowing air to flow to the cylinder 202 to open the main blow valve. The three-way valve is held in this position by the overcenter means, while the blower tube moves'throughout the remainder of the projecting and retracting portions of the-operating cycle and until the collar 250, near the completion'of the retracting cycle, again engages thetip of the plunger 269 to lift the right end of the lever 242 past the dead-center position, causing such lever to snap 'inthe counterclockwise direction and reassurne the position shown in Fig. 4, whereupon therods 315, 320 function to move the plunger 237 of the three-way valve 217 inwardly to again shut off the air supply,'vent the actuating cylinder 202 and'allow the blow valve to close.

Although when the blower is .fully retracted the lever 149 is in'the position shown in Fig. 19, wherein the valve stem 129 is pressedinwardly, the lever assumes the centered position shown in Fig. lupon commencement of forward travel of the blower, as the nut 105 and its bearing collar 250 move forwardly away from the lug.160 to permit the rodassembly 1'52.to shift forwardly, so that the roller 146 may center thearm 140. During forward travel of the blower, motor power air enters the valve body 121 from conduit-l33ithrough port 370,.passes over the valve element 372 carried by the stem 127through passage 388, piston valve chamber 374 and out of the valve body through ,port 375, =from whichitis delivered to the 'airmotor 4d through=conduit 376. The chamber v129. The other cylindrical chamber :is designated r378 and communicates with the chamber of valve element 382. The cylindrical chambers 375, 378 are in communication with one another through a smaller coaxial passage 380, and each such cylindrical chamber contains a piston valve as 384, 385.

Piston valves

384, 385 move as a unit, being connected to one another by a common axial stem 386 which extends through the passage 380. Cylindrical chamber 374 communicates with the chamber of valve element 372 through passage 388, and chamber 378 communicates with the chamber of valve 382 through a port 390. When running forwardly to project the blower, the air is delivered to the motor through conduit 376 and exhausted therefrom through conduit 392, valve port 394, chamber 378, passage 380 and port 270. It will be seen that the air entering chamber 374 maintains the double

piston valve assembly

384, 385 in the position shown in Fig. 19, wherein the piston valves are raised and the exhaust air returning through port 394 passes under valve 385 and through chamber 378 and passage 380 to the exhaust port 270.

When at the completion of its forward travel, the blower shifts the rod assembly 152 forwardly to rock the lever 140 in a direction to depress the plunger 127, the motor air is cut off from passage 388 and passes under valve 372, through a cross-connecting passage 400 in the valve body 121, over valve 382 and through passage 390 to cylindrical chamber 378 where, acting upon the outer (upper) end of piston valve 385, it shifts such valve downwardly to seat against the upper end of axial passage 380 and to unseat piston valve 384 from the opposite end of axial passage 380 and open communication between such axial passage and port 375. The air then passes from cylindrical chamber 378 through port 394 to conduit 392 and is delivered by the latter conduit to a motor 40 to drive the motor in the reverse direction. The motor exhaust is delivered through conduit 376 to port 375, passes under piston valve 384 and through passage 380 and port 270 to the exhaust conduit 117. The reverse drive imparted to the blower continues until, at the completion of retracting movement of the blower, the driving nut bearing collar 250 strikes the lug 160 and carries the rod assembly 152 to the rear, rocking the lever 140 counterclockwise to the position shown in Fig. 19, depressing the stem 129 and moving the valve element 382 to the position shown, wherein it closes off communication between the connecting passage 400 and passage 32 0. The air then passes from the connecting passage 400 under the valve element 382 to an outlet port 402. It will be noted that the air passing under the valve elements 372, 382 maintains them in their leftward positions wherein the stems 127, 129 are retracted. With both valves moved to the left, as viewed in Fig. 19, air delivery to the motor 40 is interrupted and movement of the blower stops.

When the blower is fully retracted, the operating diaphragm chamber 410 of a diaphragm valve 412 is connected through a two-way valve 406 and conduit 408 to a control line 405. Control line 405 is connected to a control panel (not shown) which may be arranged substantially in accordance with the disclosure of Curtis L. Howse application Serial No. 88,854, filed April 21, 1949, and now Patent No. 2,565,689. The control conduit is adapted to deliver air at a pressure which is less than the pressure of the motor driving air delivered through conduit 133. (For example, the motor power air may be at a pressure of approximately 80 p. s. i., and the control air pressure may be of the order of 35p. s. i.) Valve 410 controls the delivery of air through conduit 133 to the motor control valve 121. The mechanism at the control panel, which is not shown herein, but which may correspond to the disclosure of the previously mentioned Howse application, is so arranged that if the pressure in the control line is raised materially above the normal 35 p. s. i., the panel mechanism shuts off the control line completely and opens a relatively large vent, so that the pressure in the control line quickly drops to a value less than 35 p. s. i. This allows the diaphragm valve 412 to close, interrupting the delivery of air to the motor control valve and motor.

Valve 406 is operable by an arm 434 carried by a stem 435 forming an extension of the forward end of the slide 300. Arm 434 is rigidly secured to stem 435, and locked in position by a lock nut 436. Stem 435 is smaller than the forward end of slide 300 and a washer 433 is slidable upon the stem to and from engagement with the shoulder 437 defined by the plane of juncture between the end of the slide and the stem. A helical compression spring 438 is arranged upon the stem between washer 433 and arm 434 and yieldably urges the washer into engagement with the shoulder 437. Washer 433 is also engageable with the sides of a pair of abutment elements shown as the head portions of screws 439, 441, projecting from the panel 123, and which also serve as guides for the slide 300. The action of the spring 438 upon the washer 433 and the arm 434 tends to draw the slide 300 and rod assembly 152 forwardly. When the blower is fully retracted, the rod assembly 152 and slide 300 are drawn to the rear, as previously explained, and the shoulder 437 is drawn away from the washer 433, the spring 438 being thereby compressed, so that the parts stand in the position shown in Fig. 11. As soon as forward movement of the blower commences, and the rearward pressure upon the lug 160 is relieved, the rod assembly 152 and slide 300 are permitted to move forwardly a slight distance under the influence of the spring 438. Thus the arm 434 only moves the valve 406 to the open position when, and maintains this valve open while, the blower is fully retracted, and only at such time is there communication through the valve 406 between the conduits 405, 408.

When the control panel delivers control air through the open valve 406 to the diaphragm chamber 410, the valve 412 is opened to initiate forward movement of the blower, in the manner previously described. Motor power air is then delivered to the diaphragm chamber 410 through a holding connection provided by the conduit 415. Conduit 415 incorporates a pressure reducing orifice member 416 proportioned to prevent the pressure in conduit 408 from building up to too high a value before the valve 406 has been closed in response to forward movement of the rod assembly 152 and slide 300. Valve 406 closes very soon after the blower starts forward, and the pressure in the line 408 builds up to approximately the pressure in the motor air line 133 (e. g. 80 p. s. i.) during operation of the blower.

Upon completion of the cycle of operation of the blower, the return of the blower tube to the fully retracted position opens the valve 406 in the manner described, connecting the conduit 408 to the control conduit 405 and thereby imposing a high pressure impulse upon the control line to cause the mechanism at the control panel to disconnect the control line from the 35 p. s. i. control air source and vent the control line in the manner previously mentioned. Due to the restriction at the orifice member 416, the pressure in the diaphragm chamber 410 falls away, due to the venting at the control panel, more rapidly than such pressure can be maintained from the motor air source through the orifice member 416, and valve 412 accordingly closes. The pressure is thereby relieved upon the under sides of the valves 372, 382, so that these valves can again be moved to the right under the influence of the valve springs 130, 132.

During the last part of the rearward movement of the blower, the air passes through the motor control valve casing 121 and out the outlet port 402 thereof, as previously mentioned. This air is delivered through conduit 407, check valve 430, conduit 428 and branch conduit 432 to the reversing cylinder 288, causing the stem 285 to move the arm 137 in a direction to bear inwardly against valve stem 127 and to hold the valve 372 positively seated against the port 388. This positively prevents movement of the valve 372 to the right under the influence of its spring 130 during the last portion of the movement of the blower, thereby insuring against unwanted projecting movement of the blower.

It will be noted that during operation of the blower, the system at the blower itself is entirely independent of the control panel, due to the fact that valve 406 is closed. Thus even if the control panel should function improperly so that control air pressure in conduit 405 should fail, the blower would continue to operate, if the operating cycle had commenced prior to the failure, because the motor air pressure would maintain the pressure in the diaphragm chamber 410 to hold the diaphragm valve open. This will allow the blower to complete its retracting movement under such conditions.

The conduit 234 leading to the three-way valve 217 which controls the action of the blow valve, in the manner previously described, is connected to the motor air supply line 133 in advance of the diaphragm valve 412. The

acme-1o conduit 212 from-valve 217 to the operating cylinder 202 of the blow =valve is also connected to a conduit 420 leading to a two-way valve '422. Valve 422 is biased to closed positionbutadapted to be held open by a springbiased arm 446 which overcomes the bias of the valve. While held open'bythe arm-biasing spring 448, the valve 422 provides communication between conduit 420 and a conduit 424 which communicates through a restricted pressure control assembly is connected by a conduit 450 to the blowing steam "supplypipe 452 at a 'point between the blower and the blow valve 202. So long as blowing steam is being delivered to the blower, the pressure of the "blowing'steam, communicated to the pressure control assembly 445, overcomes the spring 443 to move the arm 446 away from the valve 422, so that valve 422 remains closed. If the supply of blowing steam should fail, however, the fall of pressure in the unit 445 allows the spring 448 to open the valve 422. Motor power air is thereby delivered to the emergency reverse cylinder 288 through

conduits

424, 432,and stem 235 moves valve element 372 to the left, as viewed in Fig. 19, to immediately reverse the blower, if it had previously been traveling forwardly, and cause the same to be retracted. This will be recognized as a safeguard against the damage which might result to the blower tube if it were allowed to continue its operation without blowing steam. Conduit 424 contains a restriction incorporated in an orifice member 425, serving as delaying means to prevent the functioning of the automatic reversing means just described for an interval long enough to allow the blowing steam pressure to build up in the pressure control assembly 445.

Various means may be used for supporting the rearwardly projecting portions of the blower assembly, but it will be observed that the rearwardly projecting portions are of such nature that frequent access thereto is not necessary. These parts are also such as to be virtually unaffected by the weather, so that they do not require enclosure within :the walls of a building, and may be carried by a skeletonized framework of any character which possesses the necessary mechanical strength.

The casing tube 77 is shown in Figs. 2 and 13 as supported near its rear end by a hanger structure, including a supporting clamp having a semicircular body portion 350 to which holding

lug portions

352, 354 are bolted, the lug "

portions

352, 354 being proportioned to par.-

tially embrace the casing tube, but to clear the rod structure and rear housing 171. The body portion 350 may be supported by a rod 355 attached to the upper end thereof by a clevis 356, and it will be appreciated that another clevis as 358 may be secured to the lower end of the body and that subjacent blower assemblies may be hung therefrom. The rear end of the casing assembly 27 is also supported by a hanger rod 360 secured to a flange 362 formed upon the rear end of said casing. A manually operable valve as 527 may be provided between lines 234, which communicates with motor power air line 133, and line 408 connected to diaphragm chamber v 410 of valve 412. Valve 527 is of course normally closed,

but may be opened for manual operation or test.

In Figs. and 21, I have shown a somewhat modified driving arrangement wherein the friction driving rollers are eliminated and the blower tube, designated 20a, is of polygonal cross section and slidably fitted in an internal opening of similar cross section in the sleeve a, which corresponds in its general arrangement to the sleeve 35 of the first embodiment. The sleeve 35a may be driven in an analogous manner by a worm 39a and wormwheel 37a, and due to the keying effect of the interfitted portions of polygonal cross section, the driving rollers and associated parts may be entirely eliminated. Preferably the external portions of the sleeve 35aare of circular cross section, as indicated in Fig. 21., to facilitate the rotatable support thereof in the supporting

bearings

32a, 33a, and to enable the use of conventional llubricant 'retaining sealing rings as 36a, 42a.

. Pi'g. 22 shows a modification wherein the blower tube 20b is of circular cross section'as =in'th'e'first embodiment, but is provided in its external wall with a straight longitudinal keyway 500, which slidably overengages a key 502 carried by and projecting inwardly from the inner wall of the sleeve 35b. The keyserves as driving means so that in this embodiment also the driving rollers may be eliminated and the driving components may 'be arranged substantially as indicated in Fig. 20.

in the further modification illustrated in Fig. 23, the rotary driving means may be of any of the forms previously mentioned, although for purposes of illustration it may be assumed that the rotary driving means corresponds to that disclosed in connection with the first described embodiment. The-central fee'd tube'79'c, which may be positioned and supported similarly to the screw tube 79 of the first embodiment, is not provided with threads. Packing, generally designated 820, is carried by the outer end of the tube 790 and the blower tube 200 is slidably fitted over such packing. Secured to the rear end of the blower tube is a packing assembly 5% which extends inwardly into sealed engagement with the smooth outer surface of the feed tube 7%. The space sac between the tubes 20c, 79c is thereby sealed. The blower tube also carries an outwardly projecting sealing piston portion 598 which projects into substantially sealed, but slidable, engagement with the inner wall of the casing tube 770.

in order to project the blower tube, a suitable motivating fluid, which may comprise air under pressure, is forced into the space behind the piston 598, between such piston and the back wall c, which closes at the rear end the annular space between the feed tube 7 9c and easing tube 770. Fluid for projecting the blower in this manner may be supplied through a conduit 376a from a suitable source (not shown) to a fitting 512 extending through the casing tube 770 near the rear end of the latter. During projection of the blower, the space 506 is vented through a conduit 514 which extends longitudinally through the feed tube 790, being connected at its forward end to a fitting 515 which provides communication between the conduit and the forward end of the space 5% directly behind the packing 820. At its rear end, the conduit 514 extends outwardly through the back wall portion 990 and communicates with a fitting 51.6 to which a conduit 3920 is connected. Fluid pressure is vented from the space 5% during projection of the blower through the conduit 3920, while in order to retract the blower, fluid under pressure is supplied through the conduits 392e, 5114 to the space 506 and the space to the rear of the piston 503 is vented through the conduit 3760.

It will be recognized that the control of this embodiment may also be analogous to the control means employed in the first embodiment. The air or other fluid for projecting the blower into the boiler supplied through conduit 3760 may be analogous to the air supplied to the air motor in the first embodiment through the conduit 376, while the conduit 392s of this embodiment corresponds to the conduit 392 of the firstembodiment, serving to conduct exhaust fluid away from the blower during projecting movement and to conduct fluid to the blower during retracting movement. The other principal components of the blower may also correspond to those of the previously described embodiments, and detailed reconsideration will not be required.

While it will be apparent that the preferred embodiments of the invention herein disclosed are Well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

l. A slidably extensible and retractable soot blower construction comprising guiding and supporting means including a stationary externally threaded guide tube having a free end portion adapted to extend forwardly toward a zone wherein a cleaning function is to be performed, means for securing the guide tube at a point spaced rearwardly of such zone and for feeding cleaning fluid to the interior of such guide tube, the guide tube having an opening in the region of its forward extremity, a blower tube rotatably and slidably surrounding the guide tube, an actuating nut secured to a rear portion of the blower tube and threadedly interengaged with the threads of the guide tube, and means located in a position forwardly of the rear extremity of the guide tube and engaged with a surface portion of the blower tube for rotating the same to thereby turn the actuating nut and resultantly drive the blower tube longitudinally with respect to the guide tube.

2. A blower assembly as defined in claim 1 wherein said actuating means for rotating the blower tube comprises a wedging roller element mounted for concentric rotation about an axis generally parallel to a tangent to the blower tube and also bodily rotatable in an orbit concentric with the blower tube.

3. A blower assembly as defined in claim 1 wherein said actuating means for rotating the blower tube comprises a wedging roller element mounted for concentric rotation about an axis generally parallel to a tangent to the blower tube and also bodily rotatable in an orbit concentric with the blower tube and frictionally engageable with the surface of the blower tube to turn the latter about the axis of the blower tube, said roller element being rotatable about the first-mentioned axis in response to longitudinal movement of the blower tube.

A soot blower assembly as defined in claim 1 wherein said means for rotating the blower tube about its axis comprises a wedging roller bodily rotatable in an orbit substantially concentric with the axis of the blower tube, the geometric axis of the roller lying in a plane transverse to such axis of the blower tube, and the carrier for supporting and driving said roller in its planetary movement including an element supporting said roller for limited rocking movement about an axis extending transversely through the roller and substantially parallel to the blower tube axis.

5. A soot blower assembly as defined in claim 1 wherein said means for rotating the blower tube about its axis comprises a wedging roller bodily rotatable in an orbit substantially concentric with the axis of the blower tube, the geometric axis of the roller lying in a plane transverse to such axis of the blower tube, and the carrier for supporting and driving said roller in its planetary movement including an element supporting said roller for limited rocking movement about an axis substantially parallel to the blower tube axis, said roller being of gradually increasing diameter from an intermediate portion toward an end thereof, the axis of rocking movement extending transversely through a portion of said roller of reduced diameter, and said roller being non-concentric with the blower tube in all projections of the roller.

6. A soot blower assembly as defined in claim 1 wherein said means for rotating the blower tube about its axis comprises a wedging roller bodily rotatable in an orbit substantially concentric with the axis of the blower tube, the geometric axis of the roller lying in a plane transverse to such axis of the blower tube, and the carrier for supporting and driving said roller in its planetary movement including an element supporting said roller for limited rocking movement about an axis substantially parallel to but outspaced from the blower tube axis, said roller being of gradually increasing diameter from an intermediate portion toward an end thereof, the axis of rocking movement extending transversely through a portion of said roller of reduced diameter, and means drivingly connecting the carrier to the roller including a gimbal element rockable in the carrier upon said axis parallel to but outspaced from the axis of the blower tube and defining a gimbal axis, such gimbal axis being spaced farther from the blower tube than is the geometric axis of the roller.

7. A soot blower assembly as defined in claim 1 wherein said means for rotating the blower tube about its axis comprises a wedging roller bodily rotatable in an orbit substantially concentric with the axis of the blower tube, the geometric axis of the roller lying in a plane transverse to such axis of the blower tube, and the carrier for supporting and driving said roller in its planetary movement including an element supporting said roller for limited rocking movement about an axis substantially parallel to but outspaced from the blower tube axis, said roller being of gradually increasing diameter from an intermediate portion toward an end thereof, the axis of rocking movement extending transversely through a portion of said roller of reduced diameter, means drivingly connecting the carrier to the roller including a gimbal element rockable in the carrier upon said axis parallel to but outspaced from the axis of the 16 blower tube and defining a gimbal axis, such gimbal axis being spaced farther from the blower tube than is the geometric axis of the roller, and means biasing said gimbal element and roller in one angular direction about said gimbal axis.

8. A slidably extensible and retractable soot blower construction comprising guiding and supporting means including a stationary guide tube having a free end portion adapted to extend forwardly toward a zone wherein a cleaning function is to be performed, means for securing the guide tube at a point spaced rearwardly of such zone and for feeding cleaning fluid to the interior of such guide tube, the guide tube having an opening in the region of its forward extremity, a blower tube rotatably and slidably surrounding the guide tube, drive mechanism located in a position forwardly of the rear extremity of the guide tube and engageable with a surface portion of the blower tube for rotating the latter, means completely enclosing the portion of the soot blower construction lying outside said zone, including a stationary casing tube surrounding said blower tube, a housing portion enclosing said drive mechanism and communicating interiorly with said casing tube, and a fluid motor for driving said means for rotating the blower tube, said motor having an exhaust portion connected to said casing tube at a position rearwardly of the housing portion, whereby the exhaust of the motor is conducted through the casing tube and housing portion, and means for projecting and retracting the blower tube through the casing tube and housing portion.

9. Means for rotating a rotatable and longitudinally movable tube, including a carrier rotatable externally of and substantially concentrically with the tube, and a friction driving roller carried by the carrier and engageable with the tube to exert tangential force thereon to turn the same, said roller being rotatable in the carrier on an axis transverse to the tube whereby it may rotate about such transverse axis during longitudinal movement of the tube and being rockable about an axis substantially parallel to but spaced outwardly from the tube, the tube-engaging surface of the roller diverging from the surface of the tube in a direction parallel to the axis of the roller and away from the center of the roller, whereby such rocking permits the roller to move to and from tight wedging relation with the tube.

10. Means for rotating a rotatable and longitudinally movable tube, including a carrier rotatable externally of and substantially concentrically with the tube, and a friction driving roller carried by the carrier and engageable with the tube to exert tangential force thereon to turn the same, said roller being rotatable in the carrier on an axis transverse to the tube whereby it may rotate about such transverse axis during longitudinal movement of the tube and being rockable about an axis substantially parallel to but spaced outwardly from the tube, said last-mentioned axis being spaced outwardly from the tube farther than the transverse axis, the tubeengaging surface of the roller diverging from the surface of the tube in a direction parallel to the axis of the roller and away from the center of the roller, whereby such rocking permits the roller to move to and from tight wedging relation with the tube.

11. Means for rotating a rotatable and longitudinally movable tube, including a carrier rotatable externally of and concentrically with the tube, a pair of friction driving rollers mounted in the carrier, said rollers having surface portions tangent to the tube in two angularly disposed planes and being rotatable in the carrier on transverse axes and also limitedly shiftable in transevrse planes to and from tight wedging relation with the tube.

12. Means for rotating a rotatable and longitudinally movable tube, including a carrier rotatable externally of and concentrically with the tube, a pair of friction driving rollers mounted in the carrier, said rollers having surface portions tangent to the tube in two angularly disposed planes and being rotatable in the carrier on transverse axes and also limitedly shiftable in transverse planes to and from tight wedging relation with the tube, means biasing said rollers in opposite angular directions in said transverse planes of shifting movement, and a reaction roller engaging a surface portion of the tube in opposed relation to the driving rollers.

13. A slidably extensible and retractable soot blower construction comprising a stationary guide tube, a blower tube slidably and rotatably carried by the guide tube, a

stationary casing tube open at its front end and proportioned to permit the blower tube to project into and from such front end, said casing tube surrounding the rearwardly extending portion of the blower tube and being substantially sealed with respect to the guide tube at a point to the rear of the blower tube, the forward end of the guide tube opening into the interior of the blower tube, and means appurtenant to the forward portion of the casing tube and including a rotatable collar surrounding and operatively connected to the blower tube for rotating the blower tube, said blower tube and collar having nonconcentric interfitted driving portions and the interior of the blower tube being of substantially circular cross section.

14. A slidably extensible and retractable soot blower construction comprising a stationary guide tube, a blower tube slidably and rotatably carried by the guide tube, a stationary casing tube open at its front end and proportioned to permit the blower tube to project into and from such front end, said casing tube surrounding the rearwardly extending portion of the blower tube and being substantially sealed with respect to the guide tube at a point to the rear of the blower tube, the forward end of the guide tube opening into the interior of the blower tube, means for projecting and retracting the blower tube comprising a driving element rotatable in one direction to project the blower tube and in a reverse direction to retract the blower tube and projecting inwardly across a front end portion of the casing tube into engagement with the blower tube, and means for reversing the direction of rotation of said element including a pair of shiftable trip members carried by said casing tube at longitudinally spaced positions therealong and projecting inwardly through the casing tube into engageable relation with respect to a coacting abutment carried by the blower tube, and reversible motor means having a driving connection with said driving element and operatively connected to said trip members.

15. An extensible and retractable soot blower assembly comprising a stationary tubular guide member, means for supporting the guide member from one end thereof with the other end of such guide member projecting forwardly toward a Zone to be cleaned, a blower tube slidably mounted upon said guide member, driving means including a driving part surrounding the blower tube at a point spaced forwardly from the supported end of the guide member and engageable with the blower tube to induce longitudinal movement thereof, an elongated casing and supporting structure extending rearwardly from a position near the forward end of the blower tube when the blower tube is retracted to a position near the rear of said guide element, said casing and supporting structure surrounding said blower tube, a part of said structure near said forward position and which constitutes less than the full supporting structure being displaceable, and sealing means interconnecting the forward end of said guide member and the interior of the blower tube and accessible through the opening formed by displacement of the displaceable part of such structure.

16. An extensible and retractable soot blower assembly comprising a stationary tubular guide member, means for supporting the guide member from one end thereof with the other end of such guide member projecting forwardly toward a zone to be cleaned, a blower tube slidably mounted upon said guide member, means for causing longitudinal travel of the blower tube including driving means surrounding the blower tube at a point spaced forwardly from the supported end of the guide member and engageable with the blower tube to drive the same, and sealing means carried by the forward end of said guide member and slidably engaging the interior of the blower tube.

17. An extensible and retractable soot blower assembly comprising a stationary tubular guide member, means for supporting the guide member from one end thereof with the other end of such guide member projecting forwardly toward a zone to be cleaned, a blower tube slidably mounted upon said guide member, means for causing longitudinal travel of the blower tube including driving means surrounding the blower tube at a point spaced forwardly from the supported end of the guide member and engageable with the blower tube to drive the same, and sealing means substantially fixed with relation to the guide member and slidably interconuecting the forward end of said guide member and the interior of the blower tube, the blower tube being shorter than the guide member.

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