US2018124A - Tube scraper - Google Patents

Description

0d. 22, 1935. H J R51-ER 2,018,124

TUBE S CRAPER Filed Aug. 50, 1935 @U6/722271 Haw J ,270 roer Patented Oct. 22, 1935 UNITED STATES A'rENT OFFICE 13 Claims.

My invention relates to cleaning devices, particularly adapted for scraping or cleaning the interior surface of cylindrical members, such as tubes. My device is especially adapted for cleaning the tubes in boilers where the space available for manipulating the operating rod with which devices of the kind are used is limited. In such cases it is customary to use either flexible rods or multiple jointed rods made up of several lengths swivel connected and sufcient in length to pass the cleaners through the tube being cleaned. With such rods it is difficult to urge the ordinary type of scraper through the tube on the push-in or insertion stroke, due to the buckling of the flexible or jointed rod as a consequence of the pushing force required during the operation. This is true o-f all Scrapers which are constructed for the purpose of cleaning the tube with the same adjustment of pressure on the scraper members for both the pushin and the pull-out stroke.

The objects of my present invention are to provide a simple, effective, rugged and economically constructed tube scraper; to provide .a tube cleaner or scraper, which, when properly adjusted before insertion into the tube automatically applies the major effective pressure to the scraper members or scraper blades as they are known in the art, only on pull-out movement of the device, and wherein a yielding spring tension is .applied to the scraper members automatically by the pull exerted on thevdevice on the pull-out stroke; to provide a tube or flue cleaner having one or more adjustable expanding scraper elements, which are placed under spring or yielding tension on the pull-out stroke, but wherein the spring tension is automatically released by the force applied when the device is pushed into the tube; to provide a tube cleaner comprising a mandrel by which the device is pushed into or pulled from the tube, Iand a plurality of adjustable scraper members, the arrangement being such that the Scrapers are closed by the force applied directly to the mandrel itself; to provide a tube scraper or cleaner embodying a mandrel adapted to be pushed into the tube and to be pulled out of the tube and associated adjustable Scrapers resiliently mounted with respect to the mandrel and wherein said Scrapers are automatically forced yieldingly outwardly under spring tension into contacty with the walls of the tube by a wedging action occasioned as the tube scraper is pulled as a whole out of the tube on the pull-out stroke with relation to the tube; and to provide a tube cleaner involving a mandrel, a saddle mounted on the mandrel, and a plurality of adjustable scrapers connected to the saddle and adapted to be inserted into a tube and pulled out of the tube, together with spring means for applying resilient pressure directly to the Scrapers and cam means, adjustable by turning movement of .the mandrel, for radially adjusting the Scrapers and the spring tension.

Further objects of the invention are to provide a scraper device wherein means is provided to automatically apply or release the spring ten- `sion on the Scrapers by the longitudinal movement of the mandrel by employing the back and forward movement thereof involved in the pushin and the pull-out strokes of the cleaning operation; to provide a cleaner device wherein on the push-in stroke there is automatically effective a very light and yielding Contact of the scrapers with the interior tube surface and the pull-out stroke is attendant with a strong elastic pressure of the Scrapers against the intern-a1 tube surface, which pressure is automatically applied on the pull-out movement or withdrawal stroke; to provide a clean-out device of the foregoing character embodying a mandrel having a threaded portion and a nut adjustable therealong for adjusting the initial position of the Scrapers relative to the inner wall of the tube and wherein the nut is provided with self cleaning means; to provide a scraper of the foregoing type having means threadedly engaging the mandrel and adjustable by relative turning movement between the means and the mandrel; to provide a stop to limit movement of the mandrel with respect to the scraper members in one direction, said means also functioning to apply the force exerted on the saddle to push the cleaner through the tube on the push-in stroke and to prevent dirt passing between the inner edges of the Scrapers and the mandrel on the pull-out stroke, and to provide another stop to limit movement of the mandrel relative to the scra er members in the opposite direction, said mea s also functioning to bear the strain of the force applied to the saddle to force the cleaner through the tube on the pull-out stroke; to provide these and other objects which will be more apparent from a perusal of the following speciiication when taken in connection with the accompanying drawing, wherein:

Fig. 1 is a view partly in section of my improved cleaning device being inserted in a tube 'to be cleaned, wherein the Scrapers are shown in the position they assume momentarily when they meet substantial resistance on the push-in stroke (exaggerated for illustration). The normal position of the scrapers, however, when the device is inserted, is in very light contact with the incrusted surface of the tube.

Fig. 2 is a similar view showing the device operative on the pull-out stroke;

Fig. 3 isa cross section, showing certain of the details of the device.

Fig. 4 is a section on line 4-4 of Fig. 3.

Fig.5 is a section on line 5-5 of Fig. 3.

Referring now to the details of the device and to the drawing, my improved tube cleaner or scraper is adapted to be attached. to an operating rod such as previously described and commonly used in connection with tube Scrapers for inserting and manipulating devices of the kind `tube on the withdrawal or pull-out stroke.

into tubes for cleaning purposes. In the preferred construction of my deviceY it embodies a coupling 2 adapted for threaded connections as at 3 to any type or form of such rod as mentioned, for introduction ofA the device into a tube T. For the purpose of illustration the coupling is shown threaded to the end 4'of'a multiple jointed or flexible rod.

The coupling which also acts as a guide is preferably given a. tapered formation as shown, to facilitate movement of the device through the The cleaner or scraper at its other end is likewise constructed as will be hereinafter more evident, toY permit its easy entrance to the tube on the push-in stroke.

The coupling 2 is'securely fastened by threaded engagement to the mandrel, generally indicated at 6. Pin 8 prevents relative movement of these parts, thereby preventing detachment while in the tube when the mandrel may be rotated for making adjustment of the scraper blades and thereby making the coupling and the mandrel practically one piece.

The right hand portion 5 of the mandrel 6 adjacent to the coupling 2 is free of threads, and carries freely mounted thereon the saddle 26, While at its central portion it is threaded as at I0. The left hand portion I2 of the mandrel is likewise unthreaded and carries freely thereon the rsaddle 24, and is' smaller in diameter than portions 5 and ID to allow for the application of nuts 2U and I8. An expander nut I8 in threaded engagement with portion I0 of the mandrel 6 is caused to travel back and forth over the threaded portion I8 when the mandrel is rotated since said nut I8 is held against rotation by the engagement of the slots 44 of its web 42 with lsprings 38, the direction of travel depending upon the direction of the rotationI of the mandrel. This nut I 8 is provided on opposite sides with threaded extensions I4 which are provided with cut-outs I6 at suitable portions around the circumference of the `thread to permit the discharge of dirt and other matter, and thereby keep the thread I 0 clean. The extensions I4 act as cutters for removing foreign matter as the parts I0. and I 8 are relatively rotated.

In addition to the expander nut I8 the mandrel also carries a bumper nut 28, which is tightly secured thereon. YAs shown the nut 28 is threaded upon the portion I0 of the mandrel. The parts may be relatively fixed by a mutilation of the engaging threads, by welding, or in any approved manner. This' nut 23 serves for the purposeof first to provide a stop for limiting the movement of the mandrel to the left relative to thescraper blades, thereby governing the extent' of the decamrning or release action of the expand nut I8 on the springs 38. Second, it serves to engage saddle 24 on the push-in stroke to place any strain due to the insertion of the device through the tube directly on the mandrel, and it allows a ramming action against the saddle 24 when the mandrel is worked rback and forth. It also serves to practically close the gap between the Scrapers and the mandrel to prevent scrapings from passing through on the withdrawal or pull-,out stroke. AIn addition, there is a stop nut 2,2, which threadedly engages the end of the mandrel 6 and acts as a stop against which abuts the hub or saddle 24, which is free to slide along the unthrcaded portion I2 of the mandre. This nut 22 serves a triple purpose. It limits movement of the mandrel to the right relative to the Scrapers, thereby governing and extent of the camming or expanding action of the nut I8 on the springs 38. It also serves to place strain due to the withdrawal of the device out of the tube directly on the mandrel, and it allows a ranrning action against saddle 24 when the mandrel is worked back and forth.

A plurality of Scrapers 33, consisting of a shank braced by a web construction and having scraper faces, preferably of general arcuate and sectional form as shown in Fig. 4, are provided. These Scrapers are arranged with their lateral edges 28 in overlapping"arrangement, whereby the outer circumferential edges S8 of the Scrapers provide a continuous circle of scraping cutting contact. Each of these scrapers is pivotally mounted'ny its shank as at 32 on a furcation 32 on the sadn die 24, so that it shifts outwardly and inwardly toward and away from the inner wall of the tube and relatively to the mandrel 6. The scraping face of each scraper is provided with iurcations 34, through which passes a pivot pin 35 carrying one end of a flat spring 38 of leaf-like construction. The parts 34 of the furcations 34, by acting as guides for the tube end, facilitate the insertion of the scraper blades into the tube from the left when the occasion arises as when the scraper has been passed completely through the tube.

The other end of the spring 38 is fastened rigidly by means ofthe screw 40 or other device to the hub 28. The expander nut I8 is provided with a web or plate 42 slotted as 'at 44 at the diametral points to provide a plurality of grooves in which the spring members 38 rest. The web 42 with itsgrooves operates as a cam to force the springs 33 outwardly and thereby put a yielding pressure in an outward direction on the scrapers when the expander nut I8 is threadedly actuated or is pulled by means of the mann drel to theright as viewed in Fig. 3. In addition, these grooves engaging the springs 38 prevent rotation of the expander nut I8. It will be understood that any number of springs can be used, depending upon the number of scraper segments used. These springs are preferably made of flat spring material, but it will be understood that other shapes can be used. provided the shape does not interfere withthe hinged pivotal movement of the Scrapers 33.

A coil compression spring 4E is disposed between the saddle 26 and the coupling 2. This spring presses resiliently against the Vsaddle 26 and the coupling 2 and the compression of the spring draws the mandrel with nut I3 to the right, thereby exerting a slight camming action on the springs 33 outwardly to maintain a light contact oi the Scrapers with the interior tube surface. The compression of spring 48 is of just sufcient strength for the purpose and will yield easily to the movements of the mandrel. When properly adjusted for use with a given size tube, the saddle 24 is on an intermediate position of the portion I2 of the mandrel 6, which allows the mandrel to be still further shifted to the right or to the left, such movements are limited by stop-nut 22 and bumper nut 20. When the mandrel is pulled to the right an increased pressure or expansion results over the initial set pressure or adjustment. This occurs during the withdrawal of the device from the tube. When the mandrel is pushed to the left the deca-mining of the springs 38 results and thereby releases the tension below the initial set pressure adjustment. This latter effect takes place when the device is inserted or pushed through the tube when the scrapers meet slight resistance. The object oi providing initial light contact with the tube sur- :face is to obtain friction necessary to hold back the scrapers so that positive expansion occurs before withdrawal of the device as a whole.

The bumper nut 2i is formed with a flange and is located so as to close the gap between the inner edges of the scrapers 33 when the mandrel is pulled back or to the right on the pull-out stroke, thereby practically preventing dirt removed by the scraper segments from getting back of the cleaner and being left in the tube. The outer contour of the saddle 24 and the scraper blades are shaped to serve as entering guides for the cleaner to allow easy admittance to the tube.

In the operation of my improved cleaner or scraper, the scraper blades are preliminarily adjusted prior to inserting the device in the tube. By turning the mandrel 6 with respect to the scraper blades the expander nut ES is moved right or left along the threaded portion i i) of the mandrel, depending on the direction in which the same is turned. To make the initial adjustment, the mandrel B is turned so that the expander nutI I8 4moves to the right. The flat springs 38 connecting the scrapers with the saddle 2G are in contact with the grooves of the web portion 42 of the expander nut' I 8, which prevents the nut from turning with the mandrel. The movement of this nut to the right acts upon the surfaces of the springs 38, which are set at an angle or inclined with respect to the grooves, and cams or forces the scrapers outwardly. This adjustment or any adjustment of the expander nut I8 is maintained by the action of the spring 46 pressing against the coupling 2 and the saddle 26. By the preliminary adjustment the nut I8 is moved just sufliciently to the right so that with the scrapers expanded to the position they will assume in the tube, the nut will engage springs 38, resisting spring 46 to hold the saddle 24 at an intermediate position on the part I2 of the mandrel 6. For any adjustment of the nut I8 obtained by turning the mandrel, the movement of the nut I8 thereafter from left to right and vice versa when the device is pushed in and pulled out of the tube, coincides with the movement of the mandrel, which is limited in its movement relative to the scraper blades to the right by stop nut 22 and to the left by bumper nut 20.

The cleaning device, having been given the preliminary adjustment, is now inserted in the tube, which it enters easily; the spring 46, due to the camming action of the nut I8 on springs 38, pressing the scrapers 33 into light but yielding contact with the inner wall of the tube. If resistance is met by the scrapers as the device moves to the left, as by striking a zone carrying scale, dirt or other adhering matter, the spring 46 will yield, the mandrel 6 moving to the left with the eX- pander nut I8 until the bumper nut 20 fastened on the mandrel stops against the hub or saddle 5 24. It will thus be seen that the decarnming of springs 38 plus the endwise thrust of the bumper nut 20 against the saddle 24 will cause contraction of scrapers 33 and push the device, as a whole, through the tube with a very light contact lo of the scrapers 33 with the tube. Springs 38 do not tend to prevent this inward movement as nut I8 has moved to the left out of contacting position. This action relieves the springs 38 and also forces the scrapers inwardly, permitting them to 15 yield easily to any resistance met. It will be noted, however, that any loose soot or dirt will be pushed out from the tube in this operation, as the whole action is resisted by the light force exerted by spring 4E. 20

On the pull-out stroke of the device to the right, the mandrel 6 is moved to the right relative to the scrapers, as shown in the drawing, carrying the expander nut I8. In this action the bumper nut 2E! shifts to the right with the mandrel, closingthe gap between the scrapers to prevent the passage of dirt back into the tube. and the stop nut 22 strikes the hub or saddle 24 and takes the substantial strain of the pulling action. At the same time the full tension of the springs 38 is 3o applied to the scrapers by the camming action or" the nut I8. It will be evident that the initial adjustment of the scrapers having been made with saddle 24 on an intermediate part of the mandrel il, since themandrel is now moved to the right on the pull-out stroke, this movement carries the expander nut I8 to the right from a position of light contact with springs 38 to a position where it greatly increases the pressure of the springs 38 outwardly over that t-o which they were set in 40 the initial adjustment of the cleaner. This outward pressure acts on the scrapers to force them rmly into scraping contact with the inner Wall of the tube. This pressure can be further increased or decreased by turning the mandrel 6 45 while the device is in the tube, to suit desired conditions. It will be noted that in the pull-out operation, the stop 22, bearing against the hub 24, which carries the scrapers 33, places the substantial pull-out strain of the scrapers o-n the mandrel 59 and stop nut. Conversely, when the device is pushed into the tube, the bumper nut 20 contacting against the saddle 24 when substantial resistance is met by the scrapers, takes the strain.

It will thus be seen that I have avoided the de- 55 fects oi scrapers of the prior art where heretofore attempts have been made to mount the scrapers directly on the springs themselves and in which prior constructions the springs carried both the load and the Athrust strains having the disad- 60 vantages that the scrapers tended to get out of true and the springs were put under such a strain that they would not stand up and were continually breaking or becoming weaker.

One of the manifest advantages of my present device resides in the fact that inasmuch as the scrapers exert a strong scraping force only on the pull-out stroke, I eliminate any tendency of buckling the long rods used for operating the cleaners in long tubes. In other Words, by pro- 7() viding the substantial scraping or cleaning operation only on the pull-out stroke as distinguished from the push-in stroke, I minimize the possibility of buckling or bending the rods, due to the operating force longitudinally of the rod and minimize the possibility of the cleaner sticking in the tube.

With my present cleaner, the forward stroke is made easy by the contraction of the Scrapers 33 through the intermediary of the spring 46, the easy yielding of which allows the mandrel with the nut i8 to move relatively to the left, thereby releasing tension of springs 38 on the scrapers,

and conversely, on the pull-out stroke when the connecting rods cannot buckle or bend, the scrapers are placed under a direct spring pressure of the leaf springs 3d, operating directly through the pulling action; the substantial pulling strain, however, being removed from the springs 38 and carried by the mandrel and stop nut 22. By providing a device which scrapes in a substantial manner only on the pull-out stroke, I am enabled to use either swivel jointed sectional rods or flexible rods to great advantage, the same being required where full length one-piece rods cannot be used on account of the boiler being located in cramped quarters, leaving no room to operate long single-piece rods. It will be noted with respect to the scraper segments, that they are curved on their outer edges to iit the inside contour of the tubes and that these outer edges are formed with a rake or slant so as to present a sharp edge to the part to be scraped out. In addition, by the provision oi the overlap, the scraper faces are enabled to pass each other in their shifting movement, and at the same time to maintain a true circular cutting e-dge presented to the inside surof its attendant advantages will be understood from the foregoing description and it is obvious that numerous changes may be made in the form, construction, and arrangement of the several parts without departing from the spirit and scope of my invention, or sacrificing any of its attendant advantages.

What is claimed is:

l. A tube cleaner comprising a mandrel adapted to be connected to an operating rod and to be inserted into a tube to be cleaned, a scraper blade mounted on said mandrel for movement relative thereto toward the tube wall, means for resiliently pressing the blade at a given pressure against the ,tube wall as the cleaner is pushed inwardly through the tube, and means associated with said resilient means and scraper blade and moved by engagement of the blade with a severe obstruction in the tube to reduce said pressure.

2. A tube cleaner comprising a mandrel adapted to be connected to an operating rod and to be inserted longitudinally into a tube to be cleaned, a scraper blade mounted on said mandrel for movement relative thereto toward the tube wall, means for resiliently pressing the blade at a given pressure against the tube wall as the cleaner is pushed inwardly through the tube, means associated with said resilient means and moved by engagement of the blade with a severe obstruction in the tube to reduce said pressure, and

means also associated with said resilient means having a portion engaging thev tube wall moved longitudinally by a reversal of the direction of drag on said portion upon a reversal of the travel of the cleaner through the tube to increase said pressure.

3. A tube cleaner comprising a mandrel adapted to be connected to an operating rod and to be inserted longitudinally into a tube to be cleaned,

a scraper blade mounted on said mandrel for movement relative thereto toward the tube wall,

means for resiliently pressing the blade at a given pressure against the tube wall as the cleaner is pushed inwardly through the tube, means associated with said resilient means and moved by engagement of the blade with a severeV obstruction in the tube to reduce said pressure, means also associated with said resilientY means having a portion engaging the tube wall moved longitudinally by a reversal of the direction of drag on said portion upon a reversal of the travel of 10 the cleaner through the tube to increase said pressure, and operating mechanism also associated with the resilient means operable at the will of the operator while the cleaner remains in the tube for further adjusting said pressure.

e. A tube cleaner comprising a mandrel adapted to be connected to an operating rod and to be inserted longitudinally into a tube to be cleaned, said mandrel having an operating portion extending rearwardly from the tube, a scraper blade pivotally and slidably mounted on said mandrel and extending rearwardly thereon and outwardly therefrom into engagement with the tube wall whereby to scrape said wall on the rearward stroke of the mandrel, means for resiliently pressing the blade at a given pressure against the tube wall as the cleaner is pushed forwardly through the tube, means associated with said resilient means and operated by forward longitudinal movement or the blade along the mandrel upon rearward movementof the cleaner through the tube to increase said pressure, and operating mechanism also associated withV the resilient means operable at the will of the'operator while the cleaner remains in the tube for further adjusting said pressure. Y

5. A tube cleaner comprising a mandrel adapted to be connected to an operating rod and to be inserted into a tube to be cleaned, a scraper blade mounted on said mandrel for pivotal movement 4.0 with respect thereto intoengagement with the wall of the tube and for bodily displacement longitudinally of the mandrel, means for resiliently pressing the blade at a given pressure against the tube wall as the YcleanerV is pushed inwardly through the tube, means operated by engagement of the blade with a severe obstruction in the tube to effect relative bodily longitudinal displacement between the scraper blade and the mandrel, and means associated with said resilient means and operating responsive to said bodily displacement to reduce said pressure.

6. A tube cleaner comprising a mandrel adapted to be connected to an operating rod and to be inserted into a tube to be cleaned', a member 55 Vmounted on said mandrel for longitudinal displacement therealong and for rotation thereon, a scraper blade pivoted to said member for movement into engagement with the wall of the tube, means for resiliently pressing the scraper blade at a given` pressure against the tube wall, means operating responsive to the engagement of the blade with incrustations on the tube wall to effect relative longitudinal displacement between the member and the mandrel, means associated with to eliect relative rotation of said member and V mandrel, and means also associated with said resilient means and operated by said relative rotation to further adjust said pressure.

7. A tube cleaner comprising a mandrel adapted to be connected'to an operating rod and to be 75' inserted into a tube to be cleaned, a member mounted on said mandrel for longitudinal displacement therealong and for rotation thereon, stop abutments on said mandrel spaced on either side of said member to limit the longitudinal displacement thereof, a scraper blade pivoted to said member for movement into engagement with the wall of the tube, means for resiliently pressing the scraper blade at a given pressure against the tube wall, means operating responsive to the engagement of the blade with incrustations on the tube wall to effect relative longitudinal displacement between the member and the mandrel to bring said member into engagement with one or the other of said stop abutments, means associated with. said resilient means and operated by said longitudinal displacement to adjust said pressure, operating mechanism operable at the will of the operator while the cleaner remains in the tube to effect relative rotation of said member and mandrel, and means also associated with said resilient means and operated by said relative rotation to further adjust said pressure.

8. A tube cleaner comprising a mandrel adapted to be inserted into a tube to be cleaned, said mandrel having a threaded portion intermediate its length, a pair of saddles mounted on said mandrel, one on either side of said threaded portion, and slidable relative to each other along the mandrel, a scraper blade pivoted to one of said saddles for movement into engagement with the tube wall, a exure spring connected at one end to the scraper blade adjacent the tube engaging.

end thereof and at its other end to the second saddle, said spring being inclined with respect to the mandrel axis, and a nut mounted on said mandrel threaded portion and adapted to be screwed therealong and to engage an intermediate portion of said spring to flex the same and urge the scraper into engagement with the tube Wall.

9. A tube cleaner comprising a mandrel adapted to be inserted into a tube to be cleaned, said mandrel having a threaded portion intermediate its length, a pair of saddles mounted on said mandrel, one on either side of said threaded portion, and freely slidable along the mandrel, a plurality of scraper blades pivoted to one of said saddles for movement into engagement with the tube Wall, a lexure spring for each scraper blade adjacent Athe tube. engaging end thereof connected at one end to the blade and at its other end to the second saddle, said spring being inclined with respect to the mandrel axis, and a nut mounted on said mandrel threaded portion and adapted to be screwed therealong and to engage an intermediate portion of each spring to ex the same and urge its scraper into engagement with the tube wall, and stop abutments on said mandrel spaced on either side of one of said saddles to limit the sliding movement thereof.

10. A tube cleaner comprising a mandrel adapted to be. inserted into a tube to be cleaned, said mandrel having a threaded portion intermediate its length, a pair of saddles mounted on said mandrel, one on either side of said threaded portion, and freely slidable along the mandrel, a plurality of scraper blades pivo-ted to one of said saddles for movement into engagement with the tube wall, a exure spring for each scraper blade adjacent the tube engaging end thereof con- 5 nected at one end to the blade and at its other end to the second saddle, said spring being inclined with respect to the mandrel axis, and a nut mounted on said mandrel threaded portion and adapted to be screwed therealong and to engage an intermediate portion of each spring to flex the same and urge its scraper into engagement with the tube wall, stop abutments on said mandrel spaced on either side of the saddle to which the blades are pivoted to limit the sliding movement of the saddle, and a spring for urging one of said saddles longitudinally along the mandrel.

11. A tube cleaner comprising a` mandrel adapted to be inserted longitudinally into a tube to be zo cleaned, a saddle mounted on said mandrel for slidable movement therealong, a plurality of scraper blades pivoted circumferentially around the saddle for movement into engagement with the tube wall, said blades having portions thereon forming a partial transverse barrier across the interior of the tube when the blades are in operative position against the tube wall, an abutment on said mandrel normally spaced from said blades having a portion arranged transversely of the mandrel and tube, and means having a portion engaging the tube wall moved longitudinally by a reversal of the direction of drag on said portion upon a reversal of the travel of the cleaner through the tube to shift said Scrapers: into juxtaposition with said abutment to form a complete transverse barrier across the tube.

12. A tube cleaner comprising a mandrel adapted to be inserted into a tube to be cleaned, a plurality of scraper blades mounted on said mandrel for movement relative thereto toward the tube wall, means for resiliently pressing the blades ,at a given pressure against the tube wall as the cleaner is pushed inwardly through the tube, and means associated with said resilient means and each of said blades and moved by engagement of any blade with a severe obstruction in the tube for reducing the pressure of said pressing means while the other blades remain in contact with the tube wall. 50

13. A tube cleaner comprising a mandrel adapted to be inserted into a tube to be cleaned, a pair of saddles mounted on said mandrel in spaced relation and slidable therealong, a rigid scraper blade pivoted to one of said saddles and extending outwardly from and rearwardly along the mandrel into engagement with the tube wall, an elongated exure spring extending rearwardly along and inwardly toward the mandrel and connected at one end to the scraper blade adjacent the tube engaging end thereof and rigidly xed at its other end to the second saddle, and means on the mandrel between said saddles engageable with said spring on relative movement with respect thereto, the pivotal movement of the blade being controlled by the flexure of the spring.

HARRY J. FORSTER.

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