US3739605A

US3739605A - Cleaning apparatus for materials moving in endless path

Info

Publication number: US3739605A
Application number: US00214016A
Authority: US
Inventors: D Baker
Original assignee: Bird Machine Co Inc
Current assignee: Bird Machine Co Inc; Sulzer Papertec Mansfield Inc
Priority date: 1971-12-30
Filing date: 1971-12-30
Publication date: 1973-06-19
Anticipated expiration: 1990-06-19
Also published as: JPS4875805A; CA972999A

Abstract

Apparatus for cleaning materials moving in an endless path by the application and/or extraction of liquid, has a cleaning member with ports through which the liquid passes that is reciprocated across the path of travel of the material, and reversal control means that causes the reversals of direction of the reciprocatory movement of the cleaning member to take place at a plurality of different points across the path.

Description

Umtefl States Patent 1191 1111; 3,739,605 Baker 1 June 19, 1973 CLEANING APPARATUS FOR MATERIALS 3,688,530 9 1972 Harris et al. 68/205 R MOVING IN ENDLESS PATH FOREIGN PATENTS OR APPLICATIONS Inventor: Donald Brooks Baker, Foxboro, 535,797 1/1922 France 68/205 R MaSS- 912,854 12/1962 Great Britain 68/205 R [73] Assignee: Bird Machine Company, Inc., South Walpole, Mass Primary Examiner-William 1. PrIce Assistant Examiner-Philip R. Coe [22] Filed: Dec. 30, 1971 Atmmey Edgar Kent [2]] Appl. No.: 214,016

[57] ABSTRACT [52] 0.8. CI. 68/20, 15/302, 15/306 A, Apparatus for cleaning materials m v ng in an endless 68/205 R 134/122 path by the application and/or extraction of liquid, has [51} Int. Cl Bb 13/04 a cleaning member with p r gh i h he l q i [58] Field of Search 68/20, 205 R; passes that i reciprocated across h p th of r vel f 134/64, 122; 15/302, 306 A the material, and reversal control means that causes the reversals of direction of the reciprocatory movement of 56] References Cit d the cleaning member to take place at a plurality of dif- UNITED STATES PATENTS ferent points across the path.

3,271,102 9/1966 Morgan 68/205 R X 18 Claims, 5 Drawing Figures 46 33 36 iXXAN QA" vwvx: "NA my r vbYt-WW 49 4O 64 ipgj; 31:11-22:11 16 50 52 3e 4 rt a --------l'-*|6 CLEANING APPARATUS FOR MATERIALS MOVING IN ENDLESS PATH This invention relates to apparatus for cleaning paper machine felts and other materials moving in an endless path by the application and/or extraction of liquid.

Paper machine felts are used to support and drain water from the wet-formed paper web in the course of drying it. The water absorbed by the felt needs to be removed so that the felt is in a relatively dry state when it contacts the paper web. Further, the water drained through the felt extracts with it various solid materials from the paper web, such as small fibers, fillers, sizing materials and the like. If not removed, these would soon contaminate and clog the felt, making it impervious and useless for its water extracting function.

Various apparatus has been developed for cleaning or conditioning the endless felt loops in their travel from and to engagement with the wet paper web. The type which this invention concerns is reciprocated back and forth across a surface of the felt or a portion thereof, and includes reciprocated spray headers with spaced spray ports, usually nozzles, and reciprocated suction shoes with spaced suction ports, which shoes may also be provided with ports for discharging water to the felt, these shoes usually being provided in sets which operate upon different widthwise sections of the felt. Difficulty has been experienced with such apparatus in that it tends to treat certain areas of the felt more than others, so that in time streaks develop in the felt along these areas due to increased cleaning and in time increased wear and deterioration as compared with the remainder of the felt. Such streaks not only reduce the useful wear life of the felt but also may impair the property of the paper by producing corresponding streaks therein. Similar problems may be encountered where reciprocated cleaning members of the foregoing type are used for cleaning other endless materials, for example, reciprocating sprays for cleaning the paper forming wire and dandy roll of paper machines.

A primary cause of this irregular treatment has been the dwell time of the reciprocated cleaning member at the end of each stroke which causes the discharge or suction of the ports to treat the areas of the material at the ends of their path of reciprocation longer than in the intermediate areas. This problem is accentuated by the common practice of reciprocating the apparatus a greater distance than the spacing between ports to insure that the full width of the material is treated, with the result that there is usually some overlap in areas treated at the ends of the stroke. Where several spray headers or suction shoes are provided across the width of the material, the same practice also results in overlap of areas treated by successive headers or shoes.

The object of this invention is to provide improved apparatus of the type concerned whereby irregularity of treatment and the aforesaid difficulties due thereto are essentially avoided.

In attaining the foregoing object, the invention provides such apparatus with reversal control means operative during reciprocation operation of the cleaning member to cause the reversals of motion of the reciprocated member to take place at different points across the material to be cleaned, preferably at numerous different points over a substantial width of the material. In this manner, dwell can be substantially eliminated, or the harmful effects of dwell can be dissipated by varying the dwell positions over substantial areas of the material. Similarly, overlap may be provided without increased cleaning in the areas of overlap.

According to one aspect of the invention apparatus having the customary fixed length stroke reciprocator for the cleaning member has, as the reversal control means, a mounting on which this reciprocator may itself be reciprocated together with the cleaning member which it reciprocates, longitudinally of the path of reciprocation of the member, and an additional reciprocating motor or device which so reciprocates both the first reciprocator and the cleaning member while operating and at a different rate of reciprocation, so that the reversals of direction of motion of the cleaning member are varied along its reciprocation path.

According to another aspect of the invention, the reciprocator immediately connected to the cleaning member is provided, as the reversal control means, with means which is operable to change its reciprocation stroke length while operating, in several, preferably many, increments. Thus a fluid-operated reciprocating motor having its piston connected to reciprocate the cleaning member may be provided with fluid input and output valves which may be operated to change fluid input and output from one side of the piston to the other at various different positions of the piston relative to its cylinder. The reversal control means includes a device which switches these valves from input to output and vice versa at various different time intervals, corresponding to different positions of the piston with respect to its cylinder, thereby changing the stroke length and accordingly changing the points of reversal. Alternatively, the reciprocator may carry spaced reversal control switches which alternately engage a cam between them that is rotated to change the points of engagement of the switches therewith and hence change the positions of reversal of the equipment.

In the drawings certain embodiments have been selected to illustrate the invention, it being understood that the invention can be utilized in other embodiments than those shown.

In the drawings:

FIG. 1 is a top plan view of one form of apparatus according to the invention together with a fragmentary top plan view of a spray header located beneath a paper machine felt traveling in an endless path;

FIG. 2 is a side view partly in elevation, partly in longitudinal section of the apparatus of FIG. 1 at a different position;

FIG. 3 is a diagrammatic view of pressure fluid circuits, switches and valves that may be used to control the operation of apparatus according to FIGS. 1 and 2;

FIG. 4 is a top plan view of a modification of the apparatus of FIGS. 1 and 2; and,

FIG. 5 is a fragmentary top plan view of a felt condi tioner arranged to clean a paper machine felt passing thereover and of reversal position changing apparatus accordingto the invention associated therewith.

Referring to the embodiment of FIGS. 1 and 2, a spray header 10 provided with shower nozzles 12 is mounted to reciprocate longitudinally beneath and across the path of a paper machine felt F by means of a bracket 14 slidingly mounted in ways 16 provided on a suitable base 18 at one side of the felt, the opposite end of header 10 (not shown) being similarly slidingly mounted at the other side of the felt and being provided with the usual flexible connection to a source of water under pressure. A first fluid operated motor 20 has the protruding outer end of its piston stem 22 connected to header by a yoke 24 screw threaded on the end of the piston stem, the yoke arms receiving between them a bar 26 fixed to the end of header 10 and being fastened to the bar by a bolt 28 extending through the arms and loosely through the bar and held by a nut 30. Motor is provided with

flexible tubes

32 and 33 connecting ports adjacent the opposite ends of its casing with a means for supplying thereto and exhausting therefrom alternatively a fluid under pressure.

The apparatus so far described may be conventional. However, instead of fixedly mounting motor 20 on base 18 as would be conventional, in accordance with this invention one end of its casing is fastened to a bracket 34 by a nut 36 screw threaded on a sleeve 38 fixed to the motor casing and slidably receiving piston stem 22, bracket 34 being slidingly received in the ways 16. The opposite end of the cylinder of motor 20 is rigidly connected by connector 40 to the cylinder of a second and shorter fluid operated motor 42 provided with

flexible tubes

44 and 45 connecting the opposite ends of its cylinder for alternate admission and exhaust of fluid under pressure as in the case of

tubes

32 and 33. Connector 40 may be connected to the two cylinders in any convenient manner as by spot welding flanges thereon to the respective closed ends of the cylinders.

The piston stem 46 of motor 42 is fixedly secured by

nuts

48 and 49 threaded on piston stem 46 to a bracket 50 fixed on one end of the ways 16. The cylinder of motor 42 has its end adjacent bracket 50 fixed to a bracket 52 by nut 54 on a threaded sleeve 56 fixed to the end of the cylinder which surrounds piston stem 46 and extends through bracket 52. Bracket 52 is slidingly mounted in the ways 16 so that as fluid under pressure is alternately admitted and discharged via

tubes

44 and 45 to the cylinder of motor 42, the cylinder reciprocates relative to its piston and slides bracket 52 in ways 16. The reciprocal movements of the cylinder of motor 42 are in turn imparted to the cylinder of motor 20, that cylinder being slidingly mounted in the ways 16 by bracket 14.

Limit switches are provided for each motor to control reversals of relative motion of their pistons and cylinders. The pair of

limit switches

58 and 60 for motor 20 is mounted on an arm 62 which is fixedly attached to bracket 34.

Switches

58 and 60 are therefore movable with bracket 34. The switches are operated by an actuator finger 64 fixed to piston stem 22 adjacent yoke 24. The spacing of

switches

58 and 60 is such as to permit the working stroke of piston stem 22 relative to its casing between successive actuations thereof by finger 64.

The pair of

limit switches

66 and 68 for motor 42 is fixedly mounted, switch 66 on a lateral extension of fixed bracket 50 and switch 68 on a support 70-fixed to the side of ways 16.

Switches

66 and 68 are operated by actuator finger 72 mounted on slide 52 and therefore movable with that slide and the cylinder of motor 42. The spacing of

switches

66 and 68 is such that the full working stroke of the cylinder of motor 42'relative to its piston is required for successive operation of the switches by finger 72.

In operation, the

motors

20 and 42 are adjusted so that their pistons reciprocate at different speeds (by pressure fluid regulating valves on input and output). These speeds are preferably selected according to the relative working stroke lengths of the two motors so that coincidence of full working stroke in the same direction is infrequent, and the speed for the shorter stroke motor is sufficiently less than that of the other so that when the shorter stroke motor completes a stroke the other motor will have completed several strokes. Then, if both motors are started with their pistons and cylinders in their most compressed position indicated in FIG. 2, the piston of motor 20 will complete its working stroke to the right when motor 42 has only partially completed its stroke to the right. When finger 64 engages switch to cause reversal of the piston of motor 20, that piston and spray header 10 will have actually moved to the right a total distance equal to the working stroke length of that piston plus the distance that the cylinder of motor 42 has moved to the right. Also, during reversal of motor 20, motor 42 continues to move motor 20, its piston and spray header 10 to the right so there is actually no dwell of the spray header during reversal although its speed of movement to the right will be reduced to the speed of motor 42.

Upon reversal of motor 20, motor 42 continues to move the sliding assembly to the right but, because of its greater speed, motor 20 actually moves spray header 10 to the left. By the time the piston of motor 20 has completed its working stroke to the left so that finger 64 operates reversal switch 58, motor 42 will have moved the sliding assembly a further distance to the right, and the net movement to the left of the piston and header 10 is its working stroke length minus that further distance. The second reversal of motor 20 and header 10 will take place at a distance to the right of the initial left starting position relative to the felt equal to the total movement to the right of the cylinder of motor 42. Again, since motor 42 continues to move the sliding assembly there is no dwell, reversal being instantaneous as the speed of motor 20 to the left drops below that of motor 42 to the right.

Such shifting to the right of the points of reversal of the piston of motor 20 and header 10 continues until the casing of motor 42 reaches the end of its working stroke relative to its piston, so that finger 72 contacts switch 68 causing reversal. Thereafter, the stroke of motor 42 to the left causes the points of reversal of motor 20 to shift to the left until the next reversal of motor 42, and so on.

Thus it will be seen that as operation continues, each of the two points of reversal will be shifted from left to right, then from right to left and so on over a span equal to the length of stroke of motor 42. For example, if that stroke length is 4 inches and the working stroke of motor 20 is 8 inches, the points of reversal will vary over spans of 0-4 and 81 2 inches, respectively. There is no dwell except in those rare instances in which both motors reach either end of their stroke at the same instant. Repeat locations of the points of reversal within the variation span are infrequent, so that even the effect of slowdown during reversal is dissipated. If, for example, the nozzles are spaced apart 8 inches, the overlap produces no greater spray contact with the felt than in the intermediate areas.

The relative speeds of the two motors and their stroke lengths should be such as to avoid small repeat patterns in the changed positions of the points of reversal. For example, if motor 42 were exactly operated to reverse at every second reversal of motor 20, each reversal of the header would take place at only three different points and there would be dwell at every second reversal of motor 20, as would be obviously undesirable for obtaining maximum benefits from the invention. Relative speeds and stroke lengths can be determined mathematically which will give a large number of different reversal points before a repeat. As a practical matter, however, the apparatus involved does not normally operate with such regularity and precision, due to pressure fluctuations, slight differences in valve adjustments and operating speeds, and other variables, as to maintain a precise repeat pattern very long. Consequently in time, the two motors tend to get out of phase so that even a small number repeat pattern when the motors were started becomes a large number pattern, more or less random, with many different points of reversal, and infrequent dwells.

The control circuitry for operating the motors, which is not shown in FIGS. 1 and 2 except for the limit switches, may take various forms and may be fluid, electric or mechanically actuated. FIG. 3 shows diagrammatically suitable control circuitry of the fluid ac tuated type including the limit switches and tube connections shown in FIGS. 1 and 2.

In FIG. 3, two reciprocated slide valves 100 and 102 are used. Since these are of a well known commercially available type they are shown only by diagram. Valves 100 and 102 are reciprocated from right to left and left to right as shown in the drawing by fluid pressure ap plied through an applicator at each end, designated 101, 101', 103 and 103'. A tube line 104 from a source of pressure fluid (not shown) applies the line pressure through connecting

lines

106 and 108 and pressure regulating valves 107 and 109 to the respective inlet ports of valves 100 and 102 respectively, which are located in the left hand sections of the valve casings. These casing sections also include two outlet ports connected to regulating valves symbolically indicated at 110, 110' and 112, 112' respectively. With a compressed air operated system as contemplated in FIG. 3, these exhaust valves may simply discharge to atmosphere. If an hydraulic system is used, they would be connected by return lines to a sump.

The left hand sections of the casings of valves 100 and 102 are also provided with two ports which, in valve 100, are connected to operating

tube lines

44 and 45 respectively of the motor 42 of FIGS. 1 and 2 and, in valve 102, are connected to operating

lines

32 and 33 respectively of the other motor 20, so that valve 100 controls motor 42 while valve 102 controls motor 20.

' An input tube line 114 from pressure line 104 supplies fluid pressure to the inputs of

limit switches

66 and 68 of motor 42. Similarly, an input tube line 116 from pressure line 104 supplies fluid pressure to the inputs of

limit switches

58 and 60 of motor 20. Limit switches 66, 68, 58 and 60 are arranged when actuated to apply the pressure from

lines

114 or 116 to valve reciprocators101,101,103 or 103 via

tube lines

118, 119, 120 and 121 respectively. When not actuated these limit switches

open lines

118, 119, 120 and 121 to atmosphere (pneumatic) or a line leading to a sump (hydraulic).

In the position of valves 100 and 102 shown in FIG. 3,

limit switches

66 and 58 have last been operates so that the pistons of motors 42 and are moving from left to right. This motion is produced because, as shown by the arrowed connection lines, the input ports from

lines

106 and 108 are connected through the valves to

lines

44 and 32 of

motors

42 and 20 respectively, while

lines

45 and 33 are connected to exhaust valves 110' and 112' respectively,

exhaust valves

110 and 112 being sealed off. When the piston of either motor reaches its maximum travel to the right, it actuates its

corresponding limit switch

68 or 60 which opens

line

119 or 121 to pressure from

line

114 or 116 respectively, so that the valve or 102 is shifted to the left by

pressure applicator

101 or 103 to move the left hand valve section out of the operative portion of its casing, being replaced therein by the right hand section. In the right hand section, the valve passage connection between ports, again as indicated by the arrowed lines, is such that

lines

44 or 32 are connected to exhaust valve or 112 respectively, lines 45 and 33 are connected to the

input lines

106 or 108 respectively, and

exhaust valve

110 or 112 is sealed off. Thus the respective motors reverse and their pistons move to the left until their

limit switches

66 or 58 are actuated to return the respective valves 100 or 102 to the positions shown, by pressure applied through

line

118 or 120 and applicator 101 or 1103, to reverse again the piston of the respective motor.

The embodiment of FIGS. 1 and 2 has the advantage that it produces no dwell of the spray header 10 except on the rare coincidences of maximum stroke of both motors in the same direction. On the other hand this embodiment has the disadvantage that it reciprocates the spray header at variable speed. This is because, when the piston of motor 20 and the cylinder of motor 42 are moving in the same direction their speeds are added in the movement of header 10, whereas when they are moving in opposite directions header 10 moves at the difference between their speeds. FIG. 4 shows a modification wherein the spray header is moved at uniform speed but there is dwell at each reversal, although, as in the FIGS. 1 and 2 embodiment, the points of reversal are distributed over a substantial area and therefore the otherwise harmful effects thereof on the felt are dissipated.

In FIG. 4 two motors of the fluid operated type are also provided, designated 220 and 242. However, in this embodiment the motors are fixedly mounted on the base 218. Like the motor 20 of P168. 1 and 2, motor 220 has its protruding piston stem 222 connected by yoke 224 to the spray header (not shown in FIG. 4). The limit switches for this motor 220, designated 258 and 260, are not carried by its casing but are fixed to a rod 280 which constitutes an extension of the piston stem of motor 242 and reciprocates therewith.

Limit switches

258 and 260 are actuated by finger 264 fixed to piston stem 222 of motor 220.

Limit switches

266 and 268 for motor 242 are fixedly mounted on base 218. They are actuated by finger 272 fixed to rod 280.

The embodiment of FIG. 4 operates by increasing and decreasing the length of stroke of the piston of the header operating motor 220 between reversals and therefore varying the points of reversal across a lateral area. of the felt. In FIG. 4, motor 242 is shown at maximum left stroke position in which finger 272 engages limit switch 266 to reverse the operation of motor 242 so that its piston now moves to the right. Motor 220 is shown in FIG. 4 with its piston moving to the right, par tially extended. As the pistons of both motors move to the right, the piston of motor 242 moves bar 280 and attached

limit switches

258 and 260 to the right. If motor 242 is operated at slower speed than motor 220 as is preferable, than contact finger 264 on piston stem 222 of motor 220 will catch up with, and actuate, limit switch 260 somewhere between its full line and dotted line position in FIG. 4, the dotted line positions of shaft 280 and

limit switches

258 and 260 representing their maximum movement to the right by the piston of motor 242.

When motor 220 reverses, motor 242 continues to move the

limit switches

258 and 260 to the right so that switch 258 will be engaged by finger 264 to produce another reversal with the piston of motor 220 considerably extended from its maximum position to the left. It will therefore be seen that if, for example, the piston of motor 220 has a l2 inch stroke while that of motor 242 has a 4 inch stroke and

limit switches

258 and 260 are spaced apart 8 inches, then the piston of motor 220 will reciprocate, and reciprocate the header with it, at different stroke lengths which vary each of the points of reversal across a different 4 inch width of the felt. The piston of motor 220 will move its maximum of 12 inches to the right and move the spray header accordingly only when its maximum movement to the right happens to coincide with maximum movement to the right of the piston of motor 242. Conversely, the piston of motor 220 and the header connected to it will reach their maximum movement to the left only when this happens to coincide with the maximum movement to the left of the piston of motor 242. The speed of motor 220 remains constant.

Although in the embodiment of FIG. 4 a dwell occurs between each reversal, the effects thereof are spread over a substantial area and therefore dissipated. The fewer sliding parts required in FIG. 4, plus the constant speed of reciprocation of motor 220 and connected header, may make this embodiment preferable to that of FIGS. 1 and 2 in many applications. In both embodimerits, the reciprocation paths of successive nozzles can be overlapped with no greater treatment of the felt in the overlapped area, and consequently with no adverse effect. This is because, when one nozzle operates in the area of overlap, the other does not, so that all the areas of the felt receive the same treatment.

It will be appreciated that the same operating circuitry shown in FIG. 3 for the embodiment of FIGS. 1 and 2 can be used for the embodiment of FIG. 4, substituting

motors

220 and 242 for

motors

20 and 42 respectively,

motor tube connections

232, 233, 244 and 245 for those designated respectively 32, 33, 44 and 45 in FIG. 3, and

limit switches

258, 260, 266 and 268 respectively for those designated 58, 60, 66 and 68 in FIG. 3.

The motors and controls of FIGS. 1 to 4 can also be used to reciprocate felt conditioners with points of reciprocation varying across the felt, fluid operated motors being commonly used for reciprocating felt conditioners, the length of reciprocation, however, being usually much greater, of the order of 2 feet or substantially more. Since it is common also to use mechanical reciprocation for felt conditioners, FIG. 5 shows a felt conditioner of the mechanically reciprocated type modified to vary its stroke length between reversals as in the FIG. 4 embodiment, but in this case utilizing a mechanically actuated cam instead of the fluid motor 242 of FIG. 4.

Referring to FIG. 5, the felt conditioner there shown is of a commercially available type in which reciprocation is accomplished by mechanical worm action, but the usual fixed point reversal mechanism thereof has been replaced by means to vary the reversal positions across the felt as hereinafter described. In FIG. 5, the shoes of the felt conditioner designated 300 (two only being shown) are mounted to slide transversely of the path of the felt F on an angle beam 302, the felt riding over the tops of the shoes. Each shoe is mounted on beam 302 by a mounting (not shown) which extends under the beam 302 and carries a screw threaded socket (not shown) which engages a threaded worm reciprocator 304 on a shaft 306. The shoes 300 are connected to move together in unison by an angular plate 308 which moves therewith longitudinally of beam 302.

The covers of shoes 300 are, as usual, provided with large slots 310 through which suction is applied to the surface of the felt engaged therewith, alternating with narrow slots 312, through which water is injected into the felt. The underpart of each shoe is connected to sources (not shown) of water under pressure which communicates with slots 312 and of suction which communicates with slots 310, by

flexible hoses

314 and 316 respectively. The sources of water under pressure and suction to which

hoses

314 and 316 are respectively connected may be pipes stationarilyextending under the path of the felt or located at the side thereof. Angle beam 202 on which the conditioner shoes are mounted is secured to fixed

supports

318 and 318 on a suitable support base 320, 320' at opposite sides of the path of the felt F.

The drive connections (not shown) for operating shaft 306 to produce opposite rotations thereof for reciprocating the conditioner shoes via worm 304 may be a gear box, provided with gears alternately shifted into driving engagement with gears on shaft 306 to drive it in opposite directions, or may be a reversible electric motor. As heretofore produced, such felt conditioner apparatus has caused reversals of the direction of reciprocation after a fixed length stroke and at uniform positions relative to the felt by linkage oppositely operated at each end of the stroke.

In accordance with this invention, means is provided for reversing the direction of reciprocal movement of shoes 300 by worm 304 at a plurality of different positions transversely of the path of travel of the felt. In FIG. 5 such means comprises a rod 322 connected to the near-side shoe so that it reciprocates correspondingly with the shoes through a slide bearing 324 on support 318. Rod 322 carries at its outer end a limit switch 326 of the plunger actuated type, and a U-shaped arm 328 the opposite end of which carries another limit switch 330 of the same type, in line with, and in operation opposed to, switch 326.

Switches

326 and 330 are indicated as electrical with output lines 327 and 331 respectively which, when the switch is closed, either actuate two motors or a reversible motor to operate gear shift mechanism to change the direction of rotation of shaft 306 where such drive is used, or reverse the drive of shaft 306 by a reversible motor when such drive is used, by closing a relay in the circuit to one direction of drive and opening a relay in the circuit to the opposite direction of drive.

A shaft 332 is rotatably mounted on base 320 between

limit switches

326 and 330. Shaft 332 carries eccentrically a cam 334 the plane of which lies in the plane of reciprocation of

limit switches

326 and 330 by rod 322, so that the periphery of cam 334 will contact these switches when moved toward it. Cam 334 is preferably designed in well known manner so that equal rotations thereof by shaft 332 produce equal variations in the distance from the center of shaft 332 of points on the cam periphery in line with switches 326 and 33d). Shaft 332 is rotated by a driven gear 336 fixed thereto meshing with a drive gear 338 on the drive shaft of a motor 340 mounted on base 320.

In operation, motor 340 is continually operated so that the distances moved by the

switches

326 and 330 toward shaft 332 continually increase and decrease. The effect is to increase and decrease the time of rotation of worm shaft 306 in each direction, so that the points of reversal of direction of reciprocation of shoes 300 are varied transversely of the felt. The effect is therefore the same as that produced with the reciprocated limit switches in the embodiment of FIG. 4.

It will be appreciated that the cylinder 242 with the limit switches it controls in FIG. 4, and cam 334 with the cooperating limit switches in FIG. are, in effect, variable time timers which vary the time intervals be tween reversals and consequently vary the length of stroke and points of reversal accordingly. It is possible to substitute therefor an electric timer or timers arranged to operate at various time intervals the reversal control valve for the motor 220 of FIG. 4 or reversal control switches for the motor or drive of FIG. 5. However, the arrangements shown are preferred, since the electric timing mechanism may get out of phase with the actual strokes produced by the motors, in which case pauses might occur with deleterious effects when the motor reached the end of its working stroke before the timing mechanism called for reversal.

I claim:

1. In apparatus for cleaning felts and other materials moving in an endless path by the application and/or extraction of liquid, said apparatus including a cleaning member having port means through which the liquid passes and means for mounting said member to extend and be reciprocated across said path with said port means directed at the material to be cleaned, the combination of reciprocation means for reciprocating said member across said path, and reversal control means cooperating with said reciprocating means and operable during reciprocation of said member by said reciprocating means to cause the reversals of direction of motion of said member to take place at a plurality of different points across said path.

2. Apparatus according to claim ll wherein said reversal control means comprises means mounting said reciprocation means for reciprocation together with said cleaning member in a direction across said path, and means for so reciprocating said reciprocation means and member while they are operating and at a different rate than that of reciprocation of said member by said reciprocation means.

3. Apparatus according to claim 2 wherein said reciprocation means is a first fluid pressure operated motor and the last named means of said claim is a second fluid pressure operated motor connected to said first motor.

4. Apparatus according to claim 3 wherein said reversal control means includes switch means and actuator means therefor operable to cause reversals of direction of operation of said first motor after a reciprocation stroke of constant length.

5. Apparatus according to claim 1 wherein said reversal control means comprises stroke adjustment means operable to increase and decrease the reciprocation stroke length of said reciprocation means while it is operating by a plurality of increments.

6. Apparatus according to claim 5 wherein said stroke adjustment means comprises switch means connected when actuated to cause reversal of direction of reciprocation of said reciprocation means, actuator means for said switch means, first means for producing relative reciprocation of said switch and actuator means in opposite directions to cause successive opposite reversal actuations of said switch means, and second means for producing additional relative movement of said switch and actuator means to change the points of actuating engagement thereof longitudinally of their path of relative reciprocation.

7. Apparatus according to claim 6 wherein said first and second means reciprocate said switch means and said actuator means respectively at different speeds.

8. Apparatus according to claim 7 wherein said switch means comprises a pair of spaced switches and said actuator means comprises a contact finger disposed between said switches.

9. Apparatus according to claim 6 wherein said switch means comprises a pair of spaced switches, said actuator means comprises a rotary cam disposed between said switches, and said second means comprises means for rotating said cam to present successively differently spaced portions thereof from its axis of rotation for engagement with said switch means on relative reciprocation of said switch and actuator means by said first means.

10. Apparatus according to claim 5 wherein said reciprocation means comprises a reversible motor con nected to reciprocate said cleaning member and said stroke adjustment means is operable to effect reversals of said motor at a plurality of different time intervals.

11. Apparatus according to claim 10 wherein said reversible motor is a pressure fluid operated motor.

12. Apparatus according to claim 11 wherein said motor has a cylinder and a piston therein, said cylinder and piston being relatively movable and said cylinder being provided with means for admitting and discharging fluid under pressure thereto at opposite sides of said piston, including valve means alternately operable to change fluid admission and discharge to opposite sides of said cylinder to cause reversals of direction of relative movement of said cylinder and piston and reciprocation of said cleaning member, and said stroke adjustment means includes switch means connected and actuated to cause said alternate operations of said valve means at a plurality of different positions of said piston relative to said cylinder.

13. Apparatus according to claim 12 wherein said switch means includes a pair of spaced switches con nected to produce when actuated the respective alternate operations of said valve means, an actuator for said switches disposed between them, and means for reciprocating said switches and actuator at different speeds to cause alternate operating engagement of said actuator and said switches.

14. Apparatus according to claim 13 wherein one of said speeds is the speed of reciprocation of said cleaning member.

15. Apparatus according to claim 1 wherein said cleaning member comprises a spray header and said port means comprises spaced nozzles on said header for directing spray jets onto a surface of said material to be cleaned.

said port means in a surface thereof arranged to engage a surface of the felt.

18. Apparatus according to claim 17 wherein said reciprocation means is capable of reciprocating said cleaning member a distance greater than the spacing between centers of said port means of said shoes.

Claims

2. Apparatus according to claim 1 wherein said reversal control means comprises means mounting said reciprocation means for reciprocation together with said cleaning member in a direction across said path, and means for so reciprocating said reciprocation means and member while they are operating and at a different rate than that of reciprocation Of said member by said reciprocation means.

10. Apparatus according to claim 5 wherein said reciprocation means comprises a reversible motor connected to reciprocate said cleaning member and said stroke adjustment means is operable to effect reversals of said motor at a plurality of different time intervals.

13. Apparatus according to claim 12 wherein said switch means includes a pair of spaced switches connected to produce when actuated the respective alternate operations of said valve means, an actuator for said switches disposed between them, and means for reciprocating said switches and actuator at different speeds to cause alternate operating engagement of said actuator and said switches.

16. Apparatus according to clAim 15 wherein said reciprocation means is capable of reciprocating said cleaning member a distance greater than the spacing between centers of said nozzles.

17. Apparatus according to claim 1 wherein said material to be cleaned is a felt, and said cleaning member is a felt conditioner provided with spaced shoes having said port means in a surface thereof arranged to engage a surface of the felt.