US2244033A - Automatic electric control for compensator for felt tension device for papermaking machines - Google Patents

Description

June 3, 1941. W. J. TREMPE 22%,Q33

AUTOMATIC ELECTRIC CONTROL FOR COMPENSATOR FOR FELT TENSION DEVICE FOR PAPERMAKING MACHINES Filed Dec. 28, 1956 2 Sheets-Sheet l ESE" Inventor 7 main Jili'empe June 3, 1941. w J TREMPE 2,244,033

AUTOMATIC ELECTRIC CONTROL FOR COMPENSATOR FOR FELT TENSION DEVICE FOR PAPERMAKING MACHINES Filed Dec. 28, 1936 2 Sheets-Sheet 2 .95 o M- m;

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Raven-c In mentor Mllg'a'nu J-Zkeznpe -Patented June 3, 1941 AU'IDMATIC ELECTRIC CONTROL FOR COM PENSATOR FOR FELT TENSION DEVICE FOR PAPERMAKING IQIACHIN ES William'J. Trempe, North Billerica, Mm. Application December 28, 1936, Serial No. 117,700 12 Claims. 01. 92-49) This invention relates to improved control means for an automatic compensator for the variations in tension of the traveling felts in papermaking machines, and represents an improved control for apparatus disclosed in my Letters Patent No. 1,826,103, ofoctober 6, 1931. In papermaking machines the tension on the felt varies according to the degree of moisture in the felt. The felt contracts increasingly with the moisture content and slackens as the moisture dries out so that the felts lengthen and loosen over and between the rolls."

By means of my present control, the compensator mechanism maintaining the'felts, either wet or dry, under proper tension, regardless of the moisture content of the felts, tov the end that waste and inferior grades of paper are avoided, is rendered more uniform, positive and accurate. The principal object of my invention is to ensure a positive balanced force' directly effective to maintain the same under desired tension whether the felt shrinks or increases in length on account of the moisture content.

In the prior art structures, including thatof .my prior patent, an increased strain was imposed on the strands of the felts when they were acting as the means to raise the depending (Fig. 'I) in either direction to control reversing switch circuits to the motor, the reversible motor, and not the balanced weight or spring, provides the primary positive actuating forces for positively and directly actuating or operating the compensator roll of the tension control mechanism longitudinallyin either or both directions to restore the desired normal operating tension to the felts by positive movement of the compensator roll in either one direction or the other.

Myapparatus is further simplifiedby the fact weight used to actuate the compensating mocha-j nism to restore proper tension to jthe felts. These strains were further: inorea'sedbyfriction losses in driving through sprockets,,chain and gearing. According to my presentinvention the felt itself is relieved from increased strains resulting fromthe'forces restoring normal tension to-the same. 1

The electric control of my present invention ensures a positive constant maintenance of the desired tension in the felts regardless of the moisture content of the same, and provides the positive force effective in either one direction or the other necessary to actuate the mechanism adjusting the compensator felt roll positively in' either direction to a position to provide such tension. My control acts positively tomove the compensator roll positively in either one direction or the other, both in cases of too great as well as too little tension.

Briefly, although the floatingor sliding roll controlling the electrically effective adjusting means is itself actuated by a weight (see Figures 3 to 5) or yielding, resilient members, (see Figure 6) held in desired balance by the'proper tension in the felts, which forces are eifective to move the floating roller (Figures 1, 3, 4, 5), or

pivoted post (Fig. 6), or pivoted bearing block thait the heavy bulky weights of the --prior art structures which usually depended from the sides of the machine in the way of the operatives, are avoided. The relatively small balanced weight of my present control lies parallel to the frame of the machine under normal conditions and is rapidly restored to such position once it sets the compensating means into operation.

A preferred embodiment of my invention has been shown in the accompanying drawings, in which Fig. l is a top plan view of a section of a papermaking machine equipped with my electrically controlled compensating apparatus.

Fig. 2 is a corresponding side-elevation.

Fig. 3 is a section on the line 3-3 of Fig. l. -Fig. 4 shows the electric connections from the motor to the tension actuated control.

Fig. dis a modified type of my compensator mounted on the hitch roll of, a papermaking machine.

Figs. 6 and 7 are modified forms of. my control, and

Figs. 8 and 9 are diagrams of the electric wiring therefor.

My electrically controlled compensating means is mounted on the papermaking machine at a suitable point in the run of the felt strips. The

, base of the machine on which the compensating apparatus is mounted comprises angle irons I mounted on suitable brackets I on each side of the machine.

My compensating apparatus comprises a pair of rails 4, which are supported by suitable brackets on the bases I, one on each side of the machine. The rails serve as tracks for guiding sheaves 1, 8, preferably having grooves in the peripheries thereof, the details of which are more clearly shown in my prior patent above referred to No. 1,826,103, as shown \by my patent above identified. One sheave is rotatabiy mounted on each end of the shaft In which carries the compensating roller 2 over which the felt strips 3 passes. The sheaves 1,8 are positioned within a cage or block which comprises side members open on top and bottom to permit insertion of the sheaves within the block as shown. in my patent above identified. The sheave I or 8 is rotatable upon a bushing which serves as a bearing surface for the end of the shaft III). For a; clearer and more detail disclosure of the construction and arrangement of parts referred to above, and to be referred to in the following, see my prior patent No. 1,826,103.

The ends of the block connecting the side members are threaded to receive an adjusting, oppositely-threaded bushing I6, and a rod I1 is provided threaded to correspond to the interior of the bushing. The threaded rod I1 is connected at one end to a sprocket chain l8 which chain is guided over two pairs of sprocket gears 20, each pair being rotatably mounted at opposite ends of the tracks 4. As shown, the sprocket gears are carried by shafts 2|, 22, supported at'opposite ends of the track on suitable brackets on the base I. Each end of the sprocket chains I9 are connected to the block housing the sheaves 1, 8 through the threaded rod l1.

As shown, the traveling felt 3 is guided over the rollers 24, the longitudinally movable compensating roller 2, and the roller 25. The looping of the felt over the movable compensating roller 2, which may be moved longitudinally upon the rails 4, enables relative constant tension to be maintained in the traveling felt 3 under various changes in the length of the felt strip due to contraction and expansion resulting from its moisture content.

My novel control for the apparatus described above comprises balanced floating or sliding bearing blocks 40, one on either end of the shaft 22, and mounted between the upwardly projecting portions 4| of the bearing yoke or frame 4|, 42, arranged to permit limited sliding movement of the block 40 longitudinally of the machine, one way or the other, through the spaces Y 43, 44 independent of the position and movement of the compensator roller 2 over which the traveling web or felt passes. A sliding pin 45 is positioned in an aperture 45 through the inner portion 4| and lies in contact with the block M. The pin 45 always contacts and is moved inwardly by the balanced arm 46 which. is provided with a weight 41, and which is maintained in balanced position by the tension in the felt 3 when the same is normal, so that the same lies horizontally longitudinally of the frame as shown in Figs. 1 and 4. In the case of too little moisture in the felt and a corresponding loss of tension on the compensator roll 2 and sprocket chains, the weighted arm 46, which is pivotally mounted on the pin 48 in brackets 49 on the yoke or frame M, 42, drops, forcing the pin 45 inwardly against the block 4!], carrying the same to position so that the contacts 55' carried by the block 40 contact the contacts 55 connected to the yoke 4! to complete a circuit to the reversible electric motor 56 through the electric connections shown diagrammatically in Figs. 3 and 4.

. Rotation either clockwise or counterclockwise of the sprockets 20 on the shaft 22 for obtaining direct, positive and controllable movement, right or left, of the compensator tightening roll 2 either to decrease or increase tension in the web of felt 3 passing over the compensator roll 2, is effected through the reversible electric motor U driving through reduction worms and gear 5! which drive the member 52 which in turn drives the member 53 mounted on the shaft 22, and thus rotates the sprockets. 20.

If the tension in the felt has decreased to an extent to permit the weighted arms 44, 41, through the pin 45, to move the block 40 to the left, the contacts 55 will be closed and the motor circuit will be established for rotation of the motor 50 in a direction which will rotate the shaft 22 in a clockwise direction so the roller 2. around which the felt 3 travels. will be moved to the left.unti1 suflicient tension has been developed in the felt to balance the weighted arm the contacts 85 will be opened to stop the motor 50.

If the converse situation exists in which the felt tension is too great and overcomes the balance of the weighted arm 48, 41, resulting in movement of the bearing block 40 in the opposite direction so as to close the contacts 54, 54', the motor circuit is established to cause rotation of the sprockets 20 in the opposite direction until a balance is again restored and the contacts 54, 54' are opened.

A balance may be established at any particular tension in the web felt by merely sliding the weight 41 on the pivoted arm 46 nearer to or farther from the point of pivotal support for the arm.

Suitable stop switches 56, 51 may be employed to stop the motor and prevent the tightener roll 2 or sheaves i, 8 from traveling beyond certain limits of travel.

In the modified form shown in Fig. 5, the variable tension in the web 3 acts directly on a hitch roll which may be mounted for limited movement to maintain a balance with the weighted arm 66 through a sliding pin or other suitable means acting through a system of links and levers.

The movement of the hitch roll 60, responsive to variation in web tension, may be provided for by employing what may be generally referred to as the movable or floating bearing. such for example as shown in Figs. 1, 3 and 5, or by a modified form illustrated inv Fig. 6. In this the shaft 82 and the bearing block 13 may be of the usual type, but the bearing post l4 carrying the hitch roll 50, shaft 12, and bearing block 13, may be pivotally mounted in any suitable manner to permit limited movement against the pin 65' to effect a balanced relation with the pivoted weighted arm 56.

If desired, suitable means may be provided for yieldingly maintaining the pivoted post 14 in position. As shown in Fig. 6, arms 16 extend outward in opposite directions and springs H, Il may be interposed between said arms 16 and i a fixed support. If desired one of the springs ll may be of suflicient strength to counterbalance any portion of the normal substantially constant web tension so that a lighter weight and more compact system. of levers and arms may be used to effect balance within the range of normal variation of web tension.

As shown in Fig. 6. the bearing post 14 is pivotally mounted on a pin 75 in a bearing bracket '86. In Fig. 6, the pin 65' and the weighted balance arm is not shown, but it is understood that the movably mounted hitch roll, shown in Fig. 6 of the pivoted bearing post type, may be substituted in the arrangement and combination shown in Fig. 5, for the fixed bearing post 6! having the sliding or floating type of bearing block 63 thereon.

In the modified form shown in Fig. 8, the electric contacts or the automatic control means responsive to change in tension 01' the traveling web and effective to restore the normal web tension by controlling the web tension control device to either increase or decrease the web tension, are mounted in operative relation to weighted balance arm 88. As shown in Fig. 5, two pairs of contacts are provided I8 and I8, which are effective to control the direction of rotation of the motor for either tightening or loosening the web tension in orderto restore the required normal balance and web tension. The two pair of contacts are shown mounted on the post support 88, but it is understood that various other specific means of supporting the pairs of contacts in operative relation to the weighted balance arm will occur to the person skilled in the art.

The manner in which the two pair of control contacts ll, I8, are connected in their respective circuits for controlling the direction of rotation of the motor, is shown in Fig. 7, in which the contacts are shown in operative relation to a weighted balance arm 8i, which is supported at the pivotal point 82 on a post 83 which may be, if desired, adjustably supported on the base I in order to vary the point of pivotal support for the weighted balance arm. Such a construction is well adapted to meet a wide range of web,

tensions under varying conditions of operation, use and installation.

The manner of supporting a hitch roll 84, as shown in Fig. 7, typifies a form 01' modification in which the pin such as 45 in Figs, 3 and 4, and pin 65 in Fig. 5, may be dispensed with and still obtain. movement of the roll responsive to varying web tensions, against the weighted balance arm, which movement may also be communicated to the two pair of control contacts 85 and 86. The shaft 81 01 the roll 84 is supported in a bearing 88 of usual type at one end, a bell crank lever 88 being pivotaliy supported on a pin 88 on a post 8| which may be adjustably fixed on the base I. The other end of the bell crank may serve as a weighted balance arm, or if a greater leverage is desired may serve as a link or arm which is balanced against the pivoted weighted arm, 8i through the link 82. Fixed stops may be placed on opposite sides of the arm 88 to limit movement in either direction.

As shown, one contact of each or the pair of contacts 85, 88, is mounted on and movable with and insulated from the bracket 84 which is movable with the hitch roll and its bearing about the point of pivotal support on pin 88. The other contact of each of the pairofcontacts is relatively fixed and-the respective'pairs of contacts are closed upon movement of the hitch roll in one direction or the other responsive to 'an increase or decrease in web tension.

where the direct current magnetic type 01 reversing switches is used for controlling the motor circuit, is shown in Figs. 7; and 8. In Fig. I only the control circuits are shown. In Fig, 8 both the motor circuit and the control circuits are shown.

Referring to Fig. 8, the armature of the motor is designated as A, the shunt field of the motor as F. the two reversing switch coils as IT and DT for increasing tension and decreasing tension, respectively. When the reversing switch D1 is energized, the two pair of contacts I88 and III are closed and the motor circuit is completed and drives the motor 58 in such a direction that the shaft 22 and sprocket 28 (see Figs. 1 and 2) thereon will rotate in a counterclockwise direction, which in turn will move the tension control roller 2 to the right through the action oi. the endless sprocket chains 5, so that the tension of the web 3 guided over the tension roll 2 will be decreased to a point such that the weighted arm 48 (see Figs. 1, 3 and 4) will be restored to a balanced condition and the shaft 22 has moved to the left a sumcient distance to open the pair of contacts 54 (see Figs. 3, 4 and 8) and thus interrupt the circuit for the reversing switch coil DT which in turn interrupts the motor circuit when the two pair of contacts I88 and I ()I (Fig. 8) are opened.

Under the above conditions, the closed motor circuit is traced as follows (Fig. 8) wire I82, contacts I88, -wire I83, armature A, wire I84, contacts I8I, wire I85, wire I86 to Under the above conditions the closed circuit for the reversing switch coil DT is traced as follows (Fig. 8): wire I82, wires I81, I88, start and stop switch contacts I88, wire II8, decreasing tension reversing switch coil DT, wire III, nonreversing switch back contacts II2 on the IT reversing switch, wire H3, limit switch stop contacts 51 (see also Figs. 11, 2, 3, 4, 7 and 8), wire M4, II5, decreasing tension control contacts 54 (see also Figs. 1, 3, 4, and 8; also see correspondcontacts I8 in Figs. 5 and 7), wires H6, H1, H8, M8 to In Fig. 7, two pair of tension control contacts for both increasing tension (contacts 86 and I8) and for decreasing tension (contacts and I8) are provided and are connected in series. One set of contacts is actuated by movement of the hitch roll 84 and another set is controlled and determined by movement of the weighted balance arm. It is not essential that the two pair of contacts be used. There may however be occasions when it may be desirable as a safety factor, or for purposes of stabilizing and rendering less sensitive, to employ the two sets. There may also be occasions when the sensitivity may be increased by connecting the two respective pair of contacts 85, I8 and 86, I8 (Fig. 7) in parallel, rather than in series.

In view of the fact that the motor and control circuits have, been traced in detail under one condition, 1. e. when the web tension is too great so that the contacts 54 are closed due to the movement of shaft 22 (Figs. 1, 3 and 4) to the right because of too great tension in the web 3 traveling over tension control roll 2, it is not deemed necessary to trace the motor and control circuits in detail corresponding to conditions when the webtension has decreased too much and to such an extent as to permit contacts 55 to close and cause rotation of the motor in the opposite direction to increase and restore the web tension to normal balanced condition, as any person skilled in this branch of the electrical art will readily understand the circuit diagram.

The start and stop switch I09 (Figs. 3, 4 and 8) is shown diagrammatically as a pair of contacts (Fig. 8) or as a push button (Figs. 31 and 4) butit is understood that in practice any suitable type of switch may be used. Preferably a standard'snap type of start and stop switch is used employing two buttons, one button for closing the circuit and starting, and a second button for opening the circuit or stopping.

For purposes of repairing or replacing the web 3 traveling over the roll 2, it may be desirable to relieve the tension from the web. This may be very conveniently done by the present method of automatic tension control without the necessity of removing or relieving the large masses of weights which heretofore had to be done in accordance with prior practice with structures of the prior art.

In accordance with the present invention the web tension may be entirely relieved and the tension control roll 2 may be moved to the extreme position to the right (see Figs. 1 and 2) by merely employing a reverse push button 9 which may be connected in shunt with the tension control contacts 54 (Figs. 1, 3, 4,) or contacts (Figs. 5 and 7) which energizes the reversing switch coil DT.for decreasing the tension in the web. The reversing push button H9 should be pressed for a sufficient period to permit the tension roll to move to its limit of travel and until the stop switch 51 is opened, after which the reverse button should be opened and the stop switch promptly pressed in order that the possibility of the tension roller 2 being again returned to its original position because of the closing of the tension control contacts 55, (1B in Figs. 5 and 7) upon release of the web tension. However this latter condition may be obviated by providing a stop or support for holding the weighted arm in its horizontal position midway between the two pair of tension control contacts so that upon release of the web tension for purposes of repair or replacement, the tension control contacts effective for tightening the web tension, will not and can not function.

In order to make it impossible under any circumstances for both reversing switch coils to be energized at the same time, the non-reversing back-contacts H2, H2 are provided in the respective reversing switch coil circuits. Contacts U2 are preferably back contacts which are opened when the reversing switch coil DT is energized to close reversing switch contacts Hill, It. It is impossible by normal operation to complete the circuit for the other reversing switch coil. IT while the reversing switch D1 is in operation and the contacts H2 are open. This electrical arrangement of circuits avoids the necessity of use of what is known in the art as a mechanical non-reverse walking beam.

Fig. 9 shows a conventional circuit arrangement for reversing a motor of the shunt type, where the operation is not automatic and magnetic. The two upper pair of contacts are closed for one direction, and the two lower pair of contacts are closed for the opposite direction.

The invention herein described has been installed and applied to tension control devices in papermaking machines and has proven very satisfactory and successful in practical commercial operation.

In the tension control devices of the prior art where the weights were directly eflective for actuating the tension control mechanism to vary the position of the tensioncontrol roll, when the felt contracted in length due to increase of moisture, the warp threads of the web or felt, served not only as the medium through which the forces were transmitted for balancing the weight, but were subject to the additional motive and driving force to raise the weights and to actuate the mechanism of the tension control device to effect movement of the tension control roll to a position where the tension in the felt web would merely balance the weight.

When the length of the felt was increased, due 7 to drying or decrease of moisture, the weight served as th driving force to effect movement of the tension control roll in the opposite direction to restore normal web tension against the weight. Until normal felt tension was restored there existed a condition in which the warp threads were subjected to decreased tension. The total variation of tension in the warp thread was consequently over a relatively wide range, above and below that to merely balance the weight. The eifect of the greater strains to which the warp threads were subjected, was frequently to unduly stretch the felt to the point where the normal width was decreased, which deformation altered the normal weave structure in the relation between the warp and weft threads, which in turn modified the moisture carrying characteristics of the felt. Such wide variation in web tension was also reflected in shorter life for the felt.

The present invention overcomes the above difficulties of the prior art tension control devices, and reduces the permissible variation of web tension to a determined and controllable minimum.

One of the primary and determining factors in effecting the control of tension within permissible variation of web tension, above required.

normal constant tension, is that the corrective tension control is directly responsive to an increase or decrease in length of the web, due to increase or decrease of moisture content, which variation in web length is reflected in movement of one of the rolls, which in turn controls the motive force intermittently eflfective to restore normal web tension, without imposing any added strains on the warp threads of the felt as a prime motive force in restoring the normal web tension.

In prior art tension control device in commercial use (see for example Trempe Patent No. 1,826,103), the tension control was effected by a suspended weight on a drum constantly acting through the tension control device. In the application of the present invention the tension controlmechanism is ineffective for certain periods and is called into active operation to restore normal tension only after the variation in web tension has been reflected in variation in the increase or decrease of web length to a sufficient extent as to require restoration of normal web tension.

The present invention permits a type of adjustability not obtainable in prior art devices. In accordance with the present invention the normal permissible variation of web tension without requiring the actuation and corrective influence of the tension control may be readily adjusted and varied to suit different papermaking or other machines, or to suit varying conditions on any given machine, by adjusting the extent of normal permissible variation of web length before the tension control device is actively called into corrective operation. Various specific arrangements may be employed all of which have for their purpose means for permitting varying changes inthe length of the web before the contacts are closed for initiating the independent motor control of the tension control device in the desired direction to again restore web tension within the normal permissible range of variation.

A further feature of the present invention is that it' is well adapted to permit what might be termed. a counterbalance system to be employed in which a suitable spring arrangement may be employed for a hitch roll rather than bulky weights, drums, cables, etc. required heretofore for the tension control device. The spring may be of suflicient strength to serve as a force to counter balance any portion of the constant tension normally required in the web. The weight for the balance arm may then serve as the means for determining and controlling the normal range of variation of web tension before the corrective influence of the tension control mechanism is required, or actively called into operation for corrective influence.

While a preferred embodiment and certain modifications embodying the invention, have been shown and described herein, it is understood that various changes and modifications in structure and circuit arrangement may be made by those skilled in the art without departing from the spirit and scope of the invention as defined in the following claims.

What I therefore claim and desire to secure by Letters Patent is:

1. In a papermaking machine, means to maintain relative consta nt tension in the traveling endless felt, including a compensator shaft mounted to permit substantial movement in either direction, a rotatable roller on said shaft over which said felt is guided, positively driven means to automatically vary the position of said compensator shaft by positive drive connections in either direction to maintain substantially constant felt tension without subjecting the traveling felt to abnormal increased tension in restoring the compensator roll to a position to decrease the tension therein within a normal range of permissible tension variation, said automatic means including a floating shaft mounted in such a manner as to secure limited longitudinal movement in either direction on one side of said compensator shaft and operably connected thereto, said-means also including a continuous or endless connecting member passing over said floating shaft and having its ends operatively connected to opposite sides of the compensator shaft to effect positive movement thereof in either direction to restore normal felt tension, eans arranged to exert a longitudinal force against said floating shaft to counterbalance the normal range of variation felt tension, a reversible motor operated means for positively rotating said second named floating shaft in either or opposite direction, and thereby to correspondingly vary the longitudinal position of the compensator shaft by positive movement through a positive connection and driving force in either direction, and means responsive to predetermined limited movement of said floating shaft in either direction for successively starting and stopping said motor in either direction when the web tension exceed the normal permissible variation, whereby to exert a corrective influence on the compensator shaft by positive movement in either direction.

2. Apparatus as defined in claim 1, ,in which the means for starting the motor are operatively connected with s'aid second named floating shaft and are controlled by'the tension in the felt, either greater or less than a normal permissible range of tension variation, said floating shaft being continuously and uninterruptedly subject to the influence of the web tension variation,independent of the motor drive in either direction and during period of initiation and stopping of the motor drive.

,3. Apparatus as defined in claim 1, in which the means for starting the motor comprises a bearing post for said second named floating shaft, a floating longitudinally movable bearing block on said bearing post and having limited longitudinal movement thereon, a circuit 'for said motor adapted to be closed when said floating block is moved in either direction in response to abnormal web tension, and means controlled by-the abnormal variation of tension in the web for sliding said floating block on said bearing post into and out of circuit closing position.

'4. Apparatus as defined in claim 1, in which the means for starting the motor comprises a bearing post for said second namied floating shaft,

a limited longitudinally movable bearing block on said shaft and including an electric contact. a circuit from said motor adapted to be closed when said contact on said block is moved into circuit closing position, and balance weight control means responsive to abnormal increase or decrease of variation of web tension independent of any mechanical motor drive connection for effecting corrective compensatory movement of the compensator shaft for sliding said block in said bearing post into and out of circuit closing position.

5. In a papermaking machine including a traveling felt of variable length due to the varying degrees of moisure to which the felt is subject, and an automatic compensator to maintain relative constant tension in the felt during normal running conditions, including a pair of tracks, a sheave guided on said tracks, a compensator shaft on which said sheave is rotatably mounted, and a roller mounted on said shaft and over which said felt is guided, positive driving means to automatically vary the position of said sheave by positive drive connections in .either direction to maintain substantially constant felt tension, said means comprising a weighted rod sustained in floating balanced position by the tension in the felt within a normal permissible range of tension variation. and mechanism connecting said sheave and weighted rod comprising a floating shaft on one side of said sheave, sprockets and continuous chains connecting said floating shaft to said sheave, the ends of said chains being connected to opposite sides of the sheave to effect direct and positive lengitudinal mbvement of the sheave in either direction, a bearing for said second named floating shaft, a floating bearing block on one end of said second named floating shaft movable longitudinally in said bearing, and means positively connecting said floating block with. said balanced Weight, said weight being adapted to move said floating block a limited extent in either direction as it swings from balanced position in response to abnormal decrease or increase of tension in the felt, and means actuated by predetermined movement of said block to positively rotate said second named floating shaft in either direction and thereby through said sprockets and continuous endless chains to positively move said sheave and compensator shaft longitudinally in either direction to restore the desired tension to said felt.

6. In a papermaking machine including a traveling felt of variable length due to the verying degrees of moisture to which the felt is subpensator shaft by positive actuation in either,

direction on said tracks to maintain substantially constant felt tension, said means comprising a weighted rod sustained in balanced position by the normal range of tension in the felt continuously effective at all times and independent of any rotary positive drive connection for moving said compensator shaft longitudinally in either direction, and mechanism connecting said compensator shaft and weighted rod 'comprising a second floating shaft on one side of said first named compensator shaft, positive drive means including an endless chain connected to opposite sides of said compensator shaft and connecting said floating shaft to said first named compensator shaft to effect positive longitudinal direction through the endless chain connection and positive rotation of said floating shaft in either direction, a bearing for said second named floating shaft, a floating bearing block on one end of said second named shaft movable longitudinally in said bearing in response to variation of the web tension and independent of rotary movement of said floating shaft, and means connecting said floating block with said balanced weight, said weight being adapted to move said block a limited distance in either direction as it swings from balanced position in response to the decrease or increase of tension in the felt, and means actuated by predetermined movement of said floating block to rotate said second named floating shaft and thereby through said connecting means including said endless chain to positively move said longitudinally movable compensator shaft in either direction to restore the tension to said felt within the normally permissible range of variation.

'7. Apparatus as defined in claim 6, and including a reversible motor for positively rotating the second named floating shaft, motor circuit control means actuated by movement of said block, and means positively actuated by the motor for positively rotating said second named for starting said motor in the proper direction to positively move said tension roller in either direction to proper position to restore normal web tension within the permissible normal range of variation.

9. Apparatus as defined in claim 8, said motor starting means including a longitudinally floating bearing and block for said rotatable shaft responsive to variation of web-tensiomcircult motor control means actuated by movement of said floating block, and weight balance control means responsive to increase or decrease of web tension outside of the normal permissible range of variation adapted to move said block to control said circuit motor control means to alternately start and stop the motor inaccordance -movement of said compensator shaft in either with variation of the web tension from normal to abnormal conditions.

10. In a papermaking machine including a traveling felt of variable length due to the varying degrees of moisture to which the felt is subjected and an automatic compensator to maintain relative constant tension in the felt during normal running conditions, including a tension roller over which the felt is guided, a rotatable shaft on one side of said roller, and positive drive connections including an endless chain connected to opposite sides of the tension roller between said shaft and roller adapted on rotation of the shaft in desired direction to effect positive movement of the compensator tension roller longitudinally of the machine in either direction as said tension in the felt increases or decreases, means adapted to rotate said shaft including a reversible motor, operative positive drive connections from said motor to said shaft, a'bearing for said shaft, 2. floating bearing block for said bearing and shaft slidable longitudinally in said bearing, and motor reversing means including an electric circuit from said motor adapted to be closed upon predetermined movement of said bearing block, and means adapted to move said block to circuit closing position, said means comprising a member normally contacting said block and held in weight balanced floating position by and within a normal range of felt tension variation, and operative upon decrease or increase of felt tension beyond a normally permissible range variation to move said block to circuit closing position to start said motor in the desired direction, and to open said motor circuit upon restoration of balanced position corresponding to normal permissible range of felt tension.

11. In a papermaking machine including a traveling felt of variable length due to the varyis subjected and an automatic compensator to maintain relative constant tension in the felt during normal running conditions and within a normal permissible range of tension variation, including a tension roller over which the web is guided, a. rotatable shaft on one side of said roller, and positive drive 'connections including an endless chain connected to opposite sides of the tension roller and operatively connecting said ing degrees of moisture to which the felt is subjected and a compensator to maintain relative constant tension in the felt during normal running conditions within a pre-determined permissible range of variation of web tension, said compensator including a compensator roller and positive drive connections to effect positive longitudinal movement thereof in either direction including endless chains connected to said comasaaoss pensator roller, and automatic means to control said compensator including a reversible motor, positive driving connections from said motor to positively drive said compensator in either direction, means for starting said motor comprising an electric circuit efiective when completed to cause the driving shaft of said motor to rotate in one direction, and a second circuit effective when completed to reverse the motor, and means to po itively move said compensator roller in either direction to restore the proper tension to the felt, and adjustable automatic means including a balance weight responsive to normal permissible variation of web tension without requiring the actuation and corrective influence of the tension control, and also adjustable to be automatically responsive for selectively completing either one of the circuits when the corrective influence of sion control, said means including a plurality of iii the compensator tension control is required in either direction outside of the normal permissible variation of web tension.

12. Apparatus as defined in claim 11, and including means for adjusting the range of normal permissible variation of web tension before the compensator is subject to the positive corrective v and selective influence of the compensator tensprings acting in opposition to the balanced weights to delay the period before the corrective influence of the reversible motor becomes efiective, said springs also functioning to reduce the sensitiveness oi the compensator control to respond to relatively slight and unobjectionable variations of web tension.

WILLIAM J. TREMPE.

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