US2194078A

US2194078A - Hold-down system

Info

Publication number: US2194078A
Application number: US114929A
Authority: US
Inventors: Simonds Paul
Original assignee: Oilgear Co
Current assignee: Oilgear Co
Priority date: 1936-12-09
Filing date: 1936-12-09
Publication date: 1940-03-19
Anticipated expiration: 1957-03-19

Description

Marh 19, 1940.

HOLD-DOWN SYSTEM Filed Dec. 9, 1956 P. SIMONDS 2 Sheets-Sheet 1 INVENTOR. PALIL- SIMEINDS TTORNEY.

March 19, 1940. P. SIMONDS 2,194,078

HOLD-DOWN SYSTEM TTORNEY.

Patented Mar. 19, 1940 PAT NT-O FICE 2,194.01; HOLD-DOWN srs'rm aul Simonds, Mllwaukee wia, assignor to The Oilgear Company, Milwaukee, Win, a corporation of Wisconsin Application December 9, 1936. Serial No. 114,929

9Ciaims- This invention relates to apparatus for hold ing a movable machine part or other object in contact with another object when the movable object is subjected to a variable force, and it is particularly applicable to apparatus for holding the winding roller of a paperrewinding machine against the windingdrum thereof.

Paperis ordinarily wound into rough rolls as it is deliveredby the paper making machine and later unwound from those rolls, trimmed to the desired width or cut into strips and then rewound into finished rolls upon cores which are fitted upon the winding roller .of a rewindin machine and rotated with the winding roller by contact with a constantly rotating winding drum. The paper, when being rew'ound, is led from the rough roll between and over intermediate rollers and between the winding roller and the winding drum. The winding rollerpresses' the paper against the rotating winding drum which causes the winding roller to rotate and wind the paper upon the cores thereon.

The pressure between the winding roller and the winding drum is produced by an external force and by the ,weight of the winding roller and the paper wound thereon. Since the weight of the paper on the winding roller increases continuously during the winding operation, the pressure between the rewinding roller and the winding drumwillincrease unless the external force is varied inversely to the variation in the combined weight of the winding roller and .the

paper wound thereon. I I The present invention has as an object to provide an apparatus which will press a movable object against another object and maintain the total pressure therebetween within narrow limits regardless of variations in an external force which also acts upon the movable object.

0 More specifically, the'primary object of the invention is to provide a rewinding machine with ahold-down system which will maintain a substantially. constantpressure between the winding rollefi'and the winding drum of that machine regardless of the weight of the roll of ,r finished material upon the winding roller.

An' apparatus constructed according to the invention has the advantage of being automatic in operation.

Other objects and advantages will appear from the description hereinafter given of an apparatus in which the invention is embodied.

' Hold-down systems constructed according to the invention are shown schematically in the accompanying drawings in which the views are as follows:

' Fig. 1 is a diagram of the hydraulic circuit of an apparatus in which a single hydraulic motor is employed to move the winding roller of a re- 5 winding machine toward and from the windin drum thereof, the valves being shown in the positions occupied when the apparatus is functioning to maintain a substantially constant pressure between the winding roller and the 10 winding drum. v

Fig. 2 is a diagram of the hydraulic circuit of an apparatus having a hydraulic motor connected to each end of the winding roller of a rewinding machine, the several valves being 15 shown in the positions occupied when the appa ratus is functioning to-maintain a substantially constant pressure between the winding roller and the winding drum.

Fig. 3 is a sectional view showing the control 20 valve in the position occupied when the winding roller is being raised.

Fig. 4 is a sectional view showing the control valve in the position occupied when the windin roller is being lowered. 25

Fig. 5 is a sectional view'showing a bypass valve shifted from the position shown in Fig.

1 into position to bypass the pump.

Fig. 6 is a sectional view showing a bypass valve shifted from the position shown in Fig. 2 30 into position to bypass the pump.

The invention has been shown as being embodied in apparatus for maintaining a substantially constant pressure between the winding drum I and the winding roller 2 of a rewinding 35 machine. Since the rewinding machine forms no part of the present invention, only the winding drum and the winding roller thereof have been shown. It is deemed suflicient to state that drum l is' rotated continuously in stationary bearings 40 when the machine is in operation, that roller 2 is journaled at its ends in bearings 3- and 3 which are movable vertically in stationary guides, and-that roller 2 is rotated by contact with drum i so that paper may be wound thereon. 45

\ FIG. 1

and has a pinion 8 fixed thereon intermediate the ends thereof.

Pinion 8 meshes with a rack 9 which is guided for vertical movement in suitable guides (not shown) and attached at its upper end to a piston rod II] as by means of an arm or bracket II.

Piston rod I0 is fixed to a piston I2 which is fitted in a stationary cylinder I3 and forms therewith a hydraulic motor for reciprocating rack 9. When rack 9 is moved upward by motor I 2|3, it will rotate pinion 8, shaft 6 and pinions 5 and 5 which will raise

racks

4 and 4 and thereby move winding roller 2 away from roll I. When rack 9 is moved downward by motor I 2-I3, it will rotate pinion 8, shaft 6 and pinions 5 and 5 which will lower

racks

4 and 4 and thereby move winding roller 2 toward drum and, if it moves far enough, it will press roller 2 against drum I with a force proportional to the difference between the forces acting upon the upper and lower ends of piston I2.

Liquid for operating motor I2-I3 is supplied by a pump 20 which is adapted to deliver liquid to cylinder I3 at a constant pressure when roller 2 is being urged against drum I. Pump 20 may be a constant delivery pump which discharges its excess delivery of liquid through a relief valve and thereby maintains pump pressure constant, or it may be a constant pressure pump which operates at a predetermined maximum displacement until pump pressure reaches a predetermined maximum and then automatically reduces its displacement until it is delivering just sufficient liquid to maintain that maximum pressure constant. Since both types of pumps are well known and in extensive use, neither a description nor a detailed illustration thereof is deemed necessary.

The lower end of cylinder I3 is open to pump pressure at all times when the apparatus is in operation and it may be connected direct to pump 20 so that, when it is desired to change rolls or make adjustments, piston I2 will stall at the upper end of its stroke and pump 20 will discharge substantially the entire output through the relief valve if it is a constant delivery pump or reduce its displacement substantially to zero if it is a constant pressure pump.

However, in order to avoid wasting power, the apparatus is shown provided with a valve for bypassing pump 20 when the apparatus is not functioning. As shown, a bypass valve 2| is fitted in a valve casing 22 having two annular grooves or ports 23 and 24 formed in the wall of its bore. Port 23 is connected by a channel 25 to the outlet of pump 20 and port 24 is connected by a channel 26 and a channel 21 to the lower end of cylinder I3.

When the valve 2| is in the position shown in Fig. 1, pump 20 may draw liquid from a. reservoir 28 and deliver it through channel 25. valve casing 22 and

channels

26 and 21 to the lower end of cylinder I3. When valve 2| is shifted to the position shown in Fig. 5, port 24 is blocked so that piston I2 cannot move downward under the influence of gravity and port 23 is open to a drain channel 29 which is connected to both ends of valve casing 22 and discharges into reservoir 28 so that pump 20 may discharge its entire output through channel 25, valve casing 22 and channel 29 into reservoir 28.

The operation of motor I2|3 is controlled by a control valve 3| which is fitted in the bore 32 of a valve casing 33. Bore 32 has both of its ends connected to drain channel 29 and it is provided intermediate its ends with three annular grooves or

ports

34, 35 and 36 which are controlled by valve 3|.

Port 34 has channel 26 connected thereto. Port 35 is connected by a channel 31 to the upper end of cylinder I3. Port 36 is connected by a channel 38 to the inlet of an orifice choke 39 which has its outlet connected by a. channel 40 to the inlet of a resistance valve 4|. Channel 40 is connected intermediate its ends by a channel 42 to channel 31 intermediate the ends thereof so that liquid may escape from the upper end of cylinder I3 through

channels

31, 42 and 40 and resistance valve 4| into drain channel 29 which is connected to the outlet of resistance valve 4|.

Resistance valve 4| is so constructed that it may be manually adjusted to have a relatively high resistance to the flow of liquid therethrough when piston I2 is at or near the lower end of its stroke and to have its resistance progressively decreased as piston I2 moves upward. The resistance of valve 4| may be progressively reduced by means of a cam 45 which is slidable vertically in suitable guides and is caused to move vertically with piston I2 as by having a threaded rod 46 arranged upon its lower end and fastened to bracket II by two or more nuts 41.

For the purpose of illustration, resistance valve 4| has been shown as having a valve member 48 arranged in its casing and urged against the inlet thereof by a spring 49 which reacts against an adjusting member consisting primarily of a stem 59, which is slidable through the rear end of the valve casing and engages spring 49; and an adjusting nut 5| which is threaded upon the outer end of stem 50 and provided with a roller contact 52 to engage the face of cam 45.

Operation When the control valve 3| is shifted to the position shown in Fig. 3, port 35 is opened to one end of bore 32 so that liquid from pump 20 may flow through channel 25, bypass valve casing 22 and

channels

26 and 21 to the lower end of cylinder I 3 and raise piston I2, thereby raising winding roller 2. Piston I2 will eject liquid from the upper part of cylinder I3 through channel 31, bore 32 and channel 29 into reservoir 28.

Roller 2 may be moved downward by shifting control valve 3| to the position shown in Fig. 4. In this position of valve 3|, port 36 is blocked and port 35 is open to port 34 so that liquid from pump 20 may flow through channel 31 to the upper end of cylinder I3. Both ends of cylinder I3 are open to pump pressure at this time but the upper faceof piston I2 has a greater effective pressure area than the lower face thereof so that the downward force exerted by the liquid upon piston I2 will be greater than the upward force exerted by the liquid upon the lower face of piston 2. Consequently, piston I2 will be forced downward and expel liquid from the lower end of cylinder I3 through

channels

21 and 26, valve casing 33 and channel 31 to the 'upper end of cylinder I3 so that piston I2 and roller 2 are moved downward at high speed. If roller 2 engages drum I before valve 3| is shifted, resistance valve 4| will open and pump 20 will discharge therethrough into drain channel 29.

Just before roller 2 engages drum I, the control valve 3| may be shifted to the position shown in Fig. 1 in which position port 35 is blocked, so that liquid cannot flow direct to the upper end of cylinder I3, and port 36 is open to port 34 so that liquid may flow through choke 39 at a. limited rate to move piston l2 slowly downward if valve 3| is shifted before roller 2 contacts drum I and to maintain pressure in the upper end of cylinder l3 after roller 2 contacts drum I.

5 The resistance of choke 39 to the flow of liquid therethrough is suflicient to permit pump 20 to develop its maximum pressure when it is delivering liquid through choke 33. I Consequently, when valve 3| is in the position shown in Fig. 1, the

i relatively small lower face of piston i2 is subjected to the full pump pressure while the relatively large upper face of piston I2 is subjected to a pressure equal to the pressure required to open resistance valve ll which is so adjusted that 16 the diflerence between the downward force exerted by the liquid upon the upper face of piston l2 and the upward force exerted by the liquid upon the lower face of piston I2 is equal to the force required to be exerted upon roller 2 to produce 20 the desired pressure between roller 2 and drum I.

The apparatus is initially so adjusted that,

when roller 2 is in contact with drum I and before any paper is wound thereon, contact roller 52 is in engagement with a wide part of cam 45 u and the resistance of valve ii is such that the pressure in the upper end of cylinder l3 will be just sumcient to urge piston l2 downward with the correct force to produce the desired pressure between roller 2 and drum I. 30 Then as paper is wound upon roller 2, it will gradually raise roller 2 and thereby raise piston l2 which will expel liquid from the upper end of cylinder l3 through channels 31 and 42 and resistance valve ll into drain channel 23. I 35 The paper being wound upon roller 2 adds to the weight thereof but cam 45 moves upward with piston l2 and gradually decreases the resistance of valve 4| and thereby decreases the downward force at substantially the same rate that weight is being added to roller 2 so that the pressure between roller 2 and drum l remains nearly constant.

Roller 2 will continue to move upward and cam 45 will continue to decrease the resistance 45 of valve 4| during continued winding of paper upon roller 2 until the combined weight of roller 2 and the paper thereon is suiiicient to produce the desired pressure between roller 2 and drum I at which time the resistance to valve II has been so reduced that the pressure acting upon the upper face of piston I2 is just sumcient to counterbalance the high pressure acting upon the lower face of piston l2. Consequently, piston I2 is not transmitting any force to roller 2 at this time.

If the roll of paper on roller 2 continues to increase in diameter, it will continue to move roller 2 upward and to add to the weight thereof. However, cam 45 continues to move upward and progressively decrease the resistance of valve 4| so that the downward force acting upon piston I 2 is gradually reduced and the upward forceacting thereon will cause piston l2 to support an increasing part of the combined weight of roller 2 and the paper thereon, thereby maintaining the pressure between drum l and the paper on roller 2 nearly constant.

The weight of the roll of paper wound upon roller 2 will increase proportionally to the square of the increasing roll diameter, but .the weight of roller 2 and the cores thereon will remain constant. In order to maintain the pressure between drum I and the roller 2 withi narrow limits, resistance valve 4i may be ad usted by turning nut 5| to counterbalaance. the weight of roller 2 and the cores thereon, and cam 45 may be adjusted vertically by means of rod 48 and nuts 41 to regulate the net force exerted upon roller 2 by motor l2-I3. Cam 45 is so designed as to reduce the downward force on the roll more rapidly as the diameter of the roll increases in order that the total downward force may be held nearly constant.

Frc. 2

, of the apparatus shown in Fig. 2 which are like the corresponding parts of the apparatus shown in Fig. 1 have been indicated by corresponding reference numerals with the exponent b or the exponent "0 added thereto.

As shown,

bearings

3 and 3* are connected, as by means of brackets H and l l, to the rods Ill and "F of pistons l2 and l2 which are fitted in cylinders I3 and l3, respectively, and form therewith hydraulic motors for moving roller 2 vertically and for pressing it against drum I.

For the purpose of illustration, the apparatus is shown provided with two constant pressure pumps 20'' and 20 for supplying liquid to cylinders l3 and l3 under the control of a bypass valve 60 but both cylinders may be supplied from the same pump and bypass valve 60 may be omitted and, when the motor pistons stall at the end of a stroke, the pump,or pumps caused to discharge through a relief valve or valves if of the constant delivery type or to reduce pump displacement nearly to zero if of the constant pressure type as previously explained. The two pumps are of the same'capacity and are driven in unison so that they will deliver liquid at the same rate when operating the motors at rapid traverse speeds.

Bypass valve 60 is fitted in a casing 6| having six annular grooves or

ports

62, 63, 64, 65, 66 and 61 formed in the wall of its bore.

Ports

62 and 65 and both ends of casing 8| are connected to a drain channel23 which discharges into a reservoir 28 from which the pumps draw their supply of liquid.

Port 63 is connected by a channel 25 to the outlet of pump 20''. Port v6| is connected by a channel 26 to a port 34 formed in the casing 33" of a control valve 3| which controls the operation of motor l2 -l 3". Port 66 is connected by a channel 25 to pump 20. Port 61 is connected by a channel 26 to a port 34 formed in the casing 33. of the control valve 3| which controls the operation of motor l2-l3.

When valve 60 is in the position shown in Fig. 2, port 63 is open to port so that pump 20*- may draw liquid from reservoir 28 and deliver it through valve casing 6| into channel 26, port 86 is open to port 61 so that pump 20 may draw liquid from reservoir 28 and deliver it through valve casing Bl into channel 26, and

ports

62 and 65 are blocked.

When valve 60 is shifted to the position shown in Fig. 6, port 63 is open to port 62 and port 66 is open to port 65 so that both pumps may discharge through valve caslng 6! into drain channel 29 and ports 64 and 61 are blocked so that liquid cannot escape from cylinders Iii and l3.

Control valve 3| and its casing 33 are exactly the same as the control valve and easing shown in Fig. 1. Control valve 3l and its casing 33 are exactly the same as the control valve and casing shown in Fig. 1 except that the valve has its stem extended through the opposite end of the casing so that the stems of both valves may be connected to a single control lever 10 which may be operated to eifect simultaneous operation of the motors.

The lower ends of the motor cylinders are open at all times to pump pressure when bypass valve 60 is in the position shown in Fig. 2. In order to reduce to a minimum the number of channel crossings shown in the drawing,

channels

21 and 27 have been shown as connecting the lower ends of cylinders I3 and l3, respectively, to ports 34' and 34, it being noted that channels 2'! and 21 are open, respectively, to

channels

26 and 26 even when annular grooves or

ports

34 and 34 are covered by the pistons on valves 3| b and 3l, respectively.

The upper ends of cylinders l3 and i3 are connected, respectively, by

channels

37 and 31 to ports 35 and 35 formed in

control valve casing

33 and 33 respectively.

Channels

31 and 31 are connected, respectively, by channels 42 and 42 to

channels

40 and 40 intermediate the ends thereof. Channels 40* and 40 are connected, respectively, to the inlet of resistance valves 4| and 4| which have the outlets thereof connected to drain

channels

29 and 29 respectively.

Channels

40 and 40 are also connected, respectively, through orifice chokes 39 and 39 and channels 38 and 38 to ports 36* and 36 formed in

control valve casing

33 and 33 respectively.

Resistance valves 4! and 4l have adjusting nuts 5i and 5| threaded, respectively, upon the stems thereof and provided with

roller contacts

52 and 52 to engage the faces of

cams

45 and 45 which are moved vertically with roller 2 as by being adjustably attached to brackets II and I respectively.

When lever 70 is moved upward from its central position, control valves 3| and 3I will be shifted to the position shown in Fig. 3 so that the upper ends of the motor cylinders are open to the drain. Since the lower ends of the motor cylinders are open to pumppressure, the pump will deliver liquid thereto and cause the motors to raise roller 2.

When lever 10 is moved downward from its central position, valves 3| b and 3l will be shifted to the position shown in Fig. 4 and both ends of each motor cylinder will be open to pump pressure so that the liquid from the pumps acting upon the differential areas of the motor pistons will force the pistons downward and thereby lower roller 2.

When lever 10 is in the position shown in Fig. 2, ports 35 and 35 are blocked and

ports

36 and 36 are open to pump pressure. Consequently, pressure will extend through

chokes

33 and 39 to the upper ends of cylinders 13* and l3 and liquid may escape therefrom through resistance valves 4| and 4I so that the apparatus will function in exactly the same manner that the apparatus shown in Fig. 1 functions.

The invention herein set forth is susceptible of various modifications and adaptations without departing from the scope thereof as hereafter claimed.

The invention is hereby claimed as follows:

1. The combination, with an object restrained from movement ina given direction and a second object movable in said direction toward and from said first object and subjected to a variable force tending to move 'it in said direction, of a fluid motor for exerting another force in said direction upon said second object, a source of motive fluid having a pressure above a predetermined value, fluid channels connecting said motor to said source, means for regulating the pressure of the fluid delivered to said motor to regulate the force exerted by said motor upon said second object whereby the resultant of said forces urges said second object against said first object and creates pressure therebetween, and means for adjusting said pressure regulating means to compensate for variations in said variable force and thereby maintain the pressure between said objects nearly constant.

2. The combination, with an object restrained from movement in a given direction and a second object movable in said direction toward and from said first object and subjected to a variable force tending to move it in said direction, of a fluid motor connected to said second object for moving it in said direction, a source of motive fluid having a pressure above a predetermined value, valve means for controlling the delivery of fluid to said motor to cause it to move said second object in said direction toward and from said first object, fluid channels connecting said motor to said source, means for regulating the pressure of the fluid delivered to said motor to regulate the force exerted by said motor upon said second object whereby the resultant of said forces urges said second object against said first object and creates pressure therebetween, and means for adjusting said pressure regulating means to compensate for variations in said variable force and thereby maintain the pressure between said objects nearly constant.

3. In a winding machine having a driving roller rotatable upon a stationary axis and a Winding roller supported at least in part by said driving roller to be rotated thereby and adapted to have sheet material wound thereon whereby the weight of said winding roller and the material thereon creates pressure between said rollers and the accumulation of material upon said winding roller causes said winding roller to move away from said driving roller, the combination of a hydraulic motor connected to said winding roller, control means operable to cause said motor to exert a force upon said winding roller, means for initially adjusting said control means to cause said motor to exert a positive force sufficient to create a predetermined pressure between said rollers at the beginning of a winding operation, and means responsive to movement of said winding roller away from said driving roller for adjusting said control means to cause said motor to progressively reduce said positive force to zero and to then exert a progressively increasing negative force upon said winding roller to thereby maintain the pressure between said rollers nearly constant.

4-. In a winding machine having a driving roller rotatable upon a stationary axis and a winding roller supported at least in part by said driving roller to be rotated thereby and adapted to have sheet material wound thereon whereby the weight of said winding roller and the material thereon creates pressure between said rollers and the accumulation of material upon said winding roller causes said winding roller to move away from said driving roller, the combination of a hydraulic motor connected to said winding roller, control means operable to cause said motor to exert a force upon said winding roller, means for initially adjusting said control means to cause said motor to exert a positive force sumcient to create a predetermined pressure between said rollers at the beginning of a winding operation, means responsive to movement of said winding roller away from said driving roller for adjusting said control means to cause said motor to progressively reduce said positive force to zero and to then exert 'a progressively increasing negative force upon said winding roller to thereby maintain the pressure between said rollers nearly constant, and other control means operable to cause said motor to move said winding roller a substantial distance toward and from said driving roller at high speed.

5. In a winding machine having a driving roller and a winding roller urged by gravity against said driving roller and adapted to have material wound thereon by frictional contact with said driving roller whereby accumulation of material upon said winding roller causes said winding roller to move away from said driving roller, the

combination of a reciprocating hydraulic motor for exerting a force upon said winding roller to urge it toward said driving roller whereby said force together with the weight of said winding .roller and the weight of the material thereon will create pressure between said rollers, means for supplying motive liquid to one end of said motor to cause said motor to press'said winding roller against said driving roller, means for limiting the fluid pressure in said end of said motor to thereby limit the pressure between said rollers, and means responsive to movement of said winding roller away from said driving roller for adjusting said pressure limiting means to progressively reduce the fluid pressure in said end of said motor as the roll of material upon said winding roller increases in weight to thereby maintain the pressure between said rollers nearly constant.

6. In a winding machine having a driving roller and a winding roller urged by gravity against said driving roller and adapted to have material wound thereon by frictional contact with said driving roller whereby accumulation of material upon said winding roller causes said winding roller to move away from said driving roller, the

. ers, means responsive to movement of said winding roller away from said driving roller for adjusting said pressure limiting means to progressively reduce the fluid pressure in said end of said motor as the roll of material upon said winding roller increases in weight to thereby maintain the pressure between said rollers nearly constant, and means including a valve for directing motive liquid to and from said motor independently 01' said fluid presure limiting means to cause said motor to raise and lower said winding roller at relatively high speeds.

7. In a winding machine having a driving roller and a winding roller urged by gravity against said driving roller and adapted to have material wound thereon by frictional contact with said driving roller whereby accumulation of material upon said winding roller causes said winding roller to move away from said'driving roller, the

I combination of a difierential hydraulic motor for exerting a force upon said winding roller to urge 5 it toward said driving roller whereby said force together with the weight of said winding roller and the weight of the material thereon will create pressure between said rollers, a pump for supplying liquid at a pressure above a predetermined value, means for directing liquid from said pump to the small capacity end of said motor at pump pressure, means for directing liquid from said pump to the large capacity end of said motor including means for limiting the fluid pressure in the large capacity end of said motor, and means responsive to movement of said winding roller, away from said driving roller for adjusting said pressure limiting means to progressively reduce the fluid pressure in the large capacity end of said motor as the roll of material upon said winding roller increases in diameter and weight to thereby maintain the pressure between said rollers nearly constant.

8. In a winding machine having a driving roller and a winding roller urged by gravity against said driving roller and adapted to have material wound thereon by frictional contact with said driving roller whereby accumulation of material upon said winding roller causes said winding roller to move away from said driving roller, the combination of a differential hydraulic motor for exerting a force upon said winding roller to urge it toward said driving roller whereby said force together with the weight of said winding roller and the weight of thematerial thereon will create pressure) between said rollers, a pump for supplying liquid to said motor at a pressure above a predetermined value and connected direct to the small capacity end of said motor, an orifice choke connected in series between said pump and the large capacity end of said motor, an adjustable resistance valve connected in series between the large capacity end of said motor and a drain, a cam movable by said motor in unison with said winding roller for varying the resistance of said resistance valve as said winding roller moves away from said driving roller, and a valve connected between said pump and the large capacity end of said motor and operable to connect the large capacity end 01. said motor to a drain to enable the liquid delivered to the small capacity end of said motor to cause said motor to raise said winding roller, or to connect said pump direct to the large capacity end of said motor to cause said motor to lower said winding roller, or to connect said pump to the large capacity end of said motor through said choke whereby the pressure in the large capacity end of said motor will be equal to the resistance of said resistance valve.

9. In a winding machine having a driving roller and. a winding roller urged by gravity against said driving roller and adapted to have material wound thereon by frictional contact with said driving roller whereby accumulation of material upon said winding roller causes said winding roller to move away from said driving roller, the combination of a diflerential hydraulic motor for exerting a force upon saidwinding roller to urge it toward said driving roller whereby said force together with the weight of said winding roller and the weight of the material thereon will create pressure between said rollers, a pump for supplying liquid to said motor at a pressure above 7 a predetermined value and connected direct to the small capacity end of said motor, an orifice choke connected in series between said pump and the large capacity end of said motor, an adjustable resistance valve connncted in series between the large capacity end of said motor and a. drain,

and a cam movable by said motor in unison with said winding roller for varying the resistance of said resistance valve as said winding roller moves away from said driving roller.

PAUL SIMONDS.