US2145305A

US2145305A - Fuel regulator

Info

Publication number: US2145305A
Application number: US94205A
Authority: US
Inventors: John B Hull
Original assignee: WESTINGHOUSE PACIFIC COAST BRA
Current assignee: WESTINGHOUSE PACIFIC COAST BRA; WESTINGHOUSE PACIFIC COAST BRAKE Co
Priority date: 1936-08-04
Filing date: 1936-08-04
Publication date: 1939-01-31
Anticipated expiration: 1956-01-31

Description

m. m, 1939. B, HULL 2,1453% FUEL REGULATOR Filed Aug. .4, 1936 2 Sheets-Sheet 1 INVENTOR JOHN B.HULL.

ATTORNEY.

J. B. HULL FUEL REGULATOR Filed Aug. 4, 1.936 2 Sheets-Sheet 2 Fig. 2

JOHN B. HULL.

ATTORNEY.

Patented Jan. 31, 1939 UNITED STATES ATENT OFFICE FUEL REGULATOR John B. Hull, Berkeley, Calif, assignor to Westinghouse Pacific Coast Brake Company, Emeryville, Calif., a corporation of California This invention relates to control apparatus and more particularly to apparatus adapted to be employed to control the supply of fuel to a furnace.

In many furnaces there are provided means responsive to the pressure of the steam in a boiler heated by the furnace for regulating the supply of fuel, such as oil or gas, to the furnace, and for also regulating the position of the draft and damper so as to vary the supply of air to the furnace.

It is desirable that the supply of air be at all times adequate to effect substantially complete combustion of the fuel, but that it does not greatly exceed this amount. It is essential, therefore, that the supply of air and the supply of fuel be simultaneously varied.

In the control systems heretofore provided, the relationship of the position of the fuel supply valve and of the draft and damper have been controlled by adjusting of the length and angles of the levers employed in the control apparatus. However, because of the individual characteristics of different furnaces and stacks, this arrangement did not secure most efficient control of the furnace, and it has been found that if the apparatus were arranged to properly proportion the supply of air and fuel to the furnace at one point in the range of movement of the control apparatus, the control apparatus would not properly proportion the supply of air and fuel to the furnace at other points in the range of movement of the apparatus.

It is the principal object of this invention to provide control apparatus of the type described and incorporating adjustable means by which the relationship between the extent of the opening of the fuel supply valve, and of the draft or damper, may be adjustably varied relative to each other to adapt the control apparatus to the conditions present in the furnace with which the control apparatus is employed.

A further object of the invention is to provide control apparatus of the type described having means for independently varying the relative settings of the fuel supply valve, and of the draft and damper, at a plurality of points throughout the range of movement of the control apparatus.

A further object of the invention is to provide an improved control apparatus for varying the supply of fuel to a furnace in response to variations in the pressure of the steam in a boiler heated by the furnace, and incorporating means by which the setting of the fuel supply valve may be adjustably varied in different positions of the control apparatus independently of the setting of the fuel supply valve in other pos1- tions of the control apparatus.

Another object of the invention is to provide a control member having a cam surface thereon, the shape of which may be adjustably varied.

A further object of the invention is to provide an improved control member having a cam surface thereon and incorporating means by which the contour of portions of the cam surface may be adjustably varied independently of the other portions thereof.

Another object of the invention is to provide an improved furnace control apparatus.

Other objects of the invention and features of novelty will be apparent from the following description taken in connection with the accompanying drawings, in which,

Fig. 1 is a diagrammatic view of a furnace equipped with control apparatus provided by this invention,

Fig. 2 is a sectional view of a control device employed in the control apparatus shown in Fig. 1,

Fig, 3 is a view, largely in section, of the valve device employed in the control apparatus shown in Fig. 1 to control the supply of fuel to the furnace, and

Fig. 4 is a fragmentary sectional view taken substantially along the line 4-4 of Fig. 3.

Referring to the drawings, there is illustrated in Fig. 1 thereof a furnace l, which may be of any well known construction. The furnace i has a burner, not shown, which is supplied with fuel through a pipe 2, while the flow of fuel through this pipe is controlled by a valve device indicated generally by the reference numeral 4.

The furnace I has a draft door 6 controlling the supply of air to the furnace, while a damper 8 is positioned in the smoke pipe it leading from the furnace.

A control device, indicated generally by the reference numeral I2 is provided for controlling the draft door 6, the damper 8 and the fuel supply valve device 4. The details of the construction of the control device l2 form no part of the present invention, but I prefer to employ a control device of the type shown and claimed in the application of James W. Harrie, Serial No. 100,311 filed September 11, 1936.

The construction of the control device 52 is best shown in Fig. 2 of the drawings, and, as shown, comprises a movable abutment in the form of a diaphragm l4, which is clamped between confronting flanges on a cover I6 and a body I8, which is supported from the furnace I by means of a bracket I3. The diaphragm i4 is subject on one side to the pressure of the fluid in a chamber 20, which is connected by way of a pipe 22 with the boiler, not shown, of the furnace I. The diaphragm I4 is subject on the other side to a spring 24, which extends between a follower plate 25 and a spring seat 26, which rests upon an adjustable bushing 28.

The diaphragm [4 has secured thereto a stem 30 which engages a face of a lever 32, which has one end thereof pivotally supported on the body I3. The other face of the lever 32 is engaged by the stem 34 of a pilot valve device, indicated generally by the reference numeral 36, for controlling the supply and release of fluid under pressure to and from a chamber 38 on the face of a piston 40, which is reciprocable in a bore in a cylinder 42.

The piston 40 has secured thereto a piston rod 44 which extends through an opening in a cover plate 46, the opening being sealed' by means of packing 48, which is held in place by a packnut 50.

The pilot valve device 36 comprises a ball valve 52, which is mounted in a chamber 54, which is constantly connected by way of the passage and pipe 56 with a source, not shown, of fluid under pressure, such as water under pressure. The ball valve 52 is urged by a spring 58 into engagement with a seat so as to out off the flow of fluid from the chamber 54- to a chamber 60, which communicates by way of a passage 62 with the chamber 38 at the face of the piston 40.

The stem 34 extends through a chamber 84, which is constantly connected to a drain by means of the passage and pipe 66, which also communicates with'the chamber 68 at the upper face of the piston 40. Suitable packing 10 surrounds the stem 34 and is held in place by means of a gland 12, and a packing nut 14, so as to prevent the escape of fluid from the chamber 64 to the atmosphere, while packing 16 surrounds the stem 34 and is held in place by the gland 18 to prevent the flow of fluid from the chamber 60 to the chamber 64. A spring 80 extends between the gland 18 and a spring seat 82 carried by the stem 34 and yieldingly presses the stem 34 against the lever 32.

The stem 34 has a passage 84 formed therein and communicating with the chamber 64, and with a port in the end of the stem which is surrounded by a seat adapted to be engaged by the ball valve element 52.

The control device I2 has associated therewith a bell crank 86, which is pivotally supported on a pin 88. One arm of the bell crank 86 is engaged by a spring seat 90, while a compression spring 92 extends between this spring seat and a seat 94, which engages an adjusting screw 96 carried by the end of the arm 32, and which is held in the adjusted position by a lock nut 08.

The other arm of the bell crank 86 carries a roller I00, while a portion of the body of the control device has mounted thereon adjacent the roller I00, a roller 502. A wedge I04 carried by an arm I05, which is secured to the piston rod 44, extends between the rollers I00 and I82.

The end of the piston rod carries a yoke I08, which is connected by means of a chain I08 with a lever I 10, which is pivotally supported intermediate its ends on a pin H2 carried by a bracket II4 mounted on the furnace I. The lever II 0 has secured thereon adjacent the end thereof a weight H5, which yieldingly urges the lever in a counterclockwise direction, as viewed in the drawings. The lever H8 has secured thereto adjacent the other end thereof a chain H6, which is also connected to the end of the lever H8 for operating the damper 8.

The lever II8 has a weight I20 mounted thereon, which yieldingly urges the lever H8 in a clockwise direction, so as to move the damper 8 to the full open position.

The lever I I8 also has secured thereto a chain I22, which is connected to an arm I24 associated with the draft door 6. The draft door 6 is yieldingly urged to the closed position by gravity. In addition the lever H0 has connected thereto at a point on the side of the pin IIZ adjacent the chain I08, a link I26 which is connected to an arm I28 of the fuel supply valve device 4.

The construction of the valve device 4 is shown in detail in Figs. 3 and 4 of the drawings, and, as illustrated, comprises a hollow body I30 having flanges I 3| and I32 formed integral therewith to which are attached the pipes leading from the source of fuel and to the furnace. The body I30 has a wall I 34 extending across the passage therein, and this wall has an opening therein, into which extends a sleeve I36 formed integral with a head I31, which is secured to a flange I38 on the body I30 and closes an opening in the external wall of the body I30. The sleeve I36 has a flange I39 formed thereon, and a gasket I40 is clamped between this flange and the wall I34 to prevent unintended flow of fuel from one side of the wall to the other.

The sleeve I36 has a bore therein in which is mounted a piston valve I42 having packing rings I43 fitted thereon. The piston valve I42 controls the flow of fuel from the chamber I44 on one side of the wall I34, to the chamber I45 on the other side thereof through ports M6 in the sleeve I36.

As shown in the drawings, the piston valve I42 is a cup-shaped body having a tubular skirt portion and having a head having a rod I48 formed integral therewith. A passage I50 extends through the head of the piston valve and communicates with the chambers on the opposite sides of the head.

The piston rod I48 extends through an opening in the head I31, and this opening is sealed by means of packing I60, which is held in place by a packing nut i 62. A spring I64 extends between the piston valve I42 and the wall of the body I38, and yieldingly urges the piston valve to the upper end of its range of movement so as to fully open the ports I46.

The head I31 has spaced parallel arms I66 formed integral therewith and arranged on opposite sides of the piston rod I48. The upper ends of the arms !66 have pivotally supported thereon a rod I68, and the lever I28 is rigidly secured on the end of the rod I68. The rod I68, in addition, has secured thereto at a point substantially mid-way between the arms I66, a curved member I10.

The piston rod I48 has secured to the upper end thereof a forked member I12 having arms extending along opposite sides of the curved member I10, and these arms have slots I14 formed therein through which extend the rod I68. A shaft 118 is carried by the upper end of the forked member I12, and has a roller I18 mounted thereon intermediate the arms of the forked member I12. The ends of the rod I16 extend through, and are guided by, parallel slots I19 formed in the upper ends of the arms I66, while the rod l'lB has secured thereon washers I893, which engage the outer faces of the arms IE6 to prevent displacement of the rod H5.

As is best shown in Fig. 3 of the drawings, the member Ill) is curved, and the radius of curvature of this member gradually increases away from the rod N58. The curve member l's'fi has a plurality of threaded holes therein in which are mounted threaded tappets Hi2, which are held in the adjusted positions by lock nuts I84. The tappets E82 extend through the curved member l'lil so that the inner ends thereof may be engaged by the roller H8. The inner ends of the tappets 582 are arranged in substantially the same plane, and are positioned adjacent each other, being spaced apart a distance substantially less than the radius of the roller H8.

The roller l'i'S is normally held in engagement with the inner ends of the tappets I82 on the curved member i H! by force exerted by the spring H3 3 through the piston valve M2, the piston rod Hi8, and the forked member H2 carried thereby.

When the lever 28 and the curved member l!!! are turned in a counterclockwise direction, as viewed in Fig. 3 of the drawings, the tappets I82 carried by the curved member H ll move across the roller Eli; and force the roller downwardly, as the ends of the tappets in the portion of the curved member i'lt adjacent the rod H58 are less distant from the axis of the rod 568 about which the curved member H9 is turned, than are the tappets adjacent the free end of the curved member llll.

On downward movement of the roller H8, the forked member H2 and the piston rod 38 are moved downwardly, thereby moving the piston valve M2 downwardly against the spring 584 so as to decrease the size of the openings through the ports H36, and thereby decrease the rate of flow of fuel through these ports to the furnace 1.

Likewise when the lever H8 and the curved member llii are turned in a clockwise direction, as viewed in Fig. 3 of the drawings, the tappets l 82 move across the roller l 178, and, as the tappets in the free end of the curved member Ht are more distant from the axis of the rod 568, about which the member Eli! is moved, than are the tappets in the other portion of the member HG, the roller H8 will be moved upwardly by force exerted by the spring N54, with the result that the piston valve M2 will be moved upwardly to increase the size of the openings permitted through the ports M6, and thereby increase the rate of supply of fuel to the burner of the furnace I.

As will be understood the relative size of the openings through the ports llfi permitted by the piston valve 5 2 in any position of the lever I28, and of the curved member I'm, throughout their range of movement, may be adiustably varied by adjusting the position of the tappet or tappets Hi2 carried by the curved member ll't, which are engaged by the roller HS in this position of the lever H8 and the curved member H0.

The curved member Hi3 is of such shape, and the other portions of the control apparatus are so arranged that the size of the openings through the ports M5 permitted by the piston valve M2 is substantially that required to produce eihcient operation of the furnace. The adjustable tappets 82 provide means to vary the size of the openings through the ports i 35 of the fuel supply valve device 3 at a plurality of points in the range of movement of the control apparatus. The extent of adjustment permitted by the tappets I82, while limited, is sufiicient to permit the valve device 4 to be adjusted to produce the maximum degree of efficiency of operation of the furnace at the different points throughout the range of movement of the control apparatus.

The roller H8, being of substantially larger radius than the distance between adjacent tappets #32, is able to freely move across the ends of the tappets even though there are slight inequalities in the position of the faces of these tappets.

The control apparatus is shown in Fig. 1 of the drawings in the position to condition the fuel supply valve device 4 to supply fuel to the burner of the furnace l at a rate approximately intermediate the maximum and minimum rates at which fuel may be supplied thereto, and to maintain the draft door t and damper 8 partially open.

At this time, assuming that the pressure of the steam in the boiler heated by this furnace is substantially at the pressure which the control apparatus is adjusted to maintain, the various parts of the control device l2 will be substantially in the position in which they are shown in Fig. 2 of the drawings. control device i2, fluid under pressure is present in the chamber 38 at the face of the piston 40 so as to maintain the piston in the position in which it is shown, while the further supply of fluid to this chamber is cut off as the ball valve 52 is held in the seated position by the spring 58. In addition, the release of fluid from the chamber 38 is cut off as the stem 3d is held in engagement with the ball valve 52 to cut off the flow of fluid from the chamber 68 stem 34.

If the pressure of the steam in the boiler heated by the furnace i should for any reason increase to a value above that which the control apparatus is adjusted spending increase in the pressure of the fluid in the chamber 2i! at the face of the diaphragm I l, and this diaphragm will be moved downwardly against the opposing force of the spring 24, supplemented by the spring 92.

On this movement of the diaphragm M, the stem 39 will press against the upper face of the lever 32 and cause this lever to press against the end of the stem at of the pilot valve device 35, with the result that In this position of the parts of the through the passage M in the to maintain, there will be a correthe end of the stem will press '1;

against the ball valve 52 and move the ball valve away from its seat against the spring 53. Fluid supplied by the pipe and passage 5% to the valve chamber 54 then flows to the chamber Eli, and

thence by way of the passage 88 to the chamber 38 at the face of the piston ill, thereby moving the piston upwardly in the bore in the cylinder 42.

On upward movement of the piston til the piston rod Mi is moved upwardly, thereby moving the yoke lot, and its movement is transmitted through the chain tilt to the lever lit to move this lever in a clockwise direction about the pin H2. This movement of the lever i ii? is transmitted through the chain i it to the lever i it to move the damper 8 towards the closed position in the smoke pipe l B, while the draft door 6 will be permitted to be moved towards the closed position.

In addition, on this movement of the lever lid force is exerted through the link 926 to move the lever i283 of the valve device t in counterclockwise direction, as viewed in Figs. 1 and 3 of the drawings, thus moving the curved member iii! so that the tappets 682 carried thereby press upon the roller H8, moving it downwardly, thereby moving the piston valve M2 downwardly to decrease the size of the openings permitted through the ports I46, and thus decrease the rate of supply of fuel to the burner of the furnace.

In addition, on this upward movement of the piston 46 and piston rod 44, the arm I05 carried by the piston rod 44 will be moved upwardly, thereby moving the wedge Hi4 between the rollers 10% and I02. On this movement of the Wedge i234, the roller I08 is moved to the left, as viewed in Fig. 2 of the drawings, thereby moving the bell crank 86 a short distance in a clockwise direction about the pin 88.

On this movement of the bell crank 86 an arm thereof presses against the spring seat 90 so as to compress the spring 92, and thereby increase the force exerted by this spring on the lever 32 and opposing the force exerted on the lever 32 by the fluid under pressure in the chamber 20 acting through the diaphragm l4 and the stem 30.

As a result of this increase in the force exerted on the lever 52 by the spring 922, the free end of the lever 32 will be moved upwardly, thereby permitting the spring 853 to move the stem 34 of the pilot valve device 36 upwardly. On this upward movement of the stem 34, the ball valve 52 will be moved to its seat by the spring 58.

Fluid under pressure will continue to be supplied to the chamber 38 at the face of the piston to cause upward movement of the piston until the piston has moved far enough in the cylinder 42 to move the wedge I04 between the rollers I80 and H52, and thereby move the bell crank 85 to a position such that the increase in force exer ed by the spring 92 on the free end of the lever 32 is great enough to offset the increase in the opposing force exerted on this lever as a result of the increase in the pressure of the steam in the boiler heated by the furnace I.

When the piston 4i] has been moved upwardly substantially this distance, the free end of the lever 32 will have been moved upwardly by the spring 82 an amount sufiicient to permit the spring 30 to move the stem 34 of the pilot valve device 36 upwardly far enough to permit the spring St to move the ball valve 52 to the seated position to cut off the further supply of fluid to the chamber 38 at the face of the piston 40, and thus cut off upward movement of the piston 40.

As pointed out above, on upward movement of the piston 40, the valve device 4 is operated to restrict the rate of supply of fuel to the furnace I, while the draft 6 and the damper 8 are moved towards their closed positions, and the extent of change in the adjustment of these members is substantially proportional to the extent of movement of the piston 30 in the cylinder 42.

On a decrease in the pressure of the steam in the boiler heated by the furnace I there will be a corresponding decrease in the pressure of the fluid in the chamber 20 on the face of the diaphragm 5 and the diaphragm will be moved upwardly by the spring 2 5, assisted by the spring 92. On this upward movement of the diaphragm I4, there will be a decrease in the force exerted through the stem 30 on the lever 32, with the result that the spring 8% may move the stem 34 of the pilot valve device 36 upwardly.

On this movement of the stem 34, as the ball valve 52 is held in the seated position by the spring and hence cannot move farther, the end of the stem 33 is moved away from the surface of the ball valve 52 so as to permit communication between the chamber $8 and the passage 84 in the stem Fluid from the chamber 38 at the face of the piston 40 may thereupon escape by way of the passage 62 to chamber 60, and through the passage 84 to the chamber 64, from which it flows to a sutable drain by way of the passage and pipe 66.

Upon the release of fluid under pressure from the chamber 38, the piston 40 and the piston rod 44 are moved downwardly by the weight H5 carried by the lever III], assisted by the weight I20 carried by the lever II8. This permits the lever M to be moved in a counterclockwise direction about the pin I I2, and permits the weight I20 to turn the arm I i8 so as to move the damper 8 towards its full open position.

In addition, this movement of the lever H0 is transmitted through the chain I22 to the arm I24 associated with the draft door 6 to move the draft door towards its open position.

In addition, on this movement of the lever H0 force is exerted through the link I26 to move the lever l23 in a clockwise direction, as viewed in Figs. 1 and 3 of the drawings, and thereby move the curved member I10 in a clockwise direction. On this movement of the curved member I70 the tappets I82 carried thereby are moved across the face of the roller lid so that the roller is successively engaged by the ends of tappets which are farther removed radially from the axis about which the member Il'ii is turned.

On this movement of the curved member III], the piston valve I 52 is moved upwardly by the spring I60 so as to maintain the roller H8 in engagement with the ends of the tappets I82, and on this movement of the piston valve I42 the size of the openings through the ports I46 is increased, thereby permitting an increase in the rate of supply of fuel to the furnace.

It will be seen, therefore, that on downward movement of the piston 40, the draft 6 and the damper 8 are opened, and at the same time the valve device 4 is conditioned to increase the supply of fuel to the furnace burner.

In addition, on this downward movement of the piston 40, the wedge I04 carried by the arm I secured to the piston rod 44 is moved downwardly between the rollers I00 and 502, and on this movement of the wedge N4, the bell crank 36 is moved by the spring 92 so as to maintain the roller H30 in engagement with the wedge I 04, while the spring 92 expands, thereby reducing the force exerted by this spring on the end of the lever 32. This results in a reduction in the force exerted by the spring 02 through the lever 32 and the stem 30 on the diaphragm Hi. When this force has been reduced by an amount corresponding to the reduction in the opposing force exerted on the diaphragm i4 as a result of the reduction in the pressure of the steam in the boiler, the diaphragm M will be moved downwardly by the fluid under pressure in the chamber 29, and this movement will be transmitted through the stem 30 to the lever 32 to press this lever against the end of the stem of the pilot valve device 36.

On downward movement of the stem 34 against the opposing force of the spring 80, the end of the stem is gradually moved adjacent the face of the ball valve 52 so as to reduce the rate of flow of fluid under pressure from the chamber 33 at the face of the piston 40, and eventually the end of the stem 34 is moved into engagement with the ball valve 52 so as to cut oif the flow of fluid from the chamber 38 to the passage 34 in the stem 34, through the chamber and thence to the drain by way of the passage and pipe 85. The ball valve 52 is held in the seated position by the spring 58.

When the release of fluid from the chamber 38 is cut off, further downward movement of the piston 40 is prevented.

The amount of downward movement of the piston 40 which occurs before the release of fluid from the chamber 38 is cut off is such as tomove the wedge I04 downwardly a distance sufficient to permit the bell crank 86 to be moved by the spring 92 so that the reduction in the force exerted by the spring 92 on the lever 32, and thereby on the diaphragm H3, is substantially equal to the reduction in force exerted on the diaphragm I l by the fluid in the chamber 20 as a result of the reduction in the pressure of the steam in the boiler of the furnace I.

On each subsequent change in the pressure of the steam in the boiler of the furnace controlled by this control apparatus, the control device l2 operates in the manner described in detail above to vary the setting of the valve device t, which controls the supply of fuel to the furnace burner, and also to vary the setting of the draft door 6 and the damper 8, which control the supply of air to the furnace fire box.

The relative changes in the settings of these members which occur as a result of operation of the control device l2 may be adjustably varied by changing the points of connection of the link I26, and of the chains i it and 122, with the lever H0, and with the members I28, H8 and i2 3, respectively. This permits the rate of supply of fuel and air to the furnace to be proportioned throughout the entire range of movement of the control apparatus so as to be substantially in the proportion required to efiect complete combustion of the fuel.

However, due to the peculiarities of various furnaces, if the setting of the fuel supply valve device 4, and the draft door 6 and damper 8, are simultaneously varied to the same extent, the relationship of the rate of supply of fuel and of air to the furnace will not be such as to provide for most efficient combustion of the fuel throughout the entire range of movement of the control apparatus.

It has been found if the elements of the control apparatus are arranged so that the setting of the fuel supply valve device t and of the draft and damper are adjusted to give proper combustion of the fuel at one point in the range of movement of the control apparatus, that they will not operate to produce the proper adjustment of these members at other points in the range of movement of the control apparatus, and, as a result, the most efficient and complete combustion of the fuel throughout the entire range of movement of the control apparatus has not been secured.

The control apparatus provided by this invention incorporates means by which the setting of the valve device 4 may be adjustably varied at a plurality of points throughout the range of movement of the control apparatus, so that the relative settings of the valve device 4, and of the draft and damper, may be adjustably varied to produce most efficient combustion of the fuel throughout the entire range of movement of the control apparatus.

If it is found at any point in the range of movement of the control apparatus that the relationship of the rate of supply of fuel and air are not such as to produce most efficient combustion of the fuel, the rate of supply of fuel may be changed by adjusting the tappet or tappets I82 engaged by the roller H3 at this point in the range of movement of the control apparatus to thereby alter the position of the piston valve M2 and thus change the size of the openings through the ports Hi6, and accordingly the rate of supply of fuel to the furnace burner.

In this manner the supply of fuel may be controlled so as to produce the most efficient combustion of the fuel at this point in the range of movement of the control apparatus, while the supply of fuel may be similarly regulated at other points in the range of movement of the control apparatus, and thus properly proportion the supply of fuel and air to the furnace throughout the entire range of movement of the control apparatus.

While one embodiment of the improved control apparatus provided by my invention has been illustrated and described in detail, it should be understood that the invention is not limited to these details of construction, and that numerous changes and modifications may be made Without departing from the scope of the following claims.

Having now described my invention, What I claim as new and desire to secure by Letters Patent, is:

1. In a control apparatus, in combination, a shaft pivotally supported, a member carried by said shaft and having a portion curved in a plane perpendicular to the axis of the said shaft, the distance from the axis of the shaft to the adjacent face of said portion gradually changing throughout the extent of said portion, a plurality of elements extending through said portion of said member and adjustable relative thereto in the plane in which said portion is curved, the ends of said elements projecting from the face of said portion remote from the axis of said shaft carrying means for adjusting said elements relative to said member, the ends of said elements projecting from the face of said portion adjacent the axis of said shaft cooperating to form an operating surface, and a member adapted to engage said operating surface.

2. In a control apparatus, in combination, a shaft pivotally supported, a member carried by said shaft and having a portion curved in a plane perpendicular to the axis of the said shaft, the distance from the axis of the shaft to the adjacent face of said portion gradually changing throughout the extent of said portion, a plurality of elements extending through said portion of said member and adjustable relative thereto in the plane in which said portion is curved, the ends of said elements projecting from the face of said portion remote from the axis of said shaft carrying means for adjusting said elements relative to said member, said ends of said elements also carrying means cooperating with said member for locking said elements in their adjusted positions, the ends of said elements projecting from the face of said portion adjacent the axis of said shaft cooperating to form an operating surface, and a member adapted to engage said operating surface.

3. In a control apparatus, in combination, a shaft pivotally supported, a member carried by said shaft and having a portion curved in a plane perpendicular to the axis of the said shaft, the distance from the axis of the shaft to the adjacent face of said portion gradually changing throughout the extent of said portion, a plurality of elements extending through said portion of said member and adjustable relative thereto in the plane in which said portion is curved, the ends of said elements projecting from the face of said portion remote from the axis of said shaft carrying means for adjusting said elements relative to said member, the ends of said elements projecting from the face of said portion adjacent the axis of said shaft cooperating to form an operating surface, and a member carrying a roller adapted to engage the operating surface formed by said elements, the radius of said roller being substantially greater than the distance which the ends of said elements are spaced apart.

JOHN B. HULL.