US3861763A

US3861763A - Gimbal mounting means and method

Info

Publication number: US3861763A
Application number: US355060A
Authority: US
Inventors: Charles H Perkins
Original assignee: Robertshaw Controls Co
Current assignee: Robertshaw Controls Co
Priority date: 1973-04-27
Filing date: 1973-04-27
Publication date: 1975-01-21
Anticipated expiration: 1992-01-21

Abstract

A gimbal mounting means for a control device having a frame and a control part to be operated by the gimbal mounting means, the gimbal mounting means comprising a first member pivotally mounted by pivot means to a frame and a second member pivotally mounted by pivot means to the first member at a right angle to the pivot mounting of the first member. Each pivot means comprises a ball carried by the respective member and being received in a cylinder member carried by either the other member or the frame for receiving the ball therein to provide substantially circular line contact for pivot movement therebetween, each cylinder member having another ball press fitted therein to be abutted by the pivot ball being received therein so that only point contact is provided therebetween in a thrust load direction.

Description

United States Patent n91 Perkins Jan. 21, 1975 [75] Inventor: Charles H. Perkins, Richmond, Va.

[73] Assignee: Robertshaw Controls Company,

Richmond, Va.

22 Filed: Apr. 27, 1973 21 Appl. No: 355,060

[52] US. Cl. 308/2 R, 74/471 XY, 248/183 [51] Int. Cl. Fl6c 11/00 [58] Field of Search 308/2 R, 2 A; 74/55, 5 F.

OTHER PUBLICATIONS Product Engineering 7/5/65, Maurice Conklin pages 68 & 69 Pivots Do Many Jobs."

Primary Examiner-Charles J. Myhre Assistant Examiner-R. H. Lazarus Attorney, Agent, or FirmCandor, Candor & Tassone [57] ABSTRACT A gimbal mounting means for a control device having a frame and a control part to be operated by the gimbal mounting means, the gimbal mounting means comprising a first member pivotally mounted by pivot means to a frame and a second member pivotally mounted by pivot means to the first member at a right angle to the pivot mounting of the first member. Each pivot means comprises a ball carried by the respective member and being received in a cylinder member carried by either the other member or the frame for receiving the ball therein to provide substantially circular line contact for pivot movement therebetween, each cylinder member having another ball press fitted therein to be abutted by the pivot ball being received therein so that only point contact is provided therebetween in a thrust load direction.

19 Claims, 6 Drawing Figures PATEHTED JAHZ 1 I975 SHEET 10F 2 FIG.1

PATENIH] JANE 1 I975 SHEET 2 OF 2 4o 59 e3 63' 3s GIMBAL MOUNTING MEANS AND METHOD This invention relates to an improved gimbal mounting means and method for making such a gimbal mounting means or the like.

It is well known that a pair of concentrically disposed gimbal rings have been pivotally mounted together with the outer ring being pivotally mounted to a frame means of a control device wherein the pivotal movement of the rings is controlled by pneumatically operated movable parts of the control device so that the positioning of the gimbal rings will control the position of a flapper valve member relative to a vent nozzle or the like. However, it has been found in such prior known gimbal arrangement, no satisfactory means are provided for pivotally mounting the gimbal rings in a manner that will permit slight misalignment of the pivot means and still provide for accurate operation of the rings and not non-linearity of movement as in the case of prior known gimbal mounted rings.

Accordingly, it is a feature of this invention to provide an improved gimbal mounting arrangement wherein slight misalignments between the pivot points of the pivotally mounted members can be readily compensated for without sacrificing accuracy of operation thereof.

Another feature of this invention is to provide a method for making such a gimbal mounting means or the like.

In particular, one embodiment of this invention provides a control device having a frame and a gimbal mount carried thereby for operating a control part of the device and wherein the gimbal mount comprises a first member pivotally mounted by pivot means to the frame and a second member pivotally mounted by pivot means to the first member at a right angle to the pivot mounting of the first member. At least one of the pivot means means comprises means carried by the respective member for providing substantially circular line contact for the pivot movement thereof and substantially point contact therewith for absorbing thrust loading therebetween. Such pivot means can comprise a pair of balls carried by each pivot member on opposite sides thereof and being respectively received in cylinder means carried by the other member or the frame where the pair of balls of each member make substantially circular line contact with the cylinder means during the pivot movement of the respective member. Each cylinder means has a ball initially press fitted therein to be subsequently abutted by the pivot ball of the pivot member being received therein so that substantially point contact is provided therebetween in a thrust load direction therebetween.

Thus, if slight misalignment is provided between the pivot balls and the cylinder means receiving the same, a resulting circular line contact is still provided by each pivot ball and its respective cylinder means receiving the same as well as point contact of the pivot ball with the ball ofthe cylinder means whereby pivot movement of the pivot member is still positively maintained along a straight line disposed between the centers of the pivot balls of the respective pivot member.

Accordingly, it is an object of this invention to provide an improved gimbal mounting means having one or more of the novel features set forth above or hereinafter shown or described.

Another object of this invention is to provide a method for making such a gimbal mounting means or the like.

Other objects, uses and advantages of this invention are apparent from a reading of this description which proceeds with reference to the accompanying drawings forming a part thereof and wherein:

FIG. I is a top view of a control device utilizing the gimbal mounting means of this invention.

FIG. 2 is an enlarged cross-sectional view taken substantially on line 22 of FIG. 1.

FIG. 3 is a cross-sectional view taken substantially on line 3-3 of FIG. 2.

FIG. 4 is a fragmentary, cross-sectional view taken on line 44 of FIG. 3.

FIG. 5 is a fragmentary cross-sectional view taken on line 5-5 of FIG. 3.

FIG. 6 is an exploded perspective view of the improved gimbal mounting means of this invention.

While the various features of this invention are hereinafter described and illustrated as being particularly adapted to provide a gimbal mounting means for operating a flapper valve member, it is to be understood that the various features of this invention can be utilized singly or in any combination thereof to provide gimbal mounting means for other devices as desired.

Therefore, this invention is not to be limited to only the embodiment illustrated in the drawings, because the drawings are merely utilized to illustrate one of the wide variety of uses of this invention.

Referring now to FIGS. I, 2 and 3, the improved control device of this invention is generally indicated by the reference numeral 10 and comprises a frame structure or means 11 having two pressure chambers l2 and 13 therein with each

pressure chamber

12 and 13 being formed in substantially the same manner whereby only the details of the pressure chamber 12 will be described with the understanding that such description applies to the structure of the pressure chamber I3 except that like parts of the pressure chamber 13 will be indicated by like reference numerals followed by a prime mark.

As illustrated in FIG. 2, the pressure chamber I2 is adapted to be supplied pressure fluid through an inlet 14 formed in the frame means 11 and is partly defined by a tubular bellows construction 15 having its lower open end 16 secured to frame means II and its upper open end 1') closed by an outwardly flared flange 18 of a cup-shaped member I9 disposed within the bellows construction 15 and having its end wall 20 interconnected by a flexible tying means 21 to one end 22 of a pivotally mounted motion transmitting member 23 whereby up and down movement of the movable wall 20 causes clockwise and counterclockwise movement of the motion transmitting member 23 as will be apparent hereinafter.

A compression spring 24 has one end 25 bearing against the movable wall 20 of the cup-shaped member 19 while the other end 26 thereof bears against a spring retainer 27 that has its distance relative to the movable wall 20 controlled by a threaded adjusting member 28 carried by the frame means II whereby the force of the compression spring 24 acting downwardly on the wall 20 can be adjusted by the adjusting member 28. In this manner, as the pressure differential across the wall 20 increases because of an increase in the pressure of the fluid being delivered to the chamber [2, the resulting increased pressure differential across the wall 20 causes the wall 20 to move upwardly in H0. 2 in opposition to the force of the compression spring 24 to cause a clockwise pivoting movement of the motion transmitting member 23 whereby the other end 29 of the motion transmitting member 23 moves downwardly in the drawings and pulls downwardly on a tension spring member or mean 30 having its lower end 31 interconnected thereto. Thus, the tension spring member 30 transmits such pivoting movement of the motion transmitting member 23 to a gimbal mount of this invention that is generally indicated by the reference numeral 32 in the drawings and which will be hereinafter described, Conversely, a decrease in the pressure differential across the movable wall 20 caused by a de' crease in the pressure of the fluid being delivered to the chamber 12 will cause the movable wall 20 to be moved downwardly by the compression spring 24 and thereby cause counterclockwise movement of the motion transmitting member 23 so that the end 29 of the motion transmitting member 23 moves upwardly in H0. 2 and, thus, moves the tension spring means 30 upwardly to operate the gimbal mount 32 as will be apparent hereinafter.

The motion transmitting member 23 is pivotally mounted to the frame means H by a metallic flexure member 33 secured to the frame means 11 at its outer periphery 34 and secured to the motion transmitting member 23 at its inner periphery 35 whereby pivoting movement of the motion transmitting member 23 can take place because the flexure member 33 will flex between its inner and outer peripheries 3S and 34 to permit such pivoting movement. A diaphragm seal member 36 is provided to the left of the flexure member 33 to seal the chamber 12 from the exterior of the frame means 11 at the flexure member 33.

Therefore, it can be seen that the motion transmitting members 23 and 23' of the

pressure chambers

12 and 13 are adapted to be pivoted by pressure changes in the

respective chambers chambers

12 and 13 in the manner previously described.

The gimbal mount 32 of this invention comprises a pair of

ring members

37 and 38, the

ring members

37 and 38 being concentrically disposed with the ring member 37 being smaller in diameter than the outer ring member 38 and being pivotally mounted thereto by a pair of like pivot means that are generally indicated by the reference numeral 39 so that the inner pivot ring 37 will pivot relative to the outer pivot ring 38 along a pivot axis disposed substantially between the pivot means 39 that are disposed substantially diametrically opposed each other relative to the inner pivot ring 37 whereby the pivot axis of its inner ring 37 is substantially the same as a diameter thereof. The outer pivot ring 38, in turn, is pivotally mounted to the frame means 11 by a pair of like pivot means generally indicated by the reference numeral 40 along an axis that is disposed along a line between the pivot means 40, such pivot line being substantially the same as a diameter of the outer ring 38 that is disposed substantially at right angles to the pivot axis provided by the pivot means 39 for the inner pivot ring 37.

The tension spring means 30, that has its lower end 31 interconnected to the end 29 of the motion transmitting member 23, has its upper end 41 secured to a threaded member 42 threaded into a threaded bore 43 formed in the inner annular ring 37 whereby pivoting movement of the motion transmitting member 23 causes pivoting movement of the inner annular ring 37 about the pivot means 39. Similarly, the end 29' of the motion transmitting member 23' for the pressure chamber 13 is interconnected to the lower end 31' of a motion transmitting tension spring means 30' that has its upper end 41' secured to a threaded member 42' secured in a threaded bore43' formed in the outer gimbal ring 38 in the manner illustrated in FIG. 4 whereby pivoting movement of the motion transmitting member 23' causes the outer gimbal ring 38 to pivot on its pivot means 40.

The inner pivot ring 37 has an outer cylindrical wall 44 and an inner angularly disposed wall 45 that termi nates in substantially a knife edge 46 adapted to engage against a reduced end 47 of a resilient flapper valve member 48 having the other end 49 thereof secured to the frame means 11 by fastening members 50. The end 47 of the flapper valve member 48 is disposed over a vent nozzle 51 of the control device 10 whereby the amount of fluid venting through the nozzle 51 is controlled by the position of the flapper valve member 48 relative thereto, the flapper valve member 48 having a natural resiliency that tends to move the flapper valve member 48 into full seating on the nozzle 51 to prevent any fluid flow therethrough. Thus, the pivotal movement of the gimbal mount 32 by the pressure means 12 and 13 in a manner hereinafter described controls the position of the flapper valve member 48 relative to the nozzle 51 and, thus, the amount of venting through the nozzle 51 in a manner well known in the art.

However, as previously stated, this invention provides improved

means

39 and 40 for pivotally mounting the

gimbal rings

37 and 38 and will now be described.

Each pivot means 39 and 40 includes a cylinder means 52 that is externally threaded at 53 and has a cylindrical bore 54 coaxially interrupting one end 55 thereof and terminating therein to define a flat end wall 56 spaced from the end 55 a certain amount as will be apparent hereinafter.

The other end 57 of each cylinder means 52 is provided with a slot 58 disposed diametrically across the same for receiving a screw driver or the like to permit rotational movement of the respective cylinder member 52 in an axial manner toward and away from its re

spective gimbal ring

38 or 37. For example, the two cylinder means 52 for the pivot means 40 for the outer gimbal ring 38 are respectively threadedly disposed in threaded bores 59 formed in the frame means I] as illustrated in FIG. 3 whereby the cylinder means 52 for the pivot means 40 are adapted to be axially moved toward and away from the gimbal ring 38 along a line that represents a diameter of the gimbal ring 38.

In regard to the pivot mounts 39 for the inner gimbal ring 37, the cylinder means 52 therefor are respectively threadedly disposed in threaded bores 60 formed in an aligned manner through

opposed cylinder walls

61 and 62 of the outer ring 38 whereby the cylinder means 52 carried by the outer gimbal ring 38 are adapted to be axially moved along a line corresponding to a diameter of the inner ring 37 that is disposed at substantially a right angle to the diameter of the outer ring 38 along which the cylinder means 52 for the pivot means 40 are axially movable.

Each cylinder defining means 52 initially has a spherical metallic ball 63 press fitted into the bore 54 thereof so as to be disposed against the end wall 56 as illustrated, the diameter of the ball 63 being slightly larger than the initial diameter of the bore 54 so that during the press fitting of the ball 63 in the bore 54 of the respective cylinder means 52, such movement of the ball 63 from the exterior of the bore 54 to abut against the end wall 56 of the bore 54, in effect, sizes and burnishes the bore 54 for a purpose hereinafter described even though the ball 63 remains firmly against the end wall 56 through the press fit relation thereof with the bore 54 of the cylinder means 52 for a purpose hereinafter described.

The pivot means 40 for the outer gimbal ring means 38 includes a pair of metallic balls 63' identical to the balls 63 previously described and respectively secured to the outer cylindrical wall 61, such as by welding, as illustrated in FIG. 6 so that the same are adapted to be received in the bores 54 of the cylinder means 52 of the pivot means 40 in the manner illustrated in FIG. 3 when the ring 38 is assembled to the frame means 11 whereby the secured balls 63' will make substantially circular line contact with the cylinder means 52 at the bores 54 thereof for pivotal movement of the ring 38 substantially along a line drawn through the centers of the secured balls 63' while the balls 63' respectively make only point contact with the balls 63 of the cylinder means 52 in any thrust loading direction along the pivot line of the outer ring 38.

Similarly, a pair of balls 63" are secured to the outer cylindrical wall 44 of the inner ring 37 in a manner to be received in the bores 54 of the cylinder means 52 carried by the outer ring 38 in the manner illustrated in FIG. 3 as to provide circular line contact with the cylinder means 52 of the pivot means 39 whereby the inner ring 37 will pivot along a line disposed substantially between the centers of the balls 63". Also, the balls 63" of the inner ring 37 merely make point contact with the balls 63 of the cylinder means 52 of the pivot means 39 in any thrust loading direction along the pivot line for the inner ring 37.

It is preferred that the length of the bores 54 be so sized relative to the balls 61 and that the cylinder means 52 be so adjusted that the secured balls 63' and 63" will be received in the respective bores 54 of the cylinder means 52 a distance greater than the radius of the balls 63' and 63", but a distance less than the diameter of the balls 63' and 63".

In this manner, it can be seen that the

gimbal rings

37 and 38 may be readily assembled to the frame means ll by the respective pivot means 39 and 40 and be interconnected to the motion transmitting members 23 and 23' by the tension spring means 30 and 30' to operate in a manner now to be described.

As the motion transmitting member 23 is pivoted in a counterclockwise direction by the pressure differential acting across the movable wall of the pressure chamber 20 decreasing, such upward movement of the right-hand end 29 of the motion transmitting member 23 causes the tension spring 30 to move upwardly and cause the inner gimbal ring 36 to pivot on its pivot means 39 in a manner to raise the end 47 of the flapper valve member 48 relative to the vent nozzle 51 to increase the vent flow therethrough. Conversely, as the pressure differential across the movable wall 20 of the pressure chamber 12 increases, the movable wall 20 moves upwardly in FIG. 2 and causes the motion transmitting member 23 to pivot in a clockwise direction whereby the tension spring 30 pivots the inner gimbal ring 37 on its pivot means 39 in a manner to permit the flapper valve member 48 to move closer to the vent nozzle 51 and thereby decrease the fluid flow therethrough. Similarly, an increase in pressure in the pressure chamber 13 causes the motion transmitting member 23' to pivot in a clockwise direction in FIG. 6 and thereby cause the outer gimbal ring 38 to pivot on its pivot means 40 in such a manner that the inner gimbal ring 37 being carried thereby permits the flapper valve member 48 to move closer to the vent nozzle means 51 and thereby decrease the fluid flow therethrough. Conversely, a decrease in pressure in the pressure chamber 13 causes the motion transmitting member to pivot in a counterclockwise direction in H0. 6 and thereby pivot the outer gimbal ring 38 on its pivot means 40 in a manner to cause the inner ring 37 to move the flapper valve member 48 away from the vent nozzle 51 to increase the fluid flow therethrough.

Thus, it can be seen that the pivot means 39 and 40 of this invention readily permit the gimbal rings 37 and 38 to pivot in the manner previously described for operating the flapper valve member 48.

Further, because the line of contact between the pivot balls 63' and 63' and their respective cylinder members 52 is always circular, slight misalignment of the axes of the cylinder means 52 and the axes of the

rings

37 and 38 defined by a line drawn between the centers of the respective pair of balls 63' and 63" secured thereto is accommodated without increasing bearing clearance since the bearing contact is always circular and the bearing circle can be freely positioned in space without changing the end play of the bearing structure. Thus. in effect, each pair of ball pivots acts as a universal joint, when adjusted.

Therefore, it can be seen that this invention not only provides an improved gimbal mounting means for a control device or the like, but also this invention pro vides an improved method for making such a gimbal mounting means or the like.

While the form and method of the invention now preferred have been disclosed and illustrated as required by the Patent Statute, it is to be understood that other forms and methods can be utilized and still come within the scope of the appended claims.

What is claimed is;

1. in a control device having a frame and a gimbal mount carried thereby for operating a control part of said device and wherein said gimbal mount comprises a first member pivotally mounted by pivot means to said frame and a second member pivotally mounted by pivot means to said first member at a right angle to the pivot mounting of said first member, the improvement wherein at least one of said pivot means comprises means carried by the respective member for providing substantially circular line contact for the pivot movement thereof, said one pivot means also comprising means cooperating with said means of said respective member to provide substantially point contact therebe tween for thrust load absorbing purposes, said contact being spaced from said circular line contact.

2. in a control device as set forth in claim 1 wherein said means for providing substantially circular line contact comprises ball means carried by the respective member.

3. In a control device as set forth in claim I, said respective member comprising said first member, said means for providing substantially circular line contact comprising a pair of balls disposed on opposite sides of said member and a pair of cylinder means carried by said frame and respectively receiving said balls therein.

4. In a control device having a frame and a gimbal mount carried thereby for operating a control part of said device and wherein said gimbal mount comprises a first member pivotally mounted by pivot means to said frame and a second member pivotally mounted by pivot means to said first member at a right angle to the pivot mounting of said first member, the improvement wherein at least one of said pivot means comprises means carried by the respective member for providing substantially circular line contact for the pivot movement thereof, said one pivot means comprising means cooperating with said means of said respective member to provide substantially point contact therebetween for thrust load absorbing purposes, said means of said respective member comprising ball means and said means of said one pivot means cooperating therewith comprising ball means for being disposed in contact with said first named ball means.

5. ln a control device as set forth in claim 4, said one pivot means comprising cylinder means having said ball means received therein whereby said ball means of said respective member is adapted to rotate relative to said cylinder means to provide substantially circular line contact therewith.

6. in a control device as set forth in claim 5, said ball means of said pivot means having been press fitted in said cylinder means before said ball means of said respective member has been received in said cylinder,

7. in a control device as set forth in claim 6, said cylinder means being axially adjustable toward and away from said ball means of said respective member.

8. ln a control device having a frame and a gimbal mount carried thereby for operating a control part of said device and wherein said gimbal mount comprises a first member pivotally mounted by pivot means to said frame and a second member pivotally mounted by pivot means to said first member at a right angle to the pivot mounting of said first member, the improvement wherein at least one of said pivot means comprises means carried by the respective member for providing substantially circular line contact for the pivot movement thereof. said respective member comprising said first member, said means for providing substantially circular line contact comprising a pair of balls disposed on opposite sides of said member and a pair of cylinder means carried by said frame and respectively receiving said balls therein, and another pair of balls respectively disposed in said cylinder means and respectively being abutted by said balls of said first member so that substantially point contact is provided therebetween in a thrust load direction.

9. In a control device as set forth in claim 8, said first member carrying another such pair of cylinder means respectively having a pair of balls therein, said second member having a pair of balls carried thereon on opposite sides of said second member and respectively received in said cylinder means of said first member to provide substantially circular line contact therewith for the pivot movement thereof and respectively abutting said balls of said cylinder means of said first member so that substantially point contact is provided therebetween in a thrust load direction.

10. In combination, a first member, and a second member pivotally mounted to said first member by pivot means, said pivot means comprising a pair of balls carried by said second member on opposite sides thereof and a pair of cylinder means carried by said first member and respectively receiving said balls therein whereby said second member is adapted to pivot on an axis defined by a substantially straight line passing through the centers of said balls while said balls respectively make substantially circular line contact with said cylinder means, said balls also respectively making point contact with said cylinder means in spaced relation to said circular line contact therewith.

II. A combination as set forth in claim 10 wherein said cylinder means each comprises a threaded adjust ing member threadedly carried by said first member whereby said cylinder means can be axially adjusted toward and away from said balls of said second member 12. in combination, a first member, and a second member pivotally mounted to said first member by pivot means, said pivot means comprising a pair of balls carried by said second member on opposite sides thereof and a pair of cylinder means carried by said first member and respectively receiving said balls therein whereby said second member is adapted to pivot on an axis defined by a substantially straight line passing through the centers of said balls while said balls respectively make substantially circular line contact with said cylinder means, and a second pair of balls respectively disposed in said cylinder means to be carried thereby. said second pair of balls respectively being abuttcd by the first named pair of balls whereby substantially point contact is provided therebetween in a thrust load direction,

13. A combination as set forth in claim 12 wherein said second pair of balls are press fitted into said cylinder means.

14. A combination as set forth in claim 12 wherein said first-named pair of balls each is disposed in said cylinder means a distance less than the diameter of the respective ball but greater than the radius thereof.

15. A method for pivotally mounting a second member to a first member comprising the steps of securing a pair of balls to opposite sides of said second member, securing a pair of cylinder means to said first member. and disposing said balls respectively in said cylinder means whereby said second member is adapted to pivot on an axis defined by a substantially straight line passing through the centers of said balls while said balls re spectively make substantially circular line contact with said cylinder means as well as point contact with said cylinder means in spaced relation to said circular line contact therewith.

16. A method as set forth in claim 15 and including the step of forming said cylinder means each from a threaded adjusting member so as to be threadably carried by said first member whereby said cylinder means can be axially adjusted toward and away from said balls of said second member.

17. A method for pivotally mounting a second member to a first member comprising the steps of securing a pair of balls to opposite sides of said second member, securing a pair of cylinder means to said first member. disposing said balls respectively in said cylinder means whereby said second member is adapted to pivot on an axis defined by a substantially straight line passing through the centers of said balls while said balls respectively make substantially circular line contact with said cylinder means, and disposing a second pair of balls respectively in said cylinder means to be carried thereby 19. A method as set forth in claim 17 wherein said step of disposing said first named balls into said cylinder means comprises the step of disposing said first named pair of balls respectively in said cylinder means a distance less than the diameter of the respective ball but greater than the radius thereof.

Claims

1. In a control device having a frame and a gimbal mount carried thereby for operating a control part of said device and wherein said gimbal mount comprises a first member pivotally mounted by pivot means to said frame and a second member pivotally mounted by pivot means to said first member at a right angle to the pivot mounting of said first member, the improvement wherein at least one of said pivot means comprises means carried by the respective member for providing substantially circular line contact for the pivot movement thereof, said one pivot means also comprising means cooperating with said means of said respective member to provide substantially point contact therebetween for thrust load absorbing purposes, said contact being spaced from said circular line contact.

3. In a control device as set forth in claim 1, said respective member comprising said first member, said means for providing substantially circular line contact comprising a pair of balls disposed on opposite sides of said member and a pair of cylinder means carried by said frame and respectively receiving said balls therein.

5. In a control device as set forth in claim 4, said one pivot means comprising cylinder means having said ball means received therein whereby said ball means of said respective member is adapted to rotate relative to said cylinder means to provide substantially circular line contact therewith.

6. In a control device as set forth in claim 5, said ball means of said pivot means having been press fitted in said cylinder means before said ball means of said respective member has been received in said cylinder.

8. In a control device having a frame and a gimbal mount carried thereby for operating a control part of said device and wherein said gimbal mount comprises a first member pivotally mounted by pivot means to saiD frame and a second member pivotally mounted by pivot means to said first member at a right angle to the pivot mounting of said first member, the improvement wherein at least one of said pivot means comprises means carried by the respective member for providing substantially circular line contact for the pivot movement thereof, said respective member comprising said first member, said means for providing substantially circular line contact comprising a pair of balls disposed on opposite sides of said member and a pair of cylinder means carried by said frame and respectively receiving said balls therein, and another pair of balls respectively disposed in said cylinder means and respectively being abutted by said balls of said first member so that substantially point contact is provided therebetween in a thrust load direction.

11. A combination as set forth in claim 10 wherein said cylinder means each comprises a threaded adjusting member threadedly carried by said first member whereby said cylinder means can be axially adjusted toward and away from said balls of said second member.

12. In combination, a first member, and a second member pivotally mounted to said first member by pivot means, said pivot means comprising a pair of balls carried by said second member on opposite sides thereof and a pair of cylinder means carried by said first member and respectively receiving said balls therein whereby said second member is adapted to pivot on an axis defined by a substantially straight line passing through the centers of said balls while said balls respectively make substantially circular line contact with said cylinder means, and a second pair of balls respectively disposed in said cylinder means to be carried thereby, said second pair of balls respectively being abutted by the first named pair of balls whereby substantially point contact is provided therebetween in a thrust load direction.

15. A method for pivotally mounting a second member to a first member comprising the steps of securing a pair of balls to opposite sides of said second member, securing a pair of cylinder means to said first member, and disposing said balls respectively in said cylinder means whereby said second member is adapted to pivot on an axis defined by a substantially straight line passing through the centers of said balls while said balls respectively make substantially circuLar line contact with said cylinder means as well as point contact with said cylinder means in spaced relation to said circular line contact therewith.

17. A method for pivotally mounting a second member to a first member comprising the steps of securing a pair of balls to opposite sides of said second member, securing a pair of cylinder means to said first member, disposing said balls respectively in said cylinder means whereby said second member is adapted to pivot on an axis defined by a substantially straight line passing through the centers of said balls while said balls respectively make substantially circular line contact with said cylinder means, and disposing a second pair of balls respectively in said cylinder means to be carried thereby so that said second pair of balls are respectively abutted by the first named pair of balls whereby substantially point contact is provided therebetween in a thrust load direction.

18. A method as set forth in claim 17 and including the step of press fitting said second pair of balls respectively into said cylinder means.

19. A method as set forth in claim 17 wherein said step of disposing said first named balls into said cylinder means comprises the step of disposing said first named pair of balls respectively in said cylinder means a distance less than the diameter of the respective ball but greater than the radius thereof.