US2518531A - Mechanical brake for gun mounts - Google Patents

Description

Aug. 15, 1950 F. c. EASTMAN MECHANICAL BRAKE FOR GUN MOUNTS 2 Sheets-Sheet 1 Filed Jan. 14, 1948 Aug. 15, 1950 F. c. EASTMAN 2,513,531

MECHANICAL BRAKE FOR GUN MOUNTS Filed Jan. 14,1948 2 Sheets-Sheet 2 fizz/an far F -ca' CIasi man Patented Aug. 15, 1950 UNITED STATES, earner OFFICE MECHANICAL BRAKE FOR GUN MOUNTS Fred C. Eastman, Marblehead, Mass, assignor to United Shoe Machinery Corporation, Flemington, N. 3., a corporation of New Jersey Application January 14, 1948, Serial No. 2,316

4 Claims.

limited to preclude the firing of projectiles along particular trajectories. Ordinarily the complex controls for swinging and laying a gun barrel;

may be relied upon to determine its limits of movement, but the susceptibility of such controls to disorder, especially during combat and in the instance of power driven gun mounts in airplanes, makes it essential that means be provided which shall positively prevent the :movement of a barrel beyond the desiredorpermissible extent. An important consideration in con.- nection with such means is that "the braking power efiective to stop barrel movement at a predetermined limit shall not subject the gun to rebound or rocking movement that would delay or prevent firing accuracy.

An object of the invention is .to provide in a gun mount an improved positively acting brake for limiting travel of :gun whichshall be simple, inexpensive, light in weight, and compact in structure, and which shall, independently of mechanism driving said gun, operate in a small confined space to quickly retard its motion with- 1 out efiecting reversal.

To this end a feature of the invention resides in the use of a series of contiguous wedge-like cams backed by shock-absorbing means and disposed within angular constraining walls to inter- .act frictionally on being displaced by an element movable with the gun to be braked.

A further feature is in the arrangement of the parts whereby travel of a gun in either of two opposite directions is resisted by the frictional interengagement of the cams as influenced by cushioning means, the latter being represented herein as a spring.

These and other features of the invention will best be understood from the following description of a preferred embodiment considered in connection with the accompanying drawings,

in which Fig. 1 is a view in side elevation .of a gun,

mounted to swing in azimuth and in elevation,

2 and in which the present invention has been embodied;

Fig. 2 is a deta l. on a larger scale, showing a sectional view of brake mounting, as indicated by the line II-II of Fig. 1;

Fig. 3 is an enlarged detail view of a gear segment with the braking mechanism and other parts of the gun shown inFig. 1; and

Fig. 4 is an angular view drawn to a still larger scale and explcdedzto show the parts comprising the braking mechanism.

While the description and drawings are here- .inafter directed to illustrating an application :of

the invention in limiting the movement :of a gun 1n elevation, it will be understood that a similar arrangement may limit its movement in azimuth,

or in either of any two opposite directions.

The gun mount and its driving mechanism do not materially differ in general arrangement from that disclosed in United :States Letters Patent No. 2,391,956, granted to F. C. Eastman on January 1, 19%6, and entitled Limit Stop forGun Mounts. Since the details in this connection are of no particular pertinence to the present invention, :a brief description of them will sumce. A gun It (Fig. 1) is supported for movement in elevation by being pivoted on its trunnions (not shown) in the side frames ii? of a yoke or gun mount. The trunnion on the near side supports a segment gear Hi depending from and integral with an adapter 16 arranged to rotate with the gun 45] in elevation .as will be understood. The yoke is completed by top and bottom cross supports (not shown), the top support being pivoted in a bearing 1!. to the supporting structure in which the gun ismounted and the bottom support being received in a bearing 29 secured to part of the structure in which the gun is mounted. The yoke is thus adapted to be turned about a vertical axis so that the gun may be directed in-aziinuth. Elevation (and depression) of the gun is effected by a pinion 22 which is driven through a gear train '(not .shown) by a motor 24 and which meshes with the segment gear 14.

On the segment gear I i '(Figs. '1 .and 3) are fastened limit stops .26 and 22 having rounded ends which may be .adjusta'bly spaced by a distance representing the permissible or desired limits of gun movement in elevation. The adjustment referred to 'is made by .affixing these stops to gear segment It with dowel pins 30 :inserted in holes 32 located equidistant from the turning axis of the trunnions.

Coming now more particularly. to the break-- ing mechanism, a flat, inverted L-shaped casing 34, best viewed in Figs. 3 and l, is secured to an inner portion of the near frame [2 and. preferably held relatively stationary by bolts 36. The casing 34, which may be of any angular configuration conveniently to accommodate available space, has an open side which is flush with the frame, its closed side being adjacent to, but separated from, the gear segment. The inner walls in each arm of this casing provide smooth and parallel bearing surfaces to support and constrain for frictional interaction a series of close-fitting cams or wedge-like blocks. Preferably, both the casing 34 and these blocks are of hardened tool steel. The first of the series is a double-endedbumper block 38 projecting horizontally from bearing slots 49 in the lower extremity of the casing walls. The block 38 is positioned to converge with the arcuate path of stops 26 and 28 so as to be engageable therewith, and is provided in its upper surface with a central, widthwise extending notch having its acting faces 42 inclined substantially at right angles to each other. Fitted to slide within the casing 34 for frictionalaction with its Walls is a second wedge-like block 44 which has its tapering sides 46 truncated and equally beveled so as to be fully seated in the notch and evenly bear on both faces 42 when the bumper block 38 is in its initial position and not displaced by contact with either of the stops 26, 28. The holes 48 in the several blocks have no function other than to decrease the overall weight of the assemblage without adversely affecting its structural strength.

Between projections 50 (see Figs. 3 and 4) of the upper side of the block 44 is a horizontal recess 52 in which two cylindrical rollers 54 may shift laterally for purposes hereinafter to be described. E'ach roller 54 has a lug engaging a spring 56 that yieldingly separates the rollers and normally holds them parallel with and adjacent to the projections 59. The diameter of the.

rollers 54 exceeds the depth of the recess 52 by a very small amount so that they serve to space from the block 44, and make line contacts with, a confronting wedge-like block 58 which is next in the series.

The block 58 resting on the rollers 54 is fitted to slide up and down in frictional contact with the upwardly extending walls of casing 34 and has a face 60 beveled so as to bear on a correspondingly bevelled end 62 of an adjoining block 8d. The block 64 extends horizontally in the other arm of the casing 34. The extent to which the block 58 may be displaced upwardly in the casing is less than the depth of the aforementioned notch so that the contiguity of the blocks 58 and 64 is maintained as the one slides at right angles relatively to the other. An end 66 of the horizontally movable block 54 is contiguous with an inclined face of a spring-backed plunger 68 that projects into the casing and is the last in the series of blocks. The bevel of end 66 is equal to that of the adjacent plunger face and disposed to convert its rubbing movement into displacement of the plunger 68 in directions at right angles toward and from the casing 34.

A loaded spring it engaging the plunger 63 is compressed in a cylindrical housing 12 bolted to the casing 34. The limit of outward yielding movement of the plunger 68 is determined by a stem 14 threaded in the housing 12 to engage the spring 'Hl.

' spring 10.

In operation of the driving mechanism to lay the gun in elevation, it will be seen that as the desired or permissible extent of its movement is about to be reached, the segment gear l4 will have been swung so that one of the limiting stops 26 or 28, movable with the segment ear, will contact the bumper block 38. Further elevation (or depression) causes the stop to displace in casing 34 the notched bumper block 33 to the left (or right) and away from its inoperative position, and it will'in turn consecutively displace by frictional interaction each of the successive blocks in the series. Movement of the bumper 38 away from its central and inoperative position (shown in Figs. 1 and 3) results in a face .42 rubbing on the corresponding side 56 so that block 44 is displaced. The force exerted by the block 38 acts diagonally on the block 44 so that an entire vertical side of the latter rubs with nearly uniform pressure upon the casing wall. Theblocks 44 and 58 operate in unison,

but if they were combined into an integral memher, it is probable in some installations that'the force acting on it would set up a coupling movement such that a pair of diagonally opposite and reduced portions of its sides would be subjected to excessive, even destructive, pressures locking the member against movement relatively to the casing. In order to obtain a broadly distributed frictional resistance along the vertical sides and avoid the possibility of cramping action, it is preferable that the block 58 be permitted to shift laterally a small amount upon the interposed rollers 54 during displacement of the blocks.

When the block 64 is moved by the pressure and interaction of the face 60 on the end 62, block 64 likewise sustains a friction load that resists movement along the horizontal walls of casing 34, and its other end t6 slides relatively to the complementary bevelled plunger 58 to displace the latter onl to the extent yieldingly permitted by the The compression with which the spring '50 resiliently acts to absorb and cushion the impact of the displaced plunger may be suitably variedby turning the stem 14. It is to be noted that the ultimate energy potentially stored in the spring in will have been very considerably reduced from that of the thrust of the limiting stop 26 or 28 on the block 38, the diiference in energy having been frictionally spent by the blocks and casing 34. The braking power of such friction and spring compression accumulates quickly to render the motor 24 ineffective and/or overcome the momentum of the moving mass. The greater the thrust of a stop on the bumper block, the greater will be the opposing force set up by friction of the blocks with the casing 34, by friction between contiguous sliding blocks, and by compression of spring Hi.

The position beyond which no further elevation (or depression) of the gun It may be effected is predetermined by the limits of displacement allowed the blocks and a corresponding limit of compression in the spring it. When the mass to be stopped is not moved with suificient energy to cause these limits of displacement and compression to be quite reached, its motion will be stopped by the spring compression and the retarding friction which, as will now appear, likewise prevents backlash or rocking movements. During braking and while motion is only in the direction of displacement of the wedge-like blocks, the energy of the mass being braked that is not spent in friction will be absorbed in comif no energy were dissipated in friction during 4 braking displacements of the blocks would it be possible for the spring Ill to receive and discharge energy adequate to reverse the direction of their displacement.

The amount of displacement in the blocks and the reacting force in the spring 10 tending to overcome and reverse such displacement depend on the degree of bevel in the frictionally interacting faces of the blocks. Having each of them bevelled 45 provides displacements in the blocks which are respectively equal to that of the spring 10. While other bevels, and fewer or more blocks of different contour, may be employed in some applications to meet braking requirements, 45 bevels are generally preferred since they make for ease of construction, usually aid in fully utilizing installation space available for the brake, and provide an advantageous combination in the factors of frictional resistance and extent of braking displacement. With lesser bevels on the acting faces, it will be understood, the smaller and easier displacements necessitate a stiffer spring 10, or one having an initially greater load, if the same braking power is to be elfected. Conversely, with bevels greater than 45 for the acting faces, larger displacements affording greater frictional resistance would permit the spring 10 to provide a smaller reacting force.

In many installations of the braking mechanism it may prove impractical to confine the wedge-like cams within bearing Walls of a casing, and indeed it may be advantageous to use a casing of other configuration, such as one that is T-shaped or W-shaped, or to substitute a plurality of bearing surfaces which are not even interconnected for suitably constraining cam displacements. An obvious advantage afforded by the casing, however, is that it excludes dirt and lubricants which might adversely affect the uniform friction desired along the bearing surfaces.

Within a very few degrees of segment gear turning after the stop 26 or 28 has contacted the bumper block 38, the further laying of the gun will have been stopped, and the forces being in equilibrium, only a small external force need be supplied by the motor 24 or otherwise to return the parts of the braking mechanism quickly to their initial positions. It will be clear that operation would not differ if the stops 26, 28 were to remain stationary and the casing 34 swung with the bumper block 38 upon gun movement to effect engagement with the stops; such an arrangement might prove a convenient alternative in a gun mount.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a gun mount having a frame element and a reversibly movable segmental element for swinging a gun supported on said frame element, mechanism for limiting the travel of said segmental element in either direction including a pair of spaced stops carried by one of said elements and an intermediate braking mechanism associated with the other of said elements, said braking mechanism comprising a double-ended bumper block displaceable in either of two opposite directions on engagement by one or the other of said stops, yieldable means for opposing such movement of the bumper block, said lastnamed means including a series of frictionally interacting wedge-like cams one of which bears on the face of a V-shaped notch in said bumper block and another of which is backed by a resilient member, and walls for constraining the series of cams to displacements against the resistance of said resilient member.

2. Mechanism as set forth in claim 1 further characterized in that confronting cams of the series tending to bind against said walls have interposed between their confronting cam faces means for relieving the binding pressure.

3. Mechanism as set forth in claim 2 further characterized in that the pressure relieving means comprises rollers having line contacts with said confronting cams.

4. In a gun mount having a frame element and a segmental element reversibly movable with the gun, mechanism for limiting the travel of said segmental element in either direction including a pair of spaced stops carried by one of said elements and an intermediate braking mechanism associated with the other of said elements comprising an angular casing confining a doubleended block provided with a V-shaped notch, said block being displaceable relatively to the casing on engagement by one or the other of said stops, and yieldable means constrained within the easing including resiliently movable means and a series of frictionally interacting wedge-like cams for opposing movement of the bumper block by bearing on a face of its V-shaped notch.

FRED C. EASTMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,123,853 Courson Jan. 5, 1915 1,263,374 Christy Apr. 23, 1918 1,410,436 White Mar. 21, 1922 1,561,713 Gorton Nov. 17, 1925 1,673,507 Haseltine June 12, 1928 1,826,837 Stebbins Oct. 13, 1931 1,875,096 Miller Aug. 30, 1932 2,372,096 Lessman et al Mar. 20, 1945 2,391,956 Eastman Jan. 1, 1946

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