Laboratory turret shaker

A mechanical shaker mechanism used in the laboratory for imparting oscillry motions to a military tank turret. The mechanism can be programmed to duplicate test track conditions at lesser cost then would be required to operate a complete tank on a proving ground. The mechanism is designed to include special link mechanisms between the power devices and the turret-support ring. Other stabilizer link mechanisms are provided between the turret-support ring and stationary anchorage points.

BACKGROUND AND SUMMARY OF THE INVENTION 
This invention relates to a tank turret shaker designed to oscillate a 
conventional turret in pitch and roll planes. The turret thus is caused to 
undergo stresses similar to those experienced when a complete tank 
traverses rough terrain at high or medium speeds and high 
acceleration/deceleration rates. The shaker may be used to test the 
structural integrity of equipment (computers, range finders, etc.) mounted 
in the turret. 
Use of a turret shaker is advantageous compared to actual testing of a 
complete tank on a proving ground in that the shaker can be automatically 
programmed and left unattended on a round-the-clock basis, thereby 
accelerating a given test sequence. The shaker can be programmed to 
achieve a pre-specified test; that test can be precisely repeated in a 
fashion not possible when a human driver attempts to run a tank over a 
test track at pre-specified speeds. Comparative test data can be obtained 
without degradation of a proving ground facility or change in the terrain 
profile due to degeneration of the terrain. 
A principal object of the present invention is to provide a turret shaker 
that can withstand high stresses associated with rapid oscillation of a 
turret weighing in the neighborhood of ten tons. Another object is to 
provide a relatively large size shaker that can be fabricated without 
close manufacturing tolerances or excessive dimensional control accuracy. 
A further object is to provide a shaker that is relatively light and has a 
relatively low moment of inertia.

THE DRAWINGS IN GREATER DETAIL 
FIGS. 1 and 2 illustrate a tank turret shaker that comprises an annular 
platform 10 sized to receive a conventional turret 12. Platform 10 is 
supported by means of three upright fluid cylinders 14, 16 and 18. Two of 
the three cylinders are shown in elevation in FIG. 1. All three cylinders 
are shown in FIG. 2. Vertical reciprocatory motions of the fluid cylinders 
cause turret 12 to undergo motions similar to those motions that occur 
when a tank traverses rough terrain. 
As seen in FIGS. 1 and 8, platform 10 includes a flat annular upper plate 
20, a flat annular lower plate 22, and a curved connector plate or 
cylinder 24. As seen in FIG. 2, plate 24 has an arcuate (circular) annular 
configuration; as seen in FIGS. 1 and 8, plate 24 has a flat cross 
sectional configuration. Reinforcement plates (gussets) 23 are provided at 
spaced points around the platform. FIG. 2 shows six reinforcements 23; 
however, more reinforcements may be used if necessary (depending on the 
turret weight and gage thickness of plates 20, 22 and 24). 
The conventional turret is fragmentarily shown in FIG. 8 to include an 
annular support ring 30 suitably secured to plate 20 by means of a bolt 31 
extending through plate 20. In practice, a number of such bolts would be 
provided at equally spaced points around platform 10. The turret has a 
cylindrical basket 36 depending therefrom. When the turret is bolted onto 
platform 10 basket 36 extends downwardly through the space circumscribed 
by plates 20 and 22. The basket includes a floor 38. 
FLUID CYLINDER ACTUATORS 
The three fluid cylinders 14, 16 and 18 may be double acting or single 
acting. Each fluid cylinder comprises a cylinder structure 40 and piston 
rod structure 42. Each cylinder is supplied with hydraulic fluid from a 
pressure source (not shown). Fluid flow into or out of each cylinder is 
controlled by one or more solenoid valves. 
When the solenoid valves are closed, fluid is trapped in the associated 
cylinder; under such conditions, structure 42 maintains a stationary 
position. The structure can be held stationary in a raised position, an 
intermedite position or a lowered position, depending on the quantity of 
liquid trapped within the cylinder. 
Typically, the weight of the platform-turret assembly is in the 
neighborhood of ten tons. The fluid source pressure is typically about 
3,500 p.s.i. The control valves may be controlled by any suitable 
programming device, such as a motor-driven tape (or disk) having spaced 
openings or magnetized areas thereon designed to pass over a sensing head 
(not shown). Electrical pulses are generated to selectively (alternately) 
energize the various control valves. The tape will have three control 
tracks thereon, one for each fluid cylinder 14, 16 or 18. 
The present invention is not concerned with the control valve mechanism. 
The present invention is particularly concerned with special link 
mechanisms designed to support and stabilize platform 10 (and associated 
turret 12) while pressure fluids are flowed to or from cylinders 14, 16 
and 18. 
LINK STRUCTURES 
A support link 50 is associated with each fluid cylinder 14, 16 or 18. Each 
support link is connected to the superjacent platform 10 by means of a 
universal joint 52. Each support link 50 is connected to the subjacent 
cylinder by means of a universal joint 54. Each universal joint may be a 
commercial item sized to handle the expected load. A characteristic of 
such universal joints is that the elongated link can swing in any given 
direction relative to the attached structure. For example, as seen in FIG. 
1, the rightmost link 50 can swing around the geometrical center of joint 
52 in the plane of the paper, or in a plane normal to the plane of the 
paper, or in planes obliquely angled to the plane of the paper. 
FIGS. 8 and 9 illustrate one form that each universal joint 52 or 54 can 
take. As shown, the joint comprises a spherical element 53 having a 
transverse hole adapted to receive a bolt 55. Cylindrical bushings 
(spacers) 57 are located within openings in a yoke 59 in surrounding 
relation to bolt 55. A nut 61 is tightened onto bolt 55 to thereby clamp 
spherical element 53 within the yoke. 
Link 50 carries a socket element 63 that slidably encircles spherical 
element 53. The link can swing around the center of spherical element 53; 
the swinging motion can occur in the plane of the paper (FIG. 9) as 
designated by numeral 65, and/or normal to the plane of the paper. 
The non-illustrated (lower) end of each link 50 will have a universal joint 
constructed generally as shown in FIG. 9. The yoke portion of the 
universal joint will be suitably affixed to the associated structure 42 
(FIG. 1). 
The three support links 50 transmit the weight of platform 10 and turret 12 
to the associated fluid cylinders. However, links 50 lack the lateral 
rigidity necessary to prevent lateral (horizontal) displacement of the 
platform-turret assembly. To stabilize the platform-turret assembly 
against undesired horizontal shift, I provide two stabilizer links 56 and 
58. 
Stabilizer link 56 is shown in FIG. 2 as an A-frame structure arranged with 
its wide end attached to platform 10 and its narrow end connected to a 
fixed anchorage structure 60. The A-frame may be formed of bars or tubes. 
As shown in FIG. 2, the frame is formed to include two flat bars 62, two 
convergent tubes 64, and a tubular cross piece 66. The convergent ends of 
tubes 64 are rigidly joined to a plate 68. The various elements 62, 64, 66 
and 68 may be formed into a unitary link structure by conventional welding 
operations. The wide end of the A-frame link structure is connected to 
platform 10 by means of two universal joints 67. The narrow end of the 
A-frame structure is connected to anchorage structure by means of a 
universal joint 65. 
FIGS. 5 and 6 illustrate the construction used for universal joints at the 
wide and narrow ends of the described A-frame structure. Each universal 
joint is similar to that shown in FIG. 9 (for link 50). Similar reference 
numerals are employed to designate similar component parts. 
Due to imprecision in the manufacturing process, the two plates 62 may not 
be spaced apart exactly the distance specified by the equipment designer. 
To compensate for slight dimensional differences, the universal joint for 
one of the plates 62 is built without bushings 57. For example, if one of 
the two universal joints is built as shown in FIG. 5, the other universal 
joint (for the non-illustrated plate 62) is built without bushings 57. The 
non-illustrated universal joint enables the associated plate 62 to 
"float", i.e., to take a position somewhat offset from the longitudinal 
centerline of the associated yoke 59. This is not detrimental to joint 
performance since the joint is loaded primarily in the direction of plate 
62 (i.e., longitudinally). 
Link 58 (shown in FIG. 2) is constructed as an elongated hollow tube 86. 
Each end of the tube is attached to the associated yoke structure 88 or 92 
by means of a universal joint 91. FIG. 7 illustrates the outline 
configuration of one joint; the other universal joint is similarly 
configured. Internally each universal joint may be the same as shown in 
FIG. 5 or FIG. 6. Each universal joint comprises a flat plate 89 suitably 
welded to the associated end of tube 86. 
Referring especially to FIG. 2, anchorage structures 60 and 88 are rigidly 
attached to stationary portions of the building in which the apparatus is 
housed. The stationary building portions can be walls of the building, 
columns, posts, etc. The A-frame link 60 and tubular link 58 are elongated 
structures, each approximately as long as the diameter of platform 10 
(e.g., about eight feet). By making the links relatively long, it is 
possible to minimize the disturbing effect that link motions have on the 
position or attitude of platform 10. 
CYLINDER ARRANGEMENT AND OPERATIONAL MODE 
The various fluid cylinders 14, 16 and 18 cooperate with the associated 
links 50 to define three separate support structures for platform 10 and 
turret 12. As seen in FIG. 2, the cylinders are spaced equidistantly 
around the platform circumference, i.e., the cylinders are spaced one 
hundred twenty degrees apart, as measured from platform central axis 15. 
Still referring to FIG. 2, if the longitudinal axis 72 for A-frame link 56 
is continued rightwardly through and beyond platform axis 15, it will be 
seen that axis 72 intersects the line of action of cylinder 16. Cylinder 
16 may be considered to be on axis 72 (although diammetrically opposed to 
link 56). Axis 72 may be visualized as an imaginary line representing the 
longitudinal axis of the tank designed to accommodate turret 12. Vertical 
oscillation of the cylinder 16 mechanism causes the turret to undergo a 
pitching motion similar to the motion that would occur if the turret were 
mounted in an actual tank moving over rough terrain. The pitch action can 
be accomplished by operating only cylinder 16 (cylinders 14 and 18 being 
held motionless). The pitch action can also be accomplished by operating 
all three cylinders (e.g., with cylinder 16 moving oppositely to cylinders 
14 and 18). 
The general operational mode can be visualized from FIGS. 3 and 4. The 
turret is tilted in opposite directions from its so-called "level 
attitude" position shown in FIG. 1. By programming the control valves for 
cylinders 14, 16 and 18, it is possible to oscillate the platform-turret 
assembly between the FIG. 1 "level attitude" position and the FIG. 3 
"tilted" position. Such an oscillatory motion produces "pitch" forces on 
the turret that approximate forces generated when an actual tank traverses 
rough terrain. 
During the described pitch motion, the stabilizer links 56 and 58 prevent 
lateral dislocation of the platform-turret assembly. Link 56 has a slight 
swing motion in a vertical plane. Link 58 undergoes a slight circular 
(rotational) motion around its longitudinal axis, and a slight lateral 
swinging motion (in a horizontal plane). 
While the turret is in its FIG. 1 "level attitude" position, links 56 and 
58 are in a common horizontal plane with platform 10. Anchorages 60 and 88 
are located in horizontal planar alignment with platform 10, to thereby 
determine the normal at-rest link orientation. As seen in FIG. 2, the two 
stabilizer links 56 and 58 are disposed in right angular relation to one 
another. The longitudinal axis 72 for link 56 may be visualized as the 
tank longitudinal axis. The link 58 axis 75 may be visualized as a tank 
"pitch" axis. 
To accomplish a "roll" motion around longitudinal axis 72, the two 
cylinders 14 and 18 may be simultaneously operated in opposite directions, 
with cylinder 16 held motionless. During such a roll motion link 56 
swivels around axis 72. Link 58 swings in a vertical plane going through 
the aforementioned pitch axis 75. 
If it is desired to achieve simultaneous pitch and roll motions then all 
three cylinders 14, 16 and 18 may be operated simultaneously (although not 
in phase with one another). 
During the pitching or rolling motions, it is desirable that weight support 
links 50 remain approximately vertical. Slight tilting motions of the 
support links, as shown in FIG. 4, are not objectionable. However, if the 
support links were to swing more than a few degrees from the vertical 
(e.g., fifteen degrees) the link lines of action would be undesirably 
oblique to the action lines of piston structures 42. Bending stresses 
would be imposed on the links. Also, oblique frictional forces would be 
generated at the piston-cylinder slide surfaces. Since the pistons 
normally operate at relatively high peak velocities, e.g., more than 
twenty feet per second, high frictional forces could produce undesirable 
wear actions. 
To minimize excessive lateral swing motions of support links 50, the 
support links are designed to be relatively long. As seen in FIG. 1, each 
link 50 has its lower universal joint 54 below the level of basket floor 
38 (when the basket is in a level attitude). Each link 50 has its upper 
universal joint 52 connected directly to platform 10. Each support link 50 
is relatively long, e.g., thirty three inches in a typical system. 
Excessive lateral swing motions of support links 50 are also prevented by 
constructing each stabilizer link 56 or 58 as a relatively long structure, 
such that pivot structures 67 and 91 move substantially vertically, with 
minimum lateral motion components. In a typical system, each stabilizer 
link has a length approximately the same as the outside diameter of 
platform 10. Exact dimensions are not critical. 
SIMILARITIES WITH PRIOR ART 
U.S. patent application, Ser. No. 611,572, filed in the name of Henry Borg 
on May 18, 1984 now U.S. Pat. No. 4,507,086, granted Mar. 26, 1985, 
illustrates an arrangement that utilizes three rigidly-mounted fluid 
cylinders (or multiple cylinder actuators). In this sense, the Borg 
arrangement is similar to my presently proposed arrangement. My 
arrangement differs from the Borg arrangement in the use of support links 
50 and stabilizer links 56 and 58. 
The use of support links 50 enables the various fluid cylinders 14, 16 and 
18 to be located relatively close to the central axis of platform 10 (15 
in FIG. 2). By locating the cylinders close to the platform axis, it is 
possible to achieve a given platform tilt motion with a relatively small 
piston stroke. Higher effective accelerations are possible with a given 
piston motion speed. 
U.S. Pat. No. 3,295,224 to K. L. Cappel, shows an arrangement wherein six 
fluid cylinders are used; the cylinders are grouped in pairs (for a total 
of three cylinder pairs). Each cylinder is angled obliquely to a vertical 
motion line for the support platform; each fluid cylinder has a universal 
joint connection with the floor and the supported platform. 
The arrangement shown in the Cappel patent is believed to be 
disadvantageous in that a rather complex control valve system would be 
required to achieve any given platform motion; a minimum of two cylinders 
is required to achieve the simplest motion. In Cappel, the cylinders in 
each pair of cylinders are required to travel different distances; it is 
believed that some degree of cylinder synchronization would be required to 
accomplish even the simplest motion (if loadings were to be kept fairly 
even). My proposed arrangement is believed to be advantageous over the 
Cappel arrangement in that cylinder loadings can be maintained fairly 
even; for any specific motion only one cylinder has to be actuated. 
Cylinder synchronization is not a prerequisite for operability. 
In the Cappel arrangement, six control tracks are required, one for each 
cylinder. In my proposed arrangement, only three control tracks (or tapes) 
are needed. 
Since the Cappel fluid cylinders are obliquely angled to the vertical 
motion lines of the supported platform, relatively long piston strokes are 
required to achieve a given vertical motion of the platform. My proposed 
arrangement can use shorter stroke fluid cylinders than the Cappel 
arrangement. 
In my proposed arrangement, each upright fluid cylinder is directly below a 
section of platform 10. Support links 50 extend directly upwardly from the 
fluid cylinders. The platform is constructed to have an I-beam 
cross-section for maximum resistance to bending, twisting, or other 
undesired distortion. Reinforcement ribs 23 are provided at points where 
links 50 deliver impact forces to the platform. The platform is designed 
for manufacture as a light weight structure having a low moment of 
inertia. 
I wish it to be understood that I do not desire to be limited to the exact 
details of construction shown and described for obvious modifications will 
occur to a person skilled in the art, without departing from the spirit 
and scope of the appended claims.