Gear tester controlling selected degrees of freedom

A gear suspension system is disclosed that permits movement of a gear, such as a spiral bevel or hypoid gear relative to its pinion with up to four degrees of freedom. Specifically, the gear suspension system includes a support frame with a movable carriage mounted thereon. The carriage includes a lower carriage member connected to an upper carriage member with suspension struts. The gear is mounted to the upper carriage member for rotation about a central axis. Actuators connected to the lower carriage member adjust the gear mounting distance and the shaft angle between the pinion and the gear, while actuators mounted to the upper carriage member adjust the H and V positions of the pinion relative to the gear.

CROSS-REFERENCE TO RELATED APPLICATIONS 
Reference is made to my co-pending applications Ser. No. 07/928,808, filed 
Aug. 12, 1992 entitled GEAR TESTER WITH ACTUATOR SUPPORTED PLATFORM; Ser. 
No. 07/928,900, filed Aug. 12, 1992 entitled RIGID TEST TABLE FOR GEAR 
SETS; and Ser. No. 07/929,151, filed Aug. 12, 1992 entitled CONTROLLABLE 
GEAR TESTING SYSTEM. 
BACKGROUND OF THE INVENTION 
The present invention relates to a gear tester for controlling the vertical 
and horizontal positions of mating gears, such as hypoid or spiral beveled 
gears, verify the quality of a given gear set under fixed and known 
mounting conditions to determine sensitivity of the gears to various 
programmed misalignments, changes in mounting conditions and the like 
which simulate deflections during use. 
In the prior art, it has long been the practice to test on a substantially 
100 percent basis, spiral bevel and hypoid gears to determine running 
qualities, such as tooth-bearing contact. It has further been known to use 
machines for running sets of bevel or hypoid gears together to determine 
optimum running positions of one gear relative to another. Such a device 
is shown in U.S. Pat. No. 3,795,143. The device in this patent permits 
adjusting the axes of the pinion and gear relative to each other for the 
offset of axes, as well as the positioning of the degree of intersection 
of the gear. However, this procedure involves the use of large slides and 
manual controls for the final positioning. 
In order to determine the effect of various tolerances or differences in 
gear and pinion positions, the need has existed for accurately controlling 
the position of the gear in several degrees of freedom, while determining 
loads on the gears as well as simultaneously determining other performance 
factors of the gears. Such performance factors may be noise, the 
"footprint" of the pinion on the gear, and deflections that might occur on 
the gear itself caused by loading on the gear. Thus, measuring the loads 
on the gear in the controlled degrees of freedom is beneficial in 
determining factors that may be necessary for housing designs to minimize 
deflections and alignment problems. 
Finally, in matched sets of gears, an optimum running position of pinion 
and the gear can be determined and used for final adjustment when 
assembled in a housing for use so that other than the nominal axial offset 
and positioning of the gears can occur. 
SUMMARY OF THE INVENTION 
The present invention provides for a gear suspension system that permits 
movement of a gear (a ring gear), such as a spiral bevel or hypoid gear 
relative to its pinion in two degrees of freedom, commonly known as a 
hypoid offset and pinion axial position. The invention permits the 
computerized control of servo actuators in response to input positioning 
control signals, and changing the control signals while the pinion is 
being powered to rotate the gear. The system is further controllable to 
obtain two additional degrees of freedoms, commonly known as the gear 
mounting distance and the shaft angle. In addition, the gear can be loaded 
in a suitable manner, such as by a brake, for testing under a load. 
Although the present invention will be described with respect to a hypoid 
or spiral bevel gear tester, principals forming the present invention are 
equally suited for testing other types of gears. Therefore, it is to 
understood that the present invention is not limited to nor intended to be 
limited to a gear tester for hypoid or spiral bevel gears. 
The system permits determining whether the gears are properly mating when 
set at a nominal setting. The apparatus permits controlling the hypoid or 
spiral bevel offset, which is the offset of the pinion axis from the gear 
axis in the plane passing through the gear axis and parallel to the 
spindle rotational axis, commonly called a vertical position ("V"); and 
the position of the gear axis along the pinion axis, which is commonly 
called the pinion axial position ("H") and can generally be referred 
relative to a reference plane perpendicularly to the pinion spindle axis, 
generally the plane surface supporting the back surface of the pinion. In 
other words, the distance of the gear axis from the reference plane at the 
pinion support surface is the pinion axial position, H. The terminology 
for horizontal and vertical positions are traditional references used in 
describing relative pinion and gear positions and are not intended to be 
limitations of the present invention. 
Further control of the apparatus provides two additional degrees of 
freedom. Specifically, the apparatus permits controlling movement of the 
gear along the gear rotational axis, which position is essentially the 
gear mounting distance, that determines the backlash ("Q"); and 
controlling the shaft angle ("S"), which is the angle of the axis of the 
gear shaft or spindle relative to the axis of rotation of the pinion. 
The present invention achieves these mounting conditions by providing a 
pinion spindle housing which is mounted on a mounting assembly that will 
permit movement of the pinion along the pinion shaft or spindle axis, and 
also will permit movement in a direction perpendicular thereto. The pinion 
spindle housing is movable relative to a main support table as to which 
the gear support is mounted for its necessary degrees of freedom. A unique 
linkage arrangement utilizing several controlled actuators which can be 
operated in response to digital overall controls in a known manner is 
provided for precisely relating the position of the gear to the pinion and 
determining necessary gear mating factors. The computer controls also can 
control the speed of rotation of the pinion and thus the gear, the load 
applied to the gear, and feedback devices are provided for determining the 
position of the various actuators. Torque sensing also can be provided for 
determining the loads on the gears.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A gear tester of the present invention is schematically illustrated in 
FIGS. 1-3 generally at 9. A support frame or table 10 is mounted on 
suitable pedestals 11, to make a stable platform 13 for elements of the 
present invention. The platform 13 supports a pinion spindle housing 12 
for movement in two mutually perpendicular axes in a plane parallel to an 
upper surface 10A of the table 10 to obtain a coarse setting of the 
pinion. 
When the gear testing system such as that shown in the present disclosure 
is initially set up, the procedure has to be considered as a two step 
operation. First, there are coarse settings which would establish relative 
orientation of the pinion axis versus the gear axis. For the pinion, this 
setting involves positioning the pinion housing 12 on the table 10. 
Whereas, the coarse setting for the gear is the height of the gear arbor. 
In these positions, the pinion and gear are close enough to the desired 
positions of the pinion and gear spindle to permit the gears to run. Since 
the accuracy of these settings is not very high, further adjustment is 
required to improve the relative position of the gears. This is done by a 
second positioning procedure called the fine settings movement. The 
operator has to establish the amount of movement to be produced by the 
fine setting mechanism upon the gear and thus has to determine the 
deviation of the setting after the coarse adjustment. The gear positions 
have to be measured and compared with the desired position. Both the 
coarse settings and the fine settings are described in detail in my 
co-pending application entitled CONTROLLABLE GEAR TESTING SYSTEM filed the 
same day as the present application and which is hereby incorporated by 
reference. 
Referring to FIGS. 2 and 5, the pinion spindle housing 12 is located within 
four guide rails 20A, 20B, 20C and 20D that are connected together to form 
a guide rail frame 21. The guide rail frame 21 is secured to the table 10 
with mounting pegs 23. Replaceable spacer bars 24 disposed between side 
edges 12A of the pinion spindle housing 12 and the side guide rails 20A 
and 20C orient the pinion spindle housing 12 substantially parallel to a 
longitudinal axis 26 of a pinion spindle 16 and pinion 18. Typically, the 
pinion 18 and its spindle 16 are manufactured as a single piece. 
Clamping bars 14 positioned over the side guide rails 20A and 20C and the 
spacer bars 24 secure the pinion spindle housing 12 to the table 10. Each 
clamping bar 14 includes an extending edge 25 that engages corresponding 
flanges 12B of the pinion spindle housing 12. Mounting bolts 27 through 
the clamping bars 14 and the spacer bars 24 secure the position of the 
pinion spindle housing 12 to the table 10. As illustrated, sufficient 
contact between the clamping bars 14 and the pinion spindle housing 12 is 
maintained on flanges 12B, while allowing the spacer bars 24 to be 
replaced when desired to allow transverse positioning of the pinion 
spindle housing 12 in the directions indicated by double arrow 22. In 
addition, the pinion spindle housing 12 has a longitudinal length less 
than the distance between guide rails 20B and 20D to allow longitudinal 
positioning of the pinion spindle housing 12 in the directions indicated 
by double arrow 15. 
In the embodiment as illustrated, positioning of the pinion spindle housing 
12 is made easier through pneumatic lifts. With the clamping bars 14 
removed, air from a suitable compressor, not shown, is forced into 
recesses 29 formed within the base plate of the pinion spindle housing 12. 
The forced air within recesses 29 causes upward movement of the pinion 
spindle housing 12, allowing convenient relocation of the pinion spindle 
housing 12 on the table 10. When the desired position of the pinion 
spindle housing 12 has been obtained, air pressure is removed within 
recesses 29 to lower the pinion spindle housing 12 onto the table 10. As 
described above, suitable spacer bars 24 are then located between the 
pinion spindle housing 12 and the guide rails with the clamping bars 14 
securing the assembly to the table 10. 
Pinion spindle housing 12 further carries a motor of suitable power 
indicated generally at 28, which in turn drives a pulley and belt drive 30 
to drive a shaft 32 that is coupled to the pinion spindle 16. An optical 
shaft speed encoder 34 is provided to determine the pinion spindle 16 
rotational speed. The motor 28 is controllable as to speed, through 
controls of which will be explained below, and has adequate power to load 
the pinion 18 as well as a gear indicated generally at 36, that are to be 
tested. 
Referring to FIG. 3, the gear 36 is mounted to a gear spindle 38 in a 
suitable way, while the gear spindle 38 is mounted in a gear carriage 40 
using suitable bearings. The gear carriage 40 is independent of the frame 
10, but is supported relative thereto, and in this instance the gear 
carriage 40 is supported with up to four degrees of freedom relative to 
the fixed position of the pinion 18, after nominal settings have taken 
place. 
The gear 36 has a central axis 42 that is the center of the gear spindle 
38, which is offset from the axis 26, as illustrated in FIG. 2. A gear 
pack surface indicated at 44 of gear 36 is also mounted by a distance 46 
from the pinion axis 26 The distance indicated by the arrow 46 is commonly 
known as the gear mounting distance. An angle, indicated by arrow 45, 
between the gear axis 42 and the plane containing the pinion axis 26 is 
known as the shaft angle. 
Referring to FIGS. 2 and 3, the gear carriage 40 is supported on four 
individual struts 48 at the four corners of the gear carriage 40. Struts 
48 are pivotally mounted onto the gear carriage 40 with universal pivotal 
connections 50. At ends opposite carriage 40, the struts 48 are connected 
to a lower carriage 52 with suitable pivot connections 54 to form a gear 
system carriage 53. The struts 48 pass through clearing openings 51 in the 
frame 10. 
Gear carriage 40 is guided by a pair of stiff pivoting links 56 and 58 
illustrated in FIGS. 3 and 4. Link 56 is pivotally mounted about an axis 
that is generally parallel to the plane of surface 44, as shown at 60. The 
end of the link 56 is in turn supported back to the platform 13 with a 
standoff mount 62. The opposite end of the link 56 is pivotally mounted 
about an axis generally parallel to the axis 60 with a connection joint 
shown at 64. 
A servo-controlled actuator 66 controls movement of the link 56 about the 
axis 60 and 64. The servo-controlled actuator 66 has one end connected to 
the underside of the frame 10, and the other end pivotally mounted to the 
link 56. 
The link 58 has one end pivotally mounted at connection 70 to a frame 
standoff 72, and has its other end universally pivotally and slidably 
mounted on one or more suitable slide members 73 that are guided in pads 
74, which in turn are supported in a slot 76 in the lower carriage 52. The 
sliding movement is needed as orientation of the lower carriage 52 may 
change during use. An actuator 77 is used for controlling pivotal movement 
of the link 58 about an axis of pivot connection 70, which also controls 
the axial movement of the struts 48 connected to lower carriage 52. 
The struts 48 transfer the displacement of lower carriage 52 to the gear 
carriage 40. The struts 48 can be adjustable in length for an initial 
setting, to calibrate the system. The spherical joints 50 and 54 are 
positioned at each end of each strut 48 for relative movement between the 
gear carriage 40 and the lower carriage 52, as desired. 
In order to obtain the two degrees of freedom for the gear systems carriage 
53, two actuators are required. These actuators operate in a plane 
parallel to the surface 44, and are shown in FIG. 2 schematically. A 
servo-valve controlled actuator 80 is connected as at 82 to the frame 10. 
The actuator 80 has a rod end 86 that is universally pivotally mounted to 
a bracket 84. The bracket 84 is fixed to the gear carriage 40. The 
actuator 80 controls movement of the gear system carriage 53, 
specifically, the carriage 40, in a direction indicated by arrow 81 which 
is the distance of the gear axis 42 from a reference plane at the pinion 
support surface 83 typically referred to as the H position. 
An actuator 90 is mounted as at 92 to the frame 10. The actuator 90 
controls movement in the direction indicated by arrow 85, which is the 
offset of the pinion axis 26 relative to the gear axis 42 typically 
referred to as the V position or hypoid offset. The actuator 90 is also 
connected to a bracket 94 which is fixed to the gear carriage, as at 96, 
and when the actuator is operated through a servo-control and servo-valve 
which is well known, it can change, modify, and set the V position of the 
pinion, relative to the gear 36. 
The ability to control the V position of the gear carriage 40 relative to 
the pinion spindle 16 and thereby dynamically adjust the shaft angle and 
the gear mounting distance 46 can be accomplished through the actuators 66 
and 77. For example, simultaneous, equal operations or displacement of the 
actuators 66 and 77 in the same directions will cause movement of the gear 
system carriage 52 up or down, which in turn decreases backlash ("Q") 46, 
respectively. Whereas, differential operation or displacement of the 
actuators 66 and 77 in opposite directions will cause rotation of the gear 
system carriage 52, thereby adjusting the shaft angle 45. Thus, the entire 
lower carriage 52 can be positioned in space through the use of links 56 
and 58. The movement and location of the pivot axis 64, which will move 
parallel to itself in an arc around the axis 60, and the angular position 
of the lower carriage 52 about the axis 70 is controlled by the actuator 
76. Adjustment of the shaft angle 45 and the backlash or gear mounting 
distance 46 are two additional degrees of freedom for the gear system 
carriage 53. 
It should be noted that there exists crosstalk, so that when the gear 
carriage 40 is moved by either actuators 80 or 90, the gear carriage 40 
will move in a type of arc because of the struts 48, and thus the 
compensation by the actuator 66 and 76 must take place to correct the gear 
carriage 40 position and provide for proper backlash control between the 
pinion 18 and the gear 36. A digital control system indicated generally at 
100 in FIG. 1 is used for controlling the various servo-valves to the 
actuators as well as speed control to motor 38 and brake loading on the 
gear 36 to be described below. 
As stated, the shaft angle S is controlled by differential movement of the 
actuator 66 and 76, the backlash Q is controlled by simultaneous movement 
of actuators 66 and 76, hypoid offset change V is changed by the actuator 
90, and the pinion axis or pinion mounting distance H is determined by the 
actuator 80. The relationship can be symbolically written as: 
EQU V=V (u.sub.1,u.sub.2,u.sub.3,u.sub.4) 
EQU H=H (u.sub.1,u.sub.2,u.sub.3,u.sub.4) 
EQU Q=Q (u.sub.1,u.sub.2,u.sub.3,u.sub.4) 
EQU S=S (u.sub.1,u.sub.2,u.sub.3,u.sub.4) 
Where u.sub.1,u.sub.2,u.sub.3,u.sub.4 are the strokes of actuators 66, 76 
and 80 and 90, respectively. The inverse relationship can be written 
symbolically as: 
EQU u.sub.1 =u.sub.1 (V,H,Q,S) 
EQU u.sub.2 =u.sub.2 (V,H,Q,S) 
EQU u.sub.3 =u.sub.3 (V,H,Q,S) 
EQU u.sub.4 =u.sub.4 (V,H,Q,S) 
The position of each actuator is defined by a built-in LVDT or position 
sensor, which is used as a feedback sensor. These sensors are shown 
schematically at 66A, 77A, 80A and 90A. 
In addition to positional sensors, rotational sensors are provided to 
measure rotation of the pinion 18 and gear 36. The pinion encoder 34 has 
been previously described and determines the pinion 18 rotational speed. 
The gear spindle 38 has an optical encoder indicated schematically at 102 
in FIG. 3. The spindle 38 further includes a brake assembly, which is 
shown schematically at 103 comprising a brake disk 105 and calipers 106. 
The feedback signals provided to the digital system 100 from the pinion 
sensing encoder 34 and the gear sensing encoder 102 are used as system 
parameters for controller 100 which then can place loads on the gears 
through brake assembly 103 or adjust the speed of the gears through motor 
28 for adequate testing. 
The coarse settings or nominal settings of Q, S, V and H between the pinion 
18 and the gear 36 are provided by movement of the stationary pinion 
utilizing the pinion spindle mounting assembly previously described. 
Additionally, each of the actuators and the struts can include load cells 
as shown schematically in FIG. 1. These load cells are indicated generally 
at 104 and can be used for determining the individual loads applied by 
each of the actuators and carried by each of the individual struts. 
A network to the digital controller 100 can be applied. The optical 
encoders 34 and 102 measure the transmission errors, and accelerometers 
can be utilized to measure vibration. Microphones can be used to analyze 
the acoustic noise, and different positions of the gear 36 relative to the 
pinion 18 can be tried with different results being recorded. In this 
manner gear sets can be provided with specific mounting positions for 
minimizing noise, and comparative tests also can be run to determine if 
one gear cutting machine, for example, is providing noisier or more 
vibration plague to gear sets than others. 
Suitable standards, of course, can be applied so that the results can be 
compared. 
It is common to control the input shaft for the pinion 18 as to its speed, 
and the gear spindle 38 is controlled as to load and torque. This can be 
done by the use of a braking device shown, or it could be a suitable 
dynamometer for loading the gear 36. When the brake calipers 106 are 
mounted to react the torque to the gear carriage 40, the actuators for H 
and V directions, namely actuators 80 and 90 will be used for reacting the 
torque. The brake calipers 106 can also be reacted back to the frame 10, 
through suitable universal couplings which would still permit the gear 
carriage 40 to move as explained above. 
The gear spindle 38 is held always parallel to the gear carriage plane, and 
is moved in a dynamic manner in response to a program of remote 
parameters, for example, so that tooth pattern, noise, vibration and other 
factors can be evaluated. Further, gearbox deflections can be evaluated 
and simulated by movement of the aforementioned actuators. 
Although the present invention has been described with reference to 
preferred embodiments, workers skilled in the art will recognize that 
changes may be made in form and detail without departing from the spirit 
and scope of the invention.