Method and apparatus for applying dynamic loads to a locked gear train for testing power transmission components
View Patent ↗An apparatus for testing power transmission components of a locked gear train having two helical gears coupled on a first shaft meshed with two helical pinions coupled on a second shaft, with the two gears arranged to axially translate (while rotating) with respect to the two pinions when a linear force is applied to a thrust bearing at an end of the first shaft. The axial displacement of the two gears causes torsional displacements of the meshed gear and shaft elements, creating a dynamic torque within the locked train assembly. Under rotation, this dynamic torque subjects the components within the locked gear train to a much higher power level for testing.
1. In combination with a locked gear train ( 12 ) having two helical gears ( 36 A, 36 B) carried on a first shaft ( 46 ) and two pinions ( 32 A, 32 B) carried on a second shaft ( 42 ), with a first pinion ( 32 A) meshed with a first gear ( 36 A) and a second pinion ( 32 B) meshed with a second pinion ( 36 B), an arrangement for testing a power transmission component comprising,
a support arrangement ( 30 A, 30 B) by which the first and second gears ( 36 A, 36 B) and the first shaft ( 46 ) are free to move axially with respect to the first and second pinion gears ( 32 A, 32 B) and the second shaft ( 42 )
a thrust bearing ( 50 ) coupled to a first end of the first shaft ( 46 ), and
a prime mover ( 52 ) coupled to a second end of the first shaft ( 46 ) which applies a positive torque to the second end of said first shaft, whereby
a force (F) applied axially to the thrust bearing ( 50 ) causes axial displacement (A) of the first and second gears ( 36 A, 36 B) with respect to the first and second pinion gears ( 32 A, 32 B) while establishing a negative torque in the locked gear train ( 12 ) which opposes the positive torque to produce a power level in the locked gear train greater than that produced solely by the prime mover.
2. The arrangement of claim 1 wherein,
a spline arrangement ( 54 ) couples the prime mover ( 52 ) with the second end of the first shaft ( 46 ).
3. The arrangement of claim 2 further comprising,
a measurement device by which torque applied to the thrust bearing can be determined.
4. The arrangement of claim 3 wherein the measurement device includes
a load measuring device installed in an axial force path of the first shaft ( 46 ) for measuring force F applied to the thrust bearing ( 50 ), and the torque is determined from the measurement of F by the relationship,
-
T
=
Fr
tan
Φ
,
where
+101 +0 +32
helix angle (radian) of main and pinion gears,
r +32
radius of the main gear (ft.)
T +32
torque (ft. lbs.)
F +32
axial force (lbs.).
.
5. The arrangement of claim 3 wherein the measurement device includes
a displacement indicator ( 64 ) arranged and designed to measure a displacement distance A on the first shaft and wherein,
the torque is determined from the measurement of A by the relationship,
-
T
=
Ak
tan
Φ
r
where
T +32
torque (ft. lbs.)
A +32
axial travel (ft.)
+101 +0 +32
helix angle (radian)
r +32
radius of the main gear (ft.)
k +32
spring constant (ft. lbs./radian).
.
6. The combination of claim 1 wherein,
the two helical gears ( 36 A, 36 B) are of opposite hand and the two pinions are of opposite hand.
7. A method for testing a power transmission component comprising the steps of
installing the component in a locked gear train ( 12 ) having two helical gears ( 36 A, 36 B) carried on a first shaft ( 46 ) and two pinions ( 32 A, 32 B) carried on a second shaft ( 42 ), with a first pinion ( 32 A) meshed with a first gear ( 36 A) and a second pinion ( 32 B) meshed with a second gear ( 36 B), the locked gear train having a support arrangement ( 30 A, 30 B) by which the first and second gears ( 36 A, 36 B) and the first shaft ( 46 ) are free to move axially with respect to the first and second pinions ( 32 A, 32 B) and the second shaft ( 42 ),
coupling a thrust bearing ( 50 ) to a first end of the first shaft,
coupling a prime mover ( 52 ) to a second end of the first shaft,
applying an axial force to the thrust bearing ( 50 ) to cause axial displacement (A) of the first and second gears ( 36 A, 36 B) with respect to the first and second pinions ( 32 A, 32 B), which through helix angles of the gears causes an angular deflection in opposed directions in the gears thereby establishing a torque in the locked gear train ( 12 ) which upon rotation at a test speed produces a power level in the locked gear train greater than that produced solely by the prime mover.
8. The method of claim 7 whereby
the prime mover is coupled to the second end of the first shaft by a spline arrangement.
9. The method of claim 8 further comprising the steps of
installing a load measuring device in an axial force path of the first shaft ( 46 ),
applying an axial force to the thrust bearing, and determining torque to the locked gear train from the measurement of force F from the load measuring device by the relationship
-
T
=
Fr
tan
Φ
where
+101 +0 +32
helix angle (radian) of main and pinion gears
r +32
radius of the main gear (ft.)
T +32
Torque (ft. lbs.)
F +32
axial force (lbs.).
.
10. The method of claim 8 further comprising the steps of
applying an axial force (F) to the thrust bearing,
measuring axial displacement (A) of the first shaft ( 46 ) in response to said axial force (F), and
determining torque from the relationship,
-
T
=
Ak
tan
Φ
r
where,
T +32
torque (ft. lbs.)
A +32
axial travel (ft.)
+101 +0 +32
helix angle (radian)
r +32
radius of the main gear (ft.)
k +32
spring constant (ft. lbs./radian).
.
11. The method of claim 7 wherein,
the two helical gears ( 36 A, 36 B) are of opposite hand and the two helical pinions are of opposite hand.