Method and apparatus for evaluating railroad track structure and car performance

Claim 2

Apparatus for evaluating railroad track structure and car performance comprising a railroad car truck including two side frames, an axle and a pair of wheels mounted on said axle, a pair of load cells mounted between said axle and each side frame for providing a first signal and a second signal responsive to the vertical load of each truck side frame on said axle, a pair of electrical resistance strain gauges mounted on said axle for providing a third signal and a fourth signal responsive to the bending moments in said axle as it rotates under load, and means connected to said load cells and said strain gauges for combining said signals and calculating the vertical and lateral wheel-rail forces at each wheel.

Claim 3

Apparatus according to claim 1 in which said pair of strain gauges are mounted on a common axis on said axle parallel to the axis of said axle and spaced apart from, and in near proximity to, each wheel.

Claim 4

Apparatus according to claim 1 in which said means for calculating includes a signal amplifier and conditioner module, an analog to digital converter connected to said module and a general purpose digital process computer connected to said converter.

Claim 5

Apparatus according to claim 3 which includes a trackside reference location detector connected to said module.

Claim 6

Apparatus according to claim 3 which includes a printer connected to said computer, a cathode ray tube display connected to said computer, a digital tape recorder connected to said computer, and an analog recorder connected to said module and said converter.

Claim 9

A method according to claim 6 in which the bending moments are determined by strain gauges and the bearing forces are determined by load cells and which includes statically calibrating the strain gauges and load cells, measuring the distance between the axis of the axle and the surface of the tread of the wheel, measuring the distance between each load cell and the adjacent wheel, measuring the distance between each strain gauge and the adjacent wheel, measuring the distance between the wheel treads, and said calculating of vertical and lateral forces are performed by combining an output from each strain gauge, an output from each load cell and said measurements.

Claim 10

A method according to claim 7 in which the step of calculating the vertical and lateral forces comprises the steps of simultaneously solving the four free-body equations ML LLc + BL (a + d) - VL d MR LLc + BL (a + (f - e)) - VL (f - e) MR LRc + BR (b + e) - VR e ML LRc + BR (b + (f - d)) - VR (f -d) for LL, LR, VL, and VR where LL is the lateral force on the left wheel, LR is the lateral force on the right wheel, VL is the vertical force on the left wheel, and VR is the vertical force on the right wheel and in which equations ML is the calibrated strain gauge output adjacent the left wheel, MR is the calibrated strain gauge output adjacent the right wheel, BL is the calibrated load cell output adjacent the left wheel, BR is the calibrated load cell output adjacent the right wheel, a is the measured distance between the left wheel and the adjacent load cell, b is the measured distance between the right wheel and the adjacent load cell, c is the measured distance between the axis of the axle and the surface of the tread of the wheel, d is the measured distance between the left wheel and the adjacent strain gauge, e is the measured distance between the right wheel and the adjacent strain gauge, and f is the measured distance between the wheel treads.

Claim 11

A method according to claim 8 which includes the steps of converting the outputs of the strain gauges and load cells from analog to digital form and calculating force relationships and in which said calculations are made by a general purpose digital computer.

Claim 12

A method according to claim 9 which includes recording the outputs of the strain gauges and the load cells in digital form.

Claim 13

A method according to claim 10 which includes the steps of simultaneously recording with said outputs periodic trackside reference location indicator signals.

Claim 14

A method according to claim 9 which includes the steps of determining the vertical and lateral forces for all axles of a truck.

Claim 15

A method according to claim 9 which includes the steps of determining the lateral and vertical forces for all axles of a car.

Claim 16

A method according to claim 8 which includes calculating the net lateral force on the two wheels of a single axle according to the equation LN LR - LL where LR is the lateral force on the right wheel, LL is the lateral force on the left wheel, and LN is the net lateral force which will have a positive sign if toward the right wheel and a negative sign if toward the left wheel.

Claim 17

A method according to claim 8 including calculating the total dynamic axle load B'', according to the equation B'' BR'' + BL'' where BR'' is the deviation of the right load cell output from static value expressed as a force and BL'' is the deviation of the left load cell output from static value expressed as a force.

Claim 18

A method according to claim 8 including the steps of determining dynamic vertical forces VL'' and VR'' where VL'' is the deviation from static value of VL and VR'' is the deviation from static value of VR.

Claim 19

A method according to claim 8 including calculating dynamic axle rock according to the equation RR '' BR '' - BL'' where BR'' is the deviation of the right load cell output from static value expressed as a force, BL'' is the deviation of the left load cell output from static value expressed as a force, and RR'' is the dynamic axle rock base on the right wheel expressed as a force.

Claim 20

A method according to claim 8 including calculating the lateral to vertical force ratio, R, according to the equation R L/V where L and V are the calculated lateral and vertical forces.

Claim 21

A method according to claim 13 including calculating the transfer of vertical forces to and from leading and trailing axles.

Claim 22

A method according to claim 8 including determining the frequencies of occurrence of repetitive deviations from static values of lateral and vertical forces.

Claim 23

A method according to claim 9 in which said calculations are performed for increments of travel over said sections of track thereby providing a series of values for vertical forces, a series of values for lateral forces and a series of values for each force relationship and which includes placing each value of a series in a range group, determining the frequency of occurrence of values in said range group, determining the mean of values of said group and determining one standard statistical deviation from the mean of values of said group.

Claim 24

A method according to claim 9 in which said calculations are performed for increments of travel over said section of track thereby providing a series of lateral and vertical force values, and which includes measuring the transfer of vertical forces from one rail to the other rail on curved track.

Claim 25

A method according to claim 9 in which said calculations are performed for increments of travel over said section of track thereby providing a series of lateral and vertical force values and which includes grouping said values according to track curvature.

Claim 26

A method according to claim 9 in which the vertical forces, lateral forces, and force relationships are determined for a first car truck design criterion and a second car truck design criterion and which includes the steps of comparing said forces and force relationships for the first criterion and the second criterion.

Claim 27

A method according to claim 24 in which the design criterion is the size of the suspension springs and the damping of the suspension system.

Claim 28

A method according to claim 24 in which the design criterion is the effectiveness of devices controlling movement between truck side frames and axles.

Claim 29

A method according to claim 24 in which the design criterion is the lateral clearance in the car axle assembly.

Claim 30

A method according to claim 24 in which the design criterion is the lateral clearance between truck bolster and side frames.

Claim 31

A method according to claim 24 in which the design criterion is the wheel base of the car truck.

Claim 32

A method according to claim 24 in which the design criterion is the wheel tread contour.

Claim 33

A method according to claim 24 in which the design criterion is the derailment tendency of the axle.

Claim 34

A method according to claim 24 in which the design criterion is the spacing between wheels on an axle.

Claim 35

A method according to claim 9 in which the vertical forces, lateral forces, and force relationships are determined for a car passing over a first section of track having a first condition and for said car passing over a second section of track having a second condition and which includes the steps of comparing said forces and force relationship for the first track condition and the second track condition.

Claim 36

A method according to claim 33 in which the track conditions are different track gauges on tangent track.

Claim 37

A method according to claim 33 in which the track conditions are different track gauges on curved track.

Claim 38

A method according to claim 33 in which the track conditions are the amount of super-elevation on curved track.

Claim 39

A method according to claim 33 in which the track conditions are track having welded joints and tracks having spliced joints.

Claim 40

A method according to claim 33 in which the track conditions are the amount of lateral profile.

Claim 41

A method accordiNg to claim 33 in which the track conditions are the amount of vertical profile.

Claim 42

A method according to claim 33 in which the track conditions are ballast resiliency of a first consistency and ballast resiliency of a second consistency.

Claim 43

A method according to claim 33 in which the track conditions are the amount of curvature in the track.

Claim 44

A method according to claim 9 which includes the steps of recording the values of the vertical forces, lateral forces, and force relationships for said section of track, determining a second set of vertical and lateral force values with the same rolling equipment, and comparing the recorded values with the second set of values.

Claim 45

A method according to claim 9 which includes the steps of establishing acceptable standards for values of said forces and force relationships for a test car, operating said test car on a second section of track, calculating said forces and force relationships for said test car for said second section of track and comparing said calculated values of said forces and force relationships for said second section of track with said standard values.