Locked axle detector for a multi-axled traction vehicle

Claim 2

For detecting a predetermined speed differential among a plurality of axles of a traction vehicle equipped with speed detectors that provide a corresponding plurality of input signals indicative of the speeds at which the respective axles are rotating, the improvement comprising: a. a corresponding plurality of signal conditioning means adapted to receive said input signals from said speed detectors, each of said signal conditioning means being operative to generate a train of discrete output pulses having an average value representative of the axle speed indicated by the associated input signal as that speed varies between nearly zero and a predetermined magnitude, and each of said signal conditioning means also including an electric filter energized in accordance with the corresponding output pulse train whose average value determines the magnitude of an analog output signal of said electric filter; b. control means coupled to said signal conditioning means and supplied with the output pulse trains respectively generated thereby, said control means being operative to produce a predetermined control signal in response to any one of said pulse trains having an average value indicating that the rotational speed of the associated axle is lower than a predetermined first threshold level, and c. disabling means comprising: i. an OR logic circuit coupled to the said signal conditioning means for receiving the respective analog output signals therefrom, and ii. level detecting means connected between said control means and said OR logic circuit for preventing the production of said control signal except when at least one of said analog signals exceeds a magnitude corresponding to a predetermined second threshold level of rotational speed of the associated axle, said second threshold level being higher than said first threshold level, whereby the production of said control signal indicates that the speed of at least one axle is lower than said first threshold level while the speed of another axle is higher than said second threshold level, said predetermined magnitude of axle speed being at least as high as said second threshold level.

Claim 3

For detecting a predetermined speed differential among a plurality of axles on a traction vehicle equipped with speed detectors that provide a corresponding plurality of input signals indicative of the speed at which the respective axles are rotating, the improvement comprising: a. a corresponding plurality of signal conditioning means adapted to receive said input signals from said speed detectors, each of said signal conditioning means being operative to generate a train of discrete output pulses having constant amplitude and duration and having variable frequency which is proportional to the axle speed indicated by the associated input signal as that speed varies between nearly zero and a predetermined magnitude; b. control means coupled to said signal conditioning means and supplied with the output pulse trains respectively generated thereby, said control means including: i. a NAND logic component having a plurality of inputs which respectively receive the pulse trains generated by said plurality of signal conditioning means, ii. a time delay circuit comprising a capacitor, means for charging said capacitor during intervals when said NAND logic component has a 0 output state, and a path for discharging said capacitor during intervals when said NAND logic component has a 1 output state, and iii. means for producing a predetermined control signal whenever the charge accumulated on said capacitor is less than a predetermined amount indicating that the rotational speed of any one of said axles is lower than a predetermined first threshold level; and c. disabling means coupled to said signal conditioning means and to said control means for preventing the production of said control signal so long as said input signals indicate that none of the axles is rotating at a speed exceeding a predetermined second threshold level which is higher than said first threshold level and for permitting production of said control signal when at least one of said input signals indicates that the rotational speed of the associated axle is higher than said second threshold level, whereby the production of said control signal indicates that the speed of at least one axle is lower than said first threshold level while the speed of another axle is higher than said second threshold level, said predetermined magnitude of axle speed being at least as high as said second threshold level.

Claim 4

For detecting a predetermined speed differential among a plurality of axles on a traction vehicle equipped with speed detectors that provide a corresponding plurality of input signals indicative of the speed at which the respective axles are rotating, the improvement comprising: a. a corresponding plurality of signal conditioning means adapted to receive said input signals from said speed detectors, each of said signal conditioning means being operative to generate a train of discrete output pulses having constant amplitude and duration and having variable frequency which is proportional to the axle speed indicated by the associated input signal as that speed varies between nearly zero and a predetermined magnitude; b. control means coupled to said signal conditioning means and supplied with the output pulse trains respectively generated thereby, said control means including: i. a NAND logic component having a plurality of inputs which respectively receive the pulse trains generated by said plurality of signal conditioning means, ii. a time delay circuit comprising a capacitor, means for charging said capacitor during intervals when said NAND logic component has a 0 output state, and a path for discharging said capacitor during intervals when said NAND logic component has a 1 output state, and iii. means for producing a predetermined control signal whenever the charge accumulated on said capacitor is less than a predetermined amount indicating that the rotational speed of any one of said axles is lower than a predetermined first threshold level; and c. disabling means coupled to said signal conditioning means and to said control means for preventing the production of said control signal so long as said input signals indicate that none of the axles is rotating at a speed exceeding a predetermined second threshold level which is higher than said first threshold level and for permitting production of said control signal when at least one of said input signals indicates that the rotational speed of the associated axle is higher than said second threshold level, whereby the production of said control signal indicates that the speed of at least one axle is lower than said first threshold level while the speed of another axle is higher than said second threshold level, said predetermined magnitude of axle speed being at least as high as said second threshold level.

Claim 5

The speed differential detecting means of claim 2 in which said disabling means is connected to said time delay circuit and is effective, except when at least one of said input signals indicates that the rotational speed of the associated axle is higher than said second threshold level, to keep said capacitor charged above said predetermined amount regardless of the output state of said NAND logic component.

Claim 6

In a locked axle detector for a traction vehicle having a plurality of axles adapted to rotate at speeds that can differ one from another, the combination of: a. a plurality of means for respectively sensing the rotational speeds of said axles, each of said speed sensing means comprising means for generating a train of discrete output pulses of relatively constant duration and variable frequency, the frequency of said pulse train being proportional to the rotational speed of the associated axle as that speed varies through a predetermined range; b. a NAND logic component having a plurality of inputs which respectively receive the pulse trains generated by said plurality of speed sensing means; c. time delay means comprising a capacitor, means connected to said NAND logic component for charging said capacitor during intervals when said component has a 0 output, and a path for discharging said capacitor during intervals when said NAND logic component has a 1 output, whereby the charge accumulated on said capacitor depends on the frequency of the pulse train generated by the speed sensing means associated with the axle that has the slowest rotational speed; d. means connected to said time delay means for producing a predetermined control signal in response to the charge on said capacitor being less than a predetermined amount; and e. disabling means coupled to said plurality of speed sensing means for preventing the production of said control signal except when the frequency of the pulse train generated by the speed sensing means associated with the axle having the fastest rotational speed exceeds a predetermined magnitude which is higher than the frequency at which said capacitor attains said predetermined amount of charge.

Claim 7

In a locked axle detector for a traction vehicle having a plurality of axles adapted to rotate at speeds that can differ one from another, the combination of: a. a plurality of means for respectively sensing the rotational speeds of said axles, each of said speed sensing means comprising means for generating a train of discrete output pulses of relatively constant duration and variable frequency, the frequency of said pulse train being proportional to the rotational speed of the associated axle as that speed varies through a predetermined range; b. a NAND logic component having a plurality of inputs which respectively receive the pulse trains generated by said plurality of speed sensing means; c. time delay means comprising a capacitor, means connected to said NAND logic component for charging said capacitor during intervals when said component has a 0 output, and a path for discharging said capacitor during intervals when said NAND logic component has a 1 output, whereby the charge accumulated on said capacitor depends on the frequency of the pulse train generated by the speed sensing means associated with the axle that has the slowest rotational speed; d. means connected to said time delay means for producing a predetermined control signal in response to the charge on said capacitor being less than a predetermined amount; and e. disabling means coupled to said plurality of speed sensing means for preventing the production of said control signal except when the frequency of the pulse train generated by the speed sensing means associated with the axle having the fastest rotational speed exceeds a predetermined magnitude which is higher than the frequency at which said capacitor attains said predetermined amount of charge.

Claim 8

The locked axle detector of claim 4 in which said predetermined magnitude of frequency is reached when the fastest rotating axle has a speed equivalent to a vehicle speed of approximately 5 miles per hour.

Claim 9

The locked axle detector of claim 4 in which each of said pulse trains has a period equal to the reciprocal of its frequency and the constant duration of each of its pulses is substantially the same as the period of that pulse train when its frequency is equal to said predetermined magnitude.