parker 108 hydraulic pump free sample

Parker or its subsidiaries or authorized distributors. To the extent that Parker or its subsidiaries or authorized distributors provide component or system options based upon data or specifications provided by the user, the user is responsible for determining that such data and specifications are suitable and sufficient for all applications and reasonably foreseeable uses of the components or systems.

1. Name & address of manufacturer 2. WARNING - see page 4 3. WARNING - see page 4 Parker Hannifin - Oildyne Division 4. CE Mark (if applicable) 5520 Hwy 169 North 5. Year of product manufacture (if CE marked) New Hope, MN 55428 USA 6.

Oildyne Division. Any additional information may be obtained available. The gear pump is driven through a coupling located from Parker by referencing the unit part number stamped on between the electric motor shaft and the pump drive shaft. the product label or by contacting your local authorized Parker These power units are designed to be operated with an integral Oildyne Distributor.

HIGH DENSITY POLYETHYLENE WITH UV ADDITIVE Series Power Units have the 754 CC (46 CU. IN.) 22.2 same dimensions. (.875) 265.2 (10.44) RESERVOIR F Note: All dimensions in mm (inches). STEEL 2000 CC (122 CU. IN.) Parker Hannifin HPS Division New Hope, MN 55428 USA...

(1.15) 2X 5/16-18 UNC-2A (5.00) 144.5 (5.69) 30.7 (1.21) 321.8 (12.67) MOUNTING HOLES 3/8-16 UNC-2B X 177.4 164.1 (6.98) (6.46) 101.6 112.8 Ø (4.00) (4.44) Note: All dimensions in mm (inches). Parker Hannifin HPS Division New Hope, MN 55428 USA...

152.4 (6.00) 1 QUART 1/2 GALLON 3 QUART 1 GALLON (1 LITER) (2 LITER) (3 LITER) (4 LITER) 143.4 (5.65) (8.70) 313.2 (12.33) 403.9 (15.90) Note: All dimensions in mm (inches). Parker Hannifin HPS Division New Hope, MN 55428 USA...

108/118 and 165/175 Series NN Circuit 108/118 and 165/175 Series WW Circuit N.C. N.O. 108/118 and 165/175 Series S1 - S4 Circuit (NC valve) 108/118 and 165/175 Series S5 - S8 Circuit (NO valve) Parker Hannifin HPS Division New Hope, MN 55428 USA...

Back Pressure Valve Back Pressure Valve LPRV LPRV HPRV HPRV 108/118 and 165/175 Series RB Circuit 108/118 and 165/175 Series LB Circuit (Reversible with Back Pressure) (Reversible Locking with Back Pressure) Parker Hannifin HPS Division New Hope, MN 55428 USA...

Locating Power Unit Storage: -7 to +60°C (+20 to +140°F) Please contact Parker Oildyne for usage outside of this range. The unit should preferably be installed indoors in a clean, dry environment with an ambient temperature of 16 to 37°C (60 to 108/118 and 165/175 Series Power Units should be installed 100°F).

Refer to the performance data on pages 17 - 20 for your L - 2 WHITE particular model to determine the current ratings needed BLACK for your electrical controls. Parker Oildyne does not supply MOTOR 161 - 193 MFD/125V GREEN/YEL. controls for the 108/118 and 165/175 Series Power Units.

BLACK MOTOR LEAD NOTE: AM Motor has an internal 100 amp thermal breaker; BI Motor has an internal 50 amp thermal breaker; IC Motor has an internal 33 amp thermal breaker Parker Hannifin HPS Division New Hope, MN 55428 USA...

32 cSt (150 SSU) and 64 cSt (300 SSU) at 38°C (100°F). For fluids other than these, contact Parker Oildyne with the details. If users wish to use alternative oil, hydraulic fluid or ATF, they are warned to check that they have the same properties as those recommended.

Please provide a hydraulic schematic of your circuit to assist The pump is now primed. When using an externally mounted Parker Oildyne. directional control valve (DCV), connect the tank port of the DCV to the ‘DN’ port of the power unit. Connect the ‘UP’ port of Additional Testing the power unit to the inlet port of the DCV.

It is strongly recommended that the customer have available the drawing less than 12.6 A MSDS for the fluid chosen for use in the Parker Oildyne power 2. The 108/118 Series 24 vdc Permanent Magnet motor is unit. Follow all instructions should the fluid be spilled or come in drawing less than 9.6 A.

10 minute cycle. S2 (12 V) S2 (12 V) S2 (24 V) Time at constant load followed by off time to allow the motor to cool to ambient Current Draw - Amps Parker Hannifin HPS Division New Hope, MN 55428 USA...

Percentage of "on" time in a repetitive 10 minute cycle S3 (12 V) S3 (24 V) Time at constant load followed by "off" time to allow motor to cool to ambient temperature. Current Draw - Amps Parker Hannifin HPS Division New Hope, MN 55428 USA...

Pressure - bar (psi) Pressure - bar (psi) NOTE: S2 = 5 Maximum recommended ON time for the HA/HD motors is 5 minutes, afterwhich the motors must be OFF until cooled to ambient temperature Parker Hannifin HPS Division New Hope, MN 55428 USA...

10 minute cycle. S2 (12 V) S2 (24 V) Time at constant load followed by "off" time to allow the motor to cool to ambient temperature. Current Draw - Amps Parker Hannifin HPS Division New Hope, MN 55428 USA...

(500 – 999 psi) (+/- 100 psi) 70 – 137.9 bar +/- 10.3 bar (1000 – 1999 psi) (+/- 150 psi) 138+ bar +/- 13.8 bar (2000+ psi) (+/- 200 psi) Parker Hannifin HPS Division New Hope, MN 55428 USA...

Remove the ‘B’ reservoir screw using a 4 mm (5/32 in) hex key. Retain the screw for reassembly. It is recommended that the bonded washer/rubber seal is replaced. It is Parker Oildyne part number 415067. ‘B’ reservoir screw The ‘C’, ‘D’, ‘P’, ‘Q’, ‘R’...

With the reservoir vertical, ensure the ‘V-lip’ seal is in place on the reservoir mouth. The reservoir wall is positioned inside the 8. Parker Hannifin offers an oil sampling kit which can be ‘V’. Orient the power unit over the reservoir so the reservoir used to ascertain the condition of the system fluid.

Oil temperature too high/viscosity too low oil is thick enough for application conditions Motor or voltage is incorrect Ensure motor and voltage are right Solenoid valve is open Ensure solenoid valve is closed Parker Hannifin HPS Division New Hope, MN 55428 USA...

Torque screw to spec Not properly mounted Check for incorrect mounting Solenoid not releasing Coil not energized (if N.C.) Apply proper voltage to coil Coil not de-energized (if N.O.) De-energize coil Parker Hannifin HPS Division New Hope, MN 55428 USA...

Instruction Manual Oildyne 108/118 and 165/175 Series Bulletin HY22-3210A/US Hydraulic Power Units Notes Parker Hannifin HPS Division New Hope, MN 55428 USA...

Bulletin HY22-3210A/US Hydraulic Power Units Declaration of Incorporation EC Declaration of Incorporation. Manufacturer’s Name: Parker Hannifin Corporation Manufacturer’s Address: Oildyne Division 5520 Highway 169 North New Hope, MN 55428 USA Declare that the partially complete machinery described below conforms to applicable health and safety requirements of Part 1 of Annex 1 of Machinery Directive 2006/42/EC taking full account of requirements for pressure equipment.

Tel: +358 (0)20 753 2500 parker.portugal@parker.com Free phone: 00 800 27 27 5374 parker.finland@parker.com www.parker.com © 2011 Parker Hannifin Corporation. All rights reserved. Bulletin HY22-3210A/US .25M, 11/11 BG Parker Hannifin Corporation Hydraulic Pump and Power Systems Division Oildyne Business Unit...

The present invention relates generally to hydraulic positive displacement machines, and more particularly to monitoring the health status of a hydraulic positive displacement machine to predict failure and/or estimate remaining life.

When a hydraulic positive displacement machine, such as a hydraulic pump, fails, often the internal components of the pump are in pieces. Repair costs are significantly higher when a pump reaches this state. Furthermore, an unexpected failure can result in significant downtime. As an example, the unexpected failure of an aircraft pump can lead to a flight delay or cancellation, which can be extremely costly for the airline. Thus, the ability to monitor the health of a hydraulic pump and provide advance warning of an impending pump failure has many advantages.

Due to the costs associated with unexpected pump failures, airlines and aircraft manufacturers have attempted to monitor pump health in a number of different ways. One method of addressing pump failure is to replace all pumps after a certain number of flight hours. This approach assumes that the pump failure rate increases with flight hours, which is not always the case. Sometimes, the failure rate of a particular fielded pump model may decrease with flight hours (infant failures) or remain constant with flight hours. Furthermore, this approach does not monitor the health of the pump, only the statistical likelihood of pump failure as a function of flight hours. With no information on the condition of the pump, this method will necessarily lead to the premature removal of some operationally acceptable pumps, and the failure to identify some operationally unacceptable pumps.

Another method of addressing pump failure is to place temperature indicating tape on the housing of the pump. When the tape indicates a certain temperature has been exceeded, the pump is removed and replaced. A failing pump may be a reason for unusually high pump housing temperatures. However, there are many other factors that affect pump housing temperature, including ambient temperature and duty cycle of the pump. Furthermore, this technique requires visual inspection of the pump to determine whether or not the temperature limit has been exceeded.

Another method of addressing pump failure is to utilize an algorithm that monitors the temperature difference between pump case temperature and reservoir temperature. This is an improvement over simply using temperature indicating tape for monitoring the health of the pump, as it is not as sensitive to ambient temperature. However, there are many other factors that affect this temperature delta, including case drain flow and duty cycle. Additionally, only a limited number of pump failure modes lead to elevated temperatures.

A device and method in accordance with the present invention utilize frequency-domain analysis of dynamic pressure signal(s) to determine the health of a hydraulic machine. This technique provides a more direct means of monitoring the health of the machine, is not dependent on other external variables, and allows many of the most common hydraulic failure modes to be detected well in advance of a catastrophic failure.

According to one aspect of the invention, a system for predicting the health of a hydraulic machine includes: a dynamic pressure sensor configured to measure a dynamic fluid pressure corresponding to the hydraulic machine; and a controller communicatively coupled to the dynamic pressure sensor and operative to receive dynamic pressure data from the dynamic pressure sensor, the controller configured to convert the dynamic pressure data into the frequency domain, identify dynamic pressure amplitudes in the frequency domain, and generate an indication that the hydraulic machine is damaged or worn when dynamic pressure amplitudes in the frequency domain exceed a prescribed threshold and correspond to frequencies other than pumping frequencies.

In one embodiment, the system includes a speed sensor configured to measure a speed of the hydraulic machine, wherein the controller is communicatively coupled to the speed sensor and operative to receive speed data from the speed sensor, and the controller is further configured to determine at least one of a hydraulic fluid pumping frequency corresponding to the hydraulic machine or a shaft operating frequency corresponding to the hydraulic machine based on the speed data, and associate the dynamic pressure amplitudes with one of the hydraulic fluid pumping frequency or the shaft operating frequency.

In one embodiment, the system includes the hydraulic machine, wherein the pressure sensor is fluidically coupled to a fluid port of the hydraulic machine and the speed sensor is operatively coupled to the hydraulic machine.

In one embodiment, the controller is further configured to determine the hydraulic machine is normal when the amplitudes of the dynamic pressure signals at non-pumping frequencies are less than the prescribed thresholds.

In one embodiment, the controller is configured to determine the pumping frequency based on a speed of the hydraulic machine and a number of pumping elements of the hydraulic machine.

In one embodiment, the controller is configured to analyze the dynamic pressure amplitudes in combination with hydraulic machine data other than the dynamic pressure amplitudes.

In one embodiment, the hydraulic machine data other than the dynamic pressure amplitudes comprises at least one of hydraulic machine temperature, fluid flow rate, or hydraulic machine efficiency.

In one embodiment, the controller is configured to: trend the amplitudes of the dynamic pressure signals at non-pumping frequencies over time; compare the trended values to a threshold level; and conclude the hydraulic machine is damaged or worn when the trended dynamic pressure amplitudes exceed a prescribed threshold level.

According to another aspect of the invention, a method for predicting the health of a hydraulic machine includes: obtaining, using a pressure sensor, dynamic pressure signals corresponding to operation of the hydraulic machine; analyzing, in the frequency domain, dynamic pressure amplitudes in the obtained dynamic pressure signals; and concluding the hydraulic machine is damaged or worn when the amplitudes of the dynamic pressure signals at non-pumping frequencies exceed the prescribed thresholds.

In one embodiment, the method includes concluding the hydraulic machine is normal when the amplitudes of the dynamic pressure signals at non-pumping frequencies are less than the prescribed thresholds.

In one embodiment, a pumping frequency corresponds to the operating speed of the hydraulic machine in revolutions per second multiplied by the number of pumping elements of the hydraulic machine multiplied by any positive integer.

In one embodiment, analyzing comprises analyzing the dynamic pressure amplitudes in combination with hydraulic machine data other than the dynamic pressure amplitudes.

In one embodiment, the hydraulic machine data other than the dynamic pressure amplitudes comprises at least one of hydraulic machine temperature, fluid flow rate, or hydraulic machine efficiency.

In one embodiment, the method includes: trending the amplitudes of the dynamic pressure signals at non-pumping frequencies over time; comparing the trended values to threshold levels; and concluding the hydraulic machine is damaged or worn when the dynamic pressure amplitudes trend over prescribed threshold levels.

FIG. 4 is a graphical illustration of the amplitude of the dynamic pressure at non-pumping frequencies over time, for a hydraulic pump that was run to failure.

FIG. 5 is a schematic diagram of an exemplary system for assessing the health of a pump and predicting pump failure in accordance with the present invention.

FIG. 6. Is a flow chart illustrating steps of an exemplary method for assessing the health of a pump and predicting pump failure in accordance with the present invention.

The present invention has applicability to hydraulic machines (e.g., hydraulic pumps, hydraulic motors), such as swash-plate-type axial piston hydraulic pumps utilized in aircraft, and therefore will be described chiefly in this context. It should be appreciated, however, that aspects of the invention are applicable to any positive displacement machine and/or application in which it is desired to predict the health of such positive displacement machine.

Referring to FIG. 1, illustrated is an exemplary hydraulic machine in the form of a swash-plate axial piston pump 10 to which principles of the present invention may be applied. The pump 10 includes a valve plate 12 having an inlet port 14 (also referred to as a return port or low-pressure port) that receives fluid at a first (low) pressure, and an outlet port 16 (also referred to as a supply port or high-pressure port) that outputs fluid at a second (high) pressure. The valve plate 12 includes slots 18a, 18bthat are in fluid communication with the inlet port 14 and outlet port 16, respectively. A cylinder block 20 (also referred to as a rotor or barrel) includes a plurality of bores 22, where based on an angular position of the cylinder block 20 relative to the valve plate 12 each bore can be selectively in fluid communication with the slots 18aor 18b. Arranged within each bore 22 is a respective piston 24. A drive shaft 28 is coupled to the cylinder block 20.

As the drive shaft 28 rotates, this effects rotation of the cylinder block 20. The rotation also causes reciprocating motion of each piston 24, where an angle of the swashplate 26 relative to a longitudinal axis of the drive shaft 28 determines the travel of each piston 24 within its respective bore 22 (and thus the fluid displacement of the pump 10). As each piston 24 moves outward, fluid is drawn into the respective bore 22 via the inlet port 22 and slot 18aof the valve body 12. With further rotation the piston 24 begins to move inward, expelling the fluid through the slot 18bof the valve body 12 and into the outlet port 16.

For an ideal axial piston pump, each pumping element (each piston 24 and corresponding bore 22 in the exemplary pump of FIG. 1) is identical. However, in practice this is not the case as due to tolerances and other factors there may be slight variations between the pumping elements. Further, as the pump wears over time the pumping elements may not wear evenly. Instead, one or more of the pumping elements may wear much more quickly than the others, which results in uneven pump operation (referred to as imbalance). Imbalance is a self-feeding mechanism, meaning that a pump operating with some amount of imbalance will generate forces and conditions that tend to create more imbalance. Eventually, the imbalance becomes so great that a catastrophic failure occurs within the pump, and the pump stops providing flow that produces system pressure. When this happens unexpectedly, it can lead to costly repairs and unscheduled downtime for the operator.

In accordance with the present invention, frequency-domain analysis of dynamic pressure signal(s) from the hydraulic machine taken during periods of steady-state operation are analyzed to determine the health of the hydraulic machine. The pressure signals may be obtained, for example, from the outlet port 16, within the case, or the inlet port 14. It should be appreciated, however, that the pressure signals can be collected anywhere along the discharge circuit, case circuit, or inlet circuit. For example, in aircraft, an “outlet” pressure transducer is typically located in the filter manifold, which may be fifteen feet downstream of the pump. Further, frequency-domain indicators from the dynamic pressure signals may be monitored alone or in combination with other signals from operation of the hydraulic machine, such as for example temperature, flow and machine efficiency, to assess the health of the hydraulic machine.

The device and method in accordance with the invention monitors the health of the hydraulic machine by analyzing, in the frequency-domain, dynamic pressure signal(s) produced by the hydraulic machine during periods of steady-state operation. Imbalance can be detected by analyzing certain frequency-domain indicators in the dynamic pressure data.

An example of a time-frequency domain representation of the dynamic pressure signal from a healthy hydraulic pump is shown in FIG. 2. Large dynamic pressure amplitudes 30, 32 and 34 can be observed at pumping frequencies, while the dynamic pressure amplitude is low at all other frequencies. Pumping frequencies are those frequencies that correspond to the speed of the hydraulic machine in revolutions per second, multiplied by the number of pumping elements, multiplied by any positive integer. For example, if a hydraulic pump has nine pumping elements (e.g., 9 pistons) and is operating at 50 revolutions per second, then pumping frequencies would correspond to integer multiples of 450 Hz (50*9).

The pumping frequencies may also be determined by analyzing the dynamic pressure measurements without knowledge of the rotational speed of the machine. For example, the first pumping frequency may be determined based on the number of pressure peaks in the dynamic pressure measurement over a prescribed time period.

An example of a time-frequency domain representation of the dynamic pressure signal from a damaged pump running at the same operating condition is shown in FIG. 3. In addition to the large dynamic pressure amplitudes 30, 32, 34 and 36 seen at the pumping frequencies, large dynamic pressure amplitudes 38, 40, 42 and 44 can be seen at non-pumping frequencies (e.g., at shaft frequencies). Shaft frequencies are those frequencies that correspond to the speed of the pump in revolutions per second (i.e., independent of the number of pumping elements), multiplied by any positive integer. For example, if a pump is operating at 50 revolutions per second, then the shaft frequencies would correspond to integer multiples of 50 Hz. The presence of large dynamic pressure amplitudes at shaft frequencies, or any other non-pumping frequencies, is an indication of pump imbalance and other pump issues.

To use this type of analysis for monitoring pump health, the dynamic pressure amplitudes of undesirable non-pumping frequencies can be trended over time during periods where the pump is operating at the same steady-state condition. One way to do this is to simply sum all dynamic pressure energy that exists at non-pumping frequencies, and trend this value. Borrowing the term “signal-to-noise ratio” from signal processing, where the pumping frequencies can be thought of as the signal, and all other frequencies can be thought of as noise, this summation of dynamic pressure amplitudes at non-pumping frequencies can be referred to as “noise power”. The trended values then can be compared to a threshold level such as, for example, a first threshold level indicative of “pump wear” or a second threshold level indicative of “imminent failure”. Based on the comparison, it can be concluded that the hydraulic machine is worn or damaged when the trended dynamic pressure amplitudes exceed the prescribed threshold level.

An example of the “noise power” trended over time for a failing pump can be seen in FIG. 4. In the example shown in FIG. 4, the time axis (x-axis) represents the number of flight cycles the pump has experienced, where one flight cycle is approximately two hours. The Noise Power axis (y axis) represents the total dynamic pressure energy that exists at non-pumping frequencies, as calculated in the frequency domain, and expressed in units of pressure (peak PSI, dB, etc.). As can be seen in FIG. 4, as the number of flight cycles increases, the noise power gradually increases due to pump wear. The increase in noise is relatively linear up to a certain point, and then the noise power increases at an exponential rate. Warnings can be triggered based on the noise power values or rates of change exceeding predetermined levels. For example, a first level warning can be set when the noise power reaches a level of 10, indicating that the pump should be replaced. A second level warning can be set with the noise power reaches 14, indicating that pump failure is imminent. As will be appreciated, the warning and failure levels are merely exemplary, and in practice the values may be dependent on the specific application.

When performing these calculations, care must be taken to differentiate between imbalance and control circuit instability. Control circuit instability can appear in the dynamic pressure data as a non-pumping frequency. However, instability is not an indication of pump wear/damage by itself. A simple way to avoid mistaking control circuit instability for imbalance is to apply a high pass filter to the dynamic pressure data to filter out any instability frequencies before calculating the noise power.

Another way to monitor the pump health using dynamic pressure data would be to track the amplitude of individual shaft order frequencies, without summing all non-pumping frequencies. By monitoring the amplitude of individual shaft frequencies, one may gain more insight into the specific failure mode, but at a cost of added complexity.

The setting of thresholds is the simplest way to use this type of analysis to monitor the health of a pump. For example, a warning can be set if the dynamic pressure noise power exceeds a certain level, or if the amplitude of any individual shaft order exceeds a certain level. This approach alone can be quite effective in predicting pump failure. However, more complexity can be added if other signals are available. By combining dynamic pressure data with temperature, flow, or efficiency data, the fidelity of this method may be improved. For example, a high dynamic pressure noise power reading in combination with an elevated temperature reading may be indicative of one failure mode, while a high noise power reading without elevated temperature may be indicative of a different failure mode.

This method is most effective when data are available from a large number of pumps, where thresholds can be determined by computing summary statistics of the field data. As more data are available, more sophisticated algorithms can be utilized. A pump health monitoring approach based on machine learning would utilize dynamic pressure noise power and/or shaft order amplitudes as features used to train a machine learning model.

Referring now to FIG. 5, illustrated is an exemplary system 50 for monitoring the health of a hydraulic machine, such as hydraulic pump 10. The pump 10 is driven by a prime mover (not shown), which causes the pump 10 to take in fluid via return line 52 (which is connected to the inlet port 14). The pump 10 produces flow through the outlet port 16 and to source line 54. A pressure sensor 56 monitors the pressure in the source line 54 and provides the pressure data to controller 58. While the pressure sensor 56 is shown monitoring the pressure in the source line 54, it should be appreciated that the pressure could be monitored at other locations without departing from the scope of the invention. For example, pressure could be monitored at the return line 52 or within the pump itself.

In addition to the pressure sensor 56, the system 50 may optionally include a temperature sensor 60 for monitoring a temperature of the pump 10, a speed sensor 62 for monitoring a speed of the pump 10, and/or a flow sensor 64 for monitoring a fluid flow from the pump 10. The temperature sensor 60, speed sensor 62 and flow sensor 64 may be communicatively coupled to the controller 58 to provide the temperature, speed and flow measurements thereto. This additional data may be used in combination with the pressure data to refine the determination of pump wear/failure.

The exemplary controller 58 includes a processor 66 coupled to memory 68 and an I/O module 70 via a bus 72. The I/O module 70 receives data from the respective sensors and makes the data available to the processor 66. Application instructions may be stored in the memory 68 and executed by the processor 66 to monitor the health of a hydraulic pump 10 as described herein. Further, it is noted that the illustrated controller is merely exemplary, and other configurations are possible. For example, instead of a processor that executes code stored in memory the controller 58 may be implemented using an application-specific integrated circuit (ASIC), dedicated hardware, or the like.

Referring now to FIG. 6, illustrated is a flow diagram that depicts an exemplary method 100 of predicting the health of a hydraulic machine via an electronic device, such as controller 58. Although the method descriptions and flow chart may show specific orders of executing steps, the order of executing the steps may be changed relative to the order described. Also, two or more steps described in succession may be executed concurrently or with partial concurrence. One or more of the described or illustrated steps may be omitted.

Beginning at step 102, dynamic pressure signals corresponding to operation of the hydraulic machine are obtained. Such signals may be obtained, for example, from pressure sensor 56, which monitors fluid pressure in the system 50 at one of a machine outlet, a machine case or a machine inlet. In one embodiment, the dynamic pressure is obtained during periods of steady-state operation. The dynamic pressure signals obtained by the pressure sensor 56 may be sampled at a rate of 5 kHz, and more preferably at a rate of 10 kHz. It should be appreciated, however, that the required sample rate will depend on the speed of the pump (e.g., a pump running at a lower speed would not require as high of a sampling rate as a pump running at a higher speed).

Next at step 104, the obtained dynamic pressure signals are transformed into the frequency domain. Such transformation may be implemented using conventional techniques, such as a Fourier Transform. Once in the frequency domain, the dynamic pressure amplitudes are analyzed as indicated at step 106. In this regard, analyzing may include determining if the dynamic pressure amplitudes correspond to non-pumping frequencies, as indicated at step 108. Analyzing the dynamic pressure amplitudes may also include analyzing the dynamic pressure amplitudes in combination with pump data other than the dynamic pressure amplitudes. Such other data can include, for example, at least one of pump temperature, fluid flow rate, or pump efficiency.

At step 110, the non-pumping frequency dynamic pressure amplitudes may be compared to a threshold level as indicated at step 110. If the non-pumping frequency dynamic pressure amplitudes do not exceed the threshold level (or the only amplitudes that are present correspond to pumping frequencies), then at step 112 it can be concluded that the pump 10 is normal and the method moves back to step 102 and repeats. However, if the non-pumping frequency dynamic pressure amplitudes do exceed the threshold level, then at step 114 it can be concluded that the pump 10 is abnormal (e.g., damaged or worn) and an alarm maybe generated. The method then moves back to step 102 and repeats.

Accordingly, by monitoring the dynamic pressure amplitudes in the frequency domain, an accurate indication of hydraulic pump/motor condition can be ascertained. This enables maximum use of the pump/motor and minimizes costs for maintaining systems that utilize such hydraulic pumps/motors.