[0001] The present invention relates to a system for monitoring the tension of a track of a tracked vehicle.

Background of the invention

[0002] A variety of large vehicles, particularly those used in the mining and construction industries, move on tracks which are driven by wheels or rollers. The tracks loop around two or more wheels or rollers, and the surface area of the track helps to distribute the weight of the vehicle. This particularly helps heavy vehicles to traverse soft ground.

[0003] Over time, components of a machine wear, which can result in slackness in the track. In other circumstances, such as where a tracked vehicle goes through muddy ground, mud may build up inside the track resulting in an increase in track tension. In turn, this can exacerbate wear.

[0004] Performance of a track is significantly affected by the track tension. Operation of the machine at (or near) an optimum track tension helps to reduce wear of the components, and promotes a longer track life. In turn, this can reduce operational costs.

[0005] However, it can be difficult for vehicle operators to know whether the tracks of their machine are too slack or too tight, while operating the vehicle.

Summary of the invention

[0006] Accordingly, in a first aspect of the present invention, there is provided a tension monitoring system for a tracked vehicle comprising: a tension detector to obtain a measurement indicative of a track tension of a track of the vehicle; an indicator at an operating station of the vehicle, to indicate the track tension to a vehicle operator; and communication apparatus to transmit the measurement from the tension detector to the indicator.

[0007] The present invention thereby provides a vehicle operator with a way of monitoring the track tension while operating the vehicle.

[0008] The measurement may be a direct or an indirect measurement of the track tension. The measurement may be a measurement taken from a track adjustment mechanism, such as a tension adjustment cylinder. The detector may measure the pressure in a tension adjustment cylinder of the vehicle. In that event, the tension detector may comprise a pressure sensor, such as a pressure transducer.

[0009] The communication apparatus may comprise a wireless transmitter mounted with the tension detector and a wireless receiver mounted with the indicator. This helps to compensate for the distances between the tracks and the vehicle cabin, which can be large in the case of some large mining and construction machinery. It also helps avoid the need to provide cables, for a wired connection, in the undercarriage of the vehicle, where conditions for electrical wiring can be challenging. The transmitter and the receiver may communicate using Bluetooth or WiFi wireless communication protocols.

[0010] The indicator may indicate when the measurement is indicative of a track tension outside a desired tension range. For example, the indicator may provide a warning indication when the pressure in a tension adjustment cylinder exceeds a desire maximum pressure or falls below a desired minimum pressure. The desired tension range may be calibrated for a particular vehicle, a particular vehicle track and a particular use environment.

[0011] Accordingly, by implementing an embodiment of the present invention, the vehicle operator can be alerted to an increase (or decrease) in track tension. They can then adjust the track tension (or arrange for other approved personnel to do so) to suit the underfoot conditions.

[0012] A detailed description of one or more embodiments of the invention is provided below, along with accompanying figures that illustrate by way of example the principles of the invention. While the invention is described in connection with such embodiments, it should be understood that the invention is not limited to any embodiment. On the contrary, the invention encompasses numerous alternatives, modifications and equivalents.

[0013] For the purpose of example, numerous specific details are set forth in the following description in order to provide a thorough understanding of the present invention. The present invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the present invention is not unnecessarily obscured.

Brief Description of Drawings

[0014] Various embodiments/aspects of the invention will now be described with reference to the following drawings in which:

[0015] Figure 1 is a schematic design diagram of a vehicle having a track monitoring system according to a representative embodiment of the present invention.

[0016] Figure 2 depicts a modified valve for a hydraulic cylinder to facilitate connection of a pressure transducer, according to one representative embodiment of the present invention.

[0017] Figure 3 depicts an indicator for indicating track tension, in accordance with a representative embodiment of the present invention.

Detailed Description

[0018] Referring to Figure 1, there is shown a track system 100 for a vehicle comprising a front wheel 110, a rear wheel 120, rollers 130, 135 and track 140. Tension in the track is maintained by hydraulic adjusting cylinder 150. To tension the track 140, the cylinder 150 forces the front and rear wheels 110, 120 away from each other.

[0019] Typically, the vehicle manufacturer will have a desired track tension, and will prescribe a way of measuring the track tension. For example, one known way of measuring track tension in a tracked vehicle is to measure the deflection of the track between upper wheels or rollers. As shown in Figure 1, the track tension may be measured by measuring the distance a of track deflection between upper rollers 130 and 135, and the distance b between the upper roller 135 and front wheel 110. The average of the distances a and b

[0020] To correctly tension the track 140, the track deflection is measured and, if it is not within the desired range (generally the range prescribed by manufacturer's

specification), then the adjusting cylinder 150 is actuated to adjust the track tension. By forcing the front and rear wheels 110, 120 away from each other, the track 140 can be tightened. The track 140 can be loosened by drawing the front and rear wheels 110, 120 closer together, by reducing the pressure in actuating cylinder 150.

[0021] In accordance with this embodiment of the present invention, a pressure sensor 160 is installed in the adjusting cylinder 150. The sensor 160 is in the form of pressure transducer connected to the hydraulic cylinder 150, so as to continuously monitor the pressure of the hydraulic fluid within the cylinder 150. However, this is just one mechanism for measuring tension, and other tension detectors may be used in accordance with the present invention. For example, the tension detector may comprise a strain gauge or a load cell, or could measure compression of a tensioning spring associated with the track.

[0022] Regardless, in this embodiment, a customised release valve 152 is provided on hydraulic cylinder 150, as shown in Figure 2. A hose 155 extends from the release valve 152 and connects to pressure transducer 160, such that the pressure transducer 160 is able to continuously monitor the pressure in cylinder 150. The hose 155 is of sufficient length to position the pressure transducer 160, and associated electronic components, in a secure location under the vehicle. The location of pressure transducer 160 is, in this embodiment, selected in part based on the suitability of the location for transmitting wireless signals from the undercarriage of the vehicle.

[0023] Communication apparatus 170 is provided to transmit the pressure

measurement (obtained by the pressure sensor 160) to an indicator 180 inside the vehicle cabin. The communication apparatus 170 preferably includes a wireless transmitter mounted with the pressure sensor 160, and a wireless receiver mounted with the indicator 180 in the vehicle cabin. The transmitter may be mounted within the same housing as the sensor 160, and the receiver may be mounted within the same housing as the indicator 180. The communication protocol used by communication apparatus 170 may vary, but in this embodiment the communication apparatus 170 communicates over a BlueTooth link for reduced power consumption. Potentially, however, the communication apparatus 170 could also operate on a WiFi or other wireless signal protocol, which would also avoid the need for any third party communication equipment to be used. However, in some embodiments, the communication apparatus could operate using 3G or 4G mobile communication standards, although this would likely require the use of third party telecommunication infrastructure.

[0024] The indicator 180 in this embodiment includes computer processing hardware, such as a processor and a memory in communication with the processor, and a computer display screen to display an indication of track tension.

[0025] To calibrate the system 100, the track tension is measured by a known technique, generally in accordance with manufacturer specifications - for example, by measuring the deflection distances a and b as shown in Figure 1. Hydraulic fluid is then added to the cylinder 150, or released from cylinder 150, until the track tension is within the manufacturer specifications. When the track is measured to be at the desired track tension, the pressure in the hydraulic cylinder 150 (as measured by pressure sensor 160) is taken to be indicative of the desired track tension.

[0026] The indicator 180 can be calibrated based on the pressure measured by sensor 160 at the desired track tension. An input device, such as a key switch or press button 188, may be provided as part of indicator 180, to allow a user to calibrate the system when the track tension is set correctly (as measured by deflection distances a and b).

[0027] The indicator 180 may monitor the pressure transmitted from sensor 160, and alert the user with a warning indication if the pressure falls outside a desired range - for example 150 PSI above the set temperature, or 100 PSI below the set pressure. As depicted in Figure 3, the indicator 180 of this embodiment comprises a display showing a pair of vertical bars 182, 184, with marker lines 183, 185 which are indicative of the tension in the left and right tracks of a vehicle, respectively. The marker 183 on the left bar 182 of the graph depicts the pressure in the track adjusting cylinder 150 of the left track, and the marker 185 on the right bar 184 depicts the pressure in the track adjusting cylinder 150 of the right track. The desired range of the cylinder pressure in the left and right cylinders (indicative of the desired track tension) is shown by the green section of each bar 182, 184. If the track tension becomes too high or two low, the marker line 183, 185 will move outside the green section of the bar 182, 184, to provide a warning to the vehicle operator that the track tension is outside desired limits.

[0028] A pressure increase or decrease indicates a rise or fall in track tension, respectively, which should be corrected by appropriate adjustment of the actuating cylinder 150. This can be done manually by either the vehicle operator or other approved personnel. Different stages of alerts (e.g. red light, orange light) may be provided in response to a rise or fall of sensed pressure.

[0029] The present invention therefore provides an operator with an early indication of problems in track tension, while they are operating the vehicle. The operator does not need to manually measure track deflection distances a and b (which is impractical during operation of the vehicle), but can simply refer to indicator 180 to obtain an indication of track tension. An increase or decrease in track tension can therefore be identified and addressed at an early stage. This can help avoid problems - such as premature wear of the track 140 or related components, or potentially failure of the track system 100 - caused by operating the vehicle outside the prescribed track tension range.

[0030] It should be noted that as parts wear, the pressure in the actuating cylinder 150 may need to be adjusted to maintain an appropriate track tension. This means that the track tensioning system 100 of this embodiment of the present invention will also need to be recalibrated, to ensure that the indicator 180 reflects the proper relationship between track tension and cylinder pressure. In this embodiment, key switch 188 is provided to enable simple calibration and recalibration of the tension monitoring system 100. When the track tension is measured independently (e.g. using track deflection measurements), and the cylinder 150 is set to the desired pressure, key switch 188 can be actuated to set the desired pressure range to be 'centred' around the currently measured pressure (the range may allow for more variation above or below the measured pressure, depending on the particular vehicle and application). [0031] As the present invention may be embodied in several forms without departing from the essential characteristics of the invention, it should be understood that the above described embodiments should not be considered to limit the present invention but rather should be construed broadly. Various modifications, improvements and equivalent arrangements will be readily apparent to those skilled in the art, and are intended to be included within the spirit and scope of the invention.

[0032] The word 'comprising', and forms of the word 'comprising', when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0033] In this specification where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of the common general knowledge; or known to be relevant to an attempt to solve any problem with which this specification is concerned.