AUTOMATIC TENSIONING APPARATUS AND METHOD OF USE

Abstract

An automatic tensioning apparatus is provided that includes a tensioning drive unit having: a longitudinally extending stationary base frame with a plurality of guides extending between a lower portion and an upper portion, and a plurality of rotatable feed wheels axially secured at the lower portion, as well as a translatable drive frame slidably coupled to the plurality of guides with a drive assembly coupled to the drive frame, the drive assembly including a drive motor and a tensile member interface for engaging and rotationally translating a tensile member. The tensioning drive unit further including a plurality of drive frame actuators actuatable to move the drive frame between a bottom frame position and a top frame position, as well as a sensor for at least indirectly sensing the position of the drive frame along a longitudinal base frame axis.

Claims

1. An automatic tensioning apparatus comprising: a tensioning drive unit comprising: a longitudinally extending stationary base frame with a plurality of guides extending between a lower portion and an upper portion, and a plurality of rotatable feed wheels axially secured at the lower portion; a translatable drive frame slidably coupled to the plurality of guides; a drive assembly coupled to the drive frame, and including a drive motor and a tensile member interface for engaging and rotationally translating a tensile member; a plurality of drive frame actuators actuatable to move the drive frame between a bottom frame position and a top frame position; and a sensor for at least indirectly sensing the position of the drive frame along a longitudinal base frame axis.

2. The automatic tensioning apparatus of claim 1, wherein the drive assembly further includes a plurality of rollers engaged with the plurality of guides.

3. The automatic tensioning apparatus of claim 1, wherein the plurality of drive frame actuators includes a pair of drive frame actuators, each including hydraulic or pneumatic cylinders to provide actuation.

4. The automatic tensioning apparatus of claim 1, wherein a first of the plurality of rotatable feed wheels engages the tensile member prior to engagement with the tensile member interface and a second of the plurality of rotatable feed wheels engages the tensile member after engagement with the tensile member interface.

5. The automatic tensioning apparatus of claim 4, wherein the first of the plurality of rotatable feed wheels redirects the tensile member 90 degrees and directly to the tensile member interface in a vertical orientation, and wherein the second of the plurality of rotatable feed wheels redirects the tensile member 90 degrees from a vertical orientation as it extends directly from the tensile member interface.

6. The automatic tensioning apparatus of claim 4, further including a controller in communication with the tensioning drive unit to provide activation signals to the drive motor and the plurality of drive frame actuators, based at least in part on the position of the drive frame.

7. The automatic tensioning apparatus of claim 5, wherein the first of the plurality of rotatable feed wheels and the second of the plurality of rotatable feed wheels are the only rotatable feed wheels included in the plurality of rotatable feed wheels.

8. The automatic tensioning apparatus of claim 2, wherein the tensile member interface is a sprocket having teeth to engage a tensile member.

9. The automatic tensioning apparatus of claim 1, wherein the tensile member interface rotates about a drive axis that extends perpendicular to the longitudinal base frame axis.

10. The automatic tensioning apparatus of claim 9, further including an encoder wheel that rotates with the tensile member interface about the drive axis.

11. The automatic tensioning apparatus of claim 10, wherein the drive assembly further includes a belt and pulley reduction assembly coupled to the drive motor.

12. The automatic tensioning apparatus of claim 9, wherein the drive assembly further includes a gearbox reduction coupled between the belt and pulley reduction assembly and the tensile member interface.

13. The automatic tensioning apparatus of claim 9, further including a controller in communication with the tensioning drive unit to provide activation signals to the drive motor and the plurality of drive frame actuators, based at least in part on the position of the drive frame.

14. A floor cleaning system having a circuit that includes a tensile member and a floor scraper, the system comprising: a tensioning drive unit comprising: a longitudinally extending stationary base frame with a plurality of guides extending between a lower portion and an upper portion, and a plurality of rotatable feed wheels axially secured at the lower portion; a translatable drive frame slidably coupled to the plurality of guides; a drive assembly coupled to the drive frame, and including a drive motor and a tensile member interface for engaging and rotationally translating a tensile member; a plurality of drive frame actuators actuatable to move the drive frame between a bottom frame position and a top frame position; and a sensor for at least indirectly sensing the position of the drive frame along a longitudinal base frame axis; and a controller in communication with the tensioning drive unit to provide activation signals to the drive motor and the plurality of drive frame actuators based at least in part on the position of the drive frame.

15. A method of use for an automatic tensioning apparatus comprising: positioning a drive frame and drive assembly, movably coupled to a longitudinally extending stationary base frame, in a bottom adjustment position along the base frame using a plurality of drive frame actuators coupled to the drive frame and base frame, wherein a tensile member is rotationally engaged with the drive assembly to provide translation of the tensile member; actuating the plurality of drive frame actuators to cause vertical translation of the drive frame to remove slack in the tensile member, wherein the tensile member forms part of a continuous circuit engaging a plurality of movable cleaning devices; storing as a minimum pressure, a sensed pressure exerted to extend the plurality of drive frame actuators to remove the slack; continue actuating the actuators until the sensed pressure has exceeded the minimum pressure, storing a detected current position of the drive frame relative to the base frame as a target position, and the minimum pressure as a minimum preload pressure; activating a cleaning cycle that includes rotating a drive motor of the drive assembly in a first rotational direction to move the plurality of movable cleaning devices in a first longitudinal direction; comparing the detected current position of the drive frame with the target position, if the detected current position is at or below a pre-defined maximum lower offset position measured from the target position, then actuate the plurality of drive frame actuators to move the drive frame to the target position; and detecting completion of the cleaning cycle and updating the target position value that is stored to be equal to the detected current position.

16. The method of claim 15, further including a controller for storing the activatable cleaning cycle instructions, the minimum position, the detected current position, the target position, and the maximum lower offset position, and for providing an actuating signal to the plurality of actuators and a directional rotation signal to the drive motor.

17. The method of claim 16, wherein the cleaning cycle further includes rotating the drive motor in a second rotational direction to move the plurality of movable cleaning devices in a second longitudinal direction.

18. The method of claim 17, wherein the target position that is stored is updated after every cleaning cycle has completed.

19. The method of claim 18, further comprising a hydraulic system for actuating the drive frame actuators.

20. The method of claim 19, further including stopping the drive motor and setting a pressure relief valve in the hydraulic system to a minimum preload pressure upon sensing completion of the cleaning cycle, wherein the pressure relief valve is in fluid communication with the plurality of drive frame actuators.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Embodiments of the invention are disclosed with reference to the accompanying drawings and are for illustrative purposes only. The invention is not limited in application to the details of construction, or the arrangement of the components illustrated in the drawings. The invention is capable of other embodiments and/or of being practiced or carried out in other various ways.

[0019] FIG. 1 is a top perspective view of an exemplary floor cleaning system positioned relative to an exemplary barn floor and wall. The floor cleaning system including an exemplary automatic tensioning apparatus comprising a tensioning drive unit, a controller, and a junction box.

[0020] FIG. 2 is a front perspective view of the tensioning drive unit of FIG. 1.

[0021] FIG. 3 is a rear perspective view of the tensioning drive unit.

[0022] FIG. 4 is an exploded perspective view of the tensioning drive unit.

[0023] FIG. 5 is front perspective view of an exemplary drive frame and drive assembly of the tensioning drive unit of FIG. 1.

[0024] FIG. 6 is front perspective view of the drive assembly.

[0025] FIG. 7 is a front view of the tensioning drive unit coupled with an exemplary tensile member.

[0026] FIG. 8 is a top view of the tensioning drive unit coupled with the tensile member.

[0027] FIG. 9 is a cross-sectional front view of the tensioning drive unit taken along line 9-9 of FIG. 8.

[0028] FIG. 10 is front perspective view of the tensioning drive unit and tensile member of FIG. 7 with the front cover of the tensioning drive unit removed for illustrative purposes, showing the drive frame in a top frame position.

[0029] FIG. 11 is side view of the tensioning drive unit and tensile member of FIG. 10

[0030] FIG. 12 is top view of the tensioning drive unit and tensile member of FIG. 10.

[0031] FIG. 13 is a cross-sectional view of the tensioning drive unit taken along line 13-13 of FIG. 12.

[0032] FIG. 14 is front perspective view of the tensioning drive unit and tensile member with the front cover of the tensioning drive unit removed for illustrative purposes, showing the drive frame in a bottom frame position.

[0033] FIG. 15 is side view of the tensioning drive unit and tensile member of FIG. 14

[0034] FIG. 16 is top view of the tensioning drive unit and tensile member of FIG. 14.

[0035] FIG. 17 is a cross-sectional view of the tensioning drive unit taken along line 17-17 of FIG. 16.

[0036] FIG. 18 is a flow chart 300 illustrating an exemplary method of using the automatic tensioning apparatus.

DETAILED DESCRIPTION

[0037] FIG. 1 illustrates an exemplary floor cleaning system 100 positioned relative to a wall 102 and a floor 104. The wall 102 and floor 104 are exemplary and are provided for illustrative purposes to show the layout of an exemplary barn floor cleaning configuration. For clarification, the wall 102 and floor 104 are not considered part of the floor cleaning system 100 itself, but serve as structure with which the floor cleaning system 100 can be implemented therewith. As shown in FIG. 1, the floor 104 includes two exemplary longitudinal parallel alleys 106, each having interconnected cleaning devices, such as floor scrapers 108 situated at least partially within the alley 106 and positioned to direct debris into a debris channel 107. The scrapers 108 are further coupled by a tensile member 110 to form a circuit 111 (i.e., a continuous circuit/loop of connections). The tensile member 110 can include various individual lengths (e.g., coupled between scrapers 108, etc.) or a continuous loop coupled to the scrapers 108. For simplicity, the term tensile member 110 used herein can refer to either configuration. Further, the tensile member 110 can take many forms such as a chain, a rope, a cable, etc. A plurality of roller guides 112 are provided at the corners to change the direction of the tensile member 110 accordingly. The roller guides 112 are secured in position (e.g., to the floor 104) and unlike the scrapers 108, remain anchored in place during operation of the floor cleaning system 100. The tensile member 110 is fixedly secured to the scrapers 108, but allowed to rotate along the roller guides 112.

[0038] The floor cleaning system 100 further includes an exemplary automatic tensioning apparatus 116, that in at least some embodiments, comprises an exemplary tensioning drive unit 120, a controller 122, and one or more junction boxes 124. The tensioning drive unit 120 provides a means to move/translate and properly tension the tensile member 110. When the tensioning drive unit 120 is activated to move the tensile member 110, the coupled scrapers 108 are also moved along the alleys to push waste and debris. As the floor cleaning system 100 shown in FIG. 1 is exemplary, it shall be understood that the quantity and positioning of various components, such as the scrapers 108, tensile member 110, roller guides 112, etc. can vary to accommodate a desired circuit shape and configuration.

[0039] Referring to FIGS. 2 and 3, the exemplary tensioning drive unit 120 from FIG. 1 is shown in front and rear perspective views, while FIG. 4 provides an exploded view of the tensioning drive unit 120. The tensioning drive unit 120 includes a longitudinally extending stationary base frame 126 that provides primary structural support. The base frame 126 includes a lower portion 130 and an upper portion 134. The base frame 126 further includes a first side wall 136 and a second side wall 138 extending between the lower portion 130 and the upper portion 134, wherein the sidewalls include a plurality of guides. In at least some embodiments, the plurality of guides can include a first guide 140 extending longitudinally along the first side wall 136 and a second guide 142 extending longitudinally along the second side wall 138. In at least some embodiments, the guides can take the form of slots, and can be reinforced with longitudinally extending inner or outer slotted reinforcement portions, such as reinforcement portions 144.

[0040] The tensioning drive unit 120 further includes a translatable drive frame 150. The drive frame 150 is slidably coupled to the guides 140, 142 to allow the drive frame 150 to translate between the lower portion 130 and the upper portion 134. In at least some embodiments, the drive frame 150 includes a plurality of rollers 152 rotatably secured to the drive frame 150, wherein the rollers 152 are sized and shaped to slidingly engage with the guides 140, 142 such that the drive frame 150 is restricted to move only longitudinally between the lower portion 130 and the upper portion 134 along a fixed longitudinal base frame axis 172 (see FIG. 7).

[0041] Secured to the drive frame 150 is a drive assembly 154 (see FIGS. 5 and 6). The drive assembly 154 includes a drive motor 156 coupled with a tensile member interface 158 that engages and translates the tensile member 110, to move the associated circuit 111 (i.e., causing the scrapers 108 to move as desired). The tensile member interface 158 can vary in shape and size depending on the type of tensile member 110 it is intended to be engaged with. For example, when the tensile member 110 is a chain, the tensile member interface 158 can be a sprocket, and when the tensile member 110 is a cable or rope, the tensile member interface 158 can be a wrapped drum, etc. In at least some embodiments, the tensile member interface 158 is circular.

[0042] In at least some embodiments, the drive assembly 154 can include various other components, such as a motor mount 160, a belt and pulley reduction assembly 162, a gearbox reduction 166, and an encoder wheel 168, while in other embodiments, less or more components can be included. As shown in the figures, the drive assembly 154 is secured to the drive frame 150 such that the tensile member interface 158 (and encoder wheel 168) rotates about a drive axis 170 that extends perpendicular to the longitudinal base frame axis 172.

[0043] The drive frame 150 is translatable between the lower portion 130 and the upper portion 134 of the base frame 126 using a plurality of drive frame actuators 174 coupled therewith. In at least some embodiments, the drive frame actuators 174 include telescopic hydraulic cylinders 175, while in other embodiments, any of various other known types of actuators can be utilized, such as pneumatic actuators, electric linear actuators, non-telescopic hydraulic cylinders, etc. The drive frame 150 can be adapted to utilize various types and quantities of drive frame actuators 174 including one actuator, or two or more actuators.

[0044] As noted above, the base frame 126 is stationary and configured to be secured in place, such as to the floor 104. In at least some embodiments, the base frame 126 includes a bottom mounting plate 176 for securement to the floor 104. The base frame 126 can also include a plurality of tensile member feed wheels 178 rotatably secured to wheel supports 179 on the base frame 126. The wheel supports 179 include axial wheel mounts 180.

[0045] When hydraulic drive frame actuators 174 are utilized, a hydraulic system 182 can be provided for actuating the drive frame actuators 174. The hydraulic system 182 can be mounted to the drive frame 126 as part of the tensioning drive unit 120 or can be mounted remotely and coupled to the tensioning drive unit 120. In at least some embodiments, the hydraulic system 182 includes a 184 mount, an electric pump 186, a reservoir 188, a hydraulic control valve block 189, a dump valve 190, a proportional relief valve 192, a pressure transducer 194, an accumulator 196, and a pressure gauge 198, along with various interconnections (e.g. rigid lines, hoses, fittings, etc.), while in other embodiments, less or more components can be included.

[0046] FIGS. 7 and 8 provide front and top perspective views of the tensioning drive unit 120 engaged with a tensile member 110. For illustrative purposes, only a portion of the tensile member 110 is shown, further the tensile member 110 is shown as a chain and the tensile member interface 158 is shown as a sprocket. FIG. 9 is a cross-sectional view of the tensioning drive unit 120 taken along line 9-9 of FIG. 8 showing the tensile member 110 extending horizontally and entering the tensioning drive unit 120 and engaging with the feed wheel 178 at the entrance to redirect the tensile member 110 upwards to the tensile member interface 158 and wrapping thereover, then extending downward to the other feed wheel 178 at the exit, and being redirected out along the horizontal. This configuration allows the tensile member 110, which typically extends along the floor 104 (e.g., horizontal) to enter and leave at the same level, although the position and quantity of the feed wheels 178 could vary to accommodate different entry and exit heights, and load requirements.

[0047] Referring to FIGS. 10-12, front perspective, side, and top views of the tensioning drive unit 120 and tensile member of FIG. 7 are provided with the front cover 202 of the tensioning drive unit 120 removed for illustrative purposes. FIG. 13 provides a cross-sectional view of the tensioning drive unit 120 taken along line 13-13 of FIG. 12. As seen in FIGS. 11-13, the drive frame actuators 174 are fully extended to place the drive frame 150 in a top adjustment position 204 along the base frame axis 172, situated near the top, at a distance D1 from the bottom mounting plate 176.

[0048] Referring to FIGS. 14-16, front perspective, side, and top views of the tensioning drive unit 120 and tensile member are provided with the front cover 202 of the tensioning drive unit 120 removed for illustrative purposes, similar to FIGS. 10-12, but with the drive frame repositioned. FIG. 17 provides a cross-sectional view of the tensioning drive unit 120 taken along line 17-17 of FIG. 16. As seen in FIGS. 14-17, the drive frame actuators 174 are no longer fully extended, but are retracted to place the drive frame 150 in a bottom adjustment position 206 along the base frame axis 172, situated near the bottom, at a distance D2 from the bottom mounting plate 176.

[0049] The tensioning drive unit 120 further includes at least one sensor 208 (e.g., FIG. 14) configured to at least indirectly monitor the position of the drive frame 150 relative to the base frame 126, as this can be accomplished in numerous ways, the sensor 208 can take many forms. For example, the sensor can be an ultrasonic distance sensor (FIG. 13) positioned on the base frame 126 above the drive frame 150. In other embodiments, the sensor can be located in other locations and utilize other known technologies, such as laser, proximity, photoelectric, fiber optic, etc. Further, in at least some embodiments, the term sensor can be construed to include another component that can provide position sensing indirectly.

[0050] Referring to FIGS. 13 and 17, raising or lower the drive frame 150 provides increased or decreased tension to a coupled tensile member 110 connected in the circuit 111 that has a fixed length, resulting in a decrease or increase in slack. Raising and lowering of the drive frame 150 is performed by the plurality of drive frame actuators 174 based on control signals received from the controller 122 (FIG. 1) in communication with the tensioning drive unit 120.

[0051] The controller 122 provides control of the tensioning drive unit 120 to operate the floor cleaning system 100. As the automatic tensioning apparatus 116 can utilize various hydraulic, electric, and/or pneumatic devices, one or more junction boxes 124 can be utilized to facilitate supply and/or distribution thereof, as such it should be understood that these components can be mounted in various locations and include various typical interconnecting lines, hoses, cables, wires, etc. to distribute these resources. In at least some embodiments, the drive motor 156 is controlled by a Variable Frequency Drive (VFD), which can be housed with the controller 122. For reference, the bottom adjustment position 206 along the base frame axis 172 can be considered a zero point on the base frame axis 172, with a height value along the base frame axis 172 increasing in value as it extends to the top adjustment position 204.

[0052] The controller 122 can communicate with the tensioning drive unit 120 and a user to send and receive commands and information to operate the tensioning drive unit 120. The controller 122 can be housed in a plurality of boxes and in at least some embodiments, includes a Programmable Logic Controller (PLC) and a Human Machine Interface (HMI), such as a PLC model no. FX5UC-32MT/DSS-TS and an HMI model no. GT2105-QTBDS, both manufactured by Mitsubishi. In other embodiments, the controller 122 can include any of various types of processor-driven I/O configurations capable of providing the described operations. Communication with the PLC and HMI can occur via various known methods, such as direct link, remote link, touchscreen, etc. and can utilize various software programs and/or protocols to effectuate the desired operation. The HMI provides a user interface between the user and the controller 122 and in at least some embodiments, can include a local or remote screen/interface, wherein the user can enter various pre-selected values (e.g., height values) to be utilized during the operation of the tensioning drive unit 120. In at least some embodiments the HMI can merely include various buttons, dials, switches, etc. actuatable by a user to effectuate operation of the automatic tensioning apparatus 116 as desired. The PLC can further include memory for storing values. The controller 122 can include internal memory for storing positional values, and/or be in communication with an external memory (e.g., hard drive, RAM, etc.)

[0053] Referring back to FIG. 1, the tensile member 110 is coupled to scrapers 108 to form a circuit 111. To move the scrapers 108 the drive assembly 154 is activated by the controller 122. Moving the scrapers 108 in a first direction requires the tensile member 110 to be translated through the tensioning drive unit 120 via activation of the drive assembly 154 to rotate the tensile member interface 158 in a first rotational direction to pull the tensile member 110 in and to pass it back out. Activation of the drive assembly 154 to rotate the tensile member interface 158 in a (opposite) second rotational direction causes the tensile member 110 to be pulled into the tensioning drive unit 120 on the opposite side and passed out.

[0054] The automatic tensioning apparatus 116 is configured to monitor tension on the tensile member 110 as it rotates the circuit 111 moving the scrapers 108. As discussed above, too much tension creates excessive strain on the system and too little tension allows for excessive slack, which also creates excessive strain on the system. As such it is desirable to maintain a “proper” level of tension between the extremes. To monitor the amount of tension on the tensile member 110, the downward force 210 (FIG. 14) being imparted to the tensile member interface 158 can be identified using various methods. One such method is to monitor the system pressure being exerted on the drive frame actuators 174 that support the drive frame 150 and resist the downward force 210, which in at least some embodiments, is the pressure measured at the pressure transducer 194 and/or pressure gauge 198 of the hydraulic system 182 used to extend and retract the drive frame actuators 174.

[0055] Referring to FIG. 18, a flow chart 300 is provided illustrating an exemplary method of using the automatic tensioning apparatus 116 to automatically tension the tensile member 110 in the floor cleaning system 100 having the circuit 111 that includes one or more scrapers 108 coupled to the tensile member 110. The method/process begins at step 302, with the drive frame 150 in the bottom adjustment position 206 (at the lowest available point ((zero point)) on the base frame axis 172). In this position, tensile member 110 has extra slack in the circuit 111. At step 304, the plurality of drive frame actuators 174 are actuated to begin moving the drive frame 150 along the base frame axis 172 and towards the top adjustment position 204 to place the tensile member 110 under minimum tension at a height value greater than zero along the base frame axis 172. In embodiments where the drive frame actuators 174 are hydraulically driven, the controller 122 activates the electric pump 186 to deliver hydraulic fluid from reservoir 188 to the drive frame actuators 174. Fluid enters the hydraulic cylinders 175 of the drive frame actuators 174 filling the void volume; once the void volume within the cylinders are filled pressure begins to build in the hydraulic system 182 until a minimum pressure is provided sufficient enough to begin translating the drive frame 150 along the base frame axis 172. This change in position of the drive frame 150 along the base frame axis 172 is monitored by the sensor 208. The drive frame 150 will continue to raise at this same minimum pressure until the slack in the tensile member 110 is taken up. Once the slack in tensile member 110 is removed, drive frame actuator pressure will begin to increase as measured by pressure transducer 194, as queried at step 306. At this point when drive frame actuator pressure begins to rise, it is understood that the system is now adding unwanted and unneeded preload force.

[0056] At step 308, once pressure is sensed as increasing past the minimum pressure (noting an acceptable tolerance), the controller 122 records the current position (i.e., current height value) of the drive frame 150 along the base frame axis 172 and logs it as the “target position” (i.e., target height value) for drive frame 150 for the next cycle. It also records the applied minimum pressure and saves it as “minimum preload pressure.”

[0057] At step 310, a cleaning/scraping cycle begins by activating the drive motor 156 to begin translating the tensile member 110 through the tensioning drive unit 120. The cleaning cycle is configured to move the cleaning devices for a set period of time, although various other or additional criteria could be used to determine the duration of the cleaning cycle. As debris is collected on the scrapers 108 passing along the floor 104, the tension on the tensile member 110 increases due to the added debris load. This creates a downward force 210 on the drive frame 150. This force will soon overcome the “minimum preload pressure” provided by the drive frame actuators 174 that was taking-up the excess slack in the tensile member 110 prior to the system starting the cleaning cycle. At this point, the drive frame 150 “current position” will begin to move lower (i.e., reduced height value) as identified by the sensor 208. The controller 122 monitors the “current position” of the drive frame 150 as indicated in step 312 and will allow the “current position” to continue moving down the base frame axis 172 from the “target position” to a user defined position on the base frame axis 172 called the “maximum lower offset.” This “maximum lower offset” value is indicative of the amount of additional slack in the tensile member 110 that is deemed acceptable without causing mechanical problems, such as balling of the chain or rope on the slack side.

[0058] At step 314 the current position is compared with the “maximum lower offset,” if the “current position” (i.e., current high value) of the drive frame 150 is positioned on the base frame axis 172 at or below the “maximum lower offset,” then at step 316, the controller 122 commands increased pressure to the drive frame actuators 174 by activating the electric pump 186 to increase system pressure to move the drive frame 150 to an increased height value. Pressure to the drive frame actuators 174 will continue to be increased until the drive frame 150 “current position” equals or is greater than the “target position.” At this point, the pressure in the hydraulic system 182 will have increased. To account for excessive overshoot of “target position,” the controller 122 can include a provision for a user settable “maximum upper offset.” The “maximum upper offset” being the acceptable overshoot the drive frame 150 moves above the “target position” along the base frame axis 172 before the controller 122 will open the dump valve 190 to bleed off pressure to the drive frame actuators 174 resultingly lowering the “current position” of the drive frame 150, as seen in steps 318 and 320. Thus, the “maximum upper offset” and “maximum lower offset” provide configurable dead-bands to inhibit the controller 122 from constantly running the electric pump 186 and then opening the dump valve 190. In at least some embodiments, in addition to monitoring position of the drive frame 150 (i.e., the height value), a proportional relief valve 192 can be set to an allowable “maximum pressure” for the safety of mechanical components in the event of the electric pump 186 does not shut off. The aforementioned process continues until the until the end of the cleaning cycle is detected at step 322, which can be a pre-programmed instruction based on time, scraper repetitions, user input, etc., further noting that the status of the cleaning cycle (i.e., complete or not complete) can be continuously monitored along in combination with the current position of the drive frame and the maximum lower offset position.

[0059] When the cleaning cycle ends, the process advances to step 324 where the controller 122 stops the drive motor 156 and sets the proportional relief valve 192 to the “minimum preload pressure.” The pressure on the drive frame actuators will then drop to the “minimum preload pressure.” When this occurs, “current position” of the drive frame 150 will drop to a new updated “target position” that is recorded by the controller 122 in step 326. Over time, as the cleaning process is repeated, the “target position” value will continue to slowly increase as the tensile member 110 wears/stretches, hence automatically compensating for chain/rope stretch and wear without user intervention. With the new updated “target position” set, the controller 122 in at least some embodiments, resets the proportional relief valve 192 back to a “maximum pressure” value at step 328, and then waits at step 330 for a new cleaning cycle start command from the controller 122. The aforementioned process can be performed in various other ways including more or less steps and in varying order.

[0060] Although the automatic tensioning apparatus 116 has been described utilizing drive frame position (i.e., height value) as a feedback mechanism to indicate the tension on the tensile member 110, various other mechanisms can be utilized as discussed below. For example, a loadcell can be provided in-line with the tensile member 110, or on the shaft securing the tensile member interface 158, or on any of the roller guides 112, or the axial wheel mounts 180, to measure tension in the tensile member 110 and equate the sensed load value to the required pressure in the hydraulic cylinders of the drive frame actuators 174 to provide an equal and opposite upward force. Another example includes utilizing the amperage load on the drive motor 156 to calculate the theoretical tension in the tensile member 110. This entails recording the minimum percent of output torque required with no load on the circuit 111, the downward force 210 can be equated to a required pressure within the hydraulic cylinders of the drive frame actuators 174 so as to equal the downward force 210 caused by the tensile member 110, hence providing the necessary tension to drive the load. The output torque can be calculated using the measured or known amperage and voltage drawn by the motor as well as the rotational speed of the motor shaft (measured by the rotation of the encoder wheel 168, for example). The feedback loop would then constantly adjust pressure based on the percent of output torque.

[0061] Yet another example includes using pressure feedback from the cylinders of the drive frame actuators 174. Using pressure differential between a rod-side and cap-side of a cylinder piston in the drive frame actuator 174, it is possible to control the system to provide the correct amount of tension. At no load, the controller 122 would pressurize the cylinder such that the force on both the rod-side of the piston and the cap-side of the piston is equal to zero by equation: [(Pressure on Cap-Side) x (Area of Cap-Side Piston)−(Pressure on Rod-Side)×(Area of Rod-Side Piston)=Force on Piston]. When the tensile member 110 sees a load, it will induce a delta pressure which is measured by pressure transducers on both sides of the cylinder. The controller 122 would either add or remove pressure from the load bearing side of the cylinder to bring the system back to a zero state. The dead-band would be the allowable differential in pressure between the cap-side and rod-side of the cylinder.

[0062] In addition to the disclosed shapes and sizes, the aforementioned components, can vary to include numerous adaptations. Further, the material composition of all components can also include numerous elements, such as steel, aluminum, alloys, plastics, etc. The use of the term “plurality” in the description or claims shall be understood to include “one or more,” and the terms “bottom”, “top”, “upper” and “lower” shall not be considered limiting in that they are used for convenience when referencing a vertical orientation of the invention, while other orientations of the invention have been contemplated.

[0063] Although the invention has been herein described in what is perceived to be the most practical and preferred embodiments, it is to be understood that the invention is not intended to be limited to the specific embodiments set forth above. Rather, it is recognized that modifications may be made by one of skill in the art of the invention without departing from the spirit or intent of the invention and, therefore, the invention is to be taken as including all reasonable equivalents to the subject matter of the appended claims and the description of the invention herein.