Patent Publication Number: US-11383960-B2

Title: Drop table with motor feedback

Description:
SUMMARY 
     A drop table has, in accordance with some embodiments, a lifting module is connected to a first motor and has a lifting controller. The first motor is mechanically coupled to a first lifting column by a first transmission and to a second lifting column by a second transmission with the lifting controller configured to generate a lifting strategy in response to feedback from the first motor. 
     In other embodiments, a drop table consists of a lifting module that employs a lifting controller to generate a lifting strategy in response to motor feedback received during vertical movement of a service component by first and second lifting columns connected to the lifting module. 
     Operation of a drop table, in some embodiments, involves lifting module connected to a first motor and consist of a lifting controller. The first motor is mechanically coupled to a first lifting column by a first transmission and to a second lifting column by a second transmission. A service component is lowered with the first and second lifting columns by activating the first motor that provides motor feedback. A lifting strategy is generated in response to the motor feedback and subsequently executed to move the service component to a servicing position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block representation of an example maintenance system in which various embodiments can be practiced. 
         FIG. 2  depicts a block representation of an example drop table system arranged in accordance with various embodiments. 
         FIGS. 3A &amp; 3B  represents portions of an example drop table capable of being used in the systems of  FIGS. 1 &amp; 2 . 
         FIGS. 4A-4C  depict portions of an example drop table configured in accordance with assorted embodiments. 
         FIGS. 5A &amp; 5B  respectively depict portions of an example drop table capable of being employed in the systems of  FIGS. 1 &amp; 2 . 
         FIG. 6  depicts an example lifting module that can be utilized by a drop table as part of a maintenance system. 
         FIG. 7  is an example maintenance routine that may be executed with assorted embodiments of  FIGS. 1-6 . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of a drop table are generally directed to structure and methods of utilizing motor feedback to optimize lifting operations conducted by a drop table as part of a maintenance system. 
     For years, machinery has needed maintenance to properly and safely operate. Machinery that provide transportation services, such as trucks, locomotives, and buses, can be particularly susceptible to degraded performance as a result of deferred maintenance. Hence, the efficiency, safety, and reliability of transportation machinery has a direct correlation with the efficiency and reliability of maintenance equipment. 
     For transportation machinery that consistently handles relatively large numbers of people, the moving components that provide propulsion and suspension can have a frequent maintenance schedule. Such components can be quite large, heavy, and cumbersome compared to other machinery aspects that require routine maintenance. Maintenance equipment capable of handling large, heavy, and cumbersome components have traditionally been rather crude, inefficient, and prone to dangerous failures. For instance, equipment capable of lifting and moving fifty tons or more can be powerful and robust, but experience degraded performance that is not easily identifiable until a failure. 
     Accordingly, a maintenance system is configured, in some embodiments, with a drop table that intelligently utilizes motor feedback to generate a lifting strategy that increases the efficiency, safety, and reliability of lifting operations, particularly in operations involving large, heavy, or cumbersome machinery components. By generating a lifting strategy from motor feedback, a drop table can quickly adapt to encountered operational parameters to provide optimal safety and performance. The closed-loop control of a drop table allowed by monitoring motor feedback provides efficient detection of lifting conditions and verification that altered lifting parameters result in improved lifting performance. 
     An example maintenance system  100  is depicted in  FIG. 1 . The block representation of the maintenance system  100  displays a lifting mechanism  102  that can engage machinery  104  to conduct maintenance operations. The lifting mechanism  106  can be configured to service any type, and size, of machinery  104 , such as a locomotive, bus, railcar, or semi-truck. It is contemplated that multiple separate pieces of machinery  104  can concurrently be accessed and serviced by the lifting mechanism  102  to provide vertical movement  106 , but such arrangement is not required or limiting. 
     The lifting mechanism  102  can consist of at least a motor  108 , or engine, that allows one or more actuators  110  to physically engage and move at least one machinery component. A local controller  112  can direct motor  108  and actuator  110  operation and may be complemented with one or more manual inputs, such as a switch, button, or graphical user interface (GUI), that allow customized movement of the machinery component. The local controller  112  can conduct a predetermined lifting protocol that dictates the assorted forces utilized by the motor  108  and actuator  110  to efficiently and safely conduct vertical component displacement. 
       FIG. 2  depicts a block representation of an example lifting system  120  arranged to provide maintenance operations for machinery  104 . A lifting mechanism  102  can consist of one or more motors  108 , actuators  110 , and controllers  112  that are utilized to engage and secure a machinery component  122 , such as a wheel, suspension, engine, or body, throughout a range of vertical motion  106 . Depending on the position and size of the component  122 , the lifting mechanism  102  can vertically manipulate the component  122  itself or the machinery  104  as a whole to allow efficient access, removal, and subsequent installation of the component  122  to be serviced. 
     Although assorted maintenance can be facilitated without physically moving the machinery  104 , such as engine tuning or joint greasing, other maintenance requires the separation of one or more components from the vehicle  102 . Such separation can be conducted either by lifting the machinery  104  while a component  122  remains stationary or by lowering the component  122  while the machinery  104  remains stationary. Due to the significant weight and overall size of some machinery  104 , such as a locomotive engine or railcar, the lifting system  120  is directed in some embodiments to moving a component  122  vertically while the remainder of the machinery  104  remains stationary. 
     It is contemplated that the lifting mechanism  102  can consist of one or more lifting columns  124  that operate collectively to vertically displace a component  122 . In some embodiments, multiple separate lifting columns  124  each raise a platform  126 , as shown in  FIG. 2 . That is, lifting columns  124  that are physically separated can be concurrently activated to apply force on a platform  126  that physically supports the component  122 . Such unified lifting column  124  and platform  126  can provide consistent operation over time as deviations in operating characteristics, such as lifting speed and precision, are mitigated by the platform  126  that physically brings the respective lifting columns  124  into similar operating characteristics. However, the use of a unifying platform  126  can make the lifting mechanism  102  rather large and physically restrictive to machinery  104  and/or components  122  of certain sizes and shapes. 
     Other embodiments configure the lifting mechanism  102  of multiple separate lifting columns  124  that each contact different portions of a component  122  via independent protrusions  128 . The use of independent lifting columns  124  can provide increased physical compatibility with diverse machinery  102  and/or component  122  shapes and sized. In yet, independent lifting columns  124  can be more susceptible to component  124  instability during lifting operations as a result of deviations in operating characteristics for the respective columns  124 . Such independent lifting column  124  configuration also suffers from increased complexity compared to using a unifying platform  126  due to the coordination of the respective column&#39;s  124  operation to provide secure component  122  movement. 
     It is contemplated that a lifting column  124  can be secured to a base  128 , such as a floor, foundation, or frame. A base  128  can be constructed to be permanently stationary or move upon activation to relocate the collective lifting columns  124 . The rigid connection of each lifting column  124  to a base  128  can provide increased strength to the lifting mechanism  102 , but can limit the operational flexibility of the system  120 . Conversely, the respective lifting columns  124  can have transport assemblies  130 , such as a suspension, wheels, or tracks, that allow a column  124  to move relative to a base  128  via manual or automated manipulation. 
     In accordance with some embodiments, the lifting mechanism  102  can be characterized as a drop table onto which the machinery  104  moves to position a component in place to enable component removal, and subsequent installation. A drop table can be configured to facilitated vertical component movement  106  as well as horizontal movement, as represented by arrows  132 . The relatively large size of many components  122  is accommodated by positioning the drop table lifting mechanism  102  in a shaft  134 , which may be positioned underground, to allow efficient horizontal movement  132  to a service shaft  136  that is vertically traveled to position the component  122  in a servicing position  138  away from the machinery  104 . 
     With the combination of vertical component movement  106  and horizontal component movement  132 , a drop table lifting mechanism  102  can experience a broad range of forces that jeopardize system  120  operation and safety. That is, a drop table  102  can encounter differing forces from diverse vectors during the lowering, horizontal translation, and raising of a component  122  that has a substantial weight, such as 10 tons or more, which may place a diverse variety of strain on at least the moving aspects of the drop table  102 . Hence, the range of movement of the drop table  102  has a greater risk of part failure and safety hazards compared to lifting mechanisms simply employed for vertical movement  106 . 
       FIGS. 3A &amp; 3B  respectively depict block representations of portions of an example lifting system  140  that can be employed as part of a maintenance system  100 . The top view of  FIG. 3A  displays a platform  126  disposed between and physically attached to multiple lifting columns  124 . As directed by a local controller  112 , one or more lifting motors  142 , or engines, can articulate aspects of the respective columns  124  to move the platform  126  in the vertical direction  106 . The controller  112  may further direct one or more transverse motors  144 , or engines, to activate a drive line  146  and move the platform  126  along the horizontal direction  134 . 
     It is contemplated that one or more lifting columns  124  are physically separated from the platform  126 , but such configuration would necessitate individual motors  142 / 144  for each column  124  along with complex spatial sensing and coordination to ensure a load  148  is securely lifted and moved. Instead, the platform  126  physically unifies the respective lifting columns  124  and provides a foundation onto which the load  148  can rest and provide a consistent center of gravity throughout lifting  106  and horizontal  132  movement activities. 
       FIG. 3B  displays side view and an example physical layout of the lifting system  140  where a base  128  remains stationary while the platform  126  is vertically translated. The base  128  provides a secure foundation for the various motors  142 / 144  and associated transmission to the respective lifting columns  124 . The base  128  further anchors the drive line  146  and number of constituent rollers  150 , which can be wheels, castors, trucks, or other assembly utilizing a bearing. During normal operation, the assorted lifting columns  124  provide uniform platform  126  lifting and lowering. 
     However, the fact that the multiple lifting columns  124  can independently experience failures increases the operational risk of less than all of the columns  124  experiencing an error. When a lifting column  124  experiences a failure while other columns  124  continue to operate, the platform  126  can become unstable, as illustrated by segmented platform  152 , and the very heavy load  148  can be at risk of damage and/or damaging the lifting system  140  as well as nearby equipment and users. Hence, the use of independent lifting motors  142 , or independent lifting columns  124  separate from a platform  126 , can be particularly dangerous. Furthermore, independent lifting columns  124  provide less physical space for motors  142  and limit the available motor size and power that can be safely handled by a column  124 , which reduces the efficiency and safety of lifting heavy loads  148  safely, such as over 10 tons. 
     In contrast to independent lifting columns  124  having independent lifting motors  142 , it is contemplated that a single motor can be employed to power the respective columns  124  collectively. While the base  128  could provide enough space and rigidity to handle a single motor/engine  142 , the failure rates and operational longevity of a motor/engine  142  capable of lifting a load  148  weighing tens of tons can involve increased service times and frequency that can be prohibitive in terms of lifting system  140  operational efficiency. In addition, it is noted that large parasitic energy losses can be experienced through transmission that translates the power output of a single motor/engine  142  to four separate lifting columns  124 . 
     Accordingly, various embodiments configure a drop table lifting mechanism  102  with two separate variable speed, dual drive lifting motors  142  each powering two separate lifting columns  124  that are unified by a single platform that is vertically manipulated by the collective operation of the lifting columns  124  and dual drive motors  142 . The combination of two lifting motors  142  to power four columns  124  provides an enhanced motor efficiency via relatively simple transmissions, lower service times/frequency, and relatively simple motor  142  coordination compared to independent columns  124  or a single motor powering four columns  124 . 
       FIGS. 4A-4C  respectively depict portions of an example drop table  160  that can be utilized in a maintenance system in accordance with some embodiments.  FIG. 4A  is a perspective view line representation of a locomotive component  162  resting on rail segments  164  that are supported by a platform  126 . The platform  126  is attached to four lifting columns  124  that extend from a common base  128 . In  FIG. 4A , the platform  126  is in an elevated position as directed by a lifting controller  112  activating the respective lifting columns  124  to provide consistent vertical displacement without shock or disorientation of the platform  126 . 
     During operation, the lifting controller  112  activates and controls the respective lifting columns  124  to maintain a uniform lifting speed in the vertical direction  106  from a bottom position, as shown in the side view of  FIG. 4B , to the elevated position without the platform  126  experiencing any tilt, pitch, or roll dynamics that can move the center of gravity of the platform  126  and jeopardize the lifting integrity of the component  162 . In other words, the lifting controller  112  can carry out matching, or different, lifting operations with the respective lifting columns  124  to ensure the platform  126  remains level, which can be characterized a parallel to the horizontal X-Y plane, throughout the vertical displacement. 
     The base  128  may be constructed to contain a pair of variable drive motors  166  that each are mechanically coupled to two lifting columns  124 . As shown in  FIG. 4C  where a cover  168  of the base  128  is removed, a variable drive motor  166  can be disposed between two lifting columns  124  and connected to each lifting column  124  via a transmission  170  that features at least one shearing coupling  172 . The shearing couplings  172  can provide added safety to lifting operations by failing in response to experienced force above a predetermined threshold. As a result of the shearing couplings  172 , mechanical failures can be isolated to the respective transmissions  170  of the drop table  160  instead of causing motor failures  166 . The exposed portion of the base  128  in  FIG. 4C  also shows how a transverse motor  144  can positioned to drive a pair of wheels of a drive line  130 . 
     The use of variable drive motors  166  allows for intelligent operation and enhanced safety compared to fixed speed motors or engines. By utilizing a variable speed, or variable frequency, motor  166 , the drop table can detect lifting parameters without human or electric input. In some embodiments, the monitoring of motor  166  electric consumption and frequency variations during operation can be characterized as motor feedback. For instance, a lifting controller  112  can monitor motor feedback of the respective motors  166  to determine the lifting speed of a platform and the lifting behavior of the respective columns  124 . 
     As a non-limiting example, increased electric consumption, or deviations in motor frequency, for one output shaft of a motor  166  can be compared to a default consumption/frequency and to the consumption/frequency of the other output shaft of the motor  166  to indicate a lifting error has occurred or is occurring. The ability for a controller  112  to identify errors, failures, and proper lifting operation allows for closed-loop control within the drop table  160  that can adapt to detected conditions to optimize the efficiency and safety of lifting with optimal column  124  longevity. 
     The use of motor feedback for drop table operation status alleviates the reliance on external sensors and/or user input for operational parameter detection, which increases the responsiveness of the controller  112  and effectiveness of operational adaptations choreographed by the controller  112 . While external sensors, such as acoustic, environmental, and optical type detection mechanisms, can be employed to provide data to the controller  112  that enables intelligent lifting column  124  operation, the closed-loop motor feedback detection of lifting operations is less vulnerable to sensor failure or false readings. That is, motor feedback provides actual lifting conditions that do not provide false readings and cannot fail unless the motor itself fails, which would in itself be feedback that prompts the controller  112  to deactivate the other motor  166  of the drop table. 
       FIGS. 5A &amp; 5B  respectively depict portions of another example drop table  180  arranged in accordance with various embodiments to utilize motor feedback to provide lifting operations optimized to the actual performance of the drop table  180 . The top view of  FIG. 5A  shows the drop table base  128  housing a pair of separate lifting mechanisms  182  and  184 . Each mechanism  182 / 184  has a variable drive motor  166  that powers two separate lifting columns  124  via separate transmissions  170 . 
     While a single transmission  170  may be used to power two lifting columns  124 , such configuration can be a source of mechanical degradation and failure over time, particularly when tens of tons of components  122  are cyclically raised and lowered. Accordingly, the drop table  180  has separate transmissions  170  that respectively extend from an output shaft of the motor  182 / 184  to a single lifting column  124 . As shown by the view of  FIG. 5B , each transmission  170  interacts with a threaded core  186  of a lifting column  124  to induce core  186  rotation and vertical displacement of a traveler  188  and connected platform  126 . 
     The traveler  188  is prevented from failing and failing down the core  186  by at least one safety nut  190  that vertically moves along the core  186  at a predetermined separation from the traveler  188 . The nut gap distance between the nut  190  and traveler  188  can be monitored by one or more sensors continuously extending through the nut  190  to access the nut gap  192 . The accurate and real-time sensing of the nut gap  192  can supplement the monitored motor feedback to allow a controller  112  to identify the operational parameters of the lifting columns  124 . For example, the nut gap sensor measurements can be used to verify motor feedback data and to identify a traveler  188  as faulty, degraded, or otherwise in need of service or replacement. 
       FIG. 5B  further depicts a number of other sensors  194  that can be used independently and collectively to provide a lifting controller  112  with data that supplements motor feedback data. Although the mechanical configuration of the traveler  188  and nut  190  on the core  186  can be operated at will and manually inspected at any time, it is noted that may operational defects and degraded performance occur while the core  186  is rotating and the traveler/nut are moving, which is dangerous to manually inspect. Hence, one or more sensors  194  can be positioned inside, or outside, the column housing  196  to monitor one or more operational characteristics of the lifting column  124  without any danger to a user. 
     Various embodiments can utilize any number of sensors  124  of one or more type to detect operational conditions associated with traveler  188  and nut  190  vertical manipulation. As a non-limiting example, acoustic, optical, mechanical, and environmental sensors can be placed throughout the housing  196  to measure the operating parameters associated with lifting, and lowering, such a temperature, humidity, moisture content, rotational speed, distance from the top of the core  186 , distance to the bottom of the core  186 , stress, tension, cracks, plastic deformation, and dimensions of the core  186  threads. 
     With the nearly unlimited sensor  194  configuration possibilities for a lifting column  124 , operation can be closely monitored and collected data can be used to alter core  186  operation, such as rotation speed, and/or schedule service actions that can proactively, or reactively, ensure safe, reliable, and consistent future lifting column  124  operation. One measurement that would optimize the sensing of lifting column  124  operation is the nut gap distance between the nut  190  and traveler  188 . However, the typically small nut gap  192  (&lt;1 inch) is difficult to accurately sense. That is, a small nut gap  192  distance creates difficulties in positioning a sensor  194  within, or proximal to, the nut gap  192  to accurately provide real-time operational measurements, particularly with the heat, stress, and presence of grease in the nut gap  192  during operation. 
       FIG. 6  depicts a block representation of an example lifting module  200  that can be utilized by a lifting controller  112  to provide intelligent lifting operations for a drop table as part of a maintenance system. The module  200  can be circuitry resident in a programmable processor, microcontroller, or other logic circuit that can generate an intelligent lifting strategy in response to assorted data from aspects of a drop table. The module  200  can employ some, or all, of a lifting controller  112  to log the operational characteristics of a drop table to discern the optimal operating parameters to provide efficient, safe, and reliable vertical displacement of a load, as defined in the lifting strategy. 
     The lifting controller  112  can selectively store at least input drop table data, lifting strategies, and other operational parameters in a memory  202 , such as a volatile or non-volatile data storage device like a hard disk drive or solid-state array. The lifting controller  112  can monitor motor feedback from each variable drive motor of a drop table in order to determine the quality and integrity of lifting operations in each lifting column. While not required or limiting, the motor feedback data may be supplemented with information collected from one or more sensors that is used to verify the motor feedback data as well as identify other lifting parameters. 
     For instance, an acoustic sensor can be used to collect friction information and/or information about how a load is positioned on a drop table platform, which allows the lifting controller  112  to determine the center of gravity for the platform. As another example, a mechanical sensor can be used to collect nut gap distance information that can be correlated by the controller  112  to efficiency and longevity of a lifting column traveler. One or more environmental sensors may additionally be used to provide the controller  112  with information about the operating conditions around a drop table, such as temperature and humidity, that can be used to determine at least motor, transmission, and rotating core efficiencies. 
     It is contemplated that lifting data can be manually input, or downloaded, to the lifting module  200  by a user. Manually inputted information about the load/component being lifted, such as weight, dimensions, and center of gravity, can allow the lifting controller  112  to identify potential hazards during a maintenance operation involving the raising, lowering, and horizontal displacement of the load/component. For example, the lifting controller  112  may correlate a particularly heavy load with increased strain on a transmission or a load with an odd shape and a center of gravity offset from the center of the lifting platform with increased strain on a particular lifting column. 
     While the collection of information and determination of various lifting conditions by the lifting controller  112  can be informative, the value of the lifting strategy is the optimization of lifting conditions for a variety of different hypothetical situations. That is, the lifting controller  112  can identify current conditions based on inputted data, but may not be equipped alone to correlate the current conditions with different possible lifting situations, such as if a shearing coupling fails, a lifting column seizes, or a load moves. Hence, the lifting module  200  can utilize an optimization circuit  204  that evaluates possible future lifting conditions against the current lifting conditions identified by the controller  112 . 
     It is noted that the optimization circuitry  204  and lifting controller  112  can concurrently operate during drop table operation to adapt a lifting strategy to changing drop table, load, and environmental conditions, which provides maximum operational efficiency and nearly immediate reaction to deviations to prescribed lifting parameters. The optimization circuitry  204  can function alone or in combination with a prediction circuit  206  to provide lifting strategy activities that will provide optimal lifting performance and safety for a diverse variety of encountered lifting condition changes. 
     The prediction circuit  206  can utilize one or different techniques to accurately forecast future lifting conditions as well as forecast the most likely deviations from those future conditions. One such technique can involve comparing current lifting conditions identified by the controller  112  with previously logged lifting conditions with the drop table. Another possible technique can involve using model data from a database generated from other drop table operations, such as from a drop table manufacturer. It is contemplated that the more lifting operations that are conducted by a drop table will improve the accuracy and breadth of the prediction circuit  206  as encountered operational deviations from a lifting strategy are identified and managed by the lifting module  200 . 
     With the prediction circuit  206  providing different lifting conditions that accurately reflect future parameters of a drop table, the optimization circuitry  204  can generate reactive actions that correct, or at least mitigate any performance, safety, and long-term reliability degradation that those future lifting parameters can cause. For instance, the prediction circuit  206  may forecast the performance degradation of a single lifting column and the optimization circuitry  204  can build the lifting strategy with one or more proactive and reactive actions, such as increased grease pressure, slower lifting speed, or movement of the load relative to the platform, that can be triggered by the lifting controller  112  in response to identified lifting conditions, such as lifting at a certain height or when motor feedback reaches a certain amperage/frequency. 
       FIG. 7  conveys an example maintenance routine  220  that can be carried out with at least a drop table that employs the lifting module  200  of  FIG. 6  in accordance with various embodiments. Initially, the routine  220  provides a drop table that can access a loading region under machinery, such as a locomotive or railcar, and a servicing region at the top of a service shaft, as generally depicted in  FIG. 2 . It is contemplated, but not required, that the drop table has four lifting columns powered by two variable drive motors and independent transmissions each featuring a shearing drive coupling. 
     Step  222  utilizes the drop table to load a component onto a raised platform while the machinery is securely stabilized. For instance, a locomotive can drive over a drop table and be secured as a rail truck portion of the locomotive is physically attached to rail segments supported by the drop table platform, as generally shown in  FIG. 4A . It is contemplated that information about the component to be moved by the drop table is inputted, or downloaded, by a user to a lifting controller of a lifting module. 
     Such manual inputting of data can be helpful to generate a lifting strategy, but is not required as step  224  can discern pertinent information about the component being moved from at least monitored motor feedback. In other words, the lifting module can determine assorted component information, such as weight and center of gravity, from monitored motor feedback from the respective variable drive motors. Step  224  may additionally involve one or more sensors, such as an optical or acoustic type sensor, providing information about the component loaded onto the drop table platform. 
     Regardless of the detection means for providing the lifting module with component information, the module utilizes the provided information to generate a lifting strategy in step  226 . It is noted that a default lifting strategy that is agnostic to component size, weight, and center of gravity may be initially present during component data acquisition and drop table operation. In yet, the lifting strategy generated in step  226  directly relates to the component being moved and to the operational characteristics of the drop table itself. That is, the lifting controller employs the optimization circuitry and prediction circuit of the lifting module to translate any manually inputted component information with automatically inputted component information to identify the component physical characteristics that pertain to lifting operations and correlate those characteristics with the condition of the lifting columns, drive motors, and transmissions of the drop table in the form of a lifting strategy that prescribes several different motor operations in response to predicted operating parameters. 
     Therefore, the result of step  226  is a lifting strategy customized to the past operating performance of the drop table and the component being moved while providing automatic reactive actions that can correct, or mitigate, deviations from the lifting strategy. As an example, the lifting strategy can provide a closed-loop system that initially prescribes a uniform amperage for each drive motor of the drop table and at least one reaction to a predicted spike in motor amperage that saves the respective motors from failing in the event that spike occurs. 
     The newly customized lifting strategy is then carried out in step  228  to lower the component into a maintenance shaft and subsequently traverse that shaft in route to a servicing position at the top of a service shaft that intersects the maintenance shaft. The horizontal and vertical manipulation of the component with the drop table is continuously monitored by decision  230  to determine if the operational lifting parameters are following the parameters prescribed by the lifting strategy generated in step  226 . In other words, decision  230  evaluates if the drop table is operating, and the component is moving, in a nominal manner that corresponds with past drop table operation, which indicates no errors, failures, or new issues have arisen. Such evaluation of decision  230  may involve strictly the motor feedback from each variable drive motor or may incorporate measurements from one or more sensors that can be used to validate and/or complement the motor feedback data. 
     If decision  230  discovers a deviation from the lifting strategy has occurred, or is imminent based on a sequence of events predicted by the lifting module, step  232  is triggered to execute one or more reactive actions prescribed by the lifting strategy to correct or mitigate the performance and safety operation of the drop table. It is contemplated that a lifting strategy deviation is encountered that is not predicted or correctable by reactive actions of the lifting strategy. Thus, decision  234  determines if the action(s) of step  232  actually fix the deviation discovered in decision  230 . Such deviation fixing may either eliminate the deviation or progress the deviation towards nominal operating parameters defined by the lifting strategy. 
     A fixed deviation from the lifting strategy returns routine  220  to decision  230  where the lifting strategy remains in use. If the reactive action(s) of step  232  do not fix, or progress, the deviation, step  236  executes a lifting strategy contingency condition where drop table maintenance is scheduled and maintenance actions are prescribed, such as lubricating a traveler or replacing a shearing coupling. Step  236  may or may not finish the lifting operations associated with servicing the component depending on the severity of risk to performance and safety based on the encountered deviation. 
     While lifting operations can reactively be optimized through the operational adaptations allowed by the lifting strategy that utilizes intelligent actions to correct, or mitigate, deviations from normal, default, and expected lifting parameters, the ability to proactively prevent deviations in lifting parameters provides a drop table with long-term reliability and safety. The detection of actual operational parameters that deviate from expected lifting conditions in decision  230  may also trigger the lifting module to predict future lifting behavior in step  238  based on the detected lifting behavior of the drop table and future lifting activity predicted by the lifting module in response to the detected behavior. 
     For example, a deviation from expected motor feedback at a particular location on a rotating core can be used to predict future greater deviations and identity the lifting column core as degraded. As another non-limiting example, a sensed nut gap deviation can be used to predict future motor feedback deviations corresponding with traveler damage that will increase at a known rate, such as linear or exponential. 
     The ability to predict future lifting parameters with accuracy due to the intelligence of the lifting module and the basis of the lifting strategy allows proactive actions to be efficiently generated and scheduled in step  240 . Such proactive actions can be conducted in the future to prevent at least one predicted behavior. For instance but in no way required or limiting, grease can be scheduled to be removed from a lifting column core, a traveler can be physically reinforced, or certain portions of a core can be treated with greater, or lesser, lifting operation speed. At a convenient time after step  240  generates the proactive action(s), such as when a load is not being supported, the lifting module then prompts a user to conduct the one or more proactive actions generated from step  240 . 
     In the event no deviation from expected lifting parameters is experienced during motor activation, step  242  performs service on the component once the component reaches the servicing position. The service may consist of replacing, altering, cleaning, and measuring various aspects of the component to increase the component&#39;s service life and/or operating performance. Once component service has completed, the routine  220  returns to step  224  where the component is lowered from the servicing position. It is contemplated that a single lifting strategy can be utilized while a component is on the drop table, but some embodiments generate a new lifting strategy after component service has been completed to ensure any physical alterations to the component are taken into account and lifting operations have optimal efficiency and safety. 
     Through the assorted embodiments of a maintenance system, a drop table can ensure the best possible lifting efficiency, safety, and long-term reliability by employing a lifting module. The generation of a lifting strategy based on actual drop table operation and detected component characteristics creates a nearly immediate identification of current and future lifting issues along with reactive actions that can be carried out to correct, prevent, and/or mitigate the performance and safety degradation associated with the lifting issues. By utilizing a closed-loop drop table control, the lifting module can intelligently and automatically receive operational information about the drop table and component being moved, execute the lifting strategy, and conduct actions in response to deviations from lifting parameters expected in the lifting strategy. 
     It is to be understood that even though numerous characteristics of various embodiments of the present disclosure have been set forth in the foregoing description, together with details of the structure and function of various embodiments, this detailed description is illustrative only, and changes may be made in detail, especially in matters of structure and arrangements of parts within the principles of the present technology to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. For example, the particular elements may vary depending on the particular application without departing from the spirit and scope of the present disclosure.