Patent Publication Number: US-11390503-B2

Title: Drop table with shearing drive coupling

Description:
SUMMARY 
     A drop table, in accordance with various embodiments, has a motor physically attached to a first lifting column via a first rotating input shaft and to a second lifting column via a second rotating input shaft. Each rotating input shaft is connected to the motor by a drive coupling consisting of an inner shaft attached to collar via a shearing insert. 
     Operation of a drop table, in some embodiments, involves connecting a first lifting column to a motor via a first drive coupling and connecting a second lifting column to the motor via a second drive coupling. Activation of the motor rotates each drive coupling to provide vertical motion of a platform. Upon experiencing a shear force above a predetermined physical threshold of a shearing insert of the first drive coupling, the motor is automatically disconnected from the first lifting column. 
    
    
     
       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 . 
         FIG. 4  displays a block representation of portions of an example drop table arranged in accordance with assorted embodiments. 
         FIG. 5  depicts portions of an example drop table configured and operated in accordance with some embodiments. 
         FIGS. 6A-6D  respectively convey portions of an example drop table employed in accordance with various embodiments. 
         FIG. 7  is an example lifting routine that may be executed with assorted embodiments of  FIGS. 1-6D . 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure generally relates to embodiments of a drop table with one or more drive couplings configured and operated to provide optimized lifting operations. 
     As heavy machinery, such as locomotives, industrial equipment, and large-scale tools, have become more sophisticated over time, a need remains for maintenance of assorted components of the machinery. Maintenance can involve the removal of relatively heavy, and potentially cumbersome, components from machinery and the subsequent transport of those components to a service station where maintenance operations are conducted. After maintenance work is concluded, the heavy components are then transported back to the machinery where installation takes place. Throughout these maintenance operations, the safety, efficiency, and reliability of maintenance equipment and mechanisms are jeopardized by the amount of strain placed one the equipment by the machinery components. 
     When transportation of machinery components for maintenance operations involves lifting, the maintenance equipment can experience extreme loads that gradually, or suddenly, degrade operation, which necessitates lengthy and expensive repairs. The operation of such maintenance equipment can also be very dangerous as loads can move and equipment can break under large amounts of force. Hence, various embodiments are directed to implementing drive couplings that shear and disconnect under predetermined amounts of force into maintenance equipment to optimize equipment operation, efficiency, and safety. 
       FIG. 1  depicts a block representation of an example maintenance system  100  in which various embodiments can be practiced. The system  100  can be configured to service any type, and size, of machinery, such as a vehicle  102 . It is contemplated that more than one vehicle  102  can concurrently be accessed and serviced, but such arrangement is not required or limiting. 
     Although assorted maintenance can be facilitated without physically moving the vehicle  102 , 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 vehicle  102  while a component remains stationary or by lowering the component while the vehicle  102  remains stationary. Due to the significant weight and overall size of some vehicles  102 , such as a locomotive engine or railcar, the maintenance system  100  is directed to moving a component vertically, as represented by arrow  104 , with a lifting mechanism  106  while the remainder of the vehicle  102  remains stationary. 
     The lifting mechanism  106  can consist of at least a motor  108 , or engine, that powers one or more actuators  110  to physically engage and move vehicle components. 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 vehicle 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. 
     In accordance with some embodiments, the lifting mechanism  106  can be characterized as a drop table onto which the vehicle  102  moves to position a component in place to enable component removal, and subsequent installation after service has been performed.  FIG. 2  depicts a block representation of an example drop table system  120  arranged to provide maintenance operations for a vehicle  102 . A drop table  122  can consist of one or more motors  108 , actuators  110 , and controllers  112  that are utilized to engage a vehicle component  124 , lower the component  124  to separate it from the vehicle  102 , move the component  124  to a service shaft  126 , and subsequently raise the component  124  into a service area  128  at the top of the service shaft  126 . 
     With the combination of vertical component movement  104  and horizontal component movement  130 , the drop table  122  can experience a broad range of forces that jeopardize system  120  operation and safety. That is, a drop table  122  can encounter differing forces from diverse vectors during the lowering, horizontal translation, and raising of a component  124  that has a substantial weight, such as 5 tons or more, which may place a diverse variety of strain on at least the moving aspects of the drop table  122 . Hence, the range of movement of the drop table  122  has a greater risk of part failure and safety hazards compared to lifting mechanisms simply employed for vertical movement  104 . 
       FIGS. 3A &amp; 3B  respectively depict block representations of portions of an example drop table  140  that can be utilized in the systems  100 / 120  of  FIGS. 1-2  to conduct vehicle component maintenance. The top view of  FIG. 3A  displays a platform  142  disposed between and physically attached to multiple lifting columns  144 . As directed by a local controller  112 , one or more lifting motors  146 , or engines, can articulate aspects of the respective columns  144  to move the platform  142  in the vertical direction  104 . The controller  112  may further direct one or more transverse motors  148 , or engines, to activate a drive line  150  and move the platform  142  along the horizontal direction  130 . 
     It is contemplated that one or more lifting columns  144  are physically separated from the platform  142 , but such configuration would necessitate individual motors  146 / 148  for each column  144  along with complex spatial sensing and coordination to ensure a vehicle component  124  is securely lifted and moved. Instead, the platform  142  physically unifies the respective lifting columns  144  and provides a foundation onto which the vehicle component  124  can rest and provide a consistent center of gravity throughout lifting and horizontal movement activities. 
       FIG. 3B  displays side view and an example physical layout of the drop table  140  where a base  152  remains stationary while the platform  142  is vertically translated. The base  152  provides a secure foundation for the various motors  146 / 148 , and associated transmissions, that power the respective lifting columns  144 . The base  152  further anchors the drive line  150  and number of constituent rollers  154 , which can be wheels, castors, trucks, or other assembly utilizing a bearing that allows horizontal movement  130 . During normal operation, the assorted lifting columns  144  provide uniform platform  142  lifting and lowering. However, the fact that the multiple lifting columns  144  can independently experience degraded operation and/or failures increases the operational risk of less than all of the columns  144  experiencing an error. 
     When a lifting column  144  experiences degraded operation and/or failure while other columns  144  continue to operate, the platform  142  can become unstable, as illustrated by segmented platform  156 , and the very heavy component  124  can be at risk of damage and/or damaging the drop table  140 . Hence, the use of independent lifting motors  146 , or independent lifting columns  144  separate from a platforms  142 , can be particularly dangerous. Furthermore, independent lifting columns  144  provide less physical space for motors  146  and limit the available motor size and power that can be safely handled by a column  144 , which reduces the efficiency and safety of lifting heavy components  124 , such as over 10 tons. 
     In contrast to independent lifting columns  144  having independent lifting motors  146 , it is contemplated that a single motor can be employed to power the respective columns  144  collectively. While the base  152  could provide enough space and rigidity to handle a single motor/engine  146 , the failure rates and operational longevity of a motor/engine  146  capable of lifting tens of tons of components  124  can involve increased service times and frequency that can be prohibitive in terms of drop table  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  146  to four separate lifting columns  144 . 
     Accordingly, various embodiments employ a lifting motor  146  to power two separate lifting columns  144 . The combination of two lifting motors  146  to power four columns  144  provides an enhanced motor efficiency via relatively simple transmissions, lower service times/frequency, and relatively simple motor  146  coordination compared to independent columns  144  or a single motor powering four columns  144 . 
       FIG. 4  depicts a block representation of portions of an example drop table  160  configured in accordance with some embodiments to provide efficient and safe component  124  movement during maintenance operations. The top view of  FIG. 4  conveys how a first lifting motor  162  and a second lifting motor  164  can each be mounted to the drop table base  152  and respectively connect to a pair of lifting columns  144  via separate transmissions  166 . The assorted transmissions  166  can be matching, or dissimilar, assemblies that translate rotational output of the motors  162 / 164  into vertical movement of platform  142  connected to each column  144 . 
     The operation and physical configuration of the respective lifting columns  144  is not limited, but can involve a rotating core that selectively articulates a nut and platform traveler upward or downward depending on the rotation of the core. Hence, each motor  162 / 164  and transmission  166  is designed and operated to provide bidirectional operation with enough precision to prevent shock, physical trauma, and movement of a component  124  attached to the platform  142 . The respective motors  162 / 164  may be configured with a single output while some embodiments utilize motors with dual outputs that operate concurrently with matching power in response to electrical activation. 
     During operation, it is noted that mechanical, and electrical, degradation can occur unevenly between the two lifting columns  144  connected to the respective motors  162 / 164 . The failure of a lifting column  144  or transmission  166  on one output of a motor  162 / 164  while the lifting column  144  and transmission  166  connected to the other output of the motor  162 / 164  remains operating can lead to motor failure as tension is disproportionately utilized. Likewise, a failure of both transmissions  166  connected to a motor  162 / 164  results in a failed motor due to excessive heat and friction. Such motor failures are costly to repair in terms of money, time, and inefficiency of a maintenance system. 
     With these issues in mind, assorted embodiments are directed to adding a drive coupling that shears in response to a predetermined amount of force to each transmission  166  so that excessive force experienced by a lifting column  144  fails at the transmission  166  and not the motor  162 / 164 . That is, the addition of a shearing drive coupling to each transmission  166  ensures lifting column  144  and/or transmission  166  failures do not result in subsequent motor  162 / 164  failure. It is noted that a shearing drive coupling cannot prevent all motor  162 / 164  failures, but the isolation of failures to the transmissions  166  lessen the severity of motor failures and provide for easier and more cost efficient motor repairs compared to replacing a motor  162 / 164 . 
       FIG. 5  is a block representation of a portion of an example drop table  180  that implements shearing drive couplings  182  to each transmission  166 . The respective shearing couplings  182  may be constructed with different operational characteristics, such as shear tolerance, material, and size, but various embodiments utilize shearing couplings  182  with matching operational characteristics. Each shearing drive coupling  182  is physically attached between an output shaft  184  of a motor  186  and a lifting shaft  188  of the transmission  166  that rotates to drive the raising, or lowering, of portions of a lifting column  144  and attached platform  142 . 
     The shearing drive couplings  182  can be individually, and collectively, tuned to provide optimal lifting column  144  operation with respect to efficiency and safety. By mechanically constructing each drive coupling  182  with a shearing component that fails in response to forces in excess of predetermined threshold, the respective transmissions  166  can automatically disconnect the motor  186  from a lifting column  144  and mitigate the damage experienced by the motor  186  from the excessive operational forces. It is noted that the drop table  180  can be configured to prevent an elevated platform  142  from falling in response to the physical disconnection of a drive coupling  182 . The drop table  180  may further be configured to automatically alter motor  186  operation to a protection mode, such as electrical deactivation or reduced power output, in response to physical disconnection of a drive coupling  182 . 
       FIGS. 6A-6D  respectively depict perspective and cross-sectional line representations of portions of an example drop table transmission  200  configured and operated in accordance with some embodiments to provide optimal lifting operations. A transmission  200  can have a drive shaft  202  that attaches to a collar  212  to allow unitary rotation and translation of motor output shaft movement to an attached lifting column. 
     As shown in  FIG. 6A , a drive shaft  202  can have an enlarged diameter that supports a protrusion  204  that is sized to fit within and physically engage the collar  212 . It is contemplated the protrusion  204  has one or more recesses  206  where a shearing insert  222  can fit to engage the collar  212 , as displayed in  FIG. 6D . A recess  206  can be any size and shape defined by linear, or curvilinear, surfaces. Some embodiments construct multiple separate, or interconnected, recesses  206  into a protrusion  204  to allow multiple inserts  222  to be concurrently utilized. 
     The cross-sectional view of  FIG. 6B  illustrates how the drive shaft  202  has an attachment opening  210  that allows the shaft  202  to be physically coupled to another transmission component, such as a lifting shaft. Such physical connection may be aided by one or more fasteners and/or fastening material, such as glue, that extend through a fastening aperture  208 . The use of one or more fasteners to connect the drive shaft  202  to another transmission component can provide a supplemental failure mechanism that physically disconnects in response to encountered force above a predetermined threshold. That is, the fasteners, or fastening material, that extends through the respective apertures  208  can be selected and installed to have a plastic, or elastic, deformation in response to force that is above the threshold of the shearing insert  222 , which ensures physical disconnection of the transmission  200  from a motor in response to encountered force above a critical amount. 
     In  FIG. 6C , the drive shaft  202  is shown inserted into the collar  212  to create a shearing drive coupling. The collar  212  is configured with a non-limiting balancing portion  214  that has an enlarged diameter and is disposed between receiving portions  216  that respectively have reduced diameters. The receiving portions  216  may physically attach to other transmission components, such as the drive shaft  202  or output shaft of a motor, via a keyed opening  218 , which can aid the alignment and mechanical operation of the transmission  200  once connected. 
     An example assembly of a shearing drive coupling is shown in the cross-sectional view of  FIG. 6D  where the shearing insert  222  is positioned in the drive shaft recess  206  to contact the interior of a receiving portion  216  of the collar  212 . It is contemplated, but not required, that the shearing insert  222  fills some, or all, of a keyed aspect of the inner chamber of the collar  212 . Such a keyed aspect may be similar, or dissimilar, to the linear cutout of the opening  218  that creates horizontal and radial asymmetry for the opening  218 . Although not required, the collar  212  can be physically secured to the shearing insert  222  via fasteners, or fastening material, that extends through connection apertures  220 . 
     The shearing insert  222  may be constructed of any material, but in some embodiments consists of a polymer that is dissimilar from the material of the drive shaft  202  or collar  212 . The shearing insert  222  is a separate component that is installed when the drive shaft  202  is attached to the collar  212 , which allows for efficient replacement in the event forces cause the insert  222  to shatter, break, or otherwise deform. It is noted that the size and shape of the drive shaft protrusion  204  results in the drive shaft  202  mechanically disconnecting from the collar  212  in response to physical failure of the shearing insert  222 . In other words, the drive shaft  202  and collar  212  will not collectively rotate and the drive shaft  202  will simply spin inside the collar  212  once the shearing insert  222  fails. Hence, the shearing drive coupling can mechanically disconnect a transmission  200  from a motor simply with excessive rotational forces and without vertical or transverse transmission component movement, which prevents transmission component failure subsequent to shearing insert  222  failure. 
       FIG. 7  is a flowchart of an example lifting routine  230  that can be carried out with the assorted embodiments of  FIGS. 1-6D . The routine  230  initially sets up a maintenance system that utilizes at least one drop table configured with at least one shearing drive coupling. Some embodiments result in a drop table having four lifting columns powered by a pair of motors respectively connected to transmissions via one or more shearing drive couplings. It is noted that the setting up of a maintenance system may involve various physical and electrical assembly along with testing. 
     The installation and proper set up of the maintenance system allows step  232  to maneuver vehicle over the drop table. For example, step  232  can involve driving a locomotive over the drop table so that a rail wheels, suspension, and trucks are aligned with the drop table to ensure a center of gravity that is safely conducive to lifting operations. Step  234  physically secures the machinery and step  236  proceeds to lower the drop table and attached machinery component, or component assembly, into a maintenance shaft. Step  238  then activates at least one transverse motor of the drop table to horizontally move the drop table into alignment with a service shaft. It is contemplated that a transverse motor is not physically located on the drop table and instead is mounted within the maintenance shaft and connected to the drop table via a cable, chain, wire, or shaft. 
     Once the drop table is aligned with the service shaft, step  240  activates the respective lifting motors to being raising the drop table platform and attached machinery component(s). Decision  242  mirrors the mechanical operation of one or more shearing drive couplings that attach a motor to an activated lifting column by monitoring encountered shear force. In the event a shearing drive coupling experiences a shear force above a predetermined mechanical threshold of the shearing insert(s) of the drive coupling, step  244  is induced and the drive coupling is physically disconnected to release the transmission from the motor. 
     It is contemplated that the physical disconnection of one shearing drive coupling in step  244  will cause the motor to spontaneously apply excessive shear force to the other attached shearing drive coupling that causes that shearing insert to fail and disconnect that transmission and lifting column from the motor. Hence, if both connected shearing drive couplings disconnect concurrently, or experience a cascade failure aided by the motor, the motor will be free of any connected components and will enter an over-spin protection mode in step  246 . That is, a motor will automatically diminish power or deactivate in response to being active when no load is placed on either output shaft. In contrast, having a single output shaft under load and another disconnected from a transmission will result in heat, friction, and failures in the motor. 
     The physical disconnection of the motor from the respective transmissions will cause the platform to slow or halt while placing heightened forces on the remaining shearing drive couplings of the drop table. By customizing the shear force tolerance of the shearing drive couplings and the motor, a single motor will not be able to lift a machinery component without applying excessive shear force to the shearing drive couplings that results in disconnection of the remaining transmissions in step  244  and motor protection mode in step  246 . Hence, the shearing drive couplings are configured to collectively fail and protect the respective drop table motors, gearbox, rotating core, and structural integrity of the platform and base in response to a single drive coupling failure, even if a mechanical or electrical error, degraded operation, or failure is not present in each drive coupling of the drop table. 
     While inconvenient for the drop table to collectively fail in response to experiencing excessive force on a single shearing drive coupling, the respective drive couplings can be replaced quickly and efficiently while the platform and attached machinery component(s) are locked and prevented from falling in step  248 . The installation of new shearing inserts in the failed drive couplings may coincide with the repair, or maintenance, of various other drop table components, such as greasing joints or removing debris, that contributed to the initial experience of high shear forces. 
     At the conclusion of step  248 , or if no excessive shear force is experienced in decision  242 , step  250  advances the drop table platform to a fully raised position where maintenance can readily be completed on the machinery component(s). Completion of such maintenance prompts routine  230  to operate in reverse in step  252  while decision  242  monitors drop table lowering operations at one end of the maintenance shaft and subsequent raising underneath the vehicle until the component(s) are fully installed back onto the vehicle. 
     Through the assorted embodiments of a drop table and maintenance system, safety and efficiency is heightened by involving one or more shearing drive couplings. The ability to optimize the amount of force a coupling can withstand before a shearing insert fails ensures smooth and precise operation under normal conditions. The inevitable degradation of operating conditions, errors, and/or failures over time results in mitigation of motor damage with a failed drive coupling and a subsequent relatively simple and efficient repair by replacing a shearing insert, which is safer and more desirable than replacing or repairing a motor. 
     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.