Pantograph down stop for trolley

A pantograph assembly configured to transfer electrical power from an overhead conductor to a machine is disclosed. The pantograph assembly may include a pantograph base detachably mounted to the machine, an articulated linkage assembly having a linkage assembly lower end operatively connected to the pantograph base and a linkage assembly upper end pivotally connected to the linkage assembly lower end, a collector rail assembly operatively connected to the linkage assembly upper end, and a stop member. The stop member may be connected to the pantograph base and engaging the articulated linkage assembly, or connected to the articulated linkage assembly and engaging the pantograph base, to prevent the articulated linkage assembly from being lowered toward the pantograph base below a predetermined down position or lower limit position. A latch assembly may be mounted on the pantograph base and operable to move between a latch locked position and a latch unlocked position.

TECHNICAL FIELD

The present disclosure relates generally to machines that can be powered by electricity and, more particularly, to pantograph assemblies that can be raised and lowered to selectively transfer electrical power from an overhead conductor to such machines.

BACKGROUND

Machines such as trolley-assist vehicles or electric locomotives generally employ a pantograph assembly to provide electric power to the machine. Typically, the pantograph assembly is carried on top of the machine. The pantograph assembly is configured to draw electrical power from an overhead conductor and transfer the power to the machine. On machines such as off highway trucks, the pantograph assembly is raised and lowered to make connection with the overhead conductors. When the pantograph is lowered and the machine travels over an uneven work surface, the components of the pantograph assembly may be jostled, thereby creating stresses in the components and the actuation mechanisms that control the raising and lowering of the pantograph assembly.

U.S. Pat. No. 1,844,586 issued to McLaughlin on Jul. 23, 1931, teaches a hold down device for a pantograph assembly. One type of hold down device contemplated by McLaughlin comprises generally a crank arm fixed on an actuating shaft, and a hook pivotally mounted at a pivot pin on the crank arm. Rotation of the actuating shaft in one direction causes the hook to be swung into engagement with the stirrup on an upper link of the pantograph, and then move downward in a substantially vertical direction. The hook is spring-pressed against the stirrup so that there is no danger of the hook becoming disengaged from the stirrup. The actuating shaft imparts both rotary and translational motion to the hook and the hold down device locks the pantograph in the collapsed position, and depresses the upper links of the pantograph to the limit of their downward movement. Despite the teaching by the McLaughlin patent, not all locking mechanisms provide complex motion that locks the pantograph in the collapsed position and limits movement of its components.

SUMMARY OF THE DISCLOSURE

In one aspect of the present disclosure, a pantograph assembly configured to transfer electrical power from an overhead conductor to a machine is disclosed. The pantograph assembly may include a pantograph base detachably mounted to the machine, an articulated linkage assembly having a linkage assembly lower end operatively connected to the pantograph base and a linkage assembly upper end pivotally connected to the linkage assembly lower end, a collector rail assembly operatively connected to the linkage assembly upper end, and a stop member. The stop member may be connected to the pantograph base and engaging the articulated linkage assembly, or connected to the articulated linkage assembly and engaging the pantograph base, to prevent the articulated linkage assembly from being lowered toward the pantograph base below a predetermined lower limit position.

In another aspect of the present disclosure, a pantograph assembly configured to transfer electrical power from an overhead conductor to a machine is disclosed. The pantograph assembly may include a pantograph base detachably mounted to the machine, an articulated linkage assembly, a collector rail assembly, a stop member and a latch assembly. The articulated linkage assembly may include a thrust rod pivotally mounted to the pantograph base, a lower arm having a lower arm first end connected to the thrust rod, and an upper arm having an upper arm first end pivotally connected to a lower arm second end of the lower arm. The collector rail assembly may be operatively connected to an upper arm second end of the upper arm of the articulated linkage assembly and have a locking bar, wherein rotation of the thrust rod in a first thrust rod direction raises the articulated linkage assembly relative to the pantograph base and rotation of the thrust rod in a second thrust rod direction opposite the first thrust rod direction lowers the articulated linkage assembly relative to the pantograph base. The stop member may be mounted on and rotatable with the thrust rod, and may have a lower limit surface that rotates into engagement with the pantograph base to prevent the articulated linkage assembly and the collector rail assembly from being lowered toward the pantograph base below a predetermined lower limit position. The latch assembly may be mounted on the pantograph base and operable to move between a latch locked position and a latch unlocked position. The latch assembly may be actuated to move to the latch locked position and engage the locking bar when the articulated linkage assembly is in the predetermined lower limit position. The latch assembly when engaging the locking bar may prevent the articulated linkage assembly and the collector rail assembly from moving upwardly from the predetermined lower limit position as the machine moves over a work surface.

In a further aspect of the present disclosure, a pantograph assembly configured to transfer electrical power from an overhead conductor to a machine is disclosed. The pantograph assembly may include a pantograph base detachably mounted to the machine, an articulated linkage assembly having a linkage assembly lower end operatively connected to the pantograph base and a linkage assembly upper end pivotally connected to the linkage assembly lower end, a collector rail assembly operatively connected to the linkage assembly upper end, and a stop means operatively connected to the articulated linkage assembly and engaging the pantograph base to prevent the articulated linkage assembly and the collector rail assembly from being lowered toward the pantograph base below a predetermined lower limit position.

Additional aspects are defined by the claims of this patent.

DETAILED DESCRIPTION

FIG. 1illustrates a schematic side view of a machine10having a pantograph assembly12mounted thereon. The machine10may include a vehicle such as an off-highway truck or other vehicle used in mining, construction, quarrying or other applications. One example of the machine10is the off-highway truck illustrated inFIG. 1traveling over a work surface14and including a chassis16that supports an operator cab18and a dump body20. The dump body20may be pivotally connected to the chassis16and arranged to carry a payload when the machine10is in use. The machine10may include a power source22that may be, for example, an engine such as internal combustion, gas, diesel, gaseous fuel, natural gas, propane or the like). The power source22may be of any size, with any number of cylinders, and in any configuration, such as “V,” in-line, radial or the like, that will propel the machine10over the work surface14as desired. The chassis16may also support various drive system components. The drive system components are capable of driving a set of drive wheels24to propel the machine10. A set of idle wheels26can pivot to steer the machine10to move in any desired direction.

In the illustrated embodiments, the power source22may produce an output torque at an output shaft28. The output shaft28of the power source22may be connected to a generator30. In operation, the output shaft28of the power source22rotates a rotor (not shown) of the generator30to produce electrical power to drive motors32associated with the drive wheels24. The drive motors32may be connected via intermediate assemblies or directly to drive wheels24of the machine10, and may be capable of being operated at variable speeds.

The machine10may further include the pantograph assembly12mounted at the front of the machine10. Alternatively, the machine10may include two or more pantograph assemblies12connected to each other and controlled to be raised and lowered together. The pantograph assembly12may be configured to supply electrical power from the overhead conductors34to the machine10. Electrical power from the overhead conductors34may act as a power source to assist in propulsion of the machine10. The pantograph assembly12may shortcut the power source22and the generator30, thereby directly providing electrical power to the drive motors32. For simplicity in description and clarity of illustration, the electrical components of the pantograph assembly12are not shown in the drawings except where the components are helpful for a complete description of the embodiments in accordance with the present disclosure.

FIGS. 2-5illustrate an embodiment of the pantograph assembly12in accordance with the present disclosure in a raised position. Referring toFIGS. 2 and 3, the pantograph assembly12may include a pantograph base40having a pair of front base feet42and a pair of rear base feet44that may be permanently or detachably mounted on the front of the machine10to secure the pantograph assembly12. The front base feet42and the rear base feet44may be mounted on the front of the machine10by using nuts and bolts or other appropriate type of temporary or permanent fastening mechanisms. Insulating members (not shown), such as rubber or plastic bellows, designed to keep the pantograph base40electrically insulated from the machine10may be provided at the pairs of front base feet42and rear base feet44. Moreover, the pantograph assembly12may be mounted on the top of the machine10or at any other appropriate location on the machine to facilitate selective engagement of the overhead conductors34. A front base cross-member46(FIG. 2) may extend between the front base feet42, a rear base cross-member48(FIG. 2) may extend between the rear base feet44, and a plurality of base support members50may extend from front to back of the pantograph base40between the front base cross-member46and the rear base cross-member48or corresponding pairs of the front base feet42and the rear base feet44so that other components of the pantograph assembly12can be mounted to and supported by the front base cross-member46and the rear base cross-member48and the base support members50.

An articulated linkage assembly60may be mounted on the pantograph base40. The articulated linkage assembly60may be configured to move a collector rail assembly62of the pantograph assembly12between a predetermined upper limit position shown inFIGS. 2 and 3and a predetermined lower limit position shown inFIG. 6. At the predetermined upper limit position, the collector rail assembly62may be held in contact with the overhead conductors34. In the predetermined lower limit position, the articulated linkage assembly60and the collector rail assembly62are withdrawn from the overhead conductors34and the machine10is not operating off the electrical power provided by the overhead conductors34.

The articulated linkage assembly60in the illustrated embodiment (FIGS. 2 and 3) may include a linkage assembly lower end60aoperatively connected to the pantograph base40and a linkage assembly upper end60boperatively connected between the linkage assembly lower end60aand the collector rail assembly62. The linkage assembly lower end60amay include a thrust rod64(FIGS. 2 and 4) pivotally mounted to the front base cross-member46of the pantograph base40, and a lower arm66having a lower arm first end66aconnected to the thrust rod64so that the lower arm66will rotate with the thrust rod64. The linkage assembly upper end60bmay include an upper arm68having an upper arm first end68apivotally connected to a lower arm second end66band an upper arm second end68bpivotally connected to the collector rail assembly62.

The linkage assembly lower end60aof the articulated linkage assembly60may further include a lower link70having a lower link first end70apivotally connected to the pantograph base40and a lower link second end70bpivotally connected to the upper arm68proximate the upper arm first end68a. An upper link72of the linkage assembly upper end60bmay have an upper link first end72apivotally connected to the lower arm66proximate the lower arm second end66band an upper link second end72bpivotally connected to the collector rail assembly62. The lower arm66, the upper arm68, the lower link70and the upper link72of the articulated linkage assembly60may be configured and interconnected such that the collector rail assembly62maintains an upright orientation and travels in a substantially vertical path as the articulated linkage assembly60moves the collector rail assembly62between the predetermined upper limit position shown inFIGS. 2 and 3and the predetermined lower limit position shown inFIG. 6.

Rotation of the thrust rod64in a first thrust rod direction raises the collector rail assembly62relative to the pantograph base40. Rotation in the first thrust rod direction may be clockwise rotation of the thrust rod64as indicated by the arrow74in the partial cross-sectional side view ofFIG. 4. Rotation of the thrust rod64in a second thrust rod direction lowers the collector rail assembly62relative to the pantograph base40. Rotation in the second thrust rod direction may be counterclockwise rotation as indicated by the arrow76inFIG. 4. The extent of the rotation of the thrust rod64in either direction, may be controlled by providing a stop means such as a stop member80to function in cooperation with the pantograph base40and the articulated linkage assembly60to limit the rotation of the thrust rod64. The stop member80may also be referred to as a down stop. Limiting the rotation of the thrust rod64with the stop member80correspondingly restricts movement of the pantograph assembly12to that between the predetermined upper limit position and the predetermined lower limit position. The stop member80may be operatively connected to one of the pantograph base40and the articulated linkage assembly60and engage the other of the pantograph base40and the articulated linkage assembly60to prevent the articulated linkage assembly60and the collector rail assembly62from being lowered toward the pantograph base40below the predetermined lower limit position.

In the illustrated embodiment, the stop member80may be mounted on and rotatable with the thrust rod64of the linkage assembly lower end60a. The stop member80may rotate into engagement with the front base cross-member46of the pantograph base40at the predetermined lower limit position to prevent further lowering of the lower arm66and the pantograph assembly12. The stop member80may be generally arc-shaped and have a stop member inner surface having an inner diameter that is approximately equal to an outer diameter of a thrust rod outer surface of the thrust rod64, and a stop member outer surface that may be shaped to function as a camming or guide surface for a lift cable82as discussed further below. One end of the stop member80may define an upper limit surface84configured to engage the front base cross-member46when the pantograph assembly12reaches the predetermined upper limit position as seen inFIG. 4. In the present embodiment, the front base cross-member46may have an upper limit stop pad86mounted thereon and engaged by the upper limit surface84to stop the pantograph assembly12at the predetermined upper limit position. An opposite end of the stop member80may define a lower limit surface88configured to engage the front base cross-member46when the pantograph assembly12reaches the predetermined lower limit position as seen inFIG. 7. The lower limit surface88may also be referred to as a down stop surface. A similar lower limit stop pad (not shown) may be mounted on the front base cross-member46at a position to be engaged by the lower limit surface88of the stop member80. The stop member80may be a separate component connected to an outer surface of the thrust rod64, or may be integrally formed with the thrust rod64as a single unitary component during the manufacturing process.

While the stop member80is shown inFIGS. 2, 4, 6 and 7as being mounted on the thrust rod64and engaging the front base cross-member46, alternative arrangements for the stop member80to limit movement of the pantograph assembly12are possible and such alternatives are contemplated by the inventor as having use in pantograph assemblies12in accordance with the present disclosure. For example, the stop member80may be mounted to the front base cross-member46or other component of the pantograph base40, with the upper limit surface84and the lower limit surface88engaging the thrust rod64or other component of the articulated linkage assembly60at the corresponding limit positions of the pantograph assembly12. In one embodiment, the thrust rod64may have an ovoid or other appropriate cross-sectional shape so that the thrust rod64is disengaged from the upper limit surface84and the lower limit surface88as the thrust rod64rotates between the limit positions, but rotates into engagement with the upper limit surface84and the lower limit surface88when the thrust rod64rotates to the corresponding limit position. Additional configurations and interactions between the pantograph base40, the articulated linkage assembly60and a stop means such as the stop member80are contemplated.

Movement of the pantograph assembly12between the limit positions may be controlled by a lift actuator90(FIGS. 4 and 7) that may be operatively coupled the pantograph base40and one of the thrust rod64, the lower arm66and the stop member80. The lift actuator90may be actuated to generate a torque to rotate the thrust rod64and the lower arm66in the first thrust rod direction to raise the collector rail assembly62relative to the pantograph base40. In the illustrated embodiment, the lift actuator90may include a linear actuator92operatively connected to the pantograph base40and being actuatable to move from an extended position toward a retracted position. The lift actuator90may further include the lift cable82operatively connected between the linear actuator92and the stop member80. Due to the coupling between the lift cable82and the stop member80, and the connection of the stop member80to the thrust rod64, the thrust rod64may rotate in the first thrust rod direction when the linear actuator92moves from the extended position toward the retracted position and correspondingly raise the collector rail assembly62. Conversely, the thrust rod64may rotate in the second thrust rod direction when the linear actuator92moves from the retracted position toward the extended position.

As best seen inFIGS. 4 and 7, the linear actuator92may be implemented in the form of a hydraulic cylinder actuator having a piston head (not shown) disposed within a cylinder body94and a piston rod96(visible through a flexible sleeve98illustrated as transparent) extending out of the cylinder body94. A head end100of the cylinder body94may be connected to the pantograph base40, and a rod end102of the cylinder body94may have the piston rod96extending therefrom and attached to a first end82aof the lift cable82. A second end82bof the lift cable82may be connected to the stop member80to allow the linear actuator92to apply torque to the stop member80and correspondingly to the thrust rod64. The rod end102of the linear actuator92may receive pressurized fluid from a pressurized fluid source (not show) via a rod end fluid supply line104.

When the pantograph assembly12is in the lowered position shown inFIG. 7, the piston head and piston rod96may be in the extended position with the piston head disposed proximate the rod end102of the linear actuator92and the piston rod96extending from the linear actuator92. The extension of the piston rod96and corresponding decrease in tension in the lift cable82allow the stop member80and the thrust rod64to rotate to the lowered position with the lower limit surface88of the stop member80engaging the front base cross-member46. In this position, the lift cable82may be partially wrapped around the outer surface of the stop member80. When it is desired to raise the pantograph assembly12to the raised position ofFIG. 4, pressurized fluid from the pressurized fluid source is directed to the rod end102of the linear actuator92via the rod end fluid supply line104to increase the pressure in the rod end102and move the piston head and the piston rod96toward the head end100of the linear actuator92and the retracted position against the weight of the pantograph assembly12. As the piston head and piston rod96move, tension in the lift cable82increases and creates a torque on the stop member80and the thrust rod64to rotate the thrust rod64and the lower arm66in the direction to raise the collector rail assembly62via the articulated linkage assembly60. The pressurized fluid may be added to the rod end102of the linear actuator92until the upper limit surface84of the stop member80rotates into engagement with the front base cross-member46and the pantograph assembly12is fully raised. When it is desired to lower the pantograph assembly12, the pressurized fluid in the rod end102of the linear actuator92may be drained to a low pressure reservoir (not shown) to allow the piston head and piston rod96to move toward the lowered position ofFIG. 7due to the weight of the pantograph assembly12communicated to the linear actuator92by the lift cable82. If helpful, a head end fluid supply line (not shown) may provide fluid to the head end100of the linear actuator92as the piston head moves toward the extended position to avoid cavitation or creation of a vacuum behind the piston head that can disturb smooth movement as the pantograph assembly12is lowered.

In alternative embodiments, the lift actuator90may include a solenoid actuator or other appropriate type of linear actuator capable of creating linear motion as described in the present application. In further alternative embodiments, the lift actuator90may include a rotary actuator such as a stepper motor operatively connected to the stop member80or the thrust rod64by a linkage or other appropriate mechanism known in the art for converting rotation generated by the rotary actuator into the rotation of the thrust rod64described in this application. In still further embodiments, a rotary actuator may be connected directly to the stop member80or the thrust rod64to directly drive the thrust rod64in at least the first thrust rod direction to raise the pantograph assembly12. Any other appropriate type of lift actuator means that is capable of causing the articulated linkage assembly60to move between the predetermined upper and lower limit positions as described in the present application are contemplated for use in the pantograph assemblies12in accordance with the present disclosure.

As shown inFIG. 2, the collector rail assembly62may extend along a longitudinal axis A that is approximately perpendicular to a direction of travel of the machine10and to the overhead conductors34. The collector rail assembly62may include a pair of rails such as a first collector rail110and a second collector rail112that are approximately parallel to each other, to the longitudinal axis A and to the work surface14. The lower arm66, the upper arm68, the lower link70and the upper link72of the articulated linkage assembly60may be configured and interconnected such that the first collector rail110and the second collector rail112of the collector rail assembly62remain parallel to each other and to the work surface14and perpendicular to the overhead conductors34as the articulated linkage assembly60moves the collector rail assembly62between the predetermined upper limit position shown inFIGS. 2 and 3and the predetermined lower limit position shown inFIG. 6so that both the first collector rail110and the second collector rail112engage the overhead conductors34when the articulated linkage assembly60is in the upper limit position. The collector rail assembly62may also include a metallic frame (not shown) and carbon brushes (not shown) supported by the metallic frame. It will be apparent that the carbon brushes may be designed to provide an electrical contact with the overhead conductors34.

The collector rail assembly62may further include a locking bar114oriented approximately parallel to the first collector rail110and the second collector rail112. The pantograph assembly12may further include a latch assembly120(FIGS. 5 and 8) configured to engage the locking bar114when the pantograph assembly12is at the predetermined lower limit position as shown inFIG. 8to prevent the collector rail assembly62from moving upwardly from the predetermined lower limit position relative to the pantograph base40as the machine10moves over a work surface14. As shown in the enlarged view ofFIG. 9, the pantograph assembly12may include a pair of latch assemblies120configured to engage the locking bar114when the pantograph assembly12is at the predetermined lower limit position. The combination of the stop member80and the latch assemblies120reduces the downward movement of the pantograph assembly12and the possibility of the latch assemblies120unlatching from the locking bar114when the pantograph assembly12is subjected to high gravity loads, or G-loads, as the machine10moves over the work surface14. The additional latch assembly120may allow the G-loads to be distributed between the latch assemblies120.

Each latch assembly120may include a latch member122pivotally mounted on the pantograph base40and having a latch hook124, and a latch actuator126operatively connected to the latch member122and operable to move the latch member122between a latch locked position as shown and a latch unlocked position (not shown) through a counterclockwise rotation as shown inFIGS. 5 and 8. The latch actuator126may move the latch member122to the latch locked position through a clockwise rotation when the collector rail assembly62is in the predetermined lower limit position to engage the locking bar114as shown inFIG. 8. The latch actuator126as shown may be a hydraulic cylinder actuator similar to the linear actuator92of the lift actuator90described above where pressurized fluid from a fluid source may alternately extend a piston rod128to rotate the latch member122to an unlocked position and retract the piston rod128to rotate the latch member122to a locked position and engage the locking bar114. Alternatively, the latch actuator126may be any other appropriate linear or rotary actuator such as those described above operatively coupled to the latch member122to move the latch member122between the locked and the unlocked positions.

INDUSTRIAL APPLICABILITY

The arrangement of the pantograph assembly12illustrated and described in the present application may provide a relative simple and effective mechanism for securing the pantograph assembly12in the predetermined lower limit position and preventing undue wear and tear and stresses on the components of the pantograph assembly12that can require frequent maintenance and cause premature failure of the components. Without the engagement of the lower limit surface88of the stop member80with the front base cross-member46, the latch assembly120may retain the pantograph assembly12in the lowered position, but the components of the articulated linkage assembly60are afforded a freedom of movement allowing the components to bounce up and down as the machine10traverses the work surface14. The movement can cause high stresses in the lift cable82that can increase the risk of the lift cable82breaking or detaching from the piston rod96of the lift actuator90. Moreover, slack between the latch hook124and the locking bar114can result in disengagement of the latch hook124from the locking bar114and unintended deployment of the pantograph assembly12as the machine10travels through the work area.

The engagement of the front base cross-member46by the lower limit surface88of the stop member80can further restrict the motion of the components of the articulated linkage assembly60when the pantograph assembly12is lowered. Restriction from further downward movement of the articulated linkage assembly60and rotation of the thrust rod64prevents additional stresses from being applied to the lift cable82when the lift actuator90is in the extended position. The lower limit also reduces or eliminates the slack between the latch hook124and the locking bar114, thereby correspondingly reducing the chances that the latch hook124will disengage from the locking bar114.

Additionally, effective engagement of the latch assembly120with the locking bar114is achievable with a simpler motion than devices having a combination of rotational and translational motion. The latch member122moves through pure rotation into engagement with the locking bar114instead of through a more complex combination of rotation and translation. The simpler motion may allow for a simpler and less expensive design for the latch member122. However, latching devices with more complex movement could be implemented in the pantograph assembly12in accordance with the present disclosure if such a mechanism is necessitated by the operating requirements for a particular machine10.