Removable thrust washer retainer for a motorized wheel off-highway dump truck

A thrust washer retainer is provided and includes a first retainer portion, wherein the first retainer portion defines at least one first mating structure and includes a first interface structure, a second retainer portion, wherein the second retainer portion defines at least one second mating structure and includes a second interface structure, wherein the second retainer portion is disposed relative to the first retainer portion such that the first mating structure is associated with the second mating structure and a locking member having at least one locking structure, wherein the locking structure is associated with at least a portion of the first mating structure and the second mating structure such that the first retainer portion is non-movable relative to the second retainer portion.

FIELD OF THE INVENTION

The present invention relates generally to a transmission for a mining truck and more particularly to a device that allows for easy access to a transmission inboard thrust washer.

BACKGROUND OF THE INVENTION

Large off-road, heavy-duty work vehicles, such as mining vehicles used to haul heavy payloads excavated from open pit mines, are well known and usually employ motorized wheels for propelling or retarding the vehicle in an energy efficient manner. This type of vehicle is shown inFIG. 1. This efficiency is typically accomplished by employing a large horsepower diesel engine in conjunction with an alternator and a main traction inverter. The diesel engine is directly associated with the alternator such that the diesel engine drives the alternator. The alternator is used to power the main traction inverter, wherein the main traction inverter supplies power having a controlled voltage and frequency to two drive motors disposed within the rear wheels of the vehicle. As the drive motor is operated, the drive motor causes a transmission drive shaft to rotate at a low torque and high speed about the drive shaft axis. Because the transmission drive shaft is directly associated with the vehicle transmission, the low torque high speed rotational energy of the transmission drive shaft is communicated to the vehicle transmission. The vehicle transmission then takes the low torque high speed rotational energy supplied by the transmission drive shaft and converts this energy into a high torque low speed rotational energy output which is supplied to the rear wheels.

Referring toFIG. 2, the conversion of this low torque high speed rotational energy into a high torque low speed rotational energy is typically accomplished using a double reduction gear set disposed within the vehicle transmission. A double reduction gear set is a series of gears, pinions and planets that includes a first reduction stage and a second reduction stage. The first reduction stage may include a high-speed sun pinion, a plurality of high-speed planets and a stationary ring gear and the second reduction stage may include a low-speed sun pinion, a plurality of low-speed planets and a stationary ring gear. The output of the first reduction stage is connected to the input of the second reduction stage and may be referred to as the high-speed carrier. In a similar manner, the output of the second reduction stage is connected to the vehicle wheels via a torque tube/hub assembly.

A transmission of the type described above includes a plurality of moving parts that interact and mesh with each other in order to convert the low torque high-speed energy into high torque low-speed energy. As such, it is essential to keep all of the parts of the transmission in good working order to avoid a catastrophic equipment failure. However, several problems currently exist with this type of transmission that make the maintenance and/or repair of these components labor intensive and very expensive. One of these problems involves the inboard thrust washer, which is disposed within the transmission and is used to restrain the axial motion of the high-speed carrier. Unfortunately, current transmission designs do not allow for the easy access and removal of the inboard thrust washer. In fact, current configurations require a complete disassembly of the wheel to remove the inboard thrust washer. This is undesirable because these vehicles are extremely large and heavy requiring considerable cost and labor to replace this component. This is also undesirable because of the down time or opportunity cost due to the loss of use of the vehicle while undergoing repairs and/or maintenance. Every minute that these vehicles are not operating results in lost earnings for the operators of these vehicles, and thus can result in the loss of thousands of dollars for every hour the vehicle is inactive.

SUMMARY OF THE INVENTION

A removable thrust washer retainer for an off-highway vehicle having an electric propulsion system which includes a plurality of motorized wheels, a traction motor for delivering power to a respective wheel, a transmission in the wheel for transmitting power from the motor to the wheel, wherein the transmission comprises a central drive shaft, a planetary gear train at the end of the central drive shaft, and a thrust washer enabling relative rotation of the central drive shaft and the wheel, and a cover over an opening in an outer end of the wheel for access to the thrust washer is provided, wherein the removable thrust washer includes a first thrust washer retainer portion, wherein the first thrust washer retainer portion is of generally annular configuration and defines a bearing surface engageable with a thrust washer at the end of a drive shaft of an electric propulsion system, at least one first mating structure and a first interface structure, wherein the first thrust washer retainer portion is accessible at the outer end of a wheel via an opening therein. A second thrust washer retainer portion is also provided, wherein the second thrust washer retainer portion is of generally annular configuration and defines a second mating structure surrounding and engageable with the first mating structure of the first thrust washer retainer portion for detachably connecting the first thrust washer retainer portion and second thrust washer retainer portions against relative axial movement when connected, wherein the second thrust washer retainer portion is secured in the wheel against removal without removal of the wheel from the truck, and further includes a second interface structure. Additionally, a locking member is provided, wherein the locking member is of generally annular configuration accessible via the opening at the outer end of the wheel and surrounding the first mating structure and the second mating structure of the first thrust washer retainer portion and the second thrust washer retainer portion and having at least one locking structure engageable with the first interface structure and the second interface structure of the first thrust washer retainer portion and the second thrust washer retainer portion for selectively securing the first thrust washer retainer portion and the second thrust washer retainer portion against relative annular motion, whereby with the cover removed the locking member may be detached from the first thrust washer retainer portion and the second thrust washer retainer portion and the first thrust washer retainer portion and the second thrust washer retainer portion may be detached from each other so as to enable removal and replacement of the first thrust washer retainer portion from the opening in the wheel.

A transmission assembly is provided and includes a hub assembly, wherein the hub assembly includes a sun pinion cover and defines a hub assembly cavity and a transmission opening, wherein the transmission opening is communicated with the hub assembly cavity. A reduction gear set is also provided, wherein the reduction gear set includes an inboard thrust washer and a thrust washer retainer, the thrust washer retainer including, a first retainer portion, wherein the first retainer portion defines at least one first mating structure and includes a first interface structure, a second retainer portion, wherein the second retainer portion defines at least one second mating structure and includes a second interface structure, wherein the second retainer portion is disposed relative to the first retainer portion such that the first mating structure is associated with the second mating structure and a locking member having at least one locking structure, wherein the locking structure is associated with at least a portion of the first mating structure and the second mating structure such that the first retainer portion is non-movable relative to the second retainer portion.

A thrust washer retainer is also provided, wherein the thrust washer retainer includes a first retainer portion, wherein the first retainer portion defines at least one first mating structure and includes a first interface structure, a second retainer portion, wherein the second retainer portion defines at least one second mating structure and includes a second interface structure, wherein the second retainer portion is disposed relative to the first retainer portion such that the first mating structure is associated with the second mating structure and a locking member having at least one locking structure, wherein the locking structure is associated with at least a portion of the first mating structure and the second mating structure such that the first retainer portion is non-movable relative to the second retainer portion.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIG. 3, a transmission100is illustrated and includes a sun pinion cover102. Sun pinion cover102includes a cover body structure104having a cover outer surface106and a cover inner surface108, wherein sun pinion cover102is non-movably associated with transmission100. Transmission100also includes a hub assembly110, which defines a transmission opening112and a hub assembly cavity114, wherein transmission opening112is communicated with hub assembly cavity114. Transmission100also includes a double reduction gear set116disposed within hub assembly cavity114, wherein double reduction gear set116includes a stationary ring gear118, a first reduction stage120and a second reduction stage122.

First reduction stage120includes a high-speed sun pinion124, a plurality of high-speed planets126and a high-speed carrier128, wherein high-speed carrier128transmits the output of first reduction stage120to second reduction stage122. High-speed carrier128is disposed within transmission100such that its axial motion is restrained by an outboard thrust washer130riding on the cover inner surface108and an inboard thrust washer132riding on a plug134, wherein inboard thrust washer132is non-movably associated with plug134via a thrust washer retainer136. Second reduction stage122includes a low-speed sun pinion138, a plurality of low-speed planets140and a low-speed carrier142, wherein low-speed sun pinion138is the input to second reduction stage122and receives the output of first reduction stage120from high-speed carrier128. Low-speed carrier142receives the output of second reduction stage122and transmits this high torque output to the vehicle wheels via a drive shaft, wherein the relative rotation of the drive shaft is transferred to the wheel.

Referring toFIG. 4, thrust washer retainer136is shown and includes a first retainer portion144, a second retainer portion146and a locking member148. Referring toFIG. 5andFIG. 6, first retainer portion144is shown and defines at least one first mating structure150and includes a first interface structure152having a first threaded portion154. Referring toFIG. 7andFIG. 8, second retainer portion146is shown and defines at least one second mating structure156and includes a second interface structure158having a second threaded portion160. Referring toFIG. 9andFIG. 10, locking member148is shown and defines an undercut portion149and includes at least one locking structure151.

First retainer portion144is disposed relative to second retainer portion146such that first interface structure152is adjacent to second interface structure158wherein first threaded portion154and second threaded portion160threadingly interact with each other to associate first retainer portion144with second retainer portion146. This interaction minimizes axial movement of first retainer portion144and second retainer portion146relative to each other. Moreover, first retainer portion144is disposed relative to second retainer portion146such that, first mating structure150is aligned with second mating structure156. Locking member148is lockingly disposed relative to first retainer portion144and second retainer portion146such that the at least one locking structure151is disposed within the at least one first mating structure150and the at least one second mating structure156. This may be accomplished by sliding locking, member148over first retainer portion144and second retainer portion146such that locking structure151is disposed within first mating structure150and second mating structure156. Because locking structure151is disposed within first mating structure150and second mating structure156, first retainer portion144and second retainer portion146are prevented from rotating relative to each other, thus preventing first retainer portion144and second retainer portion146from becoming unthreaded from each other.

It should be appreciated that although locking member148is shown and described as one member having multiple locking structures151, locking member148may be any locking member device suitable to the desired end purpose, such as multiple locking structures keyed to lockingly engage first mating structure150and second mating structure156. Moreover, it should be appreciated that although first mating structure150and second mating structure156are shown as cavities (female) and locking structure151is shown as a protruding member (male), it should be considered within the scope of the invention that first mating structure150and second mating structure156may be protruding members (male) and locking structure151may be a cavity (female) for containing first mating structure150and second mating structure156. It should be appreciated that at least one of the first interface structure152and the second interface structure158is configured to securingly engage the other of the first interface structure152and the second interface structure158. It should also be appreciated that first retainer portion144and second retainer portion146may be associated with each other using any device or method suitable to the desired end purpose, such as a bolt, clip and/or screw.

Referring toFIG. 11andFIG. 12, thrust washer retainer136allows inboard thrust washer132to be removed from transmission100without completely disassembling transmission100. This may be accomplished by removing sun pinion cover102to expose transmission opening112and thus, low-speed sun pinion138. Low-speed sun pinion138is removed from hub assembly cavity114to expose thrust washer retainer136and plug134. Locking member148is removed from thrust washer retainer136by sliding locking member148in an axial direction toward transmission opening112to remove locking structure151from first mating structure150and second mating structure156. Inboard thrust washer132is exposed by disassociating second retainer portion146from first retainer portion144. This may be accomplished by rotating second retainer portion146relative to first retainer portion144to disengage second threaded portion160from first threaded portion154.

Once second retainer portion146is disassociated from first retainer portion144, second retainer portion144is removed from hub assembly cavity114, exposing inboard thrust washer132. Inboard thrust washer132may then be replaced and second retainer portion146may then be re-associated with first retainer portion144by disposing second retainer portion146adjacent first retainer portion144and rotating second retainer portion146to cause second threaded portion160and first threaded portion160to threadingly engage each other. Second retainer portion146should be snugly associated with first retainer portion144such that first mating structure150is aligned with second mating structure156. Locking member148is then re-positioned over first retainer portion144and second retainer portion146such that locking structure151is contained within first mating structure150and second mating structure156. Low-speed sun pinion138is re-associated with transmission100and sun pinion cover102is mounted to hub assembly110.