Patent Application
20140166376
The disclosure generally relates to an equalizer bar assembly and in particular, to an equalizer bar end joint assembly for connecting a track roller frame to a track-type machine.
Track type machines commonly use a pair of tracks connected by an equalizer bar between to allow a degree of flexibility in movement of the tracks relative to the main frame. The equalizer bar is mounted to the main frame and each end of the equalizer bar is connected to one of the left hand or right hand side track roller frame. The connection between the equalizer bar and the track roller frame must allow some degree of movement between the equalizer bar and the track roller frame while being able to sustain severe loading. A spherical bearing may be provided at each end of the equalizer bar to provide three degrees of movement: axially, rotationally about the axis, and rotationally in the plane of the axis (or cocking).
The spherical bearing requires lubrication to allow for smooth movement and to mitigate binding. Lubrication may be accomplished by providing liquid or semi-solid lubricants, such as oil and/or grease, to the bearing surfaces. However, such methods of bearing lubrication require considerable maintenance and disposal of used lubricant. Attempting to address the issue, U.S. Patent Application Publication 2007/0009757 discloses a sintered sliding material layer including copper and/or a copper-molybdenum alloy and a solid lubricant such as polytetrafluoroethylene (PTFE), commonly known as “Teflon,” which is incorporated into a bearing for an equalizer bar suspension. However, because the solid lubricant is interspersed within the grains of the metal alloy structure, abrasion between the metal components is likely to result.
The disclosed embodiments are directed to overcoming one or more of the problems set forth above and other problems in the art.
One aspect of the present disclosure is directed to an equalizer bar end joint. The equalizer bar end joint may include a pin defining a longitudinal axis; and a bearing configured to support the pin. The bearing may include an inner race including a bore configured to cooperate with the pin and a semispherical outer surface. The bearing may also include an outer race including a semispherical inner surface, wherein the semispherical inner surface of the outer race is configured to cooperate with the semispherical outer surface of the inner race. A solid lubricant may be disposed about a surface of the bore, and a first seal may be positioned within a first groove disposed about the bore at a first end and a second seal may be positioned within a second groove disposed about the bore at a second end.
Another aspect of the present disclosure is directed to a bearing for an equalizer bar end joint. The bearing may include an inner race including a bore configured to cooperate with the pin and a semispherical outer surface and an outer race including a semispherical inner surface, wherein the semispherical inner surface of the outer race is configured to cooperate with the semispherical outer surface of the inner race. The bearing may also include a solid lubricant disposed about a surface of the bore. The bearing may also include a first seal positioned within a first groove disposed about the bore at a first end and a second seal positioned within a second groove disposed about the bore at a second end.
Another aspect of the present disclosure is directed to a machine having an equalizer bar with one or more end joints. The machine may include a first track frame and a second track frame spaced apart from the first track frame and an equalizer bar positioned between and connected to the first track frame and the second track frame. The equalizer bar may include a first passage through the equalizer bar, the first passage defining a first longitudinal axis. A first pin joint assembly may be disposed within the first passage. The first pin joint assembly may include a first pin positioned along the first longitudinal axis, and a first bearing supporting the first pin within the first passage. The first bearing may include a first inner race and a first outer race. The first inner race may include a first convex outer surface, a first bore configured to receive the first pin, a solid lubricant disposed on a surface of the bore adjacent the pin, and a pair of first seals positioned at either end of the bore. The first outer race may include a first concave inner surface configured to cooperate with the first convex outer surface, a solid lubricant disposed on the first concave inner surface, and a pair of second seals positioned at either end of the first outer race. The first pin joint assembly may be configured to allow the first pin three degrees of motion about the first longitudinal axis.
An exemplary embodiment of a machine 10 is shown in
The undercarriage 18 may further include a track frame 22, upon which the ground engaging track 20 may be mounted. Track frame 22 may also include a number of rollers 24 configured to support and guide the ground engaging track 20. The undercarriage may also include a drive member 26 coupled to the power source 14 by way of a drive train (not shown) and configured to engage and drive ground engaging track 20.
Referring now to
The first end joint 106 and the second end joint 110 may be configured to accommodate movement while maintaining alignment of the first track frame 22A and the second track frame 22B relative to each other as the machine 10 travels over uneven ground. First track frame 22A and second track frame 22B may each be connected to equalizer bar 102 in a similar manner. Therefore, only the first end joint 106 will be discussed in further detail, however, it should be understood that the same principles and teachings of the disclosure apply equally to the second end joint 110 connecting the second track frame 22B to the second end 108 of equalizer bar 102.
Referring to
The pin 204 may extend through the bearing 206 along a longitudinal axis L and may project from at least one side of the equalizer bar 102. In some embodiments, the pin 204 may extend along the longitudinal axis L and project from two sides of the equalizer bar 102. The pin 204 is further adapted to move relative to the equalizer bar 102 such that the pin 204 has a plurality of rotational degrees of freedom along the longitudinal axis L.
The pin 204 and the bearing 206 may define a connection arrangement with the equalizer bar 102 that permits the pin 204 to rotate in the direction R about the longitudinal axis L, to pivot (or cock) in the direction C along a vertical plane intersecting the longitudinal axis L, and to translate axially in the direction A along the longitudinal axis L, as shown in
In an exemplary embodiment of the present disclosure, the pin 204 may be nickel coated to provide improved surface finish and corrosion resistance over a chrome coated pin. For example, a nickel coating may be applied to pin 204 so that the surface finish has a roughness value of Ra=0.4 microns or less.
In an embodiment of the present disclosure, the bearing 206 may include, as shown, for example, in
The inner race 210 may be configured to move and rotate within the confines of the outer race 208 during normal operation. The bore 214 may be configured to receive pin 204 so that pin 204 is oriented with its longitudinal axis L extending through the bore 214 as shown.
The bearing 206 may further include a first liner 218 including a polytetrafluoroethylene (PTFE) layer disposed about an internal surface of bore 214, and a second liner 220 including a PTFE layer disposed about a surface of the concave semispherical inner profile 216 of the outer race 208. First liner 218 and second liner 220 may be arranged as a single layer of PTFE bonded to their respective bearing surfaces, a PTFE fabric, a multi-layered laminated material, or any other acceptable arrangement and/or combination thereof.
The bearing 206 may also include a set of seals configured to inhibit infiltration of dirt, dust, debris, and other contaminants into the bearing. In the exemplary embodiment shown in
Pin seals 222, 224 and bearing seals 230, 232 may be constructed from rubber, such as natural or synthetic rubber, nitrile butadiene rubber, silicone rubber, EPDM rubber, or any suitable material.
Machines having a tracked undercarriage having a pair of track roller frames mounted to the frame of the machine and connected to an equalizer bar at each end may include but are not limited to track type tractors, hydraulic excavators, tracked loaders, multi-terrain loaders, as well as other types of earth moving and industrial equipment. As a machine travels across terrain with varying contours, the pin joint assemblies on the equalizer bar allow the undercarriage some flexibility while the ground engaging members maintain contact with the ground.
The bearings in pin joint assemblies located on either end of the equalizer bar require lubrication to allow relative movement between the ground engaging members. An oil-based or grease-based lubricant requires regular maintenance, which results in higher costs and reduced machine availability. In the exemplary embodiment of the present disclosure, PTFE liners are provided as a solid lubricant, reducing the need for regular maintenance. Additionally, the equalizer bar end joint of the present disclosure eliminates the need to provide lubrication conduits or ports within either the equalizer bar or the bearing. Further, seals are provided to inhibit infiltration of dirt and other debris into the bearing, which could degrade the bearing surfaces and the PTFE liners.
Although embodiments of this disclosure have been described herein, improvements and modifications may be incorporated without departing from the scope of the following claims.
