Background Operator comfort, as well as noise reduction regulations, requires reducing the sound decibel level emanating from a machine. Perhaps one of the greatest sources of machine noise in earthmoving equipment and construction machines is a track chain contacting the undercarriage components of the equipment or machine. Typically, these earthmoving and construction machines operate using self-laying endless track chain assemblies. Idler wheels are used to guide and support portions of this track chain. Since the track chain assemblies and idler wheel surfaces are manufactured using metal components, noise and vibration are generated between the track chain assemblies and the idler wheels.

This noise is then transmitted to, and typically amplified by, the hub of the idler wheel and the track chain assemblies.

One type of idler-wheel assembly used for isolating wear segments from an idler wheel hub is disclosed in U. S. Patent No. 4,818, 041 issued to Caterpillar Inc. on 04 April 1989. In this patent, U-shaped cavities are formed in the wheel assembly hub in which resilient rings are placed. The resilient rings are held in the cavities by hardened metal wear segments. The

wear segments are clamped to the assembly by clamping plates secured to the hub by fasteners. However, a disadvantage of this idler wheel assembly is that it requires extensive casting and machining of the hub and the metal wear segments to form the shape of cavities and segments. In addition, the use of a clamping plate provides additional costs, as well as creates metal to metal contact between the clamping plate and the metal wear segments.

Accordingly, the present invention is directed to overcoming the problems as set forth above. The present invention overcomes the need for the use of a clamping plate, as well as reduces the amount of casting and machining of the hub and wear segments. Further, sound isolation can additionally be provided using, for example, sleeves on connectors which secure the segments to the hub.

Summary of the Invention The present invention provides an idler wheel assembly, which supports and guides an endless track and provides sound suppression, and a method for providing sound suppression of an undercarriage of a machine. In an embodiment of the present invention, the idler wheel assembly includes a hub having a first side surface and a second side surface onto which a plurality of segments are connected. Each of the plurality of segments has a first flange positioned adjacent the first side surface of the hub, and a second flange positioned adjacent the second side surface of the hub. At least one isolation device may be mounted between the hub and at least one of the plurality of segments to provide sound suppression.

According to a method for suppressing sound of an undercarriage of a machine according to the present invention, an isolation device is positioned between a hub of an idler wheel assembly and at least one of a plurality of segments of the wheel assembly. A first flange of the at least one of a plurality of segments is connected to an adjacent first side surface of the hub, and a second

flange of the at least one of a plurality of segments is connected to an adjacent second side surface of the hub.

Brief Description of the Drawings FIG. 1 illustrates a track type machine having an idler wheel assembly according to the present invention; FIG. 2 is a partial sectional view of an idler wheel assembly according to an embodiment of the present invention; FIG. 3 illustrates a sectional view of the idler wheel assembly according to the present invention; and FIG. 4 illustrates a sectional view of another embodiment of an idler wheel assembly according to the present invention.

Detailed Description Referring to the drawings, a track type machine 10 includes an engine 12, an operator's station 14, a main frame 16, a powered sprocket 18, and front and rear idler wheel assemblies 20 and 22. The main frame 16 supports a subframe 24, which in turn supports the idler wheel assemblies 20 and 22, as well as a plurality of guide roller assemblies 26. An endless track 28 is driven by the sprocket 18 and encircles the idler wheel assemblies 20,22 and the roller assemblies 26. The idler wheel assemblies 20,22 are substantially similar and, therefore, only the front idler assembly 20 will be described in detail.

With particular reference to Figs. 2 and 3, the idler wheel assembly 20 which supports and guides the endless track 28, includes a hub 30, which may have a first side surface 32 and a second side surface 34. A plurality of hub mounting holes 36 may extend between the first side surface 32 and the second side surface 34 of the hub. Connectors that are fit within holes 36 may be used to mount a plurality of U-shaped segments 38 to the hub 30. Of course, the plurality of U-shaped segments 38 may be mounted or connected to the hub 30 by other ways known to those of ordinary skill in the art.

As further shown in Figures 2 and 3, each of these U-shaped segments 38 may have a first flange 42 positioned adjacent the first side surface 32 of the hub 30, and a second flange 44 positioned adjacent the second side surface 34 of the hub 30. Further, each of the U-shaped segments 38 may have holes 46 aligned with respective mounting holes 36 of the hub 30.

Isolation devices 48 are mounted between at least one of the U- shaped segments 38 and the hub 30 of the idler wheel assembly 20 to provide isolation. In one embodiment of the present invention, elastomeric torics are used as the isolation devices 48. The elastomeric torics 48 may be pre-loaded at assembly for load-carrying capacity purposes. Each of the elastomeric torics 48 may be contained within a space 50 defined by a groove 52 formed in the hub, and a corresponding groove 54 formed within one of the plurality of U-shaped segments 38. In the embodiment shown in Figures 2 and 3, the space 50 is substantially quadrangular in shape.

Pins 56, or other structures serving as a connector, may be positioned within the mounting holes 36 of the hub and respective holes 46 to attach the U-shaped segments 38 to the hub 30. The pins 56 or other connectors can be secured to the U-shaped segments 38 by retaining rings 57, or by other ways known to those skilled in the art. In the embodiment of the present invention shown in Figure 3, the pins 56 or other connectors may also have sleeves 58 which can be used to seal the cavity between the pins 56 and the mounting holes 36 in the hub. As an example, the sleeves 58 may have metallic rings 60 which contain an elastic material 62, such as rubber, within the center of the metallic rings 60. The sleeves 58, including the elastic material or other sound-dampening material also help to provide sound isolation.

Figure 4 illustrates another embodiment of an idler-wheel assembly according to the present invention. Items shown in Figure 4 that are essentially similar to those shown in Figures 2 and 3, retain their same numerical identification. In Figure 4, the U-shaped segments 38 can have one or more

sprocket teeth 64 which can be used to guide the endless track 28 (not shown).

As shown in Figure 4, the space 50 defined by a groove 52 formed in the hub, and a corresponding groove 54 formed within one of the plurality of segments is triangular in shape. In this embodiment, a hypotenuse of the triangular-shaped space is formed by the corresponding groove 54 formed within one of the plurality of segments. Placing the elastomeric torics 48 in the triangular-shaped space can provide both radial and axial load-carrying capacity, and also allows for at least one of the U-shaped segments 38 to be brought down radially at assembly of the idler wheel assembly 20 to pre-load the elastomeric torics 48. Of course, the elastomeric torics 48 may be also be contained within other shaped spaces. As shown in Figure 4, pins 56 or other connectors do not necessarily have sleeves 58, such as those shown in the embodiment depicted in Figure 2.

Industrial Applicability In practice, the present invention provides for sound suppression by changing the track-link to idler impact characteristics by isolating the idler rim segments from the hub of the idler. Since isolation is provided between at least one of the segments 38 and the hub 30 of the idler wheel assembly 20 by an isolation device 48, neither the hub 30 of the idler wheel assembly nor the endless track 28 realizes the full impact of the idler wheel assembly's interface with the endless track 28. As such, sound is not transmitted to the hub 30. This is particularly important because sound is usually amplified by the hub 30.

Further sound suppression can be provided by sleeves 58 of connectors 56, which have metallic rings 60 with an elastic material 62, such as rubber, within the center of the metallic rings 60. The use of the isolation device and the sleeves allow for an idler wheel assembly that increases operator comfort by reducing the sound decibel level emanating from a machine.

In view of the foregoing, it is readily apparent that the structure of the present invention provides an idler arrangement wherein the idler rim

segments are isolated from the hub to provide sound suppression by changing the track link impact characteristics of the track idler assembly.

Other aspects, objects, and advantages of this invention can be obtained from a study of the drawings, the disclosure and the appended claims.