Tracked undercarriage roller assembly

Abstract

Tracked undercarriage roller assembly (17) comprisinga roller body (18) having an inner cavity (19) extending axially from a first access opening (18a) to a second access opening (18b);a shaft (22) inserted into the inner cavity (19) of the roller body (18) and extending axially from a first end portion (22a) to a second end portion (22b); a first end support (24) attached to said first end portion (22a) of the shaft (22) at said first access opening (18a); a second end support (26) attached to the second end portion of the shaft (22) at said second access opening (18b); a first rotating lip seal (35) attached to said roller body (18) at said first access opening (18a) and comprising a main sealing lip (43) in sliding abutment on said first support (24); a second rotating lip seal (36) attached to said roller body (18) at said second access opening (18b) and comprising a main sealing lip (49) in sliding abutment on said second support (26); and at least a first solid oil bearing (31) located in said inner cavity (19) and comprising a radially inner slewing ring (31a) coupled to said shaft (22) and a radially outer slewing ring (31b) coupled to said roller body (18).

Description

[0001] Tracked undercarriage roller assembly

[0002] DESCRIPTION

[0003] The present invention relates to a tracked undercarriage roller assembly.

[0004] Tracked undercarriages are typically used in operating machines such as earthmoving machines, mining machines, demolition machines, combine harvesters and the like, to allow the machine to be able to move on often uneven ground or with poor grip.

[0005] A tracked undercarriage typically comprises two chain assemblies spaced apart and arranged parallel to each other and configured to receive a drive torque and transfer it to the ground. Each chain assembly comprises a plurality of undercarriage components which usually comprise a closed loop chain on a driving wheel and an idler wheel (or idler) operatively connected to a tensioner assembly. The undercarriage components further comprise, between the driving wheel and the idler wheel, a plurality of roller assemblies configured to guide the chain during its motion. Roller assemblies usually include one or more upper roller assemblies and a plurality of lower roller assemblies.

[0006] The chain usually comprises a plurality of joints, the term joint referring to the single component of the chain which is articulated to the other components. Typically, each joint comprises a pair of links facing each other. The joints are interconnected by pins. Each pin is usually inserted in holes included on the links and connects two joints together. The soles are usually mounted on the joints which, being in direct contact with the ground, have the task of discharging the traction to the ground and increasing the contact surface between machine and ground. The type of sole used depends on the ground on which the machine must operate, on the conditions of the environment in which the machine must operate and on the specifications suggested by the machine manufacturer.

[0007] Each roller assembly usually comprises a roller body crossed by a shaft. The roller body is delimited by a radially inner surface facing the shaft and spaced from the shaft by a radial gap. The roller body is rotatable about the shaft which is fixed with respect to the frame of the undercarriage on which it is mounted.

[0008] To ensure that the roller bodies rotate correctly in relation to their respective shafts by transferring loads between the roller body and the shaft, active rolling bearings can be provided in the radial gap between the shaft and the roller body. As an alternative to the rolling bearings in the gap, a bushing fitted inside the roller body can be provided. The bushing is usually made of a non-ferrous metal, such as bronze, or a bimetallic alloy. The radial gap is usually filled with lubricant either to further reduce friction or to dissipate the heat generated by friction between the contact surfaces of the bushing and roller body and / or bushing and shaft, or to dissipate the heat generated by the rotation of the slewing rings of the ball bearings.

[0009] Two axial end supports are inserted on the shaft and roller body assembly at the axial ends of the roller body. The two axial end supports are fitted onto the shaft and have the function of closing the radial gap between shaft and roller body.

[0010] In order to ensure a fluid-tight seal of the radial gap between the shaft and roller body so that lubricant does not leak out of the radial gap and so that dirt, water or other contaminants from the external environment do not reach the radial gap, active sealing bodies are provided between the axial end bearing supports and the roller body.

[0011] Each sealing body acts axially between a respective end support and the roller body and is usually made up of a first, substantially annular half-part inserted into a seat in the axial end support and a second half-part also substantially annular, and substantially mirroring the first half-part, inserted into a seat in the roller body. Each half-part is inserted into its respective seat with a respective spring element, usually an O-ring, in between, which exerts an axial thrust force.

[0012] The two half-parts face each other axially at their respective sliding contact surfaces. These sliding contact surfaces are machined to remove any roughness to make them as smooth as possible. The two sliding contact surfaces are placed in contact with each other in such a way that they act as axial contact interfaces between the axial end support and the roller body. The two sliding contact surfaces are kept axially pressed against each other, guaranteeing the sealing of fluid between the two half-parts during the rotation of the second half-part (integral with the roller body) with respect to the first half-part (integral with the shaft). Specifically, the two sliding contact surfaces are kept axially pressed against each other with a predetermined load, calculated in such a way as to allow one half-part to rotate with respect to the other half-part and, at the same time, in such a way as to prevent the passage of liquids and impurities between the two sliding contact surfaces.

[0013] In order to ensure that the two sliding contact surfaces are mounted with the predetermined load, the axial end support is planted on the shaft, bringing it axially closer to the roller body until a predetermined design distance from the roller body is reached. This predetermined design distance is calculated in such a way that the two sliding contact surfaces are in mutual contact and the elastic elements exert an axial thrust equal to the aforementioned predetermined load.

[0014] The Applicant has noted that the sealing bodies described above can limit the performance of the roller assembly; in fact, the Applicant has verified that sliding contacts between the half-parts of the sealing bodies occur between metal components which can lead to overheating and limit the maximum rotation speed of the roller. The Applicant has felt the need to create a roller assembly with a higher maximum rotation speed.

[0015] The Applicant has perceived that if oil were removed from the inner cavity, there would be no need for a fluid-tight seal.

[0016] The Applicant has found that by adopting one or more solid oil bearings, there would no longer be a need to fill the inner cavity with oil.

[0017] The Applicant has perceived, however, that while removing the sealing bodies altogether would eliminate sliding contacts between components that limit the maximum rotation speed, it would concurrently allow external contaminants to penetrate the radial gap between the shaft and roller body, causing wear and / or corrosion of the components.

[0018] The Applicant has found that if a seal was adopted which, while not guaranteeing a perfectly fluid-tight seal, prevented the entry of external contaminants, it would be possible to avoid sliding contacts between metal bodies which limit the maximum rotation speed.

[0019] The present invention therefore relates to a tracked undercarriage roller assembly.

[0020] A roller body is provided having an inner cavity extending axially from a first access opening to a second access opening.

[0021] A shaft is provided, inserted into the inner cavity of the roller body and extending axially from a first end portion to a second end portion.

[0022] A first end support is provided, attached to said first end portion of the shaft at said first access opening and comprising a cylindrical radially outer surface.

[0023] A second end support is provided, attached to the second end portion of the shaft at said second access opening and comprising a cylindrical radially outer surface.

[0024] A first rotating lip seal is provided, attached to said roller body at said first access opening and comprising a main sealing lip in sliding abutment on the radially outer surface of said first support.

[0025] A second rotating lip seal is provided, attached to said roller body at said second access opening and comprising a main sealing lip in sliding abutment on the radially outer surface of said second support.

[0026] At least a first solid oil rolling bearing is provided located in said inner cavity and comprising a radially inner slewing ring coupled to said shaft and a radially outer slewing ring coupled to said roller body.

[0027] The Applicant found that by coupling the roller body to the shaft via a solid oil bearing, the lubricant is retained within the bearing and the cavity does not need to be filled with oil.

[0028] The first and second rotating lip seals close the inner cavity, preventing the entry of external contaminants that could wear or corrode the roller assembly and affect its operation.

[0029] The Applicant noted that the sealing lips slide on the support bodies without causing sliding contacts between metal components and can therefore operate at higher rotation speeds than conventional seals.

[0030] The Applicant has in fact verified that rotating lip seals effectively counteract the entry of external contaminants into the inner cavity and, as they have no sliding contacts between two components that are both metallic, they can operate at higher rotation speeds than conventional seals.

[0031] The terms "axial", "axially", "radial" and "radially", are used with reference to a rotation axis of the roller assembly.

[0032] In particular, the terms axial and axially mean references / quantities arranged / measured or extending in a direction parallel or coincident with the rotation axis of the roller assembly.

[0033] The terms "axially inner / outer" mean respectively a position closer to and further away from a point of the roller assembly placed along the rotation axis and equally spaced apart from shaft axial ends.

[0034] The terms "radial" and "radially" mean references / quantities arranged / measured or extending in a direction perpendicular to the axis of rotation of the roller assembly.

[0035] The terms "radially inner", "radially outer" and the like mean respectively a position closer to or further away from the aforementioned axis of rotation.

[0036] The term "radially overlapping" refers to a relative positioning between two components such that a first component is placed radially outwards with respect to a second component and such that a radial plane intercepts and passes through both these first and second components.

[0037] The term "radially aligned" when referring to two components refers to a relative positioning between these two components such that a first component is placed radially outwards with respect to a second component and where both this first component and this second component extend in the axial direction between a first radial plane and a second radial plane. Two radially aligned components have an identical extension in the axial direction.

[0038] The term "partially radially aligned" when referring to two components means a relative positioning between these two components such that a first component is placed radially outwards with respect to a second component and wherein two radial planes axially spaced from each other intercept and pass through both these first and second components. The term "radially aligned" when referring to points of two components means a relative positioning between these two components such that a first component is placed radially outwards with respect to a second component and a radial plane passes through both of these points of the two components.

[0039] The term "planting" refers to a joining of two parts or components, obtained by interference fit, in which the two parts or components are constrained to each other with respect to rotations and translations.

[0040] The term "rigid" and the like refers to components made of materials with a Young's modulus greater than 1000 MPa, such as steels.

[0041] The tracked undercarriage roller assembly of the present invention may comprise one or more of the following features taken individually or in combination.

[0042] Preferably, all the components of the first rotating lip seal are rotationally integral with said roller body.

[0043] Preferably, all the components of the second rotating lip seal are rotationally integral with said roller body.

[0044] The sliding seal contact is thus localised between the sealing lips and the shaft supports.

[0045] Preferably, a second solid oil bearing is provided, placed in said inner cavity axially spaced apart from said first solid oil bearing, said second solid oil bearing comprising a radially inner slewing ring coupled to said shaft and a radially outer slewing ring coupled to said roller body.

[0046] Preferably, said roller body comprises a first shoulder located in said cavity and facing said first access opening.

[0047] Preferably, said roller body comprises a second shoulder located in said cavity and facing said second access opening. Preferably, there is a ring nut mounted on said shaft and configured to axially tighten the first bearing against said first shoulder.

[0048] Preferably, said roller body also comprises a retainer mounted on said shaft and configured to axially abut the second bearing on the opposite side to said ring nut.

[0049] Preferably, said roller body comprises a first body on which said first shoulder is defined and a second body distinct from the first body on which said second shoulder is defined.

[0050] Preferably, said roller comprises a third body distinct from said first body and second body and axially interposed between said first body and second body.

[0051] Preferably, said first, second and third bodies are coupled by mechanical interference or placed in simple mutual abutment.

[0052] In this way, the ring nut and the retainer tighten the different bodies that form the roller body, fixing them together without the need for welding.

[0053] Preferably, said roller body comprises a first seal seat at said first access opening.

[0054] Preferably, said roller body comprises a second seal seat at said second access opening.

[0055] Preferably, said first rotating lip seal comprises a rigid coupling body inserted by interlocking into said first seal seat.

[0056] Preferably, said first rotating lip seal comprises a main sealing body coupled to said coupling body and comprising the main sealing lip of the first rotating seal.

[0057] Preferably, said second rotating lip seal comprises a coupling body inserted by interlocking into said second seal seat.

[0058] Preferably, said second rotating lip seal comprises a main sealing body coupled to said coupling body and comprising the main sealing lip of the second rotating seal.

[0059] Preferably, the coupling body of said first rotating lip seal comprises a cylindrical wall and a flange.

[0060] Preferably, said first rotating lip seal comprises an auxiliary sealing body axially interposed between said main sealing body and the flange of the first rotating lip seal and radially interposed between said cylindrical wall and said first support, said auxiliary sealing body comprising a radially internal surface placed in sliding abutment against said first support.

[0061] Preferably, said radially inner surface of the auxiliary sealing body of the first rotating lip seal is cylindrical.

[0062] Preferably, the coupling body of said second rotating lip seal comprises a cylindrical wall and a flange.

[0063] Preferably, said second rotating lip seal comprises an auxiliary sealing body axially interposed between said main sealing body and the flange of the second rotating lip seal and radially interposed between said cylindrical wall and said second support, said auxiliary sealing body comprising a radially internal surface placed in sliding abutment against said second support.

[0064] Preferably, said radially inner surface of the auxiliary sealing body of the second rotating lip seal is cylindrical.

[0065] Preferably, the auxiliary sealing body of said first rotating lip seal and / or said second rotating lip seal has a rectangular or square shape in a radial section view. Auxiliary sealing bodies improve the sealing of rotating lip seals in the presence of axial play between the shaft and the roller body.

[0066] Preferably, said first rotating lip seal comprises a garter spring configured to tighten the respective main sealing lip against said first support.

[0067] Preferably, said second rotating lip seal comprises a garter spring configured to tighten the respective main sealing lip against said second support.

[0068] Preferably, said first rotating lip seal comprises an auxiliary sealing lip in sliding abutment against the radially outer surface of said first support.

[0069] Preferably, said second rotating lip seal comprises an auxiliary sealing lip in sliding abutment against the radially outer surface of said second support.

[0070] Preferably, said auxiliary sealing lip of the first rotating lip seal is axially interposed between the main sealing lip and the auxiliary sealing body.

[0071] Preferably, said auxiliary sealing lip of the second rotating lip seal is axially interposed between the main sealing lip and the auxiliary sealing body.

[0072] Preferably, the main sealing body of said first rotating lip seal comprises a coupling portion placed in contact with the respective coupling body.

[0073] Preferably, said first rotating lip seal comprises a rigid insert configured to radially press said coupling portion against said coupling body. Preferably, said rigid insert is inserted into a gap between the main sealing lip and the coupling portion of the main sealing body of the first rotating lip seal.

[0074] Preferably, the main sealing body of said second rotating lip seal comprises a coupling portion placed in contact with the respective coupling body.

[0075] Preferably, said second rotating lip seal comprises a rigid insert configured to radially press said coupling portion against said coupling body.

[0076] Preferably, said rigid insert is inserted into a gap between the main sealing lip and the coupling portion of the main sealing body of the second rotating lip seal.

[0077] Further features and advantages of the invention will be more evident from the following description of a preferred embodiment thereof, made with reference to the appended drawings. In such drawings:

[0078] - Figure 1 is a schematic side view of a tracked undercarriage;

[0079] - Figure 2 is a schematic section view of a tracked undercarriage roller assembly of Figure 1 according to the present invention;

[0080] Figure 3 is an enlarged schematic view of a detail of the schematic view of Figure 2;

[0081] Figure 4 is an enlarged schematic view of a further detail of the schematic view of Figure 2.

[0082] Figure 1 is a schematic side view showing some components of a tracked undercarriage. The tracked undercarriage 10 comprises two track assemblies 11, of which only one is visible in figure 1. Each track assembly 11 comprises a chain 12, comprising a plurality of links 13 interconnected between them by pins and bushings (not shown), a return wheel 14, in the figure partially hidden by a crankcase 15, and a driving wheel 16. A plurality of roller assemblies 17 is arranged between the return wheel 14 and the driving wheel 16, in particular one or more upper roller assemblies and a plurality of lower roller assemblies arranged in contact with the links 13 and adapted to guide the chain 12 in its motion.

[0083] The lower roller assemblies 17 are arranged in the lower portion of the track assembly 11 and are configured to transfer loads between the track and an undercarriage frame (not shown). The upper roller assemblies 17 are configured to guide the chain between the driving wheel 16 and the return wheel 14 and typically are present in a lower number than the number of the lower roller assemblies. The number of the lower roller assemblies 17 varies depending on the type of machine and the weight thereof.

[0084] With reference to Figure 2, a preferred embodiment of a preferably lower roller assembly 17 in accordance with the present invention is shown. In particular, Figure 2 is a sectional view of a lower roller assembly 17. The section plane is a longitudinal plane transversal to the links 13 of the chain 12, and hence to the direction of movement of the tracked undercarriage, passing through the rotation axis X of the roller assembly 17.

[0085] The roller assembly 17 comprises a roller body 18 comprising an inner cavity 19 which extends axially from a first access opening 18a to a second access opening 18b of the roller body 18. The first access opening 18a and the second access opening 18b are located at opposite axial ends of the roller body 18.

[0086] The roller body 18 is made up of three separate bodies, namely a first body 19a, a second body 19b and a third body 19c. The first body 19a, the second body 19b and the third body 19c are either coupled together by interference or simply juxtaposed. The third body 19c is axially interposed between the first body 19a and the second body 19b.

[0087] The roller body 18 is delimited by a radially inner surface 20 which delimits the inner cavity 19 in a radially outer direction and by a radially outer surface 21 whose shape is determined by the type of chain 12 with which the roller assembly 17 must interact.

[0088] The roller body 18 is preferably made of a low-alloy steel that is boron-alloyed and subjected to at least one heat treatment. A low- alloy steel is a steel wherein other elements other than iron and carbon are present and wherein none of such other elements is present in an amount higher than 5%.

[0089] The roller assembly 17 further comprises a shaft 22 inserted into the inner cavity 19 of the roller body 18. The shaft 22 extends between a first axial end portion 22a and a second axial end portion 22b and has a radially outer surface 23 facing the radially inner surface 20 of the roller body 18.

[0090] The shaft 22 is preferably made of boron-alloyed low-alloy steel which has undergone at least one heat treatment or of micro-alloyed steel which does not require any heat treatment

[0091] The shaft 22 has a greater extension in an axial direction than the extension in an axial direction of the roller body 18. The shaft 22 protrudes slightly from the first access opening 18a and the second access opening 18b.

[0092] The shaft 22, at the first axial end portion 22a, is rigidly coupled to the undercarriage frame, or to an undercarriage component integral with the undercarriage frame, through a first end support 24.

[0093] The first end support 24 is at least partially inserted into the inner cavity 19 at the first access opening 18a.

[0094] The first end support 24 comprises a smooth cylindrical radially outer surface 24a facing the radially inner surface 20 at the first access opening 18a. The radially outer surface 24a extends around the axis of rotation X.

[0095] The first end support 24 has an internal through cavity 25. In the internal through cavity 25 the shaft 22 is inserted at its first axial end portion 22a.

[0096] The shaft 22, at the second axial end portion 22b, is rigidly coupled to the undercarriage frame, or to an undercarriage component integral with the undercarriage frame, through a second end support 26.

[0097] The second end support 26 is at least partially inserted into the inner cavity 19 at the second access opening 18b.

[0098] The second end support 26 comprises a smooth cylindrical radially outer surface 26a facing the radially inner surface 20 at the second access opening 18a. The radially outer surface 26a extends around the axis of rotation X.

[0099] The second end support 26 has an internal through cavity 27. In the internal through cavity 27 the shaft 22 is inserted at its second axial end portion 22b.

[0100] The shaft 22 is integral with both the first end support 24 and the second end support 26.

[0101] The first support 24 is fixed to the shaft 22 at the first end portion 22a, for example by means of a pin (not illustrated) inserted into respective aligned radial holes (not illustrated) made in the first support 24 and the shaft 22.

[0102] Thereby, any axial movement and any rotation about the axis of rotation X of the shaft 22 relative to the first end support 24 are prevented.

[0103] Similarly, the second support 26 is fixed to the shaft 22 at the second end portion 22b, for example by means of a pin (not illustrated) inserted into respective aligned radial holes (not illustrated) made in the second support 26 and the shaft 22.

[0104] Thereby, any axial movement and any rotation about the axis of rotation X of the shaft 22 relative to the second end support 26 are prevented.

[0105] The first support 24 and the second support 26 are preferably made of steel or spheroidal cast iron.

[0106] The roller body 18 is mounted rotatable with respect to the shaft 22 about the axis of rotation X.

[0107] A first rolling bearing 31 and a second rolling bearing 32 are provided in the inner cavity 19 of the roller body 18 active between the shaft 22 and the radially inner surface 20 of the roller body 18 (as shown in Figure 2).

[0108] The first and second bearings 31, 32 are of the solid oil type.

[0109] The first bearing 31 comprises an inner slewing ring 31a fitted onto the shaft 22 and an outer slewing ring 31b inserted into the roller body 18. Between the inner slewing ring 31a and the outer slewing ring 31b, a sealed bearing cavity 31c is defined in which a plurality of rolling elements 31d, e.g. tapered rollers, are radially housed. The bearing cavity 31c is filled with solid lubricant, i.e. a porous-structure polymer impregnated with a suitable liquid lubricant.

[0110] Similarly, the second bearing 32 comprises an inner slewing ring 32a fitted onto the shaft 22 and an outer slewing ring 32b inserted into the roller body 18. Between the inner slewing ring 32a and the outer slewing ring 32b, a sealed bearing cavity 32c is defined in which a plurality of rolling elements 32d, e.g. tapered rollers, are radially housed. The bearing cavity 32c is filled with solid lubricant, i.e. a porous-structure polymer impregnated with a suitable liquid lubricant.

[0111] During rotation, the porous-structure polymer and the liquid lubricant heat up and the liquid lubricant is released into the bearing cavities 31c, 32c. As the bearings 31, 32 cool, the liquid lubricant is reabsorbed by the porous-structure polymer.

[0112] The roller body 18 comprises a first shoulder 33a formed in the inner cavity 19 and facing the first access opening 18a. The first shoulder 33a is formed on the first body 19a.

[0113] The roller body 18 further comprises a second shoulder 33b formed in the inner cavity 19 and facing the second access opening 18b. The second shoulder 33b is formed on the second body 19b.

[0114] The two shoulders 33a, 33b are facing opposite sides.

[0115] The first bearing 31 is inserted into the inner cavity 19. Its inner slewing ring 31a is fitted onto the shaft 22, preferably with mechanical interference. Its outer slewing ring 31b is coupled to the radially inner surface 20, preferably with mechanical interference. The outer slewing ring 31b is placed in abutment against the first shoulder 33a.

[0116] Similarly, the second bearing 32 is inserted into the inner cavity 19. Its inner slewing ring 32a is fitted onto the shaft 22, preferably with mechanical interference. Its outer slewing ring 32b is coupled to the radially inner surface 20, preferably with mechanical interference. The outer slewing ring 32b is placed in abutment against the second shoulder 33b.

[0117] A ring nut 34 is mounted onto the shaft 22 between the first end portion 22a and the first bearing 31. The ring nut 34 is mounted in threaded coupling with the shaft 22. The ring nut 34 is axially adjustable by screwing / unscrewing. The ring nut 34 is configured to tighten the first bearing 31 against the first shoulder 33a. Between the ring nut 34 and the first bearing 31 a washer 34a is interposed. The ring nut 34 is configured to exert an axial force against the inner slewing ring 31a of the first bearing 31 so that the respective outer slewing ring 31b presses against the first shoulder 33a.

[0118] A retainer 34b is mounted on the shaft 22 between the second end portion 22b and the second bearing 32. The retainer 34b comprises a snap ring. The retainer 34b is fixed axially to the shaft 22. The retainer 34b is configured to axially stop the second bearing 32, in particular by abutting on its inner slewing ring 32a. A spacer 34c is placed between the retainer 34b and the second bearing 32.

[0119] When the ring nut 34 is axially tightened along the shaft 22, the first bearing 32 is pressed by the ring nut 34 against the first shoulder 33a and the second bearing 32 is pressed by the second shoulder 33b and stopped by the retainer 34c. In addition, the first body 19a is pressed against the third body 19c through the first shoulder 33a and the third body 19c is pressed against the second body 19b which is stopped by the second bearing 32 through the second shoulder 33b.

[0120] In this way the first body 19a, the second body 19b and the third body 19c are clamped together.

[0121] The inner cavity 19 of the roller body 18 is closed at the first end support 24 and at the second end support 26.

[0122] For this purpose, there is a first rotating lip seal 35 and a second rotating lip seal 36.

[0123] The first rotating lip seal 35 is placed axially outwards with respect to the first bearing 31. Similarly, the second rotating lip seal 36 is placed axially outwards with respect to the second bearing 32.

[0124] The first rotating lip seal 35 is configured to close a gap between the radially inner surface 20 of the roller body 18 and the radially outer surface 24a of the first support 24 at the first access opening 18a. The first rotating lip seal 35 is placed in sliding contact with the radially outer surface 24a so as to slide on it during the rotation of the roller body 18. The first rotating lip seal 35 is housed in a first seal seat 35a formed in the cavity 19 of the roller body 18 on the radially inner surface 20 and facing the first access opening 18a. The first seal seat 35a comprises a cylindrical surface 35b and a shoulder 35c.

[0125] The first rotating lip seal 35, illustrated in a section view in Figure 3, comprises a rigid, preferably metallic, coupling body 38. The coupling body 38 is inserted into the first seal seat 35a, preferably with interference. The coupling body 38 comprises a cylindrical wall 39 arranged against the cylindrical surface 35b, preferably with mechanical interference, and a flange 40 arranged against the shoulder 35c.

[0126] The first rotating lip seal 35 comprises a main sealing body 41. The main sealing body 41 is made of polymeric material, preferably elastomeric, e.g. nitrile rubber. The main sealing body 41 is arranged radially inside the cylindrical wall 39.

[0127] The main sealing body 41 comprises a coupling portion 42 placed against the cylindrical wall 39.

[0128] The main sealing body 41 also comprises a main sealing lip 43. The main sealing lip 43 is a conventional sealing lip. The main sealing lip 43 protrudes radially towards the first support 24 and is placed in sliding abutment against the first support 24. In particular, the main sealing lip 43 is placed in sliding abutment against the radially outer surface 24a of the first support 24.

[0129] The main sealing body 41 also comprises an auxiliary sealing lip 44. The auxiliary sealing lip 44 is offset axially outwards with respect to the main sealing lip 43. The auxiliary sealing lip 44 is also a conventional sealing lip. The auxiliary sealing lip 44 protrudes radially towards the first support 24 and is placed in sliding abutment against the first support 24. In particular, the auxiliary sealing lip 44 is placed in sliding abutment against the radially outer surface 24a of the first support 24.

[0130] The first rotating lip seal 35 further comprises a rigid insert 45. The rigid insert 45 is a flanged ring. The rigid insert 45 is inserted radially between the coupling portion 42 and the main sealing lip 43. The rigid insert 45 is placed against the main sealing body 41 and is configured to press the coupling portion 42 against the cylindrical wall 39 to adhere the coupling portion 42 to the cylindrical wall 39.

[0131] The first rotating lip seal 35 further comprises a garter spring 46. The garter spring 46 is placed circumferentially around the main sealing lip 43. The garter spring 46 is configured to tighten the main sealing lip 43 against the first support 24.

[0132] The first rotating lip seal 35 comprises an auxiliary sealing body 47. The auxiliary sealing body 47 is axially interposed between the main sealing body 41 and the flange 40. The auxiliary sealing body 47 is radially interposed between the cylindrical wall 39 and the first support 24. The auxiliary sealing body 47 is made of a polymer material, preferably elastomeric, e.g. nitrile rubber. The auxiliary sealing body 47 comprises a radially inner surface 48 placed in sliding contact against the radially outer surface 24a.

[0133] Similarly, the second rotating lip seal 36 is configured to close a gap between the radially inner surface 20 of the roller body 18 and the radially outer surface 26a of the second support 26 at the second access opening 18b. The second rotating lip seal 36 is placed in sliding contact with the radially outer surface 26a so as to slide on it during the rotation of the roller body 18.

[0134] The second rotating lip seal 36 is housed in a second seal seat 36a formed in the cavity 19 of the roller body 18 on the radially inner surface 20 and facing the second access opening 18b. The second seal seat 36a comprises a cylindrical surface 35b and a shoulder 35c.

[0135] The second rotating lip seal 36, illustrated in a section view in Figure 4, comprises a rigid, preferably metallic, coupling body 49. The coupling body 49 is inserted into the second seal seat 36a, preferably with interference fit. The coupling body 49 comprises a cylindrical wall 50 arranged against the cylindrical surface 36b, preferably with mechanical interference, and a flange 51 arranged against the shoulder 36c.

[0136] The second rotating lip seal 36 comprises a main sealing body 52. The main sealing body 52 is made of polymeric material, preferably elastomeric, e.g. nitrile rubber. The main sealing body 52 is arranged radially inside the cylindrical wall 52.

[0137] The main sealing body 52 comprises a coupling portion 53 placed against the cylindrical wall 50.

[0138] The main sealing body 52 also comprises a main sealing lip 54. The main sealing lip 54 is a conventional sealing lip. The main sealing lip 54 protrudes radially towards the second support 26 and is placed in sliding abutment against the second support 26. In particular, the main sealing lip 54 is placed in sliding abutment against the radially outer surface 26a of the second support 26.

[0139] The main sealing body 52 also comprises an auxiliary sealing lip 55. The auxiliary sealing lip 55 is offset axially outwards with respect to the main sealing lip 54. The auxiliary sealing lip 55 is also a conventional sealing lip. The auxiliary sealing lip 55 protrudes radially towards the second support 26 and is placed in sliding abutment against the second support 26. In particular, the auxiliary sealing lip 55 is placed in sliding abutment against the radially outer surface 26a of the second support 26.

[0140] The second rotating lip seal 36 further comprises a rigid insert 56. The rigid insert 56 is a flanged ring. The rigid insert 56 is inserted radially between the coupling portion 53 and the main sealing lip 54. The rigid insert 56 is placed against the main sealing body 52 and is configured to press the coupling portion 53 against the cylindrical wall 50 to adhere the coupling portion 53 to the cylindrical wall 50.

[0141] The second rotating lip seal 36 further comprises a garter spring 57. The garter spring 57 is placed circumferentially around the main sealing lip 54. The garter spring 57 is configured to tighten the main sealing lip 54 against the second support 26.

[0142] The second rotating lip seal 36 comprises an auxiliary sealing body 58. The auxiliary sealing body 58 is axially interposed between the main sealing body 52 and the flange 51. The auxiliary sealing body 58 is radially interposed between the cylindrical wall 50 and the second support 26. The auxiliary sealing body 58 is made of a polymer material, preferably elastomeric, e.g. nitrile rubber. The auxiliary sealing body 58 comprises a radially inner surface 59 placed in sliding contact against the radially outer surface 26a.

Claims

CLAIMS1. Tracked undercarriage roller assembly (17) comprising: a roller body (18) having an internal cavity (19) extending axially from a first access opening (18a) to a second access opening (18b); a shaft (22) inserted into the inner cavity (19) of the roller body (18) and extending axially from a first end portion (22a) to a second end portion (22b); a first end support (24) attached to said first end portion (22a) of the shaft (22) at said first access opening (18a) and comprising a cylindrical radially outer surface (24a); a second end support (26) attached to the second end portion of the shaft (22) at said second access opening (18b) and comprising a cylindrical radially outer surface (26a); a first rotating lip seal (35) attached to said roller body (18) at said first access opening (18a) and comprising a main sealing lip (43) in sliding abutment on the radially outer surface (24a) of said first support (24); a second rotating lip seal (36) attached to said roller body (18) at said second access opening (18b) and comprising a main sealing lip (49) in sliding abutment on the radially outer surface (26a) of said second support (26); and at least a first solid oil rolling bearing (31) located in said inner cavity (19) and comprising a radially inner slewing ring (31a) coupled to said shaft (22) and a radially outer slewing ring (31b) coupled to said roller body (18).

2. Tracked undercarriage roller assembly (17) according to claim 1, comprising a second solid oil rolling bearing (32) placed in said inner cavity (19) axially spaced apart from said first bearing (31), said second bearing (32) comprising a radially inner slewing ring (32a) coupled to said shaft (22) and a radially outer slewing ring (32b)coupled to said roller body (18).

3. Undercarriage roller assembly (17) according to claim 2, wherein said roller body (18) comprises a first shoulder (33a) located in said inner cavity (19) and facing said first access opening (18a) and a second shoulder (33b) located in said inner cavity (19) and facing said second access opening (18b); said roller assembly (17) comprising a ring nut (34) mounted on said shaft (22) and configured to axially tighten said first bearing (31) against said first shoulder (33a); said roller assembly (17) further comprising a retainer (34b) mounted on said shaft (22) and configured to axially abut the second bearing (32) on the opposite side to said ring nut (34).

4. Undercarriage roller assembly (17) according to claim 3, wherein said roller body (18) comprises a first body (19a) on which said first shoulder (33a) is defined and a second body (19b) distinct from the first body (19a) on which said second shoulder (19b) is defined.

5. Undercarriage roller assembly (17) according to claim 4, wherein said roller body (18) comprises a third body (19c) distinct from said first body (19a) and second body (19b) and axially interposed between said first body (19a) and second body (19b).

6. Undercarriage roller assembly (17) according to claim 5, wherein said first, second and third bodies (19a, 19b, 19c) are coupled by mechanical interference and / or placed in simple mutual support and tightened between said first bearing (31) and second bearing (32)7. Undercarriage roller assembly (17) according to any one of the preceding claims, wherein said roller body (18) comprises a first sealseat (35a) at said first access opening (18a) and a second seal seat (36a) at said second access opening (18b); wherein said first rotating lip seal (35) comprises: a rigid coupling body (38) interlocked in said first seal seat (35a), and a main sealing body (41) coupled to said coupling body (38) and comprising the main sealing lip (43) of the first rotating lip seal (35); wherein said second rotating lip seal (36) comprises: a coupling body (49) interlocked in said second seal seat (36a), and a main sealing body (52) coupled to said coupling body (49) and comprising said main sealing lip (54) of the second rotating lip seal (36).

8. Undercarriage roller assembly (17) according to claim 7, wherein: the coupling body (38) of said first rotating lip seal (35) comprises a cylindrical wall (39) and a flange (40); said first rotating lip seal (35) comprises an auxiliary sealing body (47) axially interposed between the main sealing body (41) and the flange (40) of said first rotating lip seal (35) and radially interposed between said cylindrical wall (39) and said first support (24), said auxiliary sealing body (47) comprising a radially internal surface (48) placed in sliding abutment against said first support (24); the coupling body (49) of said second rotating lip seal (36) comprises a cylindrical wall (50) and a flange (51); said second rotating lip seal (36) comprises an auxiliary sealing body (58) axially interposed between the main sealing body (52) and the flange (51) of said second rotating lip seal (36) and radially interposed between said cylindrical wall (50) and said second support(26), said auxiliary sealing body (58) comprising a radially inner surface (59) placed in sliding abutment against said second support (26).

9. Undercarriage roller assembly (17) according to any one of the preceding claims, wherein said first rotating lip seal (35) comprises a garter spring (46) configured to tighten the respective main sealing lip (43) against said first support (24) and said second rotating lip seal (36) comprises a garter spring (57) configured to tighten the respective main sealing lip (54) against said second support (26).

10. Undercarriage roller assembly (17) according to any one of the preceding claims, wherein said first rotating lip seal (35) comprises an auxiliary sealing lip (44) in sliding abutment against the radially outer surface (24a) of said first support (24) and said second rotating lip seal (36) comprises an auxiliary sealing lip (55) in sliding abutment against the radially outer surface (26a) of said second support (26).

Images