Patent Description:
Tracked undercarriages are typically used in operating machines such as earthmoving machines, mining machines, demolition machines and the like, to allow the machine to move on often uneven ground or with poor grip.

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.

The chain usually comprises a plurality of links, with link it is referred to the single component of the chain which is articulated to the other components. Typically, each link comprises a pair of plates facing each other. The links are interconnected between them by pins. Each pin is usually inserted into holes provided on the plates and connects two links together.

The soles are usually mounted on the links 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.

Each roller assembly usually comprises a roller body crossed by a shaft. The roller assembly is delimited by a radially inner surface facing the shaft, in particular facing the outer surface of the shaft. The roller body can rotate about the shaft which is fixed with respect to the undercarriage on which it is mounted. The roller assembly comprises a bushing which is fitted on the outer surface of the shaft so as to be interposed between the shaft and the inner surface of the roller body. The roller body and the shaft are made of metal, typically of steel, and the bushings are configured to reduce friction between the roller body and the shaft. The bushings are usually made of a non-ferrous material, such as bronze, or of a bi-metal alloy and are lubricated to further reduce friction between the bushing contact surfaces and roller body and/or bushing and shaft.

The undercarriage is usually subjected to very severe operating conditions which may derive from the overall weight of the machine, the high powers transferred from the engine of the machine to the ground and/or the conformation and composition of the terrain on which the machine must operate.

In particular, the Applicant has observed that in the operations for moving large earth-moving machines some undercarriage components are subjected to strong stresses. A particularly critical undercarriage component is the lower roller assembly which has the function of absorbing the loads transmitted by the machine as well as of guiding the chain. Typically, a large excavator is provided with a plurality of lower roller assemblies, for example <NUM> to <NUM>. When the excavator is in motion, the lower roller assemblies are subjected to rotation with a consequent significant increase in the temperature inside the roller assemblies, which might reach critical values that can affect the functional integrity of these components.

The Applicant has noted that an unsuitable lubrication of the bushing increases friction leading to a damage of the roller assembly caused by the wear of the bushing, whose thickness gradually decreases, or to the grip of the bushing on the shaft and/or on the roller body.

The Applicant has noted that by measuring the bushing temperature it is possible to determine an abnormal lubrication thereof, in particular the temperature of the lubricant increases as the temperature of the bushing increases.

Documents <CIT> and <CIT> respectively disclose a crawler roller and a wheel shaft.

Application <CIT> discloses a monitoring device in an undercarriage assembly which has a roller assembly including a shaft and a bushing. In one example, the monitoring device has a temperature sensor located inside the roller assembly to measure the temperature of the bushing. In particular, an opening is provided in the shaft which is formed parallel to the shaft, until a depth sufficient to overlap the bushing, and having a portion oriented outwardly which reaches the outer surface of the shaft. The temperature sensor is inserted into the opening and is arranged in the portion oriented towards the shaft surface. The document mentions that output signals are transferred through a wireless transmitter to a computer or the data are accessed through a port that connects to the monitoring device.

The Applicant has observed that an opening in the shaft reaching the outer surface of the shaft can allow positioning a temperature sensor in direct contact or substantially in direct contact with the bushing, thus measuring efficiently the temperature of the latter.

The Applicant has however verified that such an opening may cause leakages of lubricant inside the opening with a potential double disadvantage of damaging the temperature sensor and of reducing the amount of lubricant available between the bushing and the shaft. This second event may even lead to a premature degradation of the roller assembly due to lack or shortage of lubricant.

The Applicant has noted that an indication of unsuitable lubrication of the bushing can be not only related to the temperature of the bushing but also to the temperature of shaft portions placed near the bushing.

The Applicant has observed that, by arranging a temperature transducer in the shaft of the roller assembly so that the transducer is near the bushing but not directly facing the bushing or in contact with the bushing, it is possible to measure a temperature which, though not exactly corresponding to the actual temperature, is proportional to the bushing temperature, allowing to identify abnormal increases in the bushing temperature.

The present invention relates to a tracked undercarriage roller assembly comprising:.

Arranging the housing seat in the shaft and inserting the temperature transducer inside the measuring portion of the housing seat makes it possible to detect the temperature of the shaft at the measuring portion of the housing seat.

Since, as known, the shaft of a tracked undercarriage roller assembly is typically made of a ferrous alloy, such as steel, the shaft has such a thermal conductivity as to allow portions of the shaft placed near the bushing to change temperature as the temperature of the bushing changes.

The Applicant has observed that, depending on the size of the roller assembly and on the material actually used to manufacture the shaft, a radial distance of the temperature between <NUM> millimetres and <NUM> millimetres from the bushing allows to detect sudden or abnormal increases in the bushing temperature.

An increase in the temperature detected by the temperature transducer beyond a predetermined threshold can be associated to an abnormal increase in the temperature of the bushing, due, for instance to the leakage of lubricant from the annular chamber, a too high friction of the bushing on the shaft or in any case to an out of scope bushing functioning.

It is thereby possible to intervene on the roller assembly restoring its functions before an irreversible damage on the roller assembly occurs.

Furthermore, by arranging the inlet portion facing an axial end surface of the shaft with the inlet portion and the measuring portion aligned between them along an axial direction, it is possible to prevent lubricant leakages from the annular chamber towards the housing seat or towards the temperature transducer, as the housing seat is completely obtained inside the shaft without having openings facing the bushing.

The lubricant can be for instance lubricant oil or grease.

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

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.

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

The terms "radially inner" and "radially outer" mean respectively a position closer to or further away from the aforementioned rotation axis.

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.

The term "transducer" means a device which interacts directly with the measured quantity, that is to say the first element of a measurement chain that converts a physical quantity into an electric signal related to the measured quantity.

Preferably, the measuring portion is placed at a radial distance from the bushing between <NUM> millimetres and <NUM> millimetres, still more preferably between <NUM> and <NUM> millimetres, for instance about <NUM> millimetres.

Preferably, the housing seat is an axial-symmetry blind cavity with a symmetry axis parallel to an axial direction.

Thereby, the housing seat can be obtained by piercing the shaft until the desired depth for inserting the temperature transducer inside the shaft is reached.

Preferably, the blind cavity has a rectilinear extension and does not comprise deviations or branches radially branching from the symmetry axis parallel to an axial direction.

This prevents the housing seat from reaching a radially outer surface of the shaft or facing directly to the bushing or the annular chamber containing lubricant, avoiding possible leakages of lubricant from the annular chamber.

Preferably, the inlet portion has an extension in radial direction greater than the extension in the radial direction of the measuring portion.

Preferably, the inlet portion has an extension in radial direction which is almost double the extension in the radial direction of the measuring portion.

Preferably, an electronic sensor module is provided configured to generate measurement signals in wireless mode including data representative of temperature; the electronic sensor module being placed in the inlet portion of the housing seat.

Preferably, the electronic sensor module comprises: circuit components, an electronic processor, a power supply source, and a wireless transmitter operatively connected to the electronic processor so as to receive respective measurement signals including data representative of temperature, the wireless transmitter generating corresponding measurement signals in wireless mode that include data representative of temperature.

Preferably, the electronic processor of the electronic sensor module is configured to receive measurement signals from the temperature transducer.

Thereby, for example, an operator who is far from the tracked vehicle incorporating the roller assembly will be able to remotely view data related to the current temperature of the shaft portion near the bushing connecting a mobile terminal or a PC to a WI-FI network which the electronic sensor module is connected to.

Preferably, the inlet portion comprises an annular groove engaged by a stop ring, the annular groove being axially external to the electronic sensor module so that the electronic sensor module is axially retained in the inlet portion by the stop ring.

The electronic sensor module is thereby retained inside the housing seat avoiding possible damages to the electronic sensor module while the roller assembly is being used and ensuring proper functioning thereof.

Preferably, a closing plug is provided for the inlet portion of the housing seat. The closing plug is preferably axially interposed between the stop ring and the electronic sensor module.

The closing plug prevents liquids, mud, dirt or other from entering into the housing seat.

Preferably, the stop ring is removable from the annular groove in the inlet portion of the housing seat.

The stop ring holds the plug in the operative position however allowing for removal thereof in case access inside the housing seat is required for an inspection or replacement of the temperature transducer and/or of the electronic sensor module.

Preferably, the temperature transducer is connected to the electronic sensor module by electric wires.

Preferably, the temperature transducer is a thermistor with a resistance decreasing as the temperature increases.

As the temperature of the shaft portion near the bushing increases, the resistance value of the thermistor decreases. Thereby, in case of a thermistor malfunction (such as in case of electrical breakdown between thermistor and electronic sensor module), the resistance value detected would be significantly misaligned from an expected resistance value, providing immediate indication of a thermistor malfunction.

Preferably, a pin inserted into a radial cavity of the shaft is provided to make the shaft integral with an undercarriage frame; the housing seat not crossing the radial cavity of the shaft.

The pin has the task of engaging the shaft to the undercarriage frame (or to an undercarriage component integral with the undercarriage frame) to keep the roller assembly in position and to allow the roller body to rotate about the shaft.

The pin is typically removable so as to remove the roller assembly from the undercarriage carriage.

In case the temperature transducer is connected to the electronic sensor module with electric wires and in case the housing seat crosses the pin, the removal of the pin would permanently damage the connection between the temperature transducer and the electronic sensor module, as the pin would be crossed by electrical connections. Furthermore, by preventing the housing seat from crossing the pin, the positioning of the temperature transducer inside the housing seat may be carried out even when the roller assembly has not been yet mounted on the undercarriage frame.

Preferably, the roller body comprises an opening which puts in fluid communication the outer environment with the annular chamber filled with lubricant; the opening being closed by a plug.

Further characteristics 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:.

<FIG> is a schematic side view showing some components of a tracked undercarriage. The tracked undercarriage <NUM> comprises two track assemblies <NUM>, of which only one is visible in <FIG>. Each track assembly <NUM> comprises a chain <NUM>, comprising a plurality of links <NUM> interconnected between them by pins and bushings (not shown), a return wheel <NUM>, in the figure partially hidden by a crankcase <NUM>, and a driving wheel <NUM>. A plurality of roller assemblies <NUM> is arranged between the return wheel <NUM> and the driving wheel <NUM>, in particular one or more upper roller assemblies and a plurality of lower roller assemblies arranged in contact with the links <NUM> and adapted to guide the chain <NUM> in its motion.

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

According to the present disclosure, at least a lower or upper roller assembly <NUM> includes a sensor device for monitoring the temperature.

<FIG> is a section view of a roller assembly <NUM> according to an embodiment. In this embodiment the roller assembly <NUM> is a roller assembly of a lower roller. The section plane is a longitudinal plane transversal to the links <NUM> of the chain <NUM>, and hence to the direction of movement of the tracked undercarriage, passing through the rotation axis X of the roller assembly <NUM>.

The roller assembly <NUM> comprises a roller body <NUM> comprising a cylindrical through cavity <NUM> which extends from one first axial end 18a to a second axial end 18b of the roller body <NUM>.

The roller body <NUM> is delimited by a radially inner surface <NUM> usually having a cylinder shape facing the cylindrical cavity <NUM> and a radially outer surface <NUM> whose shape is determined by the type of track <NUM> with which the roller assembly <NUM> must interact.

The roller body <NUM> is made of a low-alloy steel that is boron-alloyed and submitted to at least a 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 <NUM>%.

The roller assembly <NUM> further comprises a shaft <NUM> inserted into the cylindrical cavity <NUM> of the roller body <NUM>. The shaft substantially has a cylindrical shape, it extends between a first axial end 22a and a second axial end 22b and has a radially outer surface <NUM> facing the radially inner surface <NUM> of the roller body <NUM>.

The shaft <NUM> is preferably made of a low-alloy steel that is boron alloyed and submitted to at least a heat treatment.

The shaft <NUM> has a greater extension in an axial direction than the extension in an axial direction of the roller body <NUM>. In other words, the distance in the axial direction between the first axial end 22a and the second axial end 22b of the shaft <NUM> is greater than the distance measured along the same direction between the first axial end 18a and the second axial end 18b of the roller body <NUM>.

The shaft <NUM> extends axially beyond the first 18a and the second axial end 18b of the roller body <NUM>. In particular, the shaft extension in axial direction beyond the first axial end 18a of the roller body <NUM> is substantially equal to the extension in axial direction of the shaft <NUM> beyond the second axial end 18b of the roller body <NUM>, as shown in <FIG>.

The shaft portion <NUM> which extends in an axially outer direction from the first axial end 18a of the roller body <NUM> is made integral with the undercarriage frame or with an undercarriage component integral with the undercarriage frame.

For this purpose a support <NUM> is provided that is made integral with the undercarriage frame or with an undercarriage component integral with the undercarriage frame provided with an inner through cavity <NUM> in which the shaft portion <NUM> is inserted extending in an axial outer direction from the first axial end 18a of the roller body <NUM>, as shown in <FIG>.

To make the shaft <NUM> integral with the support <NUM>, the shaft <NUM> comprises a radial cavity <NUM> which crosses the shaft <NUM> in a radial direction. On the support <NUM> two radially opposite through holes are formed which can be aligned between them and aligned to the radial cavity <NUM> of the shaft <NUM>. A pin <NUM> is inserted in the radial cavity <NUM> so as to cross the radial cavity <NUM> and intercept the two through holes of the support <NUM>. Thereby, any axial movement and any rotation about the rotation axis X of the shaft <NUM> relative to the support <NUM> is prevented.

Similarly, the shaft portion <NUM> which extends in an axial outer direction from the second axial end 18b of the roller body <NUM> is made integral with the undercarriage frame or with an undercarriage component integral with the undercarriage frame.

For this purpose a further support <NUM> is provided that is made integral with the undercarriage frame or with an undercarriage component integral with the undercarriage frame provided with an inner through cavity <NUM> in which the shaft portion <NUM> is inserted that extends in an axial outer direction from the second axial end 18b of the roller body <NUM>, as shown in <FIG>.

To make the shaft <NUM> integral with the further support <NUM>, the shaft <NUM> comprises a radial cavity <NUM> which crosses the shaft <NUM> in a radial direction. On the further support <NUM> two radially opposite through holes are formed which can be aligned between them and aligned to the radial cavity <NUM> of the shaft <NUM>. A further pin <NUM> is inserted in the radial cavity <NUM> in such a way that it crosses the radial cavity <NUM> and intercepts the two through holes of the support <NUM>. Thereby, any axial movement and any rotation about the rotation axis X of the shaft <NUM> relative to the further support <NUM> is prevented.

The roller body <NUM> is rotatable with respect to the shaft <NUM> about the rotation axis X. In order to reduce the friction between the roller body <NUM> and the shaft <NUM> a bushing <NUM> is provided that is radially interposed between the roller body <NUM> and the shaft <NUM>, as shown in <FIG>.

The bushing <NUM> is made of brass, bronze, copper or other preferably metal material that is more ductile than the material used to make the shaft <NUM> and the roller body <NUM>. The bushing material <NUM> also has a good thermal conductivity coefficient, for instance higher than <NUM> W/m°C.

In the preferred embodiment of the invention, the bushing <NUM> is integral in rotation with the roller body <NUM> and thus rotates with respect to the shaft <NUM>.

As shown in <FIG>, the bushing <NUM> extends throughout the axial extension of the roller body <NUM> between one first axial end 32a and one second axial end 32b. The bushing <NUM> comprises a radially inner surface <NUM> facing directly the shaft <NUM>. Between the radially inner surface <NUM> of the bushing <NUM> and the radially outer surface 22c of the shaft <NUM> an annular chamber is defined <NUM> which is filled with a lubricant, such as oil or grease, to further reduce friction between the shaft <NUM> and the bushing <NUM>.

The annular shaft <NUM> is in fluid communication with a tank <NUM> obtained in the roller body <NUM> through one or more passage radial holes 33a obtained in the bushing <NUM>. The tank <NUM> also has an annular shape and is in fluid communication with a channel (not shown) obtained in the roller body <NUM> which extends radially between the tank <NUM> and the radially outer surface <NUM> of the roller body <NUM>. The channel has the purpose of allowing introducing the lubricant into the tank <NUM> and thus into the annular chamber <NUM>. The channel is closed by a leak proof plug (nor shown).

At the first 18a and second annular end 18b of the roller body <NUM> respective hydraulic sealing rings <NUM> are arranged to avoid lubricant leakages between the bushing <NUM> and the supports <NUM>, <NUM> of the shaft <NUM>. At the two portions of shaft <NUM> which extend in an axial outer direction from the first 18a and second axial end 18b of the roller body <NUM>, they are further provided respective hydraulic sealing gaskets placed between the shaft <NUM> and the supports <NUM>, <NUM> to avoid lubricant leakages between the shaft <NUM> and the supports <NUM>, <NUM>.

A housing seat <NUM> is obtained inside the shaft <NUM> that is defined by a blind cavity <NUM> in the shaft <NUM>. The blind cavity <NUM> has an axial symmetry with a symmetry axis parallel to the rotation axis X.

The housing seat <NUM> extends along an axial direction deep down in the shaft from an inlet portion <NUM> to a measuring portion <NUM>. The inlet portion <NUM> is placed at an axial end surface 22d of the shaft <NUM> placed in the first axial end 22a of the shaft <NUM>. The inlet portion <NUM> is open such to define an opening for the cavity <NUM>.

The measuring portion <NUM> is placed deep down inside the shaft <NUM>, in particular it is placed axially at the bushing <NUM>. As shown in <FIG>, the measuring portion <NUM> is placed axially between the first 32a and the second axial end 32b of the bushing <NUM>.

The inlet portion <NUM> and the measuring portion <NUM> are aligned along an axial direction such that the blind cavity <NUM> is parallel to the rotation axis X.

The measuring portion <NUM> is spaced in a radial direction from the radially outer surface <NUM> of the shaft <NUM>. The measuring portion <NUM> does not contact and is not open on the radially outer surface <NUM> of the shaft <NUM>.

As better shown in <FIG>, the measuring portion <NUM> is placed at a radial distance RD from the bushing <NUM> between <NUM> millimetres and <NUM> millimetres.

The radial distance RD is measured in a radial direction between the point of the inner cavity <NUM> that is radially closer to the bushing <NUM> and the radially inner surface <NUM> of the bushing <NUM>, as shown in <FIG>.

Inside the measuring portion <NUM> of the housing seat <NUM> a temperature transducer <NUM> is inserted.

The temperature transducer <NUM> is configured to generate an electric signal representative of the measured temperature. For example, the temperature transducer <NUM> is a thermal probe, preferably an NTC (Negative Temperature Coefficient) probe having a negative temperature coefficient which causes a decrease in electrical resistance as the temperature increases. Preferably, the temperature transducer <NUM> is adapted to measure temperatures until about <NUM>.

In the inlet portion <NUM> there is arranged an electronic sensor module <NUM> configured to generate measuring signals in wireless mode which include data representative of a temperature measured by the temperature transducer <NUM>.

As better shown in <FIG>, the inlet portion <NUM> has an extension in the radial direction that is greater than the extension in the radial direction of the measuring portion <NUM>, so as to house the electronic sensor mode <NUM>.

In the preferred embodiment of the invention, the extension in radial direction of the inlet portion <NUM> is about double the radial direction extension of the measuring portion <NUM>.

The extension in axial direction of the inlet portion <NUM> is selected so as to substantially house by fitting the electronic sensor module <NUM>.

The electronic sensor module <NUM> and the temperature transducer <NUM> are electrically connected between them by electric wires <NUM>.

As schematically shown in <FIG>, the electronic sensor module <NUM> comprises a connector <NUM> for the connection with electric wires <NUM>. The sensor electronic module <NUM> comprises circuit components <NUM> operatively connected to electric wires <NUM> to capture signals from the temperature transducer <NUM> and generate output electric signals representative of the measured temperature.

The circuit components <NUM> of the electronic sensor module <NUM> comprise circuit components for the management of the signals from the temperature transducer <NUM>, which can comprise a conditioning circuit for the analogue signals from the temperature transducer <NUM> and a possible amplifier for converting the input signals into a voltage or current, analogue or digital output signal. Typically, the electric signals output from the circuit components are digital electric signals. For this purpose, the circuit components <NUM> may comprise an analogue-to-digital A/D signal converter. The electric signals output from the first circuit components include data representative of the instantaneous temperature measured by the temperature transducer <NUM> in the shaft <NUM>.

The electronic sensor module <NUM> comprises an electronic processor <NUM>, in particular a microprocessor, associated with a memory which receives the measurement signals coming from the circuit components <NUM> and stores them to later send them to a wireless transmitter <NUM> for the transmission in wireless mode of measurement signals via an antenna <NUM>.

The wireless transmitter <NUM> is configured to generate radio frequency signals. In particular, the wireless transmitter <NUM> is a radio frequency transmitter configured to receive, from the processor <NUM>, measurement signals which include data representative of temperature and to generate respective radio frequency (RF) signals which include representative data of temperature. The wireless transmitter <NUM> is operatively connected to an antenna <NUM> for transmitting RF signals.

The electronic sensor module <NUM> further comprises a supply source <NUM>, such as a button battery, to supply the circuit components <NUM> and the microprocessor <NUM>.

Preferably, the electronic sensor module <NUM> is inserted in a container <NUM> arranged inside the inlet portion <NUM> of the housing seat <NUM>, as shown in <FIG>. The container <NUM> ensures a greater protection of the circuit components and electronic devices included in the electronic sensor module <NUM>. In the preferred embodiment, the container <NUM> is a synthetic rubber case capable of absorbing vibrations with a front opening <NUM> which faces the axially outer surface 22d of the shaft <NUM> (<FIG>). The container <NUM> can be filled with an epoxy resin to further dampen external stresses and make the electronic sensor module <NUM> leak-tight.

The container <NUM> is closed by a closing plug <NUM> which closes, preferably tightly, the front opening <NUM> and which fits in the inlet opening <NUM> of the housing seat <NUM>, so as to seal the blind cavity <NUM>. The closing plug <NUM> is made of a material that is transparent to the passage of radio signals transmitted via the antenna <NUM>. The closing plug <NUM> is axially external to the electronic sensor module <NUM>. The closing plug <NUM> is axially external to the container <NUM>.

The inlet portion <NUM> of the housing seat <NUM> comprises an annular groove <NUM> obtained in the blind cavity <NUM> and placed at the surface 22d of axial end 22a of the shaft <NUM>. The annular groove <NUM> is configured to receive and retain a stop ring <NUM>. The stop ring <NUM> is a ring preferably made of steel and elastic, wherein elasticity is given by the fact that the outer circumference of the ring is not complete. The stop ring <NUM> is axially external to the electronic sensor module <NUM>. The stop ring <NUM> is axially external to the closing plug <NUM>. The stop ring <NUM> is axially external to the container <NUM>.

Starting from an axially inner position to an axially inner position, the stop ring <NUM> is provided as fitted in the annular groove <NUM> (which is placed in the same axial position of the stop ring <NUM>), followed by the closing plug <NUM> followed by the electronic sensor module <NUM> contained in the container <NUM>.

The housing seat <NUM> extends in a radial direction so as to house the stop ring <NUM>, the closing plug <NUM> and the container <NUM>.

As shown in <FIG> and <FIG>, the housing seat <NUM> does not intercept, i.e. does not cross, the radial cavity <NUM> which crosses the shaft <NUM> in a radial direction and which houses the pin <NUM>. The blind cavity <NUM> is not in fluid communication and does not cross the radial cavity <NUM> which crosses in a radial direction the shaft <NUM> and which houses the pin <NUM>.

Claim 1:
Tracked undercarriage roller assembly (<NUM>) comprising:
a roller body (<NUM>) having a through cavity (<NUM>) delimited by a radially inner surface (<NUM>);
a shaft (<NUM>) inserted in the through cavity (<NUM>) of the roller body (<NUM>);
a bushing (<NUM>), which develops from a first axial end (32a) to a second axial end (32b) and radially interposed between the roller body (<NUM>) and the shaft (<NUM>);
an annular chamber (<NUM>) at least partially filled with lubricant radially interposed between the shaft (<NUM>) and the bushing (<NUM>);
a housing seat (<NUM>) obtained in the shaft (<NUM>) and comprising an inlet portion (<NUM>) at an axial end surface (22d) of the shaft (<NUM>) and a measuring portion (<NUM>) placed inside the shaft (<NUM>) in an axial position between the first axial end (32a) and the second axial end (32b) of the bushing (<NUM>), wherein the inlet portion (<NUM>) and the measuring portion (<NUM>) are aligned with each other along an axial direction;
a temperature transducer (<NUM>) located inside the housing seat (<NUM>) at the measuring portion (<NUM>);
wherein the measuring portion (<NUM>) is placed at a radial distance from the bushing (<NUM>) between <NUM> millimetres and <NUM> millimetres.