Transfer case - lubrication control method - Eco mode operation

Abstract

A vehicle transfer case comprising: a housing (10); a primary shaft (16) rotatably mounted in the housing (10), the primary shaft (16) having a sprocket (44) which is non-rotatably connected to it by a clutch; a secondary shaft (34) rotatably mounted on the housing (10), the secondary shaft (34) being driven by a belt (40) via a second sprocket (38) when the clutch (50) is engaged; a lubricant collection container (96, 212) positioned in a loop of the belt (40) to collect lubricant splashed by the belt (40) and the sprockets (44, 38) by gravity, characterized in that the lubricant collection container (96, 212) has a drain which is controlled by a valve.

Description

AREA OF INVENTION The present invention relates to transfer cases for motor vehicles. In particular, the field of the present invention relates to transfer cases for vehicles with selectively selectable all-wheel drive, especially the application in vehicles with a conventional rear-wheel drive and longitudinally mounted engines. BACKGROUND OF THE INVENTION Most rear-wheel-drive vehicles that can be converted to all-wheel drive by selective engagement have a transfer case. The transfer case typically has a primary shaft connected to the output of the vehicle's transmission. A sprocket, engaged by a chain, is usually rotatably mounted on the primary shaft. The chain typically engages with another sprocket, which is usually connected to a secondary shaft. The secondary shaft is rotatably mounted within the transfer case. The secondary shaft is non-rotatably connected to a front axle driveshaft, which in turn is non-rotatably connected to a front axle differential to drive the vehicle's front wheels.A clutch mechanism is provided for selectively engaging the vehicle's front wheels. This mechanism selectively engages the sprocket on the primary shaft with the primary shaft to transfer torque from the primary shaft to the secondary shaft, thereby selectively engaging the vehicle's front wheels. Under ideal road conditions, the clutch is generally not engaged, so the transmission is only locked to the rear wheels. Typically, a control system that detects wheel slip conditions is provided to automatically control the clutch engagement. In some all-wheel-drive configurations, the clutch can also be engaged upon operator request. In many transfer cases, the secondary shaft will still rotate in two-wheel drive mode due to the movement of the non-driven (in most cases, front) wheels. This condition persists even when the clutch is disengaged and no torque is being transmitted to the secondary shaft. Most transfer cases incorporate some type of lubricant pump to provide lubrication for the clutch within the associated friction assembly, shafts, bearings, sprockets, and chain. The operation of this pump either mechanically imposes a load on the vehicle's engine by drawing power from the drivetrain or indirectly by generating a parasitic electrical load. Providing a transfer case where the lubrication requirements can be met more passively through the operation of the transfer case housing is desirable. DE 10 2006 034 153 A1 describes a vehicle transfer case with a primary shaft and a secondary shaft connected by a chain. A reservoir for collecting lubricant is arranged in a loop of the chain. Similar oil collection ribs for forming a reservoir in the loop of a chain are also known from US 4 940 446 A. Furthermore, JP H09-109 712 A discloses an oil sump housing in the loop of a chain. DE 10 2006 022 573 A1 discloses a lubrication device in the housing of a transfer case, wherein the lubrication device has a chamber for receiving fluid and is arranged outside a loop formed by a transmission chain. The chamber has an opening that leads into a flow tube. A suitable valve is activated to control the flow. It is desirable to minimize the amount of lubricant exposed to the secondary sprocket within the transfer case to prevent foaming and heat generation. Reducing or minimizing oil agitation improves transfer case efficiency. Ideally, a transfer case should maximize lubricant performance, minimize the distance between the sprocket and the bottom of the transfer case, and further minimize the amount of fluid exposed to the secondary sprocket during two-wheel or four-wheel operation at higher engine speeds, when low torque demands are placed on the wheels connected to the differential linked to the secondary shaft. BRIEF DESCRIPTION OF THE INVENTION To meet the aforementioned requirements and provide further numerous advantages, a disclosure of the present invention is cited. In one embodiment, the present invention provides a transfer case with a primary shaft that can be selectively engaged with a secondary shaft via a clutch mechanism. The clutch mechanism comprises a friction pack. A hub of the clutch mechanism is connected to the primary shaft, and the clutch housing is rotationally fixed to a primary sprocket that is rotatably mounted on the primary shaft. The transfer case has a lubricant reservoir located away from a sump under the secondary shaft, thus allowing a larger lubricant capacity to be accommodated in the transfer case.Since the reservoir is located away from the sump, less lubricant is exposed to the secondary sprocket when the vehicle is in a two-wheel drive mode or all-wheel drive mode at high engine speeds with low torque requirements for the vehicle's wheels, which are non-rotatably connected to the secondary shaft. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be better understood with reference to the detailed description and the accompanying drawings; in the drawings: Fig. 1 shows a cross-section of a transfer case; Fig. 2 shows a rear elevation of the transfer case shown in Fig. 1; Fig. 3 shows a perspective front view of the transfer case shown in Figs. 1 and 2, with a front cover plate removed; Fig. 4 shows a perspective rear view showing parts of the transfer case shown in Figs. 1-3 in a through view; Fig. 5 shows a partial cross-sectional view showing a lubrication path extending between the hub and a primary shaft of the transfer case shown in Figs. 1-4; Fig. 6 shows a view of a transfer case corresponding to the one shown in Fig.Figures 1-5 show a functionally similar transfer case in which a lubricant reservoir is provided in the loop of the belt that non-rotatably connects the sprockets provided on the primary and secondary shafts of the transfer case; Figure 7 shows a cross-sectional view along line 7-7 of Figure 6; Figure 8 shows a view similar to Figure 6 of a transfer case of an alternative preferred embodiment of the present invention with an actively controlled lubricant reservoir according to the present invention; Figure 9 shows a view similar to Figure 8, illustrating the operation of the actively controlled fluid reservoir of the transfer case shown in Figure 8; Figure 10 shows a view similar to Figure 8.3. Similar view of a transfer case of an alternative preferred embodiment of the present invention with a passively hydraulically actuated valve that controls the flow connection between a lubricant reservoir and a friction pack interface between a hub and a clutch housing of a clutch used for selectively connecting a sprocket on a primary shaft to the sprocket on a secondary shaft, according to an alternative preferred embodiment of the present invention; Fig. 11 a perspective rear view of a transfer case shown in Fig. 10; Fig. 12 a cross-sectional view primarily through the primary shaft of the transfer case shown in Fig. 10; Fig. 13 a partial cross-sectional view of the transfer case shown in Fig. 10 from the rear; Fig.Fig. 14 is an enlarged cross-sectional view showing part of the hydraulically actuated valve that controls the flow connection between the lubricant reservoir and the friction pack of the clutch; Fig. 15 is a view similar to Fig. 14 showing the operation of the fluid-actuated valve that controls the flow connection between the lubricant reservoir and the friction pack of the clutch of the transfer case shown in Fig. 10; Fig. 16 is a view similar to Fig. 14 showing a valve that is an alternative to the valve shown in Fig. 14; and Fig. 17 is a view similar to Fig. 15 of the valve shown in Fig. 16. DETAILED DESCRIPTION OF PREFERRED EXECUTION FORMS The following description of the preferred embodiment(s) is merely exemplary and is not intended to limit the invention, its scope of application or its uses in any way. With reference to Fig. 1-5, an example of a transfer case 7 is provided. The transfer case 7 has a housing 10. The housing 10 has a front cover plate 12, which is screwed to a main body 14. A primary shaft 16 is rotatably mounted in the transfer case housing 10. The primary shaft 16 has a front end 18 adapted for connection with an output shaft (not shown) of a vehicle's transmission. Typically, the vehicle will be a rear-wheel-drive vehicle with a longitudinally mounted engine. The vehicle's drivetrain is configured such that power from the rear axle can be selectively diverted to be shared with the front axle to provide all-wheel-drive capability. The primary shaft is secured to the front cover plate 12 by a front bearing 20.A rear section of the primary shaft 16 is rotatably mounted in the main housing body 14 by a rear bearing 22. A rear end 24 of the primary shaft is connected to a fork 26 by a nut 28, which engages a washer 30. The fork 26 is connected to a driveshaft that extends to a rear axle differential and a rear axle of a vehicle (not shown). Further down, a secondary shaft 34 is also attached to the transfer case 7. The secondary shaft 34 is configured to have splined teeth 36 on its inner diameter to drive a front axle driveshaft (not shown), which is non-rotatably connected to a differential for the front wheels of the vehicle, either directly or via a universal joint. In another embodiment (not shown), the secondary shaft can be connected to the front axle driveshaft via a flange connection. A connected sprocket 38, provided with a series of sprocket teeth 39, forms an outer portion of the secondary shaft. The sprocket teeth 39 engage a flexible link for transmitting torsional force or a belt (40) (shown schematically), which is typically provided by a multi-link chain. The belt 40 engages with the sprocket teeth 42 provided on the primary sprocket 44.The primary sprocket 44 is rotatably mounted on the primary shaft 16 by means of needle bearings 46. In other embodiments not shown, the primary sprocket can instead be a gear in direct or indirect gear connection with the secondary shaft. To allow selective, rotationally fixed engagement of the primary shaft 16 with the secondary shaft 36, a coupling 50 is provided. The coupling 50 includes a coupling housing 52. The coupling housing 52 is rotationally fixed to the primary shaft sprocket 44. The coupling housing 52 has a series of radial folds 54 that provide radially inwardly projecting teeth which engage with correspondingly shaped radial edges of friction discs 56. The friction discs 56 are combined with corresponding friction plates 58. The friction plates 58 have a gear-tooth profile along their inner diameter, which allows them to be rotationally fixed to a hub 62 that has corresponding folds on its radial outer surface. The hub 62 is rotationally fixed to the primary shaft 16 by welding, splined connection, or a shrink-fit arrangement. A support plate 64 is also provided.The support plate 64, as well as the friction plates 58 and friction discs 56, form a friction package that allows a selective connection of the clutch housing 52 with the clutch hub 62, which causes the sprocket 44 to be connected to the primary axle 16. The hub 62 has several axially extending lubrication channels 70. The axial channels 70 are intersected by radially outwardly projecting lubrication holes 72 through which lubricant is supplied to the friction pack. A piston 74 is provided for selectively engaging the friction pack. The piston 74 has a radially inner seal 76 and a radially outer seal 78. Axially behind the piston 74 is a pressurized chamber 79, which is connected by a channel (not shown) to a source of pressurized fluid (not shown). When actuated, the piston 74 engages a bearing 82 located next to the support plate 64 to engage this friction pack, thereby connecting the hub 62 and the primary shaft 16 to the sprocket 44, the belt 40, and the secondary shaft 34 in a rotationally fixed manner to drive the front wheels of the vehicle. When torque is required at the front wheels, lubricant must be supplied to the clutch assembly primarily for cooling the friction pack. Lubricant is also supplied to the belt 40, the sprockets 44, and the secondary shaft 36. When the chain moves, lubricating oil is sprayed. A large portion of the oil is injected into a storage system comprising a collecting diverter plate 90, which has an inlet 92 generally located next to the primary sprocket 44. The torque of the lubricating oil causes the lubricant to be transported axially over the primary shaft 16 and over the piston 74, the clutch 50 and its associated friction assembly, as well as axially across these components. The lubricant is then collected in a lubricant reservoir 96. The lubricant reservoir 96 is formed in the body 14 of the housing. The reservoir 96 is stationary. The collection of the oil leads to the formation of a pressure head, which enters a vertical stationary housing channel 98. The vertical channel 98 leads to the rear bearing 22 for its lubrication. A stationary, generally axial housing channel 100 leads to the vertical channel 98.Thus, the oil flow also extends radially within the friction pack. The axial channel 100 allows the oil to move axially in a generally forward flow direction under the pressure heads provided by the accumulator into an axially extending lubrication channel 70 provided in the hub. A factor improving lubrication performance according to the present invention is that the lubricant, during its vertical inward transport through the channel 98, does not have to flow past any rotating elements. Oil entering the axial lubrication channel 70 is then forced radially outward through the lubrication holes 72 by rotation to lubricate the friction pack. Radially inside the lubrication channel 100 is an inner lubrication channel 101. The inner lubrication channel 101 opens into a disc-shaped chamber 103. The disc-shaped chamber 103 is bounded by a path block 112, which prevents lubricating oil from being flung outwards towards the piston 74. The primary shaft 24 is connected to the hub 62 by means of a splined connection via a series of radially outward extending teeth 116, which engage with radially inward extending teeth 118 of the hub. One or more of the teeth 116 or 118 are omitted to provide a lubrication channel 114 extending between the interface of the hub and a primary shaft, thus allowing lubricant to flow from the rear of the hub to the front of the hub and thereby reach the needle bearings 46, which rotatably mount the primary sprocket 44 to the primary shaft. With reference to Figures 6 and 7, a transfer case 207 is provided which is almost identical in function and structure to the transfer case 7 described above. In the transfer case 207, an additional reservoir or lubricant collection tank 212 is provided between a loop of the belt or chain 210. The tank 212 is formed by walls 213 and 215, which project from a front section 217 of the housing and a rear section 221 of the housing, meeting along a line 223. The collection tank 212 has an opening 214. The opening 214 allows the collection tank 212 to collect, by gravity, lubricant that is splashed by the primary and secondary sprockets 205, 209 and the chain 210. Next to the collection tank 212, the housing has a formed or drilled channel 218 in the direction of the secondary shaft 216.Channel 218 intersects a transverse channel 220 (which is shaped in the illustration but could also be a transverse bore closed at its outer ends) and longitudinal channels 222 (which are shaped in the illustration but could also be blind bores) to provide a path for the lubricant in the reservoir 212 to passively lubricate the secondary shaft bearings 224. When the secondary shaft drives the front wheels at high vehicle speed, lubricant tends to accumulate in the reservoir 212 faster than it flows out through channel 218 to lubricate the secondary shaft bearings, thus passively removing or storing lubricant away from the sump located beneath the secondary shaft 216.The lubricant reservoir 212 can, if desired in certain applications, be configured to hold 20% or more of the total lubricant capacity of the transfer case. This removal of lubricant from an area adjacent to the shaft 216 in its connected sprocket 226 reduces lubricant agitation, thereby reducing potential foaming or heat generation and increasing the efficiency of the transfer case. With reference to Figures 8 and 9, a transfer case 247 according to the present invention can additionally be provided with an actively controlled lubricant reservoir 250 having an open top 252. The reservoir 250 can be a separate container or a container that can be formed wholly or partially by the frame or other components of the transfer case. The open top primarily collects lubricant splashed by gravity from the chain 253 (shown in view) and the upper sprocket (not shown), as well as lubricant splashed from the housing walls. The reservoir 252 is connected to the bottom of the sump area 256 via a line 254 that extends into the secondary shaft. A schematically shown electromagnetically actuated valve 258 controls the flow through the line 254. During normal operation or operation at low speeds, overflowing lubricant enters the reservoir 250 up to its upper limit; overflowing lubricant may flow into the sump to achieve a level within the sump 264. When the vehicle then transitions to a high speed level in two-wheel drive mode (where no torque requirements are necessary for the clutch), the valve 258 closes, causing the reservoir 250 to refill and bringing the lubricant level up to that of 266 to prevent or minimize fluid agitation. Agitation of lubricant can cause heat generation and undesirable foaming. The control of the valve 258 opening can be proportional and can be based on the rotational speed of the secondary shaft or derivatives thereof, which will generally be proportional to the vehicle speed.The control of the solenoid valve 258 can also be a function of the torque demand on the clutch of a vehicle transfer case. Higher torque demands allow for the release of larger quantities of lubricant through the valve 258. Typically, the control of the valve 258 is a function of an electronic control unit. With reference to Figures 10-15, a transfer case 307 of an alternative preferred embodiment according to the present invention is provided. The transfer case 307 has a housing 310 with a front cover 312 and a main body 314. The transfer case 307 has a primary shaft 316 which is rotatably mounted to the front cover plate 312 by a front bearing 320. A hub 362 is connected to the primary shaft 316 via a splined connection and is connected to the primary shaft 316 in the manner described above. It also has an axially extending lubrication channel 383 and interacts with the primary shaft 316 as described above. Furthermore, it has a lubrication channel (not shown) similar to the channel 114 (as described for hub 52 in Figure 1). A primary sprocket 344 is rotatably mounted on the primary shaft 316 by needle bearings 346. The primary sprocket 344 is fixedly connected to a clutch housing 352. The clutch housing 352 can be selectively engaged with the primary shaft 316 and the hub 362 in the manner described above by a friction pack, which can be selectively engaged by a hydraulically extended piston 374. A deflector plate 315 is connected to the front cover plate 312. The deflector plate 315 is generally positioned next to a chain 340, which transmits torque between a primary sprocket 344 and a secondary sprocket 238. The transfer case 307 also has a lower adjuster 363, from which two lubricant reservoirs 335 extend.The lubricant reservoirs 335 serve to retain lubricant in the chain 340 as the chain 340 moves from the lower secondary sprocket 238 to the primary sprocket 344. Under normal operating conditions, the lubricant collects at the bottom of the housing 310. The clutch housing 352 also has a series of axially spaced holes 353 to allow lubricant in the friction pack to escape from the clutch housing. The holes 353 are typically located on the top of the radial folds 354 of the clutch housing. When the chain 340 rotates, oil escapes from the chain 340 and is diverted by the deflector plate 315 to an adjacent inlet of the storage system 329; oil also escapes from the holes 353 and flows into the storage system 329. A lubricant reservoir 361 is formed by the housing 314 on one side 331 of the housing opposite a side facing the clutch housing 352. A cover for the lubricant reservoir 361 is provided by a plate 333. An axial needle bearing 373 (Fig. 12) is located next to thrust washers 375 and 377, which allow the housing to absorb the axial force caused by the engagement of the clutch and provided by the clutch housing 352 and the hub 362 into the primary shaft 316. The housing has a channel 401. One end of the channel 401 is connected to the reservoir 361 and forms a drain for the reservoir 361. The channel 401 has an opposite end that is connected to a chamber 403 having a different diameter. The chamber 403 is connected to a channel 371, which is connected to a lubrication channel 381, which can convey lubricant into an axial hub lubrication channel 383, which meets a radial hub channel 384, which can lubricate the friction pack 359, which is located at the interface between the hub 362 and the clutch housing 352. Chamber 403 has a first section 407 in which a ball 409 is placed. The first section 407 is fluidically connected to a channel 402. The channel 402 is fluidically connected to a control volume that pressurizes the clutch actuating piston 374. The chamber has a reduced section 411 that meets a larger section 413. The section 413 meets channel 371 and channel 401. Chamber 403 is sealed by an end cap 421. A piston valve 425 is slidably mounted in chamber 403. The piston valve 425 has a bore 427 to which a coil spring 429 is attached. The coil spring 429 pushes the piston 425 towards the ball 409, causing the head 431 of the piston valve 425 to abut against a valve seat 433. An inner section of the cap supports a remote end of the coil spring 429.The spring 429 pushes the piston valve 425 towards the ball 409, causing the head 431 to sit on the valve seat 433 and thus interrupting the flow connection from the channel 401 and reservoir 361 to the hub lubrication channel 383. Accordingly, under normal circumstances, the reservoir 361 will be completely full, and the overflow is then allowed to drain into a sump in the transfer case. When the clutch 359 is engaged by the hydraulically driven piston 374, fluid pressure builds up in the channel 402, pressing the ball 409 against a stem 437 of the piston valve 425. This action compresses the spring 429 and pushes the piston valve head 435 out of the valve seat 433. Lubricant is now allowed to flow by gravity to lubricate the friction pack 359 when the clutch is engaged. Figures 16 and 17 show an alternative fluid-actuated valve 525. A channel 501 connects the reservoir 361 directly to a chamber 503. The spring-loaded valve 525 has a side 539 on which valve regulation for a channel 571 is provided. The channel 571 is connected to the channel 381. A stem of the valve 525 is moved by the ball 409 when the coupling piston 374 is activated, in the same manner as described above for the valve 425. The description of the invention is purely exemplary, and therefore variations that do not deviate from the core of the invention are to be considered within the scope of protection of the invention. Such variations are not to be regarded as a deviation from the concept and scope of protection of the invention.

Claims

A vehicle transfer case comprising: a housing (10); a primary shaft (16) rotatably mounted in the housing (10), the primary shaft (16) having a sprocket (44) which is non-rotatably connected to it by a clutch; a secondary shaft (34) rotatably mounted on the housing (10), the secondary shaft (34) being driven by a belt (40) via a second sprocket (38) when the clutch (50) is engaged; a lubricant collection container (96, 212) positioned in a loop of the belt (40) to collect lubricant splashed by the belt (40) and the sprockets (44, 38) by gravity, characterized in that the lubricant collection container (96, 212) has a drain which is controlled by a valve. Vehicle transfer case according to claim 1, wherein the belt (40) is a chain. Vehicle transfer case according to one of the preceding claims, wherein the reservoir (96, 212) contains at least 20% of the lubricant in the transfer case. Vehicle transfer case according to one of the preceding claims, wherein the transfer case has a housing (10) with a front section (217) and a rear section (221) and the reservoir (96, 212) is formed by walls projecting from the front and / or rear section (12; 14) of the housing (10). Vehicle transfer case according to one of the preceding claims, wherein the container (96, 212) has an outlet path for lubrication from the secondary shaft (34) associated bearings (224). Vehicle transfer case comprising: a housing (310); a primary shaft (316) rotatably mounted in the housing (310), the primary shaft (316) having a first sprocket (344) selectively and non-rotatably connected to it by a clutch (352); a secondary shaft (338) rotatably mounted on the housing (310), the secondary shaft (338) being driven by a belt (340) via a second sprocket (238) when the clutch (352) is engaged; a lubricant collection container (250, 361) positioned in the housing (310) to collect lubricant splashed by the belt (340) and the sprockets (344, 238) by gravity, the lubricant collection container (250, 361) having a drain (254, 401);and wherein the process (254, 401) is controlled by a valve (258, 425, 525), characterized in that the valve (425, 525) opens a path between the lubricant reservoir (361) and the clutch (352) when a friction pack of the clutch is engaged, the clutch friction pack (359) is engaged by a hydraulically operated piston (374) and the valve (425, 525) is opened hydraulically. Vehicle transfer case according to claim 6, wherein the valve (258) is an electromagnet that controls the current through it based on an angular velocity of the secondary shaft (338) or integrals or derivatives thereof. Vehicle transfer case according to claim 6 or 7, wherein the valve (258) controls the flow through it based on a torque request from the clutch (352). Vehicle transfer case according to one of claims 6 to 8, wherein lubricant released from the outlet (254, 401) flows into the housing sump (256, 264). Vehicle transfer case according to one of claims 6 to 9, wherein the clutch (352) comprises a hub (362) connected to the primary shaft (316) and a clutch housing which is rotationally fixed to the first sprocket (344), and the clutch (352) is lubricated with lubricant which is released by gravity from the drain (401) and directed to an interface between the clutch hub (362) and the clutch housing. Vehicle transfer case according to one of claims 6 to 10, wherein the valve is opened hydraulically in a lubrication path connecting the lubricant reservoir (361) and the interface between the clutch hub (362) and the clutch housing. Vehicle distribution housing according to one of claims 6 to 11, wherein the valve (425, 525), when opened hydraulically, comprises a piston which is lifted out of a valve seat (433). Vehicle transfer case according to one of claims 6 to 12, wherein there is a lubricant flow path (114) along the primary shaft (316) under the hub (362). Vehicle transfer case (307) for a vehicle with conventional rear-wheel drive, the transfer case (307) comprising: a housing (310); a primary shaft (316) rotatably mounted in the housing (310); a secondary shaft (338) for driving a front axle differential of a vehicle, the secondary shaft (338) being selectively driven by the primary shaft (316) and rotatably mounted in the housing (310); a hub (362) non-rotatably mounted on the primary shaft (316), the hub (362) having an axially extending lubrication channel (383) perforated with generally radial lubrication holes (384), the hub (362) being fixably connected to the primary shaft (316) and the hub (362) having holes (116, 118, 114); a clutch housing (352) connected to the hub (362) is selectively connected in a rotationally fixed manner via a friction package (359);a primary sprocket (344) which is rotatably attached to the primary shaft (316) and fixed to the clutch housing (352) in a rotationally fixed manner; wherein the sprocket (344) engages with a chain (340) which connects the primary sprocket (344) to the secondary shaft (338) in a rotationally fixed manner; a hydraulically actuated piston (374) for engaging a friction pack (359) which connects the clutch housing to the hub; a storage system (329) fixed with respect to the housing (310) for collecting lubricant, which is set in motion by the operation of the primary shaft (316) and the secondary shaft (338), wherein the storage system (329) supplies lubricant to a lubricant reservoir (361); a stationary channel (401, 371, 381) formed in the housing (310) for supplying lubricant from the lubricant reservoir (361) from the friction pack (359) radially inwards to the hub lubrication channel (383);and a valve (425) positioned in the stationary channel (401), which is hydraulically actuated and is activated when the piston (374) is actuated in such a way as to allow the flow of lubricant from the lubricant collection container (361) to the hub lubrication channel (383).

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