Shift control arrangement in a gearbox

A shift control arrangement in a gearbox comprising a first shift rod having a first end connectable to a first power means and second end connected to a first shift fork; a second shift rod having a first end connectable to a second power means and a second end connected to a second shift fork; a first set of grooves arranged in the first shift rod, a second set of grooves arranged in the second shift rod; and first and second lock pins arranged between the first and second shift rods, which together with the first and second set of grooves restricts or allows axial movement of the respective first and second shift rod.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application (filed under 35 § U.S.C. 371) of PCT/SE2018/050570, filed Jun. 4, 2018 of the same title, which, in turn, claims priority to Swedish Application No. 1750956-3 filed Jul. 24, 2017; the contents of each of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The invention relates to a shift control arrangement in a gearbox for vehicles, a gearbox comprising such a shift control arrangement and a vehicle comprising such a gearbox, according to the appended claims.

BACKGROUND OF THE INVENTION

In vehicles, and especially for heavier vehicles such as trucks, a range gearbox device may often be connected a main gearbox device to double the number of gears. Such an auxiliary gearbox device may include a planetary gear, which may have a low gear and a high gear, wherein the shift facilities of the main gearbox device may be divided into a low range gear position and a high range gear position. In low range gear, a downshift may take place through the planetary gear, and in the high range gear, the gear ratio may be 1:1 in the planetary gear.

The range gearbox device may be provided between the main gearbox device and a propeller shaft coupled to the drive wheels of the vehicle. The main gearbox device may be accommodated in a main gearbox housing and the range gearbox device may be accommodated in a range gearbox housing. The range gearbox device may comprise an input shaft coupled to the main gearbox device and an output shaft and between the input shaft and the output shaft, the planetary gear may be disposed. The planetary gear may comprise three components, which may be rotatable arranged relative to each other namely a sun gear wheel, a planet carrier with planet gear wheels and a ring gear wheel. With knowledge of the number of teeth of the sun gear wheel and the ring gear wheel, the relative speed of the three components can be determined during operation. In a range gearbox device the sun gear wheel can be rotatable connected to the input shaft, a number of planet gear wheels which engage said sun gear wheel, which planet gear wheels may be rotatable mounted on the planet carrier which may be fixedly connected to the output shaft, and the ring gear wheel which surrounds and engages the planet gear wheels.

In a known range gearbox device the low range gear position and high range gear position may be obtained by displacing an axially displaceable sleeve between the low range gear position, in which the ring gear may be rotationally locked relative to the range gearbox housing, and high range gear position in which the ring gear wheel may be rotatable relative to the range gearbox housing and where the ring gear wheel, the planet gear wheels and the sun gear wheel rotate as a common unity.

The axially displaceable coupling sleeve may be provided with splines and by controlling the transmission to synchronous speed between the two components to be connected, an axial displacement of the coupling sleeve along the two components may be made possible in order to connect them. When the components should be detached, the transmission may be controlled so that torque balance occurs between the components so that the coupling sleeve may not transmit torque. It then may be possible to move the coupling sleeve along the components in order to disengage them from each other.

The document U.S. Pat. No. 6,196,944 shows a planetary gear comprising a sun gear, a planet carrier with planet gears and a ring gear. The sun gear may be connected to the input shaft by means of a coupling sleeve in a low range gear position and disengaged from the input shaft in a high range gear position. In the high range gear position the input shaft may be connected to the planet carrier by means of the same coupling sleeve. The ring gear may be firmly connected to a gearbox housing. The known planetary gear may be arranged in an auxiliary gearbox, having only two gear positions.

The reverse gear in a transmission in a vehicle may often be arranged in the main gearbox, which then comprises a gear, which may be engaged when the vehicle is to be driven in the reversed direction. The gear wheel, which may be intended for the reverse gear, causes an elongation of the main gearbox device, and an undesired increase in weight of the vehicle. The reverse gear wheel may rotate in the opposite direction to the other gears in the main gearbox device, which may cause losses. Said gear wheel, which may be intended for the reverse gear, may have a tendency to produce undesirable noise in the transmission, which may be a result of an intermediate gear wheel disposed between a lay shaft and a main shaft in the main gearbox device.

Therefore, the reverse gear in the main gearbox device may be replaced by means of a reverse gear arranged in the range gearbox device. The reverse gear arranged in the range gearbox device may be shifted by means a second axially displaceable sleeve. When the range gearbox device may be shifted into the reverse gear, the second axially displaceable sleeve may connect the ring gear wheel with the propeller shaft at the same time as the first axially displaceable sleeve may connect the planet carrier with the range gearbox housing.

The document U.S. Pat. No. 6,196,944 shows a gearbox for motor vehicles comprising a planetary gear comprising a first and a second sleeve acting on the planet carrier, the ring gear, the gearbox housing and the output shaft. The first and second sleeves may be controlled as one connected unit.

The axial displacement of the first and second coupling sleeves may be provided with a first and second shift fork arranged in an outside circumferential groove in the respective coupling sleeve. The shift forks may be influenced by a first and second power means, which may be a pneumatic or hydraulic cylinder. Shift rods connected to the power means and the shift forks may transfer the axial movement from the power means to the shift forks. When assembling and disassembling the range gearbox device to and from the main gearbox device the shift rods may be connected to and disconnected from the power means.

In order to prevent damage in the range gearbox device due to selecting an impropriate gear when shifting gears in the range gearbox device the shift control arrangement for the range gearbox device may be provided with a shift interlock. Such an impropriate selection of gears may be the selection of the low range gear when the range gearbox device may be shifted into the reverse gear. In this case both gear wheels and the coupling sleeves could be damaged.

A known shift interlock for a transmission is disclosed in document U.S. Pat. No. 4,120,212. The shift interlock comprises a pair of lock pins, which may be disposed in lock pin bores arranged in a housing. The lock pins may be designed to engage annular grooves in a pair of shift rods, which may be restricted to move axially when the lock pin engages the annular groove. Thus, an impropriate gear when shifting gears can be avoided. However, the known shift interlock may only be appropriate for transmissions in which only one shift rod may be controlled when shifting between a forward and reverse mode.

SUMMARY OF THE INVENTION

Known transmissions often requires complete disassembly of the gearbox for replacement of the range gearbox device, which means that it may take much time and it may become costly to repair the range gearbox device. In addition, when the vehicle is assembled at the construction plant it may take much time to assemble the range gearbox device due to the shift interlock in the shift control arrangement.

There is a need to further develop a shift control arrangement in a gearbox in which an inadvert selection of a forward or reverse mode may be prevented. There is also a need to further develop a shift control arrangement in a gearbox in which make it easy to assemble and disassemble the gearbox in a vehicle. There is also a need to develop a shift control arrangement in a gearbox that may be easy to repair. In addition, there is a need to develop a shift control arrangement in a gearbox, which save manufacturing and maintenance costs. There is also a need to further develop a shift control arrangement in a gearbox, which arrangement has a compact design and only need a small space at the gearbox.

The object of the invention is therefore to develop a shift control arrangement in a gearbox in which an inadvert selection of a forward or reverse mode may be prevented.

Another object of the invention is to develop a shift control arrangement in a gearbox, which shift control arrangement may make it easy to assemble and disassemble the gearbox in a vehicle.

A further object of the invention is to develop a shift control arrangement in a gearbox that may be easy to repair.

A further object of the invention is to develop a shift control arrangement in a gearbox, which may save manufacturing and maintenance costs.

A further object of the invention is to develop a shift control arrangement in a gearbox, which arrangement may have a compact design and may only need a small mounting space at the gearbox.

The herein mentioned objects may be achieved by the above-mentioned shift control arrangement in a gearbox according to the independent claims.

According to the invention the shift control arrangement in a gearbox may comprise a first shift rod, provided with a first and second end part, which first end part may be connectable to a first power means and the second end part may be connected to a first shift fork; a second shift rod, provided with a first and second end part, which first end part may be connectable to a second power means and the second end part may be connected to a second shift fork. A first set of grooves may be arranged in the first shift rod and a second set of grooves may be arranged in the second shift rod. A first and a second lock pin may be arranged between the first and second shift rods, which first and a second lock pins, together with the first and second set of grooves, may be arranged to restrict or allow axial movement of the respective first and second shift rod. The first set of grooves may comprise at least one groove arranged in the first shift rod above a plane passing through the first and second shift rods, and at least one groove arranged below the plane, and the second set of grooves may comprise at least one groove arranged in the second shift rod above the plane and at least one groove may be arranged below the plane.

Such shift control arrangement may effectively prevent an inadvert selection of a forward or reverse mode. With such shift control arrangement it may be easy to assemble and disassemble the gearbox be in a vehicle. The shift control arrangement may also be easy to repair. In addition, the shift control arrangement may save manufacturing and maintenance costs. A situation where the gearbox would be damaged may be when the gearbox is shifted into a low range gear and the reverse gear mode may be selected. Another example is when the gearbox may be shifted into the reverse mode and where the forward mode may be selected. Such impropriate selection may be made by a driver of a vehicle in which the gearbox may be arranged or when a component that controls the gearbox fails.

According to a further aspect of the invention, the first lock pin may be arranged above the plane and the second lock pin may be arranged below the plane. Such arrangement may have a compact design and may only need a small mounting space at the gearbox. The shift control arrangement may also make it easy to assemble and disassemble the gearbox in a vehicle.

According to a further aspect of the invention, the first and second lock pins may be arranged in a common guide hole in a main gearbox housing, which at least partly surround the main gearbox device. Such arrangement may have a compact design and may only need a small mounting space at the gearbox. The shift control arrangement may also make it easy to assemble and disassemble the gearbox in a vehicle. In addition, shift control arrangement may also be easy to produce since only one guide hole in the main gearbox housing has to be made. When arranging the lock pin at the main gearbox housing, the axial extension of a range gearbox device arranged on the main gearbox device may be reduced. The range gearbox device can therefore be designed with a short axial extension, which reduces the weight of the range gearbox device. Thus, assembling and disassembling the gearbox in the vehicle may be easy.

According to a further aspect of the invention, the first lock pin may be arranged on the second lock pin, and the first and second lock pins may be slidable arranged against each other. Such arrangement has a compact design and only need a small space at the gearbox. The surfaces of the lock pins may act as guide surfaces to each other. The guide hole may contain a lubricant for achieving a smooth sliding of the lock pins against each other's surfaces. The surfaces of the lock pins may also be provided with a friction reducing coating, so that they may slide smooth on each other.

According to a further aspect of the invention the second set of grooves, may comprise a first and second groove, each extending in an axial direction of the second shift rod, so that each of the first and second groove may be common for two shift gears in the gearbox. Such a shift control arrangement may effectively prevent an inadvert selection of a forward or reverse mode in the gearbox. When each of the first and second grooves has an axial extension, so that the first and second grooves may be common for two shift gears, the gearbox may not be shifted to the forward or reverse mode in situations where the gearbox could be damaged.

According to a further aspect of the invention, the first groove may relate to a neutral and a reverse shift gear in the gearbox and the second groove may relate to a neutral and a forward shift gear in the gearbox. When each of the first and second grooves may have an axial extension, so that the first and second grooves may be common for two shift gears, the gearbox may not be shifted to the forward or reverse mode in situations where the gearbox could be damaged.

According to a further aspect of the invention, the first set of grooves may comprise a third, fourth, fifth and sixth groove, each related to a shift gear in the gearbox. The grooves in the first shift rod may relate to the different possibilities of shift gears in the gearbox. Their function may be to receive the lock pins in different gearshift modes.

According to a further aspect of the invention, the first groove may be arranged to cooperate with the third and fourth grooves by means of the first lock pin and the second groove may be arranged cooperate with the fifth and sixth grooves by means of the second lock pin. When the first lock pin is received in the first groove, it will not restrict the movement of the first shift rod. When the first lock pin may be received in the third and fourth grooves, it may not restrict the movement of the second shift rod. When the second lock pin may be received in the second groove, it may not restrict the movement of the first shift rod. When the second lock pin may be received in the fifth and sixth grooves, it may not restrict the movement of the second shift rod.

According to a further aspect of the invention, the third and fourth grooves may relate to a low range gear and a high range gear, respective, and the fifth and sixth grooves may relate to a reverse gear and a high range gear, respective. When the gearbox is shifted into a low range gear, the reverse gear mode may not be selected. Thus, an inadvert selection of a reverse mode may be prevented which would otherwise damage the gearbox. When the gearbox is shifted into the reverse mode, the forward mode may not be selected. Thus, an inadvert selection of a forward mode may be prevented which would otherwise damage the gearbox.

According to a further aspect of the invention, the first end part of the first shift rod may be connectable to the first power means by means of a first coupling element; and in that the first end part of the second shift rod may be connectable to the second power means by means of a second coupling element. Such first and second coupling elements may make it possible to connect and remove the shifting rods from the power means when assembling and disassembling the gearbox in the vehicle.

According to a further aspect of the invention, the first and second shift forks may be arranged in a range gearbox device, which may be connectable to the main gearbox device. Thus, the shift control arrangement may be arranged to control the gear shifting in the range gearbox device.

According to a further aspect of the invention the first set of grooves together with the first and a second lock pins may be arranged to prevent the first shift rod to move axially and to allow the second shift rod to move axially; and in that the second set of grooves together with the first and a second lock pins may be arranged to prevent the second shift rod to move axially and to allow the first shift rod to move axially. The grooves may be arranged to receive the first and a second lock pins for different shift gears and thereby restrict either the first or second shift rod to move axially in order to prevent an inadvert selection of a forward or reverse shift gear mode, which may otherwise damage the gearbox.

A reverse gear in the power train may be achieved when a first axially movable coupling sleeve may be arranged to engage a planet carrier with the range gearbox housing and a second axially movable coupling sleeve may be arranged to engage a ring gear with an output shaft. The reverse gear can be easily shifted to by controlling the first and second axially displaceable coupling sleeves. However, a malfunction in a control system of the gearbox may unintentional be activating the power means and move one of the first and second axially displaceable coupling sleeves. Thus, if the gearbox may be unintentional shifted into the reverse gear when the vehicle is moving forward it may cause damage to the gearbox. The shift control arrangement in a gearbox may be arranged to avoid such an incident.

Additional objectives, advantages and novel features of the invention will be apparent to one skilled in the art from the following details, and through exercizing the invention. While the invention is described below, it should be apparent that the invention is not limited to the specifically described details. One skilled in the art, having access to the teachings herein, will recognize additional applications, modifications and incorporations in other areas, which are within the scope of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1shows schematically a vehicle1in a side view with a gearbox2, which may be provided with a shift control arrangement3according to an embodiment. The vehicle1may also be provided with an internal combustion engine4, a clutch5, a propeller shaft10and drive wheels8. The internal combustion engine4may be coupled to the gearbox2via the clutch5. The gearbox2comprises a main gearbox device11and a range gearbox device6. The main gearbox device11may be surrounded by a main gearbox housing12and the range gearbox device6may be surrounded by a range gearbox housing13. However, the main gearbox device11and the range gearbox device6may be surrounded by a common housing. The gearbox2may be connected to the drive wheels8of the vehicle1via the propeller shaft10. Instead of, or in addition to, an internal combustion engine4the vehicle may be provided with an electric engine as part of a powertrain15in the vehicle1.

FIG. 2shows a schematic sectional view of a gearbox2having a shift control arrangement3according to an embodiment. The range gearbox device6comprises a planetary gear14which has a low and a high gear, so that the shifting capability of the gearbox2can be divided into a low range gear position and a high range gear position. In a first gear position, corresponding to the low range gear position a downshift takes place in the planetary gear14. In the high range gear position the gear ratio may be 1:1 in the planetary gear14.FIG. 2shows the range gearbox device6in the first gear position, corresponding to the low range gear position.

The gearbox2also comprises a split gearbox device7and a lay shaft9. The main gearbox device11may be provided with a main shaft26, which may be connected to the planetary gear14of the range gearbox device6. The planetary gear14may comprise three main components, which may be rotatable arranged in relation to each other, namely a sun gear18, a planet carrier20and a ring gear22. A number of planet gears24may be rotatable arranged with bearings on the planet carrier20. With knowledge of the number of teeth32of sun gear18and the ring gear22, the relative gear ratio of the three components can be determined. The sun gear18may be connected to the main shaft26of the main gearbox device11and the planet gears24engage the sun gear18. The ring gear22may surround and engage the planet gears24. The main shaft26may be connected to a shaft38of the sun gear18by means of a splines connection34, which has an axial extent and which allows an axial displacement between the main shaft26and the shaft38of the sun gear18when assembling and disassembling the range gearbox device6to and from the gearbox2. The input shaft16may at its end be provided with a sleeve36, which internally cooperates with the circumference of a portion of the shaft38of the sun gear18by mean of the splines connection34. Thus, the splines connection34may be designed such that the range gearbox device6can be assembled and disassembled in one piece to and from the rest of the gearbox2. Thus, the maintenance costs may be reduced, since the time required for the repair may decrease.

A first axially displaceable coupling sleeve42may in the first gear position be arranged to connect the range gearbox housing13with the ring gear22and in a second gear position arranged to disconnect the range gearbox housing13from the ring gear22. The first axially displaceable coupling sleeve42may in the first gear position be arranged to disconnect the shaft38of the sun gear18from the planet carrier20. In the second position, the first axially displaceable coupling sleeve42may connect the shaft38of the sun gear18with the planet carrier20.

A second axially displaceable coupling sleeve43may in the first and second gear positions be arranged to interconnect the planet carrier20with the output shaft28. The second axially displaceable coupling sleeve43may in a third gear position be arranged to couple the ring gear22with an output shaft28of the gearbox2. The output shaft28may be coupled to the propeller shaft10of the vehicle1. In the third gear position, corresponding to a reverse gear, the first axially displaceable coupling sleeve42may be arranged to disconnect the shaft38of the sun gear18from the planet carrier20and instead may be arranged to interconnect the planet carrier20with the range gearbox housing13.

The first axially displaceable coupling sleeve42may on an inner and outer surface be provided with first splines50, which on the inner surface may be arranged to interact with the corresponding first splines50arranged on the ring gear22. The first splines50on the outer surface may be arranged to interact on the inner periphery of a projection52, which may be fixedly connected to the range gearbox housing13. The first splines50on the inner surface of the first axially displaceable coupling sleeve42may also be arranged to cooperate with corresponding first splines50arranged on the input shaft16. Corresponding first splines50disposed on the input shaft16may be made on the periphery of a first sprocket46, which may be mounted on the shaft38of the sun gear18. However, it may also be possible to arrange the first sprocket46on the input shaft16instead of on the shaft38of the sun gear18. Thus, the first sprocket46may be arranged on either side of the splines connection34. The first splines50on the inner surface of the first axially displaceable coupling sleeve42may also be arranged to cooperate with corresponding first splines50arranged on the planet carrier20. Corresponding first splines50disposed on the planet carrier20may be made on the periphery of a second sprocket44, which may be mounted on the planet carrier20.

The second axially displaceable coupling sleeve43may on an inner surface be provided with second splines51, which may be arranged to cooperate with corresponding second splines51arranged on the ring gear22, the planet carrier20and the output shaft28. The corresponding second splines51arranged on the planet carrier20may be formed on the periphery of a third sprocket49, which may be mounted on the planet carrier20. The corresponding second splines51provided on the output shaft28may be formed on the periphery of a fourth sprocket53, which may be mounted on the output shaft28.

An axial stop54arranged on the planet carrier20may be adapted to abut against the ring gear22, which axial stop54may prevent the ring gear22to be moved axially. The axial stop54may consist of a disc-shaped plate, which by a first thrust bearing56may be mounted on the planet carrier20. The axial stop54may be rotatable relative to the planet carrier20and the input shaft16, and follows the rotation of the ring gear22. The axial stop54fixates the ring gear22axially, and leads to that the axial bearing of the input shaft16in the gearbox2may be subjected to less stress when the gears18,22,24may be provided with helical teeth. However, instead of, or in combination with the axial stop54a pair of thrust bearings55may be arranged on both distal surfaces of the ring gear22. Thus, the thrust bearings55may be arranged between the ring gear and the planet carrier20. A second thrust bearing57may be disposed between the shaft38of the sun gear18and the planet carrier20to accommodate axial forces generated in the sun gear18.

The low gear in the gearbox2may obtained by displacing the first coupling sleeve42axially, so that the ring gear22may be connected to the range gearbox housing13.

The range gearbox device6according to an embodiment functions as follows when shifting from the first to the second gear position, that is, from the low range gear position to the high range gear position. InFIG. 2, the range gearbox device6may be shifted into the low range gear position, which means that the first coupling sleeve42has been shifted to a position to connect the ring gear22with the range gearbox housing13. Thus, when the range gearbox device6may be in the low range gear position, a downshift may take place through the planetary gear14. The shifting operation from the low range gear position to the high range gear position may be made by disconnecting the first ring gear22from the range gearbox housing13by means of the first coupling sleeve42when the torque transmission between the ring gear22and range gearbox housing13ends, which may be accomplished by disconnecting the internal combustion engine4from the main gearbox device11through disconnection of the clutch5and disconnecting the output shaft from the planet gear carrier by displacing the second axially displaceable coupling sleeve43to a neutral position. A neutral position may be achieved by displacing the second coupling sleeve43to a position where the second coupling sleeve43only may be connected to the fourth sprocket53, which may be mounted on the output shaft28. When the first coupling sleeve42no longer transmits any torque and the planetary gear14has been brought to a standstill position the axial displacement of the first coupling sleeve42may be possible. In the high range gear position the first coupling sleeve42may be displaced to a position where the first coupling sleeve42connects the planet carrier20to the first sprocket46. When the range gearbox device6has been shifted into the high range gear position the clutch5may be engaged and the planet carrier20may be synchronized to the speed of the output shaft28before the second coupling sleeve43may be displaced to a position for connecting the planet carrier20to the output shaft28. Thus, the range gearbox device6may operate in the high range gear position.FIG. 3shows the range gearbox device6in the second gear position, corresponding to the high range gear position.

In order to shift gear to the low range gear position, the first coupling sleeve42may be shifted by the first shift fork60in the right direction inFIG. 3for releasing the planet carrier20from first sprocket46and thus from the input shaft16. This may be made possible when the torque transmission between the input shaft16and planet carrier20ends, which may be accomplished by disconnecting the internal combustion engine4from the main gearbox device11by means of the clutch5and disconnect the planetary gear14from the output shaft28by means of axially displace the second coupling sleeve43to a neutral position. When the first coupling sleeve42no longer transmits any torque and the planetary gear14has been brought to a standstill position the axial displacement of the first coupling sleeve42may be possible. The first coupling sleeve42may then shifted by the first shift fork60in the direction of the range gearbox housing13to thereby connect the ring gear22with the range gearbox housing13. When the ring gear22is stationary, the first coupling sleeve42may be displaced axially and interfere with the first splines50on the ring gear22and the range gearbox housing13. Thus, in the low range gear position a downshift may occur through the range gearbox device6. When the range gearbox device6has been shifted into the low range gear position the clutch5may be engaged and the planet carrier20may be synchronized to the speed of the output shaft28before the second coupling sleeve43may be displaced to a position for connecting the planet carrier20to the output shaft28.

FIG. 4shows the range gearbox device6in the third gear position, corresponding to the reverse gear position mode. The second axially displaceable sleeve43may be in the third gear position, i.e. in the reverse gear position arranged to connect the ring gear22with output shaft28. Thus, the second coupling sleeve43may be shifted by the second shift fork61, so that the ring gear22may be connected to the output shaft28. The first coupling sleeve42may be shifted by the first shift fork60to couple the planet carrier20with the range gearbox housing13. The displacement of the respective coupling sleeve42,43may be performed when the input and the output shaft16,28are stationary, which corresponds to a stationary operating state of the vehicle1, or when the vehicle1, travels backwards and the planetary gear14are disconnected from the output shaft28by means of the second coupling sleeve43. The second coupling sleeve43may thereafter be displaced to connect the output shaft28with the second coupling sleeve43when the speed of the planetary gear14may be synchronized to the speed of the output shaft28by means of the engine4. In order to provide a stationary position of the input shaft16the clutch5of the vehicle1may be transferred to a disconnected mode. When the range gearbox device6is operated in the third gear position, torque may be transmitted from the input shaft16to the sun gear18and further to the planet gears24, which transmits the torque to the ring gear22and further to the output shaft28via the second coupling sleeve43. The planet carrier20may be stationary as the first coupling sleeve42connects the planet carrier20with the range gearbox housing13.

When the first coupling sleeve42is displaced from the right to left inFIG. 2the first coupling sleeve42may shift the range gearbox device6from the low range gear position to the reverse gear position and further to the high range gear position.

The shift control arrangement3according to an embodiment comprises first and second power means66,67which may be provided for the axial displacement of the first and second coupling sleeves42,43. The first power means66may be connected to a first shift fork60, which may be arranged in an outside circumferential groove62in the first coupling sleeve42. The first power means66may be connected to the first shift fork60by means of a first shift rod68, which may be detachable from the first power means66by means of a first coupling element69. The second power means67may be connected to a second shift fork61, which may be arranged in an outside circumferential groove62in the second coupling sleeve43. The second power means67may be connected to the second shift fork61by means of a second shift rod70, which may be detachable from the second power means67by means of a second coupling element71. The first and second power means66,67may be a pneumatic or hydraulic cylinder, or an electric actuator. The shift rods68,70connected to the power means66,67transfers the axial movement from the power means66,67to the shift forks60,61. When assembling and disassembling the range gearbox device6to and from the main gearbox device11the shift rods68,70may be connected to and disconnected from the power means66,67. The shift rods68,70and power means66,67are schematically shown on top of the main gearbox housing12and on the range gearbox housing13inFIGS. 2-4.

A first end part72of the first shift rod68may be connectable to the first power means66by means of the first coupling element69. A first end part73of the second shift rod70may be connectable to the second power means67by means of the second coupling element71. Such first and second coupling elements69,71make it possible to connect and remove the shifting rods68,70from the power means66,67when assembling and disassembling the gearbox2in the vehicle1.

In order to prevent damage in the range gearbox device6due to selecting an impropriate gear when shifting gears in the range gearbox device6the shift control arrangement3according to an embodiment may be provided with a shift interlock74. Such an impropriate selection of gears may be the selection of the low range gear when the range gearbox device6may be shifted into the reverse gear. A malfunction in a control system of the gearbox2may unintentional be activating the power means66,67and move one of the first and second axially displaceable coupling sleeves42,43. As a result the gear wheels in the range gearbox device6and also the coupling sleeves42,43could be damaged.

The shift interlock74comprises a first and a second lock pin75,79which may be arranged at the main gearbox housing12, which at least partly surrounds the main gearbox device11. When arranging the lock pins75,79at the main gearbox housing12, the axial extension of a range gearbox device6arranged on the main gearbox device11can be reduced. The range gearbox device6can therefore be designed with a short axial extension which may reduce the weight of the range gearbox device6. Thus, assembling and disassembling the range gearbox device6in the vehicle1will be easy.

FIG. 5shows schematically a cross section of the gearbox inFIG. 2in a disassembled condition. The first and second shift rods68,70have been disconnected from the first and second coupling element69,70, and the range gearbox device6has been disassembled from the main gearbox device11. The main shaft26has also been disconnected from the shaft38of the sun gear18by means of the splines connection34. The propeller shaft10may also have been disconnected from the output shaft28of the range gearbox device6before the range gearbox device6may be disassembled from the main gearbox device11. Thus, the range gearbox device6has been disassembled in one piece from the rest of the main gearbox device11, which may reduce the maintenance costs since the time required for the repair may decrease.

FIGS. 6a-6bshow schematically a shift control arrangement3according to an embodiment from above and in a cross section.FIG. 6ashows the shift control arrangement from above. The first shift rod68may be provided with a first and second end part72,82, which second end part82may be connected to the first shift fork60. The second shift rod70may be provided with a first and second end part73,84, which second end part84may be connected to the second shift fork61. A first set of grooves86may be arranged in the first shift rod68and a second set of grooves88may be arranged in the second shift rod70. The first and second lock pins75,79may be arranged on top of each other. The first and second lock pins75,79may be arranged in a common guide hole92in the main gearbox housing12. The first and second lock pins75,79may be arranged between the first and second shift rods68,70. The second set of grooves88may comprise a first and second groove94,95, each extending in an axial direction of the second shift rod70, so that each of the first and second grooves94,95may be common for two shift gears in the gearbox2. The first set of grooves86comprises a third, fourth, fifth and sixth groove96,97,98,99, may each be related to a shift gear in the gearbox2.

FIG. 6bshows a cross section of the shift control arrangement3through line I-I inFIG. 6a. The first and second lock pins75,79may be arranged close to each other and between the first and second shift rods68,70. They may be slidably arranged on each other so that they may be allowed to move back and forth in their longitudinal direction. The first and second lock pins75,79may be provided with a surface with reduced friction, so that the lock pins75,79may slide easy on each other and against the inner surfaces of the guide hole92in the main gearbox housing12. Such surface of the lock pins75,79may be achieved by polishing or by arranging a layer on the surface, which layer may provide for low friction. Depending on the position of the shift rods68,70they may move in their longitudinal direction into one of the grooves96,97,98,99or they may be restricted to move in the longitudinally direction by the outer circumferential surface of the shift rods68,70if one of the grooves96,97,98,99may not be positioned in the longitudinal direction of the lock pins75,79.

The first, third and fourth grooves94,96and97may be arranged above a plane101passing through the first and second shift rods68,70. The second, fifth and sixth grooves95,98,99may be arranged below the plane101passing through the first and second shift rods68,70. The plane101passing through the first and second shift rods68,70may coincide with a centreline of the first and second shift rods68,70. However, the plane101may pass through the first and second shift rods68,70without coinciding with the centreline of the first and second shift rods68,70. The plane101may be not a physical plane such as component, which cooperates with other components in the shift control arrangement3. The plane101may only be used for describing how the grooves94,95,96,97,98,99, the lock pins75,79and the shift rods68,70relate to each other. The first lock pin75may be arranged to slide into the first groove94arranged in the first shift rod68and into the third and fourth grooves96and97arranged in the second shift rod70depending on the position of the respective shift rod68,70. The second lock pin79may be arranged to slide into the second groove95arranged in the first shift rod68and into the fifth and sixth grooves98,99arranged in the second shift rod70depending on the position of the respective shift rod68,70.

FIGS. 7a-12bshow schematically a shift control arrangement3according to an embodiment in different shift gear positions. InFIGS. 7a-15athe shift control arrangement3is shown from above.FIGS. 7b-15bshow a cross section of the shift control arrangement3through line II-II inFIG. 6b.

InFIGS. 7aand 7bthe second set of grooves88comprises the first and second groove94,95, each extending in an axial direction of the second shift rod70, so that each of the first and second grooves94,95may be common for two shift gears in the gearbox2. The first set of grooves86comprises the third, fourth, fifth and sixth grooves96,97,98,99, each may be related to a shift gear in the gearbox2. The first groove94may be arranged to cooperate with the third and fourth grooves96,97by means of the first lock pin75, and the second groove95may be arranged to cooperate with the fifth and sixth grooves98,99by means of the second lock pin79. The first groove94may relate to a neutral and a reverse shift gear in the gearbox2and the second groove95may relate to a neutral and a forward shift gear in the gearbox2. The third and fourth grooves96,97may relate to a low range gear and a high range gear, respective, and the fifth and sixth grooves98,99may relate to a reverse gear and a high range gear, respective. The first and second shift rod68,70may each have a central axis77,76, respective. The first and second shift rod68,70each may be arranged in a guide bore90in the main gearbox housing12. However, the first and second shift rods68,70and first and second lock pins75,79may alternatively be arranged in guide bores and guide holes in the range gearbox housing13.

The first end parts72,73of the first and second shift rod68,70may be provided with an axial directed cut out78for non-conflicting with the lock pins75,79, and the first end parts72,73of the first and second shift rod68,70may be provided with a control surface80for axial movement of the lock pins75,79.

The control surfaces80and the axial directed cut outs78may make it easy to assemble and disassemble the gearbox2in a vehicle1, because the shift rods68,70may be assembled to the power means66,67after a main gearbox device11first has been mounted to the vehicle1. In addition, instead of removing the complete gearbox2from the vehicle1only the range gearbox device6may need be disassembled from the vehicle1. When moving the shifting rods68,70in an axial direction during assembling and disassembling the gearbox2the lock pins75,79may allow this movement due to the control surfaces80and the axial directed cut-outs78.

InFIGS. 7aand 7b, the shift control arrangement3is shifted into a neutral position, and the shift control arrangement may be prepared to shift the range gearbox device6into a low range position.

The first and second lock pins75,79may be arranged between the first and second shift rod68,70, which lock pins75,79together with the first set of grooves86and the second set of grooves88may be arranged to restrict or allow axial movement of the respective first and second shift rod68,70.

The first and second lock pins75,79may have a pointed shape in both ends, which may make it possible for the shift rods68,70to move the lock pins75,79axially in the main gearbox housing12when shifting gears in the gearbox2. The first set of grooves86together with the lock pins75,79may be arranged to prevent the first shift rod68to move axially and to allow the second shift rod70to move axially. The second set of grooves88together with the lock pins75,79may be arranged to prevent the second shift rod70to move axially and to allow the first shift rod68to move axially. When the lock pins75,79is arranged within a groove96,97,98,99in the first set of grooves86, the second shift rod70may be allowed to move axially and the first shift rod68may be restricted to move. When the lock pins75,79is arranged within a groove94,95in the second set of grooves88, the first shift rod68may be allowed to move axially and the second shift rod70may be restricted to move.

InFIGS. 7aand 7b, the second shift rod70has been moved to a neutral position and the first lock pin75is free to move into the first groove94of the second shift rod70when the second shift rod70is moved into the neutral position. The first shift rod68has been moved into the low range position. When the first shift rod68is moved into the low range position, the third groove96in the first shift rod68may be positioned in line with the first lock pin75. In order to move the second shift rod70to the forward position mode the second shift rod70will move the first lock pin75axially and into the third groove96in the first shift rod68. The second lock pin79may be prevented to move axially because the second lock pin79may not be aligned with a groove in the first shift rod68. However, since the second groove in the second shift rod70may be extended in the axial direction of the second shift rod70, the second shift rod70may be free to move into the forward position mode. InFIGS. 8aand 8bthe range gear box may be shifted into the low range position in the forward position mode.

It is evident fromFIGS. 7aand 7bthat it is not possible to move the second shift rod70to the critical reverse position. The second shift rod70cannot push the second lock pin79in the axial direction when trying to move the second shift rod70in the left direction inFIGS. 7aand 7b. Therefore, the second groove95together with the second lock pin79prevents the second shift rod70to the critical reverse position. This is also evident fromFIG. 2. If the second coupling sleeve43would be axially displaced into the reverse position, in which the second coupling sleeve43connects the ring gear wheel22with the output shaft28, the output shaft28would be locked to a standstill position, because the ring gear wheel22may be locked to the range gearbox housing13by means of the first coupling sleeve42. This would probably damage the gearbox2or other components in the powertrain15.

FIGS. 9aand 9bshow schematically a shift control arrangement3according to an embodiment in a neutral position, and which may be prepared to shift the range gearbox device6into a reverse position.

The first lock pin75may be restricted to move axially but the second lock pin79may be allowed to move axially due to the fifth groove98in the first shift rod68. Therefore it may be possible to move the second shift rod70since the first groove94in the second shift rod70may be extended in the axial direction of the second shift rod70and also that it may be possible to displace the second lock pin79into the fifth groove98and allow the second shift rod70to move axially. InFIGS. 10aand 10b, the range gearbox device6may be shifted into the reverse position.

It is evident fromFIGS. 9aand 9bthat it is not possible to move the second shift rod70to the critical forward position. The second shift rod70cannot push the first lock pin75in the axial direction when trying to move the second shift rod70in the right direction inFIGS. 9aand 9b. Therefore, the first groove94together with the first lock pin75prevents the second shift rod70to the critical forward position. This is also evident fromFIG. 3. If the second coupling sleeve43would be axially displaced into the forward position, in which the second coupling sleeve43connects the planet wheel carrier20with the output shaft28, the output shaft28would be locked to a standstill position, because the planet wheel carrier20may be locked to the range gearbox housing13by means of the first coupling sleeve42. This would probably damage the gearbox2or other components in the powertrain15.

FIGS. 11aand 11bshow schematically a shift control arrangement3according to an embodiment in a neutral position, and which may be prepared to shift the range gearbox device6into a high range position. In the high range position both forward and reverse modes may be optional because neither the forward mode nor the reverse mode may be critical for the gearbox2when the range gearbox device6is shifted into the high range mode.

It is evident fromFIGS. 11aand 11bthat it is possible to move the second shift rod70to the forward position as well as the reverse position. The second shift rod70may be able push the first lock pin75in the axial direction when trying to move the second shift rod70in the right direction inFIGS. 11aand 11band thus shift the gearbox2into the forward mode. In addition, the second shift rod70may be able push the second lock pin79in the axial direction when trying to move the second shift rod70in the left direction inFIGS. 11aand 11band thus shift the gearbox2into the reverse mode. This is also evident fromFIG. 3. The second coupling sleeve43can be axially displaced into the forward position and into the reverse position without damage the gearbox2or other components in the powertrain15. The reason for this is that the first coupling sleeve42may not be connected to the range gearbox housing13. InFIGS. 12aand 12b, the second shift rod70has been moved to the forward position mode.

FIGS. 13aand 13bshow schematically the shift control arrangement according to an embodiment in a first pre-assembled position. When assembling the range gearbox device6to the main gearbox device11the first and second shift rods68,70may already be mounted on the range gearbox device6. The lock pins75,79have been mounted on the main gearbox device11before the main gearbox device11was mounted to the vehicle. Because the shift control arrangement3may be situated on top of the range gearbox device6to the main gearbox device11the lock pins75,79will not be easy to remove before the range gearbox device6is assembled to the main gearbox device11. Since the first end parts72,73of the first and second shift rods68,70may be provided with a control surface80for axial movement of the lock pins75,79, and the first end parts72,73of the first and second shift rod68,70may be provided with an axial directed cut out78for non-conflicting with the lock pins75,79it may be easy to assemble the range gearbox device6in the vehicle1even though the main gearbox device11may be already mounted in the vehicle1.

During the assembling of the range gearbox device6in the vehicle the first and second shift rods68,70may be pushed axially through guide bores90in the main gearbox housing12. When the first and second shift rods69,70reaches the lock pins75,79, the control surface80of the first end parts72,73of the first and second shift rods68,70urge the lock pins75,79to move axially in the guide hole92in the main gearbox housing12. The lock pins75,79move axially in the direction of the respective first and second shift rods68,70which may be provided with the axial directed cut outs78on the first end parts72,73of the respective shift rods68,70.

InFIGS. 14aand 14bthe shift control arrangement3according to an embodiment is schematically shown in a second pre-assembled position, where the lock pins75,79have been moved axially in the direction of the first and second shift rods68,70and has reached the axial directed cut outs78on the first end parts72,73of the first and second shift rods68,70. Since the axial directed cut-outs78is non-conflicting with the lock pins75,79both the first and second shift rods68,70is free to move axially in direction to the first and second power means66,67in order to be connected to the first and second connection elements69,71.

The disassembling of the range gearbox device6from the main gearbox device11takes place in the opposite direction.

The control surfaces80of the first and second end parts72,73of the first and second shift rods68,70may have an angle between 10° and 80°. Alternatively, they may be 30°-60° in relation to a central axis76of the shift rods68,70. Such a control surface80will move the lock pins75,79axially when the first and second shift rods68,70may be moved axially and the control surfaces80may be in contact with the lock pins75,79. The first and second coupling elements69,71shown inFIGS. 2-5may be adapted to the control surfaces80and the axial directed cut outs78so that they may be connected to the first and second end parts72,73of the first and second shift rods68,70. However, according to an embodiment shown inFIG. 15, the shift interlock74, comprising the first and second lock pins75,79, may be arranged at the range gearbox housing13. The first and second end parts72,73of the first and second shift rods68,70may be arranged as free ends, which are not connected to any coupling elements. Instead, the first and second shift rods68,70may be connected to the first and second power means66,67at opposite distal ends. The first and second shift forks60,61may be arranged on the first and second shift rods68,70at a position between the first and second end parts72,73and the first and second power means66,67.

FIGS. 16a-16bshow schematically two different embodiments of a cross section through line III-III of the second shift rod70inFIG. 7a. According to an embodiment shown inFIG. 16a, the second groove95of the second shift rod70may be flat and the overall cross section of the second shift rod70may be circular. This makes it possible to move the second shift rod70axially when the second lock pin79may be received in the second groove95. A cross section through the first groove94of the second shift rod70shows similar characteristics.

According to the embodiment shown inFIG. 16bthe second groove95of the second shift rod70may be flat and the overall cross section of the second shift rod70may be square. This makes it possible to move the second shift rod70axially when the second lock pin79may be received in the second groove95. A cross section through the first groove94of the second shift rod70shows similar characteristics according to this embodiment. However, the second shift rod70may also have another shaped cross section.

In addition, the first shift rod68may have a cross section provided with a shape that may be similar to the shape of the second shift rod70.

The foregoing description of the preferred embodiments has been furnished for illustrative and descriptive purposes. It is not intended to be exhaustive, or to limit the embodiments to the variants described. Many modifications and variations will obviously be apparent to one skilled in the art. The embodiments have been chosen and described in order to best explicate principles and practical applications, and to thereby enable one skilled in the art to understand the embodiments in terms of its various embodiments and with the various modifications that are applicable to its intended use. The components and features specified above may, within the framework of the embodiments, be combined between different embodiments specified.