Abstract:
A PTO (power take off) sprocket  65  driving belt or chain  80  is attached to input shaft  42  of a transversely mounted vehicle gearbox  40 . The driving face of sprocket  65  is outside casting  52 ; its driven part  58  is attached to sprocket  46  by bolts  59 , running in bearing  64  in flanged spigot  55 . Shaft  42  is driven through sprocket  46  by belt or chain  48 . Decouplers may be fitted to wheel drive shafts, and to the PTO drive at  76 . FIGS.  3, 4 , and  6  show automatic and manual gearboxes mounted alongside engines; FIG.  5  also shows marine jet drive  88 , bevel gears  84 , and Cardan shaft  82 . FIG.  7  shows in-line transmission  240 . FIG.  8  shows a sandwich PTO  365  with manual gearbox  341  and clutch assembly  336 ; or automatic gearbox  341  and torque converter  336 . Applications are disclosed to semi-automatic, sequential shit automated manual, and CVT gearboxes.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a transversely mountable power train for a vehicle comprising a power take off, and more particularly but not exclusively to such a transversely mountable power train for an amphibious vehicle. The invention also relates to a vehicle having a transversely mounted power train with a power take off. 
     1. Description of the Relevant Art 
     In an amphibious vehicle it is advantageous to use a transverse power train for driving the rear wheels of the vehicle, because the power train does not extend far forward of the rear wheels. The weight of the power train is therefore positioned towards the back of the vehicle, which is necessary for good vehicle performance when the vehicle is in marine mode. Furthermore, the position of the power train maximizes the space available towards the front of the vehicle for the passenger compartment. 
     In a conventional mid-engined vehicle having a transverse power train, there is usually no power take off. However, in the case of an amphibious vehicle, it is usually necessary to provide power to a marine propulsion unit, for example a water jet or propeller, positioned at the rear of the vehicle, and therefore a power take off is required. 
     2. Summary of the Invention 
     It is an object of the invention to provide a power take off from a transverse power train, which is suitable for powering a marine propulsion unit of an amphibian vehicle. 
     According to a first aspect of the invention, there is provided a power train for a vehicle comprising an engine and gearbox adapted for mounting transversely within the vehicle, characterised in tat a power take off means is mounted to an input shaft of the gearbox for rotation therewith, the power take off means being arranged externally of a casing of the gearbox. 
     According to a second aspect of the invention, there is provided a vehicle having a power train in accordance with the first aspect of the invention. Preferably the vehicle is an amphibious vehicle and the power take off drives a marine propulsion unit of the vehicle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Several embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: 
     FIG. 1 Is a perspective view of a conventional transverse power train for a vehicle; 
     FIG. 2 is a cross-sectional view through part the transmission of the conventional power train of FIG. 1; 
     FIG. 3 is a perspective view of a first embodiment of a transverse power train for a motor vehicle having a power take off in accordance with the invention; 
     FIG. 4 is a plan view, partly in cross-section, of part of the transverse power train of FIG. 3; 
     FIG. 5 is a cross-sectional view through part of the transmission of the power train of FIGS. 3 and 4; 
     FIG. 6 is a view similar to that of FIG. 4 but showing a modified embodiment in which the transmission comprises a manual change gearbox; 
     FIG. 7 is a schematic plan view of a further embodiment of a transverse power train with power take off in accordance with the invention; 
     FIG. 8 is a view similar to that of FIG. 7 showing a yet further embodiment of a transverse power train with power take off in accordance with the invention. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows a known transverse power train for a vehicle (not shown). The power train comprises an engine  92  and a transmission  40  which provides drive to the rear wheels (not shown) of a vehicle via drive shafts  68 ,  69 . The transmission comprises a gearbox and an integrated final drive unit. 
     FIG. 2 shows part of the transmission  40  of the power train of FIG. 1. A drive tube  12 , which is mounted in bearings  14 , runs axially of the transmission  40  and provides an input to the gearbox of the transmission. A driven sprocket  16  at one end of the drive tube  12  is connected to a driving sprocket (not shown) which is driven by the engine  92  via a torque converter (not shown), by means of an endless chain or toothed belt  18 , shown in dotted outline. 
     An axle shaft  20  is axially mounted inside, and concentric with, the drive tube  12 , and receives power from the final drive (not shown) of the transmission. The transmission has a casing  22 , which is apertured at  24 , and a circular boss  26  extends into the transmission from the periphery of the aperture  24  The boss  26  terminates in a shoulder  28  which extends into the aperture. Bearings  30 , which locate against the shoulder  28 , mount the end of the axle shaft  20  in the boss  26  of the casing  22 . The axle shaft  20  extends through the aperture  24  and is connected to a constant velocity joint  32  which provides drive to one of the rear wheels of the vehicle (not shown). An oil seal  34  seals between the boss  26  and the axle shaft  20 , and protects the bearings  30 . 
     A first embodiment of a transverse power train in accordance with the invention will now be described with reference to FIGS. 3 to  5 . Parts in common with the conventional power train of FIGS. 1 and 2 are given the same reference numerals. 
     The power train is similar to the power train of FIG.  1  and comprises an engine  92  and a transmission  40 . The transmission comprises a automatic gearbox  41  and a final drive unit  96  which provides drive to the rear wheels of the vehicle (not shown) via drive shafts  68 ,  69 . The crankshaft  94  of the engine, a part of which can be seen in FIG. 4, is arranged parallel with and overlapping an input shaft, in the form of a drive tube  42 , of the gearbox  41 . This arrangement is commonly known as a wrap around transmission. 
     In accordance with the invention, a power take off in the form of a sprocket  65  is secured to the drive tube  42  of the gearbox for rotation therewith. As is shown in FIGS. 3 and 4, the power take off can be used to provide drive to a marine propulsion unit  88  of an amphibious vehicle. In the embodiment shown, the drive is provided via a decoupler  76 . The decoupler  76  has a driven sprocket  78  connected to the power take off sprocket  65  by means of an endless belt or chain  80 , shown in dotted outline. Alternatively, the power take off could use a gear drive. A cardan shaft  82  connects the drive from the decoupler  76  to a pair of bevel gears  84 . An impeller  86  of a jet drive  88  (FIG. 3) is driven by a drive shaft  90  from one of the bevel gears  84 . 
     The attachment of the power take off sprocket  65  to the input shaft  42  of the gearbox is shown in more detail in FIG. 5 which shows part of the transmission  40 . The transmission  40  is similar to the conventional transmission  40  described above with reference to FIG. 2 but has been adapted to provide a power take off. As in the conventional transmission  40  already described, the drive tube  42  runs axially of the transmission  40  and provides drive to the gears (not shown) of the gearbox. A driven sprocket  46  at one end of the drive tube  42  is connected to a driving sprocket  47  (see FIG. 4) by means of an endless chain  48 , shown in dotted outline. The driven sprocket  46  is formed on a flange  50  at the left-hand end (as viewed) of the drive tube  42 . The driving sprocket  47  is itself driven from the engine via a fluid flywheel such as a torque converter  95 . 
     The transmission  40  is housed in a casing  52  which is modified from the standard casing  22 , previously described with reference to FIG.  2 . The aperture  24  of the casing  22  is increased in size to form a new aperture  54 . The aperture  54  is circular and a flanged spigot  55  with an internal diameter  56  is bolted  57  around the periphery of the aperture  54 . 
     A spacer ring  58  is attached by threaded screws  59  to the flange  50  and extends through the aperture  54 . The spacer ring  58  has an external diameter  60 , an internal diameter  62  and a power take off sprocket  65  formed on the periphery of the spacer ring  58 , in a position outside the transmission casing  52  remote from the flange  50  of the driven sprocket  46 . 
     Bearings  64  locate on the external diameter  60  of the spacer ring  58  and abut a shoulder  61  of the spacer ring  58 . The bearings  64  are mounted in the aperture  54  in the casing  52 , on the internal diameter  56  of the flanged spigot  55 . An oil seal  66  seals the spacer ring  58  against the flanged spigot  55  and protects the bearings  64 . 
     As in the conventional transmission  40 , an axle shaft  20  is axially mounted inside, and concentric with, the drive tube  42 , and receives power from the final drive  96  of the transmission  40 . The axle shaft  20  extends through the aperture  54  and is connected to a constant velocity joint  70 , which provides drive to one of the rear wheels of the vehicle (not shown). The spacer ring  58  extends beyond the end of the axle shaft  20 , and the sprocket  65  is positioned around the outer casing of the constant velocity joint  70 . Although constant velocity joints are shown, other types of articulating rotating joints could be used. 
     Bearings  72  locate on the internal diameter  62  of the spacer ring  58  abutting a shoulder  63 , and mount the end of the axle shaft  20 . An oil seal  74  seals between the internal diameter  62  and axle shaft  20  and protects the bearings  72 . 
     Although the power train has been described above as having transmission with an automatic gearbox, this is not essential to the invention and the gearbox can be of any suitable type. For example the gearbox could be a semi-automatic gearbox, a manual change gearbox, an automated manual change gearbox or a continuously variable transmission unit. These types of gearbox are well known in the art and so need not be described in any detail. 
     FIG. 6 shows a modification to the first embodiment in which the gearbox is a manual change gearbox. In this arrangement, drive is transferred from the engine crankshaft  94  to the driving sprocket  47  via a flywheel  135  and a friction clutch assembly  136 . The friction clutch  136  is disengaged by movement of a release lever  137  in the direction of arrow A. The release lever may be moved manually by a driver of the vehicle in a conventional manner. 
     Alternatively, the release lever can be moved by means of a hydraulic or electronic actuator when operation of the gearbox and/or the clutch is automated or semi-automated, including sequential shift transmissions, as is known in the art. 
     A power take off sprocket  65  is attached to the input shaft  142  of the gearbox in a manner similar to that described above in relation to the previous embodiment. The input shaft  142  drives the gearbox via an input gear indicated schematically at  143  whilst an output gear of the gear box is indicated schematically at  144 . The construction of the gearbox is otherwise conventional and so is not shown in any detail. 
     As with the previous embodiment, the power take off can be used to drive the impeller  86  of a marine propulsion unit  88  via a decoupler  76 . 
     A second embodiment of a transverse power train with power take off in accordance with the invention is shown in FIG.  7 . Parts in common with the embodiment shown in FIGS. 3 to  5  are given the same reference numerals but increased by 200. 
     In this embodiment, the transmission  240 , which comprises a gearbox  241  and a final drive unit  296 , is mounted substantially in line with the transverse engine  292 . The final drive unit  296  providing drive to left and right wheels  297 ,  298  of the vehicle via drive shafts  268 ,  269  respectively. V joints or other articulating rotating joints would normally be required in these drive shafts  268 ,  269  but are omitted in FIG. 7 for clarity. 
     Indicated schematically in dotted lines are the crankshaft  294  of the engine and an input shaft  242  of the gearbox  241 . The gearbox can be of any suitable type. For example the gearbox may be an automatic, semi-automatic, manual or automated manual gearbox. A drive coupling unit  236  is provided between the engine and the gearbox to transfer drive from the crankshaft of the engine to the input shaft of the gearbox. The drive coupling unit may be a friction clutch or a fluid flywheel depending on the type of gearbox used in the transmission. 
     In accordance with the invention, a power take off sprocket  265  is mounted for rotation with the input shaft  242  of the gearbox  241 . In this embodiment, the power take off sprocket is mounted to the end of the input shaft farthest from the engine. The power take off sprocket may be connected to the input shaft by any suitable means such as by means of a spacer ring (not shown) as described with reference to FIG. 5 above. Those skilled in the art will understand that it will be necessary to provide suitable sealing between the gearbox casing and the input shaft or the power take off sprocket spacer to ensure that fluid within the transmission does not leak out, and bearings will also be necessary to support the input shaft and the power take off sprocket. 
     The power take off sprocket  265  can be used to provide drive to a marine propulsion unit of an amphibious vehicle in a manner similar to that described above in relation to FIGS. 3 to  5 . To this end the power take off sprocket  265  is connected to a driven sprocket  278  of a decoupler by means of an endless chain or belt  280 . The decoupler and the remainder of the power take off drive line to the marine propulsion unit have been omitted in this Figure for clarity. 
     A third embodiment of a transverse power train with power take off in accordance with the invention is shown in FIG.  8 . Parts in common with the embodiment shown in FIGS. 3 to  5  are given the same reference numerals but increased by 300. 
     The power train of the third embodiment is similar to that of the second embodiment except that the power take off sprocket  365  in this arrangement is attached to the gearbox input shaft  342  toward the end of the shaft which is closest to the engine. As shown in FIG. 8, the power take off sprocket  365  is attached to the input shaft  342  between an end  353  of the gearbox casing and the drive coupling unit  336 . As with the previous embodiments, the gearbox can be of any suitable type, and the drive coupling unit can be a fluid flywheel or a friction clutch as required. 
     The power take off sprocket  365  can be used to provide drive to a marine propulsion unit of an amphibious vehicle in a manner similar to that described above in relation to FIGS. 3 to  5 . To this end the power take off sprocket  365  is connected to a driven sprocket  378  of a decoupler by means of an endless chain or belt  380 . The decoupler and the remainder of the power take off drive line to the marine propulsion unit have been omitted for clarity. 
     Although not shown in FIG. 8, a cowling or bell housing may be provided between the gearbox and the engine to enclose the drive coupling unit  336  and the take off sprocket  365 , an opening in the cowling or bell housing being provided to enable the chain or belt  380  to extend outwardly to the decoupler sprocket  378 . 
     The above described embodiments all provide a compact and cost effective means of providing a power take off from a transverse engine and transmission unit which has particular application in an amphibious vehicle where it is necessary to provide drive for a marine propulsion unit. 
     By providing the power take off from the input shaft of the gearbox, it is possible for the marine propulsion unit to be driven whilst the gearbox is in neutral when there will be no drive to the road wheels. However, in certain gearbox constructions, the input shaft does not rotate when the gearbox is in neutral. In such cases, it will be necessary to have a gear engaged when providing drive to the marine propulsion unit and to provide at least one decoupler in the drive line to the road wheels so that drive to the wheels can be decoupled when the amphibious vehicle is in marine mode. Also, the decoupler on the power take off to the marine drive is not essential to the concept of the invention, and may therefore be omitted and replaced by continuous drive means in road mode.