A powertrain for an amphibian

Abstract

The present invention provides, with reference to FIG. 1 , a power train for an amphibian operable in land and marine modes. The power train comprises a prime mover having an integral speed change transmission, at least a first land propulsion unit, at least a first marine propulsion unit, and a power transmission unit. The prime mover is arranged to drive the at least first land propulsion unit through/via the integral speed change transmission in the land mode, and the prime mover is arranged to drive the at least first marine propulsion unit through/via the power transmission unit in both the marine mode and the land mode. The present invention also relates to an amphibian comprising such a powertrain.

1 . A power train for an amphibian operable in land and marine modes, the power train comprising:
 a prime mover having an integral speed change transmission;   at least a first land propulsion unit;   at least a first marine propulsion unit; and   a power transmission unit, wherein:   the prime mover is arranged to drive the at least first land propulsion unit through/via the integral speed change transmission in the land mode; and   the prime mover is arranged to drive the at least first marine propulsion unit through/via the power transmission unit in both the marine mode and the land mode.   
     
     
         2 . A power train as claimed in  claim 1  further comprising a second marine propulsion unit. 
     
     
         3 . A power train as claimed in  claim 2  wherein the prime mover is arranged to drive the second marine propulsion unit through/via the power transmission unit in both the marine mode and the land mode. 
     
     
         4 . A power train as claimed in any one of the preceding claims wherein a crankshaft or other drive shaft of the prime mover is arranged to drive the first and/or the second marine propulsion unit(s) through/via the power transmission unit, and drive is not provided through/via the integral speed change transmission of the prime mover. 
     
     
         5 . A power train as claimed in any one of the preceding claims wherein the power transmission unit provides a fixed input/output ratio. 
     
     
         6 . A power train as claimed in any one of the preceding claims wherein the power transmission unit provides a fixed input/output ratio of 1:1. 
     
     
         7 . A power train as claimed in any one of  claims 1  to  5  wherein the power transmission unit provides a fixed input/output ratio not equal to 1:1. 
     
     
         8 . A power train as claimed in  claim 6  or  claim 7  wherein the fixed input/output ratio is a ratio of input drive speed received from the prime mover to the power transmission unit relative to the output drive speed provide by the power transmission unit to the first and/or second marine propulsion unit(s). 
     
     
         9 . A power train as claimed in any one of the preceding claims wherein the integral speed change transmission of the prime mover comprises a neutral, and drive from the prime mover to the at least first land propulsion unit through/via the integral speed change transmission is decoupled in marine mode by engaging the neutral. 
     
     
         10 . A power train as claimed in any one of the preceding claims wherein the prime mover further comprises an integral clutch, and wherein drive from the prime mover to the at least first land propulsion unit through/via the integral speed change transmission is decoupled in marine mode by disengaging the integral clutch. 
     
     
         11 . A power train as claimed in  claim 10  further comprising an actuator to disengage the integral clutch. 
     
     
         12 . A power train as claimed in  claim 11  wherein the actuator is an external actuator arranged to open the integral clutch. 
     
     
         13 . A power train as claimed in  claim 11  wherein the integral clutch is a centrifugal clutch and the actuator restricts motion of centrifugal masses of the centrifugal clutch to disengage the centrifugal clutch. 
     
     
         14 . A power train as claimed in any one of the preceding claims further comprising an external clutch, and wherein drive from the prime mover to the at least first land propulsion unit through/via the integral speed change transmission is decoupled in marine mode by disengaging the external clutch. 
     
     
         15 . An amphibian comprising the power train of any one of the preceding claims. 
     
     
         16 . An amphibian as claimed in  claim 15  comprising a hull, wherein the at least first land propulsion unit may be retracted above the lowest point of the hull of the amphibian for use on water in marine mode, and may be protracted below the lowest point of the hull for use on land in land mode. 
     
     
         17 . An amphibian as claimed in  claim 15  or  claim 16 , wherein when the amphibian is operated in a marine mode the first or the first and the second marine propulsion unit(s) can power the amphibian to a speed where sufficient hydrodynamic lift is achieved for the amphibian to plane. 
     
     
         18 . An amphibian as claimed in any one of  claims 15  to  17  comprising only two wheels and which is configured as an amphibian motorcycle. 
     
     
         19 . An amphibian as claimed in any one of  claims 15  to  17  comprising three wheels and which is configured as an amphibian tricycle. 
     
     
         20 . An amphibian as claimed in  claim 19  wherein the three wheels are arranged two at the front, and one at the rear. 
     
     
         21 . An amphibian as claimed in  claim 19  wherein the three wheels are arranged one at the front, and two at the rear. 
     
     
         22 . A power train for an amphibian substantially as hereinbefore described with reference to or as shown in the accompanying drawings. 
     
     
         23 . An amphibian comprising a power train substantially as hereinbefore described with reference to or as shown in the accompanying drawings.