D
duivendyk
Guest
Reading about the 50 cc Dax Titan with the jack shaft intermediate drive, it struck me that this type of setup lends it self to incorporating two speed drive without too much of a hassle.This is how it would work:
Equip the engine's PTO with two sprockets, say 10 and 12T, on the jack shaft have a complementary setup,that is 12 and 10T,that gives a range of 10/12 to 12/10 or 1.44. overall depending on which set is selected.Because of the complementary sizes the chains will be of EQUAL lenghts,otherwise you would be sure to get in trouble with the chains.The jack shaft sprockets are rotating freely on the jack shaft but can be engaged by a dog clutch splined to the shaft,which can engage either one or the other.
Since the primary sprockets would be sitting side by side on the PTO shaft there may not be adequate room for this clutch on the jack shaft.The way around this is to make the larger size receiving sprocket a freewheel sprocket.It would be keyed to the jack shaft and the outer, smaller one engaged by the dog clutch gear shift.Now there is plenty of room for the clutch.In high gear the larger sprocket just free wheels along.The final drive ratio would have to be adjusted to either increase top speed,or more likely to get some extra low-end grunt.Different sprocket combinations could be used of course,but the ratios get quickly out of hand,for instance 13T/10T gives a 1.69 overall ratio.This arrangement looks like a winner to me and is not all that hard to complement the Titan drive setup with.
Equip the engine's PTO with two sprockets, say 10 and 12T, on the jack shaft have a complementary setup,that is 12 and 10T,that gives a range of 10/12 to 12/10 or 1.44. overall depending on which set is selected.Because of the complementary sizes the chains will be of EQUAL lenghts,otherwise you would be sure to get in trouble with the chains.The jack shaft sprockets are rotating freely on the jack shaft but can be engaged by a dog clutch splined to the shaft,which can engage either one or the other.
Since the primary sprockets would be sitting side by side on the PTO shaft there may not be adequate room for this clutch on the jack shaft.The way around this is to make the larger size receiving sprocket a freewheel sprocket.It would be keyed to the jack shaft and the outer, smaller one engaged by the dog clutch gear shift.Now there is plenty of room for the clutch.In high gear the larger sprocket just free wheels along.The final drive ratio would have to be adjusted to either increase top speed,or more likely to get some extra low-end grunt.Different sprocket combinations could be used of course,but the ratios get quickly out of hand,for instance 13T/10T gives a 1.69 overall ratio.This arrangement looks like a winner to me and is not all that hard to complement the Titan drive setup with.