Dual jack shaft gear ratio calculations

[MakersPhilippines]

I'm with a small group of makers in the Philippines setting up the first ever makers space here and one of the first projects will be building a full suspension, geared, chainsaw surf bike. The chainsaw rpms are to high for one jackshaft utilizing available materials and sprockets here. I searched but couldn't find a formula or calculator for using 2 jack shafts.

 

[MakersPhilippines]

chainsaw is brand new

SPecifications

Cylinder displacement 70.7 cc
Power output 5.3 hp
Maximum power speed 9600 rpm
Fuel tank volume 26.04 fl oz
Fuel consumption 490 g/kWh
Idling speed 2700 rpm
Spark plug Champion RCJ7Y, NGK BPMR7A
Electrode gap 0.02 "
Torque, max. 4.3 Nm/6600 rpm

 

[tbuelna]

Yikes! Looking at the picture of your prototype I'm a bit hesitant to give advice.

I assume you are using the CF clutch and existing output shaft location of the chainsaw engine. So you simply need to design a multi-stage chain drive that provides the required speed reduction. When designing a multi-stage chain drive, you will just use the speed/torque/hp values from the output of the previous stage as your inputs for the next stage. Just be aware that the torque at the output of your final stage will be substantially higher than what any bicycle chain is designed for. Also, make sure that you provide adequate tensioners and guides for the high speed stages of the drive.

Good luck to you.
Terry

 

[MakersPhilippines]

Thanks for the response and don't worry. That was just a day one throw it on the table and get a feel for the design. NO I wont be using levels for the frame. Pictured sprockets are what we have on hand but motorcycle sprockets are easily acquired.