How to disconnect connecting rod and crank

[Apache]

I have a mechanism
wish to disconnect connecting rod and crank when i cycling so that i do nt need to use additional force to turn connecting rod also
but connect them once my driving system is set up and piston that connected to rod can rotate my crank
how can i set up this mechanism?

 

[jim hardy]

look up "overriding clutch "

http://www.formsprag.com/litportal/pdfs/P-1052-FCLO.pdf

 

[Apache]

Great idea! I have figured it out and learned a new thing!
Thanks!