Don't know about mechanical gear systems. But one answer could be hydraulic press. Remember Pascals law

Hi

I advice you to see these documents. You will find what you need.

I hope that I helped you, let us know if you have another questions or you need more details.

Best regards

https://www.google.fr/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&uact=8&ved=0ahUKEwiM8rWPpuPJAhXM2xoKHYpoC00QFgguMAM&url=http%3A%2F%2Focw.mit.edu%2Fresources%2Fres-tll-004-stem-concept-videos-fall-2013%2Fvideos%2Flinearity%2FMITRES_TLL-004F13_GearTra.pdf&usg=AFQjCNEjXDjHLvsPNXBrz2P56FGY_JJdKA&sig2=81X0kAVIFv4U4z_pPJeBBg&bvm=bv.110151844,d.ZWU

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&arnumber=6342332

https://www.google.fr/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&cad=rja&uact=8&ved=0ahUKEwi4q4HTpePJAhWHlxoKHbpdD9oQFghQMAc&url=http%3A%2F%2Fwww.aerotech.com%2Fmedia%2F136335%2Flinear-motors-application-en.pdf&usg=AFQjCNFWkLtsUywEHw4v9HbR4ak8HskFbA&sig2=kD6A7HQUE05RhXdkX65iyA&bvm=bv.110151844,d.ZWU

https://www.google.fr/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwi4q4HTpePJAhWHlxoKHbpdD9oQFggmMAE&url=http%3A%2F%2Feisenhower.sd54.org%2Ftyung%2Ffiles%2F2014%2F04%2F2.2.2.A-Mechanisms.pptx&usg=AFQjCNGlbItCZm0eu5AzF8AJeBeJrPNjtw&sig2=VWb7MBzeYeFVadGEfzwp9A&bvm=bv.110151844,d.ZWU

Why don't you consider cable mechanism? By changing size of pully or by inserting movable pully, you can change the gear ratio.

Best regards. 

Thanks for your input.I came across a magnetic Linear gear,So I got a doubt that is is possible to realize that arrangement mechanically http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6027603&url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F20%2F6027540%2F06027603.pdf%3Farnumber%3D6027603