Ram Pump design

I am very ​interested in ​the design of ​hydraulic ram ​pumps.  ​

A hydraulic ​ram pump is ​a cyclic ​water pump ​powered by ​hydropower and ​therefore ​requires no ​external power ​source.  ​

Can someone ​please share ​design details ​for ram pumps ​or tell me when ​I can find them?​   ​