Patent ID: 8087345
Filing Date: 2012-01-03
Classification: F01L,F04B,Y10T

Abstract:
1. A reciprocating drive mechanism comprising: a. a housing having upper and lower internal chambers; b. a spool slidably positioned inside said upper internal chamber; c. at least one fluid inlet and fluid exhaust communicating with said upper internal chamber; d. at least one slide valve positioned within said upper internal chamber and traveling with said spool; e. a piston positioned in said lower internal chamber and dividing said lower internal chamber into an upper and lower cylinder space; f. at least one fluid conduit communicating between said upper internal chamber and said upper cylinder space; g. at least one fluid conduit communicating between said upper internal chamber and said lower cylinder space; h. a valve stem connected to said piston and including a bore communicating with said upper internal chamber; i. an exhaust passage positioned between said upper and lower internal chambers; j. a first side passage formed on said valve stem and connecting to said bore in said valve stem; and k. a second side passage formed in said valve stem below said first passage and shaped to bridge a seal positioned between said exhaust passage and said upper internal chamber.