A drive system for a cryogenic pump is provided including a spool housing having a plurality of valves disposed therein about a pump axis and a tappet housing including a plurality of tappet bores, each tappet bore in communication with a respective one of the plurality of valves. A collection cavity collects hydraulic fluid from the tappet bores. A pump flange includes a fluid inlet and a fluid outlet. An inlet manifold directs hydraulic fluid received through the fluid inlet to each of the plurality of valves. An outlet manifold directs hydraulic fluid from each of the valves and the collection cavity to the fluid outlet.

A cryopump comprises a refrigerator, a condensing array cooled by the refrigerator, a radiation shield surrounding the condensing array and cooled by the refrigerator. The radiation shield has a frontal opening covered by a frontal array that is also cooled by the refrigerator. The frontal array comprises louvers across an otherwise substantially open center region of the frontal opening and an orifice plate across an outer region of the frontal opening. The hybrid frontal array allows for pumping speeds approximating those of a louver frontal array but with flow control comparable to an orifice plate.

A cryogenic pump system includes a supply of liquid natural gas, a source of hydraulic fluid, a cryogenic pump, and an electronic control module. The cryogenic pump is operatively arranged with the supply of liquid natural gas and the source of hydraulic fluid. The cryogenic pump is configured to operate using the source of hydraulic fluid to compress at least some of the supply of liquid natural gas for delivery to an engine. The electronic control module is operably arranged with the cryogenic pump and configured to selectively operate the cryogenic pump. Control strategies for operating the cryogenic pump system are disclosed which have reduced power demands.