In the current 4 DOF LHPOST configuration, two MTS Model 243 servo-controlled dynamic horizontal actuators equipped with high flow servo-valves power the shake table. The actuators are single ended actuators ported to allow flows over 20,000 liter/min. For the future upgrade to six degrees of freedom, the actuators are capable of accepting additional swivel ends. Dual 10,000 liter/min servo-valves are mounted to each actuator. The technical specifications for the actuator consist of a maximum compression and tension force of 4.2 MN and 2.6 MN, respectively, resulting in a combined force of ± 6.8 MN on the table. The pilot stage rated flow capacity of the servo-valves is 19 liter/min @ 7 MPa servo-valve pressure drop. At the intermediate stage, the rated flow is 630 liter/min @ 7 MPa servo-valve pressure drop, and at main stage the rated flow is 15,000 liter/min @ 16 MPa servo-valve pressure drop and 10,000 liter/min @ 7 MPa servo-valve pressure drop.