Abstract: An electrical command signal to a direct drive valve is compensated by a digital signal processor to cause the output hydraulic fluid flow from the valve to conform to a desired predetermined flow. The compensation is accomplished by measuring flow from the valve using a standard direct drive valve code. This flow is compared to a desired flow and the difference is taken on a point to point basis. A compensation is then calculated to change the command signal so as to cause the flow to be according to the desired flow.

Abstract: An electrical command signal to a direct drive valve is compensated by a digital signal processor to cause the output hydraulic fluid flow from the valve to conform to a desired predetermined flow. The compensation is accomplished by measuring flow from the valve using a standard direct drive valve code. This flow is compared to a desired flow and the difference is taken on a point to point basis. A compensation is then calculated to change the command signal so as to cause the flow to be according to the desired flow.

Abstract: A fluid device (pump or motor) comprises a case having a closed chamber, a rotating element mounted for rotation within the closed chamber, a reciprocating piston drivingly connected to the rotating element such that rotation of the rotating element corresponds to reciprocating movement of the piston, passages for admitting and discharging fluid to and from a cylinder in which the piston reciprocates, and scavenger pump means drivingly connected to the rotating element and operable to pump fluid out of the closed chamber at a rate greater than the rate at which fluid leaks or otherwise is metered into the interior chamber, thereby to maintain the level of fluid within the closed chamber below a predetermined level.

Abstract: An electrohydraulic servovalve having a pair of linear, variable, differential transducers (LVDT) affixed thereto in side by side relationship. A spool valve driven by the electrohydraulic servovalve is connected to the movable core in each of the LVDTs so that as the spool valve moves, each of the LVDTs develops a position output signal representative of the position of the spool. The connecting mechanism between the driven spool valve and the LVDT cores is a rod which is attached to the spool and includes a pair of flanges at the opposite end defining a groove therebetween. A pair of plates spaced apart at the center define a slot centrally thereof. The plates at the slot are spaced apart so that the width of the two plates plus the space between them is greater than the width of the groove in the rod. The outermost flange is formed so that it will fit through the slot in the plates. The two cores of the LVDTs include rods which are in turn permanently affixed at each end of the plates.