Abstract: A variable displacement hydrostatic pump (11) having its displacement varied by a controller (17) in response to movement of a manual control lever (95) from a neutral position (FIG. 1). The vehicle has at least one other device (125,127) which provides an electrical output signal (133) indicating when operation of the pump (11) is "acceptable", in terms of either vehicle performance or operator safety. Associated with the control lever (95) is an input shaft (103) defining at least one stop surface (121,123). A solenoid assembly (109) has a moveable plunger (111), disposed adjacent the stop surfaces, and moveable between a retracted position (FIG. 4a) and an extended position (FIGS. 2 and 4), engaging one of the stop surfaces, when the output signal (133) indicates that operation of the pump is not acceptable.

Abstract: A spool valve assembly (11) including a valve spool (33) defining a Raise position (R) operable to provide fluid communication from an inlet port (21) to a work port (25), and a Neutral position (N) blocking such flow. The spool valve (33) has a Lower position (L) in which return flow from the work port (25) flows past a pilot operated check valve (77) is then metered by a metering notch (75) defined by the valve spool. The valve spool (33) also has a separate Float position (F) in which the inlet port (21), the work port (25) and the return port (23) are interconnected. In the Float position (F), fluid at the valve spool (33) is in communication with the return port (23) through a back-pressure valve (59), which may be manually adjusted to control the back-pressure on a work implement (15) as it is permitted to "float".