Automatic control valves

Apparatus for controlling the flow of a pressure fluid to a fluid actuator operatively connected to a variable speed drive in the rotary transmission to a cooling fan for a vehicle motor, including two automatic temperature sensing fluid control valves connected in series between a source of pressure fluid and the said fluid actuator, each valve having two operative positions in one of which the valve connects an inlet port to an outlet port, while in the other position it closes the connection between the inlet and outlet ports and connects the outlet port to a relief passage, the arrangement being such that when either valve is in its second position the pressure line leading to the actuator is disconnected from the pressure supply and connected to relief, and in which each of the two valves is directly exposed to a fluid flow associated with said vehicle motor so as to sense the fluid temperature directly.