Improvements in and relating to hydraulic control systems

801,006. Lift trucks. LIFTING GEAR SERVICES, Ltd. Oct. 3, 1956 [Oct. 3, 1955], No. 28057/55. Class 78 (3). [Also in Group XXIX] An hydraulic system for the control of a fork lift truck comprises hydraulic motors 17, 27a, 32 selectively operable under the control of a manually actuated selector valve 16 and supplied with liquid from a pump 1 having a lowpressure high-capacity part and a high-pressure low-capacity part. The selector valve comprises a body having a central bore 45 containing a valve member 53 and bores 46 containing valve members 47. A handle 48 is rotatable and rockable, being pivoted to the valve member 53 and carrying rollers 55 which engage selected valve members 47 to depress them when the handle is rocked. A member 57 is rotated with the handle, and is brought over the unselected valve members 47 to prevent them rising above a neutral position. In the central position of the handle 48 the pump discharge line is collected through the central bore 45 with an exhaust line 26, and the valve members 47 are in their neutral positions in which they close the motor lines, thereby locking the motors. Rocking of the handle 48 initially depressed one or two of the valve members 47 to thus open the line or lines to the selected motor or motors. Further movement of the lever raises the central valve member 53 to close the exhaust line 26 and cause oil to be delivered. When the load is light both parts of the pump deliver to the selector valve; if the load increases so that the pressure in the system rises above a predetermined value, the output of the low-pressure part is automatically by-passed to a reservoir. Specification 793,972 is referred to.