Carburetor throttle and choke control mechanism

Abstract

A control mechanism for a carburetor having a throttle valve and a choke valve each having at least a cold-starting position and a full-speed position. The throttle valve is spring biased toward its third, low idle position, and the choke valve is spring biased toward its full-speed open position. When the choke valve is moved from its open position toward its cold start closed position a fast idle lever associated with the choke valve engages, via releasable latch parts, another lever associated with the throttle valve. The interengaging latch parts of these levers hold both valves in their respective cold-starting positions in opposition to the biasing springs. These latch levers can be released by operator actuation of the throttle valve control, thereby causing the choke valve to be automatically returned to its open position by its biasing spring, or, alternatively, the choke valve can be moved independently to its full-speed position. One of these latch levers has a row of fine ratchet teeth, and the other has a pawl selectively engaging whichever ratchet tooth becomes aligned therewith when the latch levers are operator actuated to their respective cold start positions. Upon release of operator actuating force, this feature prevents most, if not all of the retrograde movement of the choke and throttle valves out of their design cold start positions, despite operating slack in the latch system due to manufacturing tolerance stack-up in the various parts of the control mechanism in their assembly and operation.