Patent ID: 7789173

Claim:
A hydraulically driven vehicle comprising an engine mounted on a vehicle frame, a left hydrostatic transmission that is driven by the engine and that drives a left drive wheel, a right hydrostatic transmission that is driven by the engine and that drives a right drive wheel, and a gear-shifting mechanism for transmitting to the hydrostatic transmissions the movement of a speed setting device that is operated by an operator to adjust the traveling speed of the vehicle frame, and the movement of left and right steering devices that are operated by the operator to turn the vehicle frame, the gear-shifting mechanism comprising: a unitary frame bracket mounted to the vehicle frame; a first swinging member that is swingably attached to the frame bracket with left and right first pins and that is moved by the speed setting device; a left second swinging member that is swingably attached to the first swinging member at a position away from the left and right first pins and that is moved by the left steering device connected at one end; a left resilient member that urges the left second swinging member into the first swinging member so that the left second swinging member swings together with the first swinging member when the left steering device is not operating; a right second swinging member that is rotatably attached to the first swinging member at a position away from the left and right first pins and that is moved by the right steering device connected to one end; a right resilient member that urges the right second swinging member into the first swinging member so that the right second swinging member swings together with the first swinging member when the right steering device is not operating; a left drive plate swingably attached to the frame bracket to control the left hydrostatic transmission; a left link plate that connects the left drive plate to the other end of the left second swinging member; a right drive plate swingably attached to the frame bracket to control the right hydrostatic transmission; and a right link plate that connects the right drive plate to the other end of the right second swinging member, wherein the speed setting device is operated to incline the first swinging member and to simultaneously incline the left and right drive plates, whereby a high forward speed, a low forward speed, stopping, a low reverse speed, and a high reverse speed can be arbitrarily set, and the left steering device can be operated to return the left drive plate to the stopped position, and the right steering device can be operated to return the right drive plate to the stopped position when the first swinging member is inclined.