Single ratchet actuator with dual air drivers

In a semitrailer landing gear of the type having a pair of spaced arms, a mounting bracket for each arm, a leg for each arm geared to extend and retract relative to its respective arm, and a gear box positioned to control extension and retraction of the legs by a cross drive shaft extending between the arms, the improvement comprising:

• an air driven actuator mounted to the gearbox and having a main housing;
• a drive tube rotatably mounted to the housing and having a single ratchet fixed thereto, wherein the single ratchet has a plurality of teeth wherein the cross drive shaft is connected to the drive tube;
• at least one drive plate rotatably mounted to the drive tube;
• a pawl rotatably mounted to the at least one drive plate and positioned to engage the teeth on the single ratchet;
• and
• first and second air drivers mounted to opposite sides of the main housing, each having a reciprocating stroke shaft pivotably connected to the at least one drive plate in a position to cause the at least one drive plate to rotate as the stroke shafts reciprocate;
• wherein when the pawl is engaged with one of the teeth, activation of one of the first and second air drivers will cause the at least one drive plate and the single ratchet in a power stroke to urge the drive tube and the cross drive shaft to rotate in a first direction, and activation of the other of the first and second air drivers will cause the at least one drive plate to rotate in an opposite direction on the drive tube in a return stroke to move the pawl to engage another of the teeth on the single ratchet.