This is the anti-reversing drive setup for the pump. The power is transferred from right to left with clockwise rotation positive in this direction. The piston actuator was designed to work with clockwise rotation, so it was necessary to ensure that the left-side drive shaft only rotates clockwise. This was accomplished by splitting the shaft and connecting both with a shaft coupler (directly to the left of the first gear) holding one-way bearing that was inserted to lock on clockwise rotation between the right-side input shaft and the shaft coupler. Another one-way bearing was inserted between the first gear and the right-side input shaft to lock on counter-clockwise rotation.
During clockwise rotation, the right-side input shaft rotates independently of the first gear and locks on the shaft coupler thereby transferring rotation to the left-side drive shaft. The left-side drive shaft also rotates the chain drive clockwise which transfers this rotation to the gears. The offset gear reverses the rotation of the first gear to counter-clockwise, but since this one-way bearing allows the shaft to rotate independently from the gear, no rotation is transferred back to the input shaft.
During counter-clockwise rotation, the right-side input shaft locks the one-way bearing thereby transferring counter-clockwise rotation to the first gear. The offset gear reverses the rotation to clockwise and transfers this rotation to the chain drive and then to the left-side drive shaft. The second one-way bearing allows the input shaft to rotate independently from the shaft coupler during counter-clockwise rotation so no rotation is transferred from the left-side drive shaft back to the right-side input shaft allowing them to rotate independently of each other.