Most Wright mowers use hydraulic pumps instead of transaxles so we can position the operator and center of gravity for maximum stability. The axial piston pumps contain a rotating set of pistons. This variable flow type pump provides accurate control of flow and pressure at all times. The ZK and MMZ models use large body pumps that can pump as much as 16ccs per revolution. Stander X, Sport X™ and Large Frame Standers® use 12cc pumps. Walk behinds, Small Frame Standers®, Stander Intensity™ and Sport Intensity™ models use 10cc pumps.