Heavy Duty Piston For applications with the most demanding requirements, play it safe and stick with heavy-duty components from Eaton. With their cast-iron housing and fixed-clearance slipper design, both the Heavy-Duty Model Series 1 Fixed Displacement and Model Series 1 Variable Displacement piston motors are known by engineers and operators for exceptional quality, longevity and efficiency. Features Cast-iron housing improves durability and reduces operational noise Fixed clearance slipper design allows for efficient operation