Numerical and experimental study on flat roller/cam pair in a two-dimensional piston pump

The two-dimensional piston pump with flat roller/cam transmission mechanism enables high-speed operation, frequent load-carrying start-ups, and rotational direction changes, making it suitable for electro-hydrostatic actuators. This study investigates the rolling friction loss and starting torque characteristics of the friction pair under high-speed and high-load conditions. Numerical simulations show that the flat roller/cam friction pair is unsuitable for elastohydrodynamic lubrication when the roller surface hardness exceeds the cam surface. Experimental results reveal a friction coefficient of 0.0042 during load-carrying start at 1400 N, equivalent to 28 MPa pump load pressure, and 0.001 at 10000 rpm and 1400 N. The study highlights the high transmission efficiency of the designed mechanism, allowing load-carrying start-ups without relying on an oil film.