Hydraulic Pumps Make Mower Run Cooler, Quieter

By combining a large charge pump with a design that employs roller bearings, instead of the more traditional ball bearings, a new hydraulic pump line is making riding lawnmowers run cooler and quieter.

The KP hydraulic pump, designed by engineers at White Hydraulics (Hopkinsville, KY), is delivering the improved performance to the Silver Eagle zero-turn-radius mowers made by Dixie Chopper (Coatesville, IN).

“It gives them quieter operation and longer life, primarily because it runs cooler,” notes Phillip Groves, pump project manager for White Hydraulics.

The ability to run cooler and quieter is critical for zero-turn-radius lawnmowers in particular, because hydraulic pressures in the pumps of those mowers can spike up during 360-degree turns and repeated stop-start cycles. The mowers, which are known for their ability to pivot 360 degrees around a point, are popular among consumers and lawn maintenance pros because they can maneuver in small spaces for precision cutting.

White Hydraulics’ axial piston, variable displacement pump plays an important role in the new Silver Eagle line because its design suppresses the pump noise that can occasionally overwhelm other noises, even those of a gasoline-powered engine. It also reduces operating temperatures by as much as 20 degrees F.

White Hydraulics engineers accomplished that by endowing the drive pumps with roller bearings, instead of the more traditional ball bearings. “By using a roller bearing, we’re spreading the loads across the sides of the roller, rather than the tips of the ball bearings,” Groves says. By doing so, he adds, the lawnmower’s pumps run quieter. For additional noise suppression, the company’s engineers also opted for a bronze-plated wear plate on the back end of each pump, rather than the more typical steel wear plate.

To enable the Silver Eagle to run cooler, White Hydraulics engineers also employed a 3-cc charge pump, up from 1.9 cc on earlier pumps, as a means of making the pump’s heat exchanger more efficient. As a result, the pump’s engineers claim they knocked the operating temperatures down by more than 10%.

“Most pumps run between 150 and 170 degrees, which tends to be hot,” says Paul Klassy, director of marketing for White Hydraulics. “Here, we’re taking about 15 to 20 degrees of temperature out of the system.”

The KP Series pumps, available in 10-, 13-, and 18-cc/revolution displacements, can also be employed in so-called concrete buggies, walk-behind trenchers, and mini-skid-steer loaders, the company says.