EHLA-Coated Carbide-Reinforced Control Plates in Axial Piston Pumps First Results from Real-Life Application

Hydraulic pumps are a crucial part of every hydraulic system and have been built with similar tribological systems for decades. In a typical axial piston pump, the high surface pressures are hydrostatically balanced, and the residual contact is taken by a steel – special brass contact. Due to the increasingly complex requirements, such as higher requested speeds and operating pressures, as well as legal constraints, such as the restriction of lead and the use of biodegradable oils, alternatives have to be found for the often-used lead-containing special brass. Laser coatings applied by means of Extreme High-Speed Laser Application (EHLA) are a possible alternative. These promise almost complete freedom in terms of material selection and impress with a fast and cost-effective coating process. In preliminary work, the process of material pre-selection by disc-disc tribometer testing up to the first running pump prototype was shown. The results obtained indicated, that with the choice of much harder contact partners, the run-in process also needs to be reconsidered. In this study, a completely new, laser coated tribological system is tested in a real application. Special focus is set on the operational behavior and efficiency during the first 1000 h of operation, compared to the standard pump.