Cylinder Drum of a Hydrostatic Axial Piston Machine having a Wear-Resistant Layer

Abstract

A cylinder drum of a hydrostatic axial piston machine has a plurality of cylinder bores formed in the cylinder drum. A respective piston is moved in each of the cylinder bores in a manner subject to intensive wear. The cylinder bores are nitrocarburized in a salt bath or in gas to minimize the wear and include a thin uniform connecting layer that has a thickness of 4 to 16 μm and a comparatively thick underlying diffusion layer.

What is claimed is: 
     
         1 . A cylinder drum of a hydrostatic axial piston machine, comprising:
 a wear-resistant layer formed by nitrocarburizing in a salt bath or by gas nitrocarburizing, the wear-resistant layer having a comparatively thin ductile connecting layer.   
     
     
         2 . The cylinder drum according to  claim 1 , wherein the connecting layer has a thickness of 4 to 16 μm. 
     
     
         3 . The cylinder drum according to  claim 1 , wherein the wear-resistant layer is formed by nitrocarburizing in a salt bath, and wherein the connecting layer has a thickness of 10 to 16 μm. 
     
     
         4 . The cylinder drum according to  claim 1 , wherein the wear-resistant layer is formed by gas nitrocarburizing, and wherein the connecting layer has a thickness of 5 to 12 μm. 
     
     
         5 . The cylinder drum according to  claim 1 , wherein the wear-resistant layer is formed by nitrocarburizing in a salt bath, and wherein the connecting layer has a thickness of 4 to 8 μm. 
     
     
         6 . The cylinder drum according to  claim 1 , wherein the cylinder drum is configured as a bushingless swash plate cylinder drum. 
     
     
         7 . The cylinder drum according to  claim 1 , wherein the cylinder drum is configured as an oblique-axis cylinder drum. 
     
     
         8 . The cylinder drum according  claim 1 , wherein the wear-resistant layer has a comparatively thick diffusion layer. 
     
     
         9 . The cylinder drum according to  claim 8 , wherein a thickness of the diffusion layer is at least 50 μm. 
     
     
         10 . The cylinder drum according to  claim 8 , wherein the wear-resistant layer is formed by gas nitrocarburizing in two stages, the first stage comprising a comparatively low treatment temperature and a comparatively long treatment duration, and the second stage comprising an increase in the carbon content of the connecting layer by the addition of carbon donors at a comparatively high treatment temperature.