Universal joint lubrication

Abstract

Improved lubrication of bearing cups in universal joints is provided. A cross of a universal joint has four trunnions extending therefrom along two mutually perpendicular lines. Bearing cups are rotatably received on the trunnions and the cups in turn are held by universal joint yokes. Lubrication passages extend from a central portion of the cross outwardly toward the ends of the trunnions. When the universal joint is stationary, lubricant such as grease may drain from an upper bearing cup down to a lower cup, leaving the upper cup devoid of lubrication when the universal joint is again placed in operation. In accordance with the invention, a cavity is in the end of each trunnion communicating with the bearing cup and a passage extension extends substantially through the cavity from the lubrication passage toward the end of the trunnion. Lubricant is trapped in an annular space formed between the passage extension and the wall of the cavity with this lubricant being readily available to lubricate the corresponding cup when the universal joint is placed in operation.

I claim: 
     
       1. A cross for a universal joint comprising a body forming four trunnions extending therefrom along two mutually perpendicular lines, passages in said body from a central portion thereof to positions near the ends of said trunnions, a cavity in the end of each of said trunnions communicating with one of said passages, and passage extensions communicating with the passages and extending into said cavities, said passage extensions having substantially cylindrical outer surfaces forming annular lubricant reservoirs with said cavities.Iadd., means at the outer ends of the trunnions providing passageways between the outer portion of each lubricant reservoir and the outer cylindrical bearing surface of the trunnion, said lubricant reservoirs having a volume in excess of the passageways.Iaddend.. 
     
     
       2. A cross according to claim 1 characterized by each of said passage extensions terminating short of the end of the corresponding trunnion, each of said passage extensions having means cooperating with the corresponding trunnion to resist outward movement of said extension toward the outer end of the trunnion.  .[.3. A cross for a universal joint comprising a body forming a trunnion extending therefrom, said trunnion having a cavity formed centrally in the end thereof, said body having a passage communicating with said cavity, and tubular wall means extending from the end of said passage at the entrance to said cavity through a substantial portion of said cavity to a location near the end of said trunnion, said tubular wall means forming an annular lubricant reservoir with said cavity over at least most of the length of said tubular wall means..]. .[.4. A cross according to claim 3 characterized by said wall means being made of a plastic material, and having a substantially uniform cross section throughout most of its length..]. .[.5. A cross according to claim 3 characterized by said wall means having a transversely-extending flange extending substantially to the inner surface of said cavity..]. .[.6. A cross according to claim 5 characterized by said flange having a force fit with the surface of said cavity..]. .[.7. A cross according to claim 3 characterized by said wall means having an end portion extending into said passage..]. .[.8. A cross according to claim 7 wherein said portion of said wall means extends into said passage with a force fit..]. 
     
     
         . A universal joint comprising a cross having trunnions extending outwardly therefrom, a bearing cup rotatably mounted on each of said trunnions, each of said trunnions having a substantially cylindrical cavity formed therein communicating with the interior of the corresponding bearing cup, said cross having passages extending from a central portion thereof and communicating with each of said cavities, and wall means extending through a substantial portion of each of said cavities and communicating with the passages in said cross, said wall means being spaced from the surface of the corresponding cavity throughout substantially the entire length of said wall means .Iadd.to form lubricant reservoirs extending therearound, means at the outer ends of the trunnions providing passageways between the outer portion of each lubricant reservoir and the outer cylindrical bearing surface of the trunnion, said lubricant reservoirs having a volume in excess of the passageways.Iaddend..  .[.10. A universal joint according to claim 9 characterized by each of said wall means having a transverse flange extending to the inner surface of the corresponding cavity..]. .[.11. A universal joint according to claim 9 characterized by said wall means having a portion extending into the corresponding passage..]. .[.12. A cross according to claim 2 characterized by each of said passage extensions having at least one notch in its outer end..].  .[.13. A cross for a universal joint comprising a body forming a trunnion extending therefrom, said trunnion having a cavity formed centrally in the end thereof, said body having a passage communicating with said cavity, and tubular wall means extending from the end of said passage at the entrance into said cavity through a substantial portion of said cavity to a location near the end of said trunnion, said wall means being structurally 
     
     
        integral with said body..]. 14. A universal joint comprising a cross having trunnions extending outwardly therefrom, a bearing cup rotatably mounted on each of said trunnions, each of said trunnions having a cavity formed therein communicating with the interior of the corresponding bearing cup, said cross having passages extending from a central portion thereof and communicating with each of said cavities, and wall means extending through a substantial portion of each of said cavities and communicating with the passages in said cross .Iadd.to form a lubricant reservoir defined by the outer portion of said wall means and the inner surface of said cavities.Iaddend., said wall means being structurally integral with said cross.Iadd., means at the outer ends of the trunnions providing passageways between the outer portion of each lubricant reservoir and the outer cylindrical bearing surface of the trunnion, said lubricant reservoirs having a volume in excess of the passageways.Iaddend..