Pitch point action gearing

Abstract

A system of helical or spiral bevel gearing that by violating the "law of gearing" restricts the tooth action entirely to the pitch point. The greatly reduced sliding velocity between the teeth of mating gears permits them to be made of "dry bearing" or other moldable materials without exceeding rated PV values, and a multiplicity of contact points moving transversely along the pitch line insures continuity of action.

I claim: 
     
       1. In a pair of mating gears, teeth formed to extend across the rims of said gears in a direction slantingly disposed with respect to the pitch line of said pair to produce at least one area of contact between said pair for all rotational positions of said pair,   .[.said teeth being formed so that the centroid of said area of contact lies substantially on said pitch line for all rotational positions of said gears..]..Iadd.   said teeth having in sections perpendicular to said pitch line active profiles of relative radius of curvature at the pitch lines less than the product of the pitch radii of said pair times the sine of the pressure angle divided by the sum of said pitch radii,   addendum height of the teeth of one of said pair being greater than 0.5 divided by the normal diametral pitch and the pitch and pressure angle of the teeth are such that when the maximum allowable torque is applied to said gears each said area of contact occupies substantially the full height of the tooth face..Iaddend. .[.2. In a pair of mating gears,   teeth formed to extent across the rims of said gears at a sufficient angle with respect to the pitch line of said pair to produce at least two separate areas of contact between said pair,   said teeth having in sections perpendicular to said pitch line active profiles of relative radius of curvature at the pitch line less than the product of the pitch radii of said pair times the sine of the pressure angle divided by the sum of said pitch radii..]..[.3. A pair of mating gears according to claim 1 or 2 wherein the pitch and pressure angle of the teeth are such that when the maximum allowable torque is applied to said gears each said area of contact occupies substantially the full   
     
     
        height of the tooth face..]. 4. A pair of mating gears according to claim 1 .[.or 2.]. wherein the centers of curvature of said teeth at said area 
     
     
        of contact are substantially removed from said pitch line. 5. A pair of mating gears according to claim 1 .[.or 2.]. wherein the teeth of at least 
     
     
        one gear are formed of moldable material. 6. A pair of mating gears according to claim 1 .[.or 2.]. wherein the active profiles of the teeth 
     
     
        in the normal plane are circular arcs. 7. A pair of mating gears according to claim 1 .[.or 2.]. wherein the active profiles of the teeth in planes 
     
     
        normal to the pitch line are circular arcs. 8. A pair of mating gears according to claim 1 .[.or 2 wherin.]. .Iadd.wherein .Iaddend.the active 
     
     
        faces of the teeth of at least one gear are of dry bearing material. 9. A pair of mating gears according to claim 1, wherein said teeth have in sections perpendicular to the elements of the respective pitch surfaces of said gears active profiles which are intersected by said pitch surfaces at the central portions of said profiles .[., the relative radius of curvature of engaging segments of said central portions being less than the relative radius of curvature of conjugate profiles.]..  .[.10. The method of reducing the average sliding velocity of the teeth of mating gears below the average sliding velocity attainable with conjugate gears of the same pitch line velocity, comprising forming said teeth: (a) to extend across the rims of said mating gears in a direction slantingly disposed with respect to the pitch line of said mating gears,   (b) with active profiles which are intersected by the respective pitch surfaces of said mating gears, and   (c) with active profiles of relative radius of curvature less than the relative radius of curvature of conjugate profiles..].