the opposing diametrically opposite cam surfaces 104 u2032 are formed as integral parts of the corresponding valve bodies 12 u2032 and 14 u2032 preferably the valve bodies 12 u2032 and 14 u2032 are machined from a metal such as aluminum using an automatic machining tool center thus the integral cam surfaces 102 u2032 and 104 u2032 may be easily formed on the valve bodies by appropriate programming of the machining tool center from the drawings and the above description it is apparent that a breakaway coupling constructed in accordance with the invention provides desirable features and advantages as a primary advantage the breakaway coupling of the invention may be conveniently and quickly inspected for regular or periodic maintenance and to insure proper operation of the internal valve members by simply rotating the valve bodies relative to each other with conventional hand tools or wrenches in addition the separation of the valve bodies may be performed without disconnecting any flexible hoses from the valve bodies also the resilient tubular cover 20 or 20 u2032 protects the cam surfaces 102 and 104 or 102 u2032 and 104 u2032 and prevents dust and dirt from entering the gap 114 or 114 u2032 as mentioned above it is also apparent that the above opposing cam surfaces 102 and 104 or 102 u2032 and 104 u2032 may be formed on a coaxial breakaway coupling with a vapor return passage such as disclosed in above mentioned u s pat no 5 433 247 the separation means of the invention also eliminates the need for a specially formed tool as disclosed in above mentioned u s pat no 6 182 695 while the forms of coupling herein described.