The mathematical analysis for estimating the performance rate "RP" of wheel type trenching machine was studied. The mathematical analysis ended with an equation for this type. This mathematical equation was checked under different operating conditions. The practical study of the performance rate showed that the deviation of the theoretical performance rate from the actual performance rate ranged from five to seven percent for the 60.4 and 90.5 cm trench depth respectively. The machine field efficiency ranged between 43 and 50.1 percent for 90.5 cm and 60.4 cm trench depth respectively.