The torque and power of a tractor are two important decision making factors when buying an agricultural tractor.  These factors are generally extracted through PTO tractor testing.  Such testing is accomplished using a device called dynamometer. Since commercial dynamometers are expensive, research efforts are encouraged to develop similar dynamometer for tractor tests. The aim of this study was to fabricate and adapt an automobile brake system to become a PTO shaft brake loading system for measuring torque and power. A commercial torque transducer was fixed to the tractor PTO for both toque and rotational speed measurements.  Tests were performed on a Helwan 35 IMT tractor with 26.12 kW of power.  The laboratory demonstration test showed that the measurement of torque magnitude at PTO of the tractor was satisfactory. The results were compared to those obtained through loading the same tractor with a  shop AW commercial dynamometer and the relative error between the data sets was -2.59%.  A t–test showed no significant differences in the averages of power. Considering the results of this study, the PTO shaft brake loading system can feasibly applied to tractor performance evaluation.