<div class="htmlview paragraph">Analysis of the performance of a split-torque or input-coupled hydrostatic transmission by means of a mathematical model reveals features which are important to the designer and user alike.</div> <div class="htmlview paragraph">The quality of the hydraulic components of the transmission has profound effect on the performance. Generally, better components produce better over-all performance, but exceptions are shown to exist.</div> <div class="htmlview paragraph">The split-torque transmission is expected to perform with higher efficiency than the straight hydrostatic transmission, and it does through much of the speed range, but there are exceptions to this generalization too.</div> <div class="htmlview paragraph">The value of the mathematical model in describing transmission performance for both the straight hydrostatic transmission and the differential transmission is established. The inadequacy of the concept of an ideal loss-free transmission is emphasized and illustrated.</div>