Normally, agricultural tractors require frequent shifting due to load changes or repetitive forward and reverse travel requirements. From the standpoint of maneuverability and workability, there is a strong demand for tractors with clutchless-transmission-operation similar to automobiles. However, power loss from the transmission is not desirable for heavy duty tractors, so should be eliminated as much as possible.To solve this problem, Kubota, Ltd. has developed the Glide Shift Transmission (GST) which employs a power synchro shift and single clutch pack system resulting in improved maneuverability and workability while obtaining a power efficiency equivalent to that of manual gear type transmissions. The GST has been applied to the L2550DT-GST (17.5 PTO kW) and L2850DT-GST (20.1 PTO kW) farm tractors. These tractors have been marketed since 1987.This report covers the design philosophy of the power synchro shift transmission and explains how it functions.