Two disc type clutch packs serve a dual purpose in the TULSA two-speed planetary winch drive. In the driving mode of operation either high or low clutch is hydraulically selected to transmit power to the planetary system. In the “holding” or stopped mode of operation, the high and low clutch packs interact automatically by spring force to provide a static brake. Either one of two mechanical power flow routes through a planetary system is hydraulically selected to obtain the two-speed operation. When the two power flow routes are simultaneously restrained from rotation a lock-up of the planetary reduction is effected to provide the static load brake. Dynamic braking is provided by a counterbalance valve in the hydraulic system.This paper discusses the detailed operation and basic design elements involved in developing the patented two-speed planetary transmission.