Abstract: A hydrostatic transmission having a housing with a sump and a pair of hydraulic displacement units interconnected by first and second fluid passages. A pair of bypass valves can be opened to place said first and second fluid passages in fluid communication. A recess, formed in the lower part of the housing, holds make-up oil and communicates with said first and second fluid passages when the bypass valves are opened. A passage extends upwardly from the housing recess and has its upper end normally sealed by seal means. A manually operable bypass rod extends lengthwise of the passage into the area of the housing recess and has structure associated therewith for causing opening of the bypass valves.