Abstract: A hydraulic transmission control circuit includes a hydraulically responsive modulating valve for modulating a first fluid pressure and a differential valve for establishing a second fluid pressure communicated to a master clutch, the control circuit also including a manually controlled modulating valve for precisely adjusting the second pressure and for selectively adjusting the first fluid pressure during regulation of the second fluid pressure, the manual modulating valve also being adapted for selectively communicating the hydraulically responsive modulating valve with a drain in order to assure a proper rate of modulation for both the first and second fluid pressures.