A variable transmission comprises a first fluid working machine (1) for connection to a prime mover (2), a second fluid working machine (5) for connection to a mechanical load (6) and a fluid system linking the first and second working machines, the fluid system having a high-pressure side (3) and a low-pressure side (4) each connected to both said first and said second fluid working machines (1, 5), a fluid accumulator (7) on the high-pressure side, a means to admit fluid from the reservoir to the low-pressure side and a pressure control valve to maintain the correct pressure in the low-pressure side, wherein the second fluid working machine (5) includes chambers of variable volume having electronically controllable valves such that each of said chambers has pumping, motoring and idling modes of operation, and the second fluid working machine (5) is operable to both source fluid to and sink fluid from each of said high-pressure side (3) and said low-pressure side (4).