Abstract: A low pressure fluid powered motor or pump comprises a non-rotatable cover (k); an undulating lobe cam track (e) attached to the cover (k) and defining multiple crests and troughs; a rotatable cylinder block (c); at least three reciprocable pistons (d) each housed within a bore of the cylinder block (c) and each providing at one end a crown (d1), and at the other end a spherical seating cup (d2); a ball (f), adapted to engage with the cam track (e); a non-rotatable manifold block (n) incorporating a plurality of ports (s), each being radially disposed at equal intervals in an end face of the manifold block adjacent the pistons (d), with the ports (s) linked to galleries connected to a higher pressure delivery circuit, and a lower pressure return circuit, with the angular arrangement of the ports (s) being such that the higher pressure is supplied to the crown (d1) of each piston (d) only whilst the piston (d) is moving from a crest to a trough of the cam track (e), with a switch to the lower fluid pressure ci