A hydraulic motor or pump (2) that generates a relatively high torque, and further allows an unprecedented high specific displacement that makes the motor suitable yaw motor for large wind turbines of horizontal axis wind turbines or wheel yaw motor on Heavy Carriers. The characteristic by the hydraulic motor or pump (2) is that if the number of barriers in the annular cavity (12) of engine or pump is n then the number of radial displaceable sliders (20) will be larger than (n+1).