An industrial robot arm

A robot arm (500) for end-effector motion. The robot arm comprises a first actuator (4) and a first kinematic chain from the first actuator to an end-effector platform, which gives a first degree of freedom for positioning the end-effector platform. The robot arm also comprises a second actuator (5; 5b) and a second kinematic chain from the second actuator to the end-effector platform, which gives a second degree of freedom for positioning the end-effector platform. The robot arm further comprises a third actuator (6; 6b, 512) and a third kinematic chain from the third actuator (6; 6b) to the end-effector platform, which gives a third degree of freedom for positioning the end-effector platform. The robot arm also comprises a fourth actuator (50; 150) and a fourth kinematic chain configured to transmit a movement of the fourth actuator to a corresponding orientation axis (65) for an end-effector (28). The fourth kinematic chain comprises an orientation linkage (52, 57, 59; 202, 204, 207, 209; 284, 286; 251, 25