Gantry components

A method for displacing an on-gantry component of a radiotherapy system, the method comprising:

• when the on-gantry component is retained at a first position on a gantry by a first locking mechanism, unlocking the first locking mechanism such that the on-gantry component is free to move towards a second position on the gantry;
• causing the gantry to rotate in a first direction about a rotation axis such that a gravitational force acting on the on-gantry component causes the on-gantry component to travel from the first position to the second position under influence of gravity;
• controlling a speed of the on-gantry component while the on-gantry component is travelling from the first position to the second position, wherein controlling the speed of the on-gantry component comprises at least one of:
• using a pneumatic or magnetic braking system to limit the speed of the on-gantry component;
• or
• rotating the gantry while the on-gantry component is travelling between the first position and the second position to adjust a gravitational acceleration vector acting on the on-gantry component;
• and
• when the on-gantry component reaches the second position, retaining the on-gantry component at the second position using a second locking mechanism such that further rotation of the gantry will not cause further movement of the on-gantry component.