Mounting shaft device, mounting head, and surface mounter

A mounting shaft device configured to mount an electronic component, the mounting shaft device comprising;

• a spline shaft including a supply passage for air pressure therein and extending through a shaft hole in a support;
• a conduit in communication with a valve and allowing the air pressure from the valve to be introduced to the supply passage of the spline shaft;
• a component retainer located at an axial end of the spline shaft and configured to receive the air pressure through the supply passage of the spline shaft to hold an electronic component;
• a spline nut connected to the spline shaft through a spline mechanism;
• and
• a bearing supporting the spline shaft in the shaft hole in the support both in a linearly movable manner in an axial direction and in a rotatable manner about an axis thereof,
• wherein
• the bearing, the conduit, and the spline nut are arranged on an axis of the spline shaft in this order from the component retainer;
• the spline shaft has a ball groove extending in an axial direction of the spline shaft and receiving a ball connecting the spline shaft and the spline nut to each other through a spline mechanism, and
• the ball groove is provided only on an upper portion of the spline shaft where the spline nut is disposed and is not provided on a portion corresponding to the conduit and a portion corresponding to the bearing located below the spline nut.