Hi Folks,

Does anybody know the intended use for the large hole on the left side
of a Schulz tracker bar?  This is the version of the Schulz with the
swinging arm centering device.

On the left side of the spool box is a 'Loud Pedal' on/off switch label.
 The switch is missing and there is nothing connected here either, but
it appears that something used to be attached (screw holes).  Was this
a mechanical or pneumatic device?

On top of the main bellows suction connection box is a blanked off hole
that may have been the source for some device.

Any help would be much appreciated.

Thanks,
Jeff Lofton