You are right..original Hammond's don't have a sustain pedal....or a volume pedal...it has an "Expression" Pedal though. Its used for much more than just adjusting volume.

On an arranger a volume pedal will adjust total volume, but an expression pedal should only adjust the right hand sound (not rhythm). You can use the pedal to create a delay or decay on the sound as well as simply changing the volume as needed.

Also on a Hammond (going right back to day one) the expression pedal also adjusts frequency at the same time as volume. Not so many people realise that.