The Crescendo pedal on a pipe organ is simply another pedal to the right of the swell pedals.
Its function is not to create a swell rather to add stops in a sequenced order 'blind'. i.e. the stops themselves do not actually move.
The sequence is normally soft to loud however some organists have their own special way of setting the pedal.
The John Compton Organ company had a habit of setting up the crescendo pedal so as gradually to achieve a full church organ build up, i.e. no tibias, no celestes, no vox humanas and the trems going off at the very last movement of the pedal. This is great if you play in the traditional English style but not perhaps what most Americans are looking for.
Since most home players will be registering tibias on the upper manual and Flutes on the lower for their basic combinations, one of the most useful ways I have found of setting up the Crescendo pedal is to have the pedal evenly add power and brightness until full Theatre organ is obtained. Because many specifications limit the number of 16' voices and because the sub octave coupler can easily derive this manual pitch, I will detail a suggested progression as a point from which you can start to evaluate whether such a basic crescendo will fit in with your style of playing..
1 Flute 8
2 Viole 8
3 Diapason 8
4 Viole 4
5 Fifteenth (Viole) 2
6 Orchestral Oboe 8
7 Tuba 8
8 Trumpet 8
9 English Horn 8
There are of course other approaches but try the above first. It should give a gradual increase in brightness and volume, both with and without the Sub and Super couplers.
Another approach which is real fun is to use the Crescendo pedal as a 3 position device which brings on three distinctive groups of sounds which are widely, as opposed to progressively spaced on the Cresc. pedal thus saving out on pistons. First position/movement - All Strings.
Second position/movement All Flues.
Final full open position - All reeds
The latter idea can be useful for gaining accents in dance music but requires that you 'ride' the Crescendo pedal rather than the swell pedals.