How to interpret rumblers ?

[Jack_E]

I'm experimenting with the rumblers on my gamepad and when I 'read' the gamepad
with JInput, it finds 5 rumblers.

So I expected the gamepad to have two rumblers on each side and one in the middle.
However, that seems not to be true, because :

The rumbling always comes from one side,

If I let 3 or 5 rumblers rumble simultaneously, then the rumble is only a little bit
stronger than just one rumbler rumbling, not the expected 3 or 5 times stronger.

So I don't know what to think of this. 
Can someone explain how to interpret the five rumblers ?

[endolf]

Hi

I'm not too sure if there is a standard way. On my rumbling game pad I have 2 rumblers, one seems to be a 'fine' rumble, and one a harsh rumble, they don't seem to have any axis or rumble, just a different feel to them.

Endolf