sorry....keep spraying with crc and hope it works.

cap and then the pin and axle nut?

If its wheels, then you only need to take the wheel nuts off to get them off.  If they won't move, it has to be corrosion between the rim and hub.  As mentioned, try CRC / WD40 etc.  But as Southcity104 says, if you are trying to get the hub off, you need to take the axle nut off.  It will (or at least should) be buried in grease.  You will need to take the cap or bearing buddy off, remove some grease so you can see, take out the split pin from the castle nut, and then take the castle nut off.  The hub should come off easily if the bearing is in good shape, but may need lots of persausion if the bearings have corroded or worse still have collapsed. If the bearings are stuffed, have a good look at the axle.  If it is chewed out, you may need to replace that too.

If you are trying to get the hubs off a trailer that has disc brakes, you will almost certainly have to remove the brake calipers to allow the hub to come off the axle. 

 Penetrene rust rinse or acid or a rust converter 

Get a gas torch heat up wheel around hub it will break down the rust then should be able to tap off

Ig rims are fused to the hub via corrosion just loosen the nuts slightly and then do a few tight figure 8's (slowly) this will crack the bond between the two, if you need to drive to a car park to do this obvoiusly don't losen the nuts until you get there and then tighten then back up before driving home. the rims should then come off normally.  Had the same problem with my car and the above got the wheel off.

Cheers

Paul