When I have liquid in one big vessel/container like a big cooking pot, barrel or reservoir which is very heavy, it is difficult to lift and pour out the liquid in other smaller vessels. Could you suggests other methods for moving the liquid into other smaller vessels.
The easy way: a siphon.
You need a hose long enough to reach from the bottom of the source vessel, over the edge, and to a lower point outside the source, and a way to place the receiving vessel below the source. Fill the hose with your liquid (if it's not something you'd want to drink, there are pump-hose combinations available for this operation), and as long as the lower end is below the surface of the liquid in the upper vessel, and you don't allow air to enter the upper end, the liquid will flow. Flow may be slow, but the siphon requires no effort to maintain, and can be left unattended as long as the receiving vessel is large enough not to overflow.
Easiest solution when you can't carry the larger vessel is to use a Baster Syringe(I think everyone knows them as the turkey syringe), it might be a bit tedious, but once you've emptied the large vessel enough you might be able to carry the vessel and finish the task at a faster pace, unless the vessel itself is already too heavy or in reality just too large to handle.
Another option(and probably a bit messier one) is to use an old cup(or whatever measure works best) and start taking out the liquid, then use a funnel to pour it into the smaller vessel, and if it's cooking oil what you're transferring you can put a coffee filter in the funnel that way you can avoid any residues to enter the smaller vessel.
Even if Zeiss Ikon has already mentioned a siphon, I have to mention that you can actually use some sort of cloth that soaks water (i.e your tshirt) as a siphon. Just make the whole thing wet, and make sure that the part sticking out of the container hangs lower then the top of the liquid in the big container that you want to drain. And preferably a good deal lower.
Get some bendy straws, join them together to create a 'hose' by inserting the end of one straw inside the end of the next straw, until you have a suitable length. Seal the connections with tape to prevent liquid/air escaping. place one end into your source container, and the other end over your destination container, which must be lower than the source. repeatedly seal and unseal the destination end of the 'hose' with the pad of your finger to create suction and start siphoning the liquid.